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http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #Ada | Ada | --
-- The Rosetta Code Virtual Machine, in Ada.
--
-- It is assumed the platform on which this program is run
-- has two's-complement integers. (Otherwise one could modify
-- the vmint_to_vmsigned and vmsigned_to_vmint functions. But
-- the chances your binary integers are not two's-complement
-- seem pretty low.)
--
with Ada.Characters.Handling; use Ada.Characters.Handling;
with Ada.Command_Line; use Ada.Command_Line;
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
with Ada.Strings.Unbounded.Text_IO; use Ada.Strings.Unbounded.Text_IO;
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Text_IO.Text_Streams; use Ada.Text_IO.Text_Streams;
with Ada.Unchecked_Conversion;
procedure VM
is
bad_vm : exception;
vm_limit_exceeded : exception;
vm_runtime_error : exception;
status : Exit_Status;
input_file_name : Unbounded_String;
output_file_name : Unbounded_String;
input_file : File_Type;
output_file : File_Type;
-- Some limits of this implementation. You can adjust these to taste.
strings_size : constant := 2_048;
stack_size : constant := 2_048;
data_size : constant := 2_048;
code_size : constant := 32_768;
type byte is mod 16#100#;
type vmint is mod 16#1_0000_0000#;
subtype vmsigned is Integer range -2_147_483_648 .. 2_147_483_647;
op_halt : constant byte := 0;
op_add : constant byte := 1;
op_sub : constant byte := 2;
op_mul : constant byte := 3;
op_div : constant byte := 4;
op_mod : constant byte := 5;
op_lt : constant byte := 6;
op_gt : constant byte := 7;
op_le : constant byte := 8;
op_ge : constant byte := 9;
op_eq : constant byte := 10;
op_ne : constant byte := 11;
op_and : constant byte := 12;
op_or : constant byte := 13;
op_neg : constant byte := 14;
op_not : constant byte := 15;
op_prtc : constant byte := 16;
op_prti : constant byte := 17;
op_prts : constant byte := 18;
op_fetch : constant byte := 19;
op_store : constant byte := 20;
op_push : constant byte := 21;
op_jmp : constant byte := 22;
op_jz : constant byte := 23;
strings : array (0 .. strings_size - 1) of Unbounded_String;
stack : array (0 .. stack_size - 1) of vmint;
data : array (0 .. data_size - 1) of vmint;
code : array (0 .. code_size) of byte;
sp : vmint;
pc : vmint;
output_stream : Stream_Access;
function vmsigned_to_vmint is new Ada.Unchecked_Conversion
(Source => vmsigned, Target => vmint);
function vmint_to_vmsigned is new Ada.Unchecked_Conversion
(Source => vmint, Target => vmsigned);
function twos_complement
(x : in vmint)
return vmint
is
begin
return (not x) + 1;
end twos_complement;
function vmint_to_digits
(x : in vmint)
return Unbounded_String
is
s : Unbounded_String;
z : vmint;
begin
if x = 0 then
s := To_Unbounded_String ("0");
else
s := To_Unbounded_String ("");
z := x;
while z /= 0 loop
s := Character'Val ((z rem 10) + Character'Pos ('0')) & s;
z := z / 10;
end loop;
end if;
return s;
end vmint_to_digits;
function digits_to_vmint
(s : in String)
return vmint
is
zero : constant Character := '0';
zero_pos : constant Integer := Character'Pos (zero);
retval : vmint;
begin
if s'Length < 1 then
raise bad_vm with "expected a numeric literal";
end if;
retval := 0;
for i in s'Range loop
if Is_Decimal_Digit (s (i)) then
retval :=
(10 * retval) + vmint (Character'Pos (s (i)) - zero_pos);
else
raise bad_vm with "expected a decimal digit";
end if;
end loop;
return retval;
end digits_to_vmint;
function string_to_vmint
(s : in String)
return vmint
is
retval : vmint;
begin
if s'Length < 1 then
raise bad_vm with "expected a numeric literal";
end if;
if s (s'First) = '-' then
if s'Length < 2 then
raise bad_vm with "expected a numeric literal";
end if;
retval :=
twos_complement (digits_to_vmint (s (s'First + 1 .. s'Last)));
else
retval := digits_to_vmint (s);
end if;
return retval;
end string_to_vmint;
procedure parse_header
(s : in String;
data_count : out vmint;
strings_count : out vmint)
is
i : Positive;
j : Positive;
begin
i := s'First;
while i <= s'Last and then not Is_Decimal_Digit (s (i)) loop
i := i + 1;
end loop;
j := i;
while j <= s'Last and then Is_Decimal_Digit (s (j)) loop
j := j + 1;
end loop;
data_count := digits_to_vmint (s (i .. j - 1));
i := j;
while i <= s'Last and then not Is_Decimal_Digit (s (i)) loop
i := i + 1;
end loop;
j := i;
while j <= s'Last and then Is_Decimal_Digit (s (j)) loop
j := j + 1;
end loop;
strings_count := digits_to_vmint (s (i .. j - 1));
end parse_header;
function parse_string_literal
(s : in String)
return Unbounded_String
is
t : Unbounded_String;
i : Positive;
--
-- A little trick to get around mistaken highlighting on the
-- Rosetta Code site.
--
quote_string : constant String := """";
quote : constant Character := quote_string (1);
begin
t := To_Unbounded_String ("");
i := s'First;
while i <= s'Last and then s (i) /= quote loop
i := i + 1;
end loop;
if s'Last < i or else s (i) /= quote then
raise bad_vm with "expected a '""'";
end if;
i := i + 1;
while i <= s'Last and then s (i) /= quote loop
if s (i) /= '\' then
Append (t, s (i));
i := i + 1;
elsif s'Last < i + 1 then
raise bad_vm with "truncated string literal";
elsif s (i + 1) = 'n' then
Append (t, Character'Val (10));
i := i + 2;
elsif s (i + 1) = '\' then
Append (t, '\');
i := i + 2;
else
raise bad_vm with "unsupported escape sequence";
end if;
end loop;
return t;
end parse_string_literal;
function name_to_opcode
(s : in String)
return byte
is
retval : byte;
begin
if s = "halt" then
retval := op_halt;
elsif s = "add" then
retval := op_add;
elsif s = "sub" then
retval := op_sub;
elsif s = "mul" then
retval := op_mul;
elsif s = "div" then
retval := op_div;
elsif s = "mod" then
retval := op_mod;
elsif s = "lt" then
retval := op_lt;
elsif s = "gt" then
retval := op_gt;
elsif s = "le" then
retval := op_le;
elsif s = "ge" then
retval := op_ge;
elsif s = "eq" then
retval := op_eq;
elsif s = "ne" then
retval := op_ne;
elsif s = "and" then
retval := op_and;
elsif s = "or" then
retval := op_or;
elsif s = "neg" then
retval := op_neg;
elsif s = "not" then
retval := op_not;
elsif s = "prtc" then
retval := op_prtc;
elsif s = "prti" then
retval := op_prti;
elsif s = "prts" then
retval := op_prts;
elsif s = "fetch" then
retval := op_fetch;
elsif s = "store" then
retval := op_store;
elsif s = "push" then
retval := op_push;
elsif s = "jmp" then
retval := op_jmp;
elsif s = "jz" then
retval := op_jz;
else
raise bad_vm with ("unexpected opcode name");
end if;
return retval;
end name_to_opcode;
procedure parse_instruction
(s : in String;
address : out vmint;
opcode : out byte;
arg : out vmint)
is
i : Positive;
j : Positive;
begin
i := s'First;
while i <= s'Last and then not Is_Decimal_Digit (s (i)) loop
i := i + 1;
end loop;
j := i;
while j <= s'Last and then Is_Decimal_Digit (s (j)) loop
j := j + 1;
end loop;
address := digits_to_vmint (s (i .. j - 1));
i := j;
while i <= s'Last and then not Is_Letter (s (i)) loop
i := i + 1;
end loop;
j := i;
while j <= s'Last and then Is_Letter (s (j)) loop
j := j + 1;
end loop;
opcode := name_to_opcode (s (i .. j - 1));
i := j;
while i <= s'Last and then Is_Space (s (i)) loop
i := i + 1;
end loop;
if s'Last < i then
arg := 0;
else
if not Is_Decimal_Digit (s (i)) and then s (i) /= '-' then
i := i + 1;
end if;
j := i;
while j <= s'Last
and then (Is_Decimal_Digit (s (j)) or else s (j) = '-')
loop
j := j + 1;
end loop;
arg := string_to_vmint (s (i .. j - 1));
end if;
end parse_instruction;
procedure read_and_parse_header
(data_count : out vmint;
strings_count : out vmint)
is
line : Unbounded_String;
begin
Get_Line (Current_Input, line);
parse_header (To_String (line), data_count, strings_count);
end read_and_parse_header;
procedure read_parse_and_store_strings
(strings_count : in vmint)
is
line : Unbounded_String;
begin
if strings_count /= 0 then
if strings_size < strings_count then
raise vm_limit_exceeded with "strings limit exceeded";
end if;
for i in 0 .. strings_count - 1 loop
Get_Line (Current_Input, line);
strings (Integer (i)) :=
parse_string_literal (To_String (line));
end loop;
end if;
end read_parse_and_store_strings;
function opcode_takes_arg
(opcode : in byte)
return Boolean
is
retval : Boolean;
begin
if opcode = op_fetch then
retval := True;
elsif opcode = op_store then
retval := True;
elsif opcode = op_push then
retval := True;
elsif opcode = op_jmp then
retval := True;
elsif opcode = op_jz then
retval := True;
else
retval := False;
end if;
return retval;
end opcode_takes_arg;
procedure read_parse_and_store_instructions
is
line : Unbounded_String;
address : vmint;
opcode : byte;
arg : vmint;
j : Positive;
begin
while not End_Of_File (Current_Input) loop
Get_Line (Current_Input, line);
j := 1;
while j <= Length (line) and then Is_Space (Element (line, j))
loop
j := j + 1;
end loop;
if j <= Length (line) then
parse_instruction (To_String (line), address, opcode, arg);
if opcode_takes_arg (opcode) then
if code_size - 4 <= address then
raise vm_limit_exceeded with "code space limit exceeded";
end if;
code (Integer (address)) := opcode;
--
-- Little-endian storage.
--
code (Integer (address) + 1) := byte (arg and 16#FF#);
code (Integer (address) + 2) :=
byte ((arg / 16#100#) and 16#FF#);
code (Integer (address) + 3) :=
byte ((arg / 16#1_0000#) and 16#FF#);
code (Integer (address) + 4) :=
byte ((arg / 16#100_0000#) and 16#FF#);
else
if code_size <= address then
raise vm_limit_exceeded with "code space limit exceeded";
end if;
code (Integer (address)) := opcode;
end if;
end if;
end loop;
end read_parse_and_store_instructions;
procedure read_parse_and_store_program
is
data_count : vmint;
strings_count : vmint;
begin
read_and_parse_header (data_count, strings_count);
read_parse_and_store_strings (strings_count);
read_parse_and_store_instructions;
end read_parse_and_store_program;
procedure pop_value
(x : out vmint)
is
begin
if sp = 0 then
raise vm_runtime_error with "stack underflow";
end if;
sp := sp - 1;
x := stack (Integer (sp));
end pop_value;
procedure push_value
(x : in vmint)
is
begin
if stack_size <= sp then
raise vm_runtime_error with "stack overflow";
end if;
stack (Integer (sp)) := x;
sp := sp + 1;
end push_value;
procedure get_value
(x : out vmint)
is
begin
if sp = 0 then
raise vm_runtime_error with "stack underflow";
end if;
x := stack (Integer (sp) - 1);
end get_value;
procedure put_value
(x : in vmint)
is
begin
if sp = 0 then
raise vm_runtime_error with "stack underflow";
end if;
stack (Integer (sp) - 1) := x;
end put_value;
procedure fetch_value
(i : in vmint;
x : out vmint)
is
begin
if data_size <= i then
raise vm_runtime_error with "data boundary exceeded";
end if;
x := data (Integer (i));
end fetch_value;
procedure store_value
(i : in vmint;
x : in vmint)
is
begin
if data_size <= i then
raise vm_runtime_error with "data boundary exceeded";
end if;
data (Integer (i)) := x;
end store_value;
procedure immediate_value
(x : out vmint)
is
b0, b1, b2, b3 : vmint;
begin
if code_size - 4 <= pc then
raise vm_runtime_error with "code boundary exceeded";
end if;
--
-- Little-endian order.
--
b0 := vmint (code (Integer (pc)));
b1 := vmint (code (Integer (pc) + 1));
b2 := vmint (code (Integer (pc) + 2));
b3 := vmint (code (Integer (pc) + 3));
x :=
b0 + (16#100# * b1) + (16#1_0000# * b2) + (16#100_0000# * b3);
end immediate_value;
procedure machine_add
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
put_value (x + y);
end machine_add;
procedure machine_sub
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
put_value (x - y);
end machine_sub;
procedure machine_mul
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
put_value
(vmsigned_to_vmint
(vmint_to_vmsigned (x) * vmint_to_vmsigned (y)));
end machine_mul;
procedure machine_div
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
put_value
(vmsigned_to_vmint
(vmint_to_vmsigned (x) / vmint_to_vmsigned (y)));
end machine_div;
procedure machine_mod
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
put_value
(vmsigned_to_vmint
(vmint_to_vmsigned (x) rem vmint_to_vmsigned (y)));
end machine_mod;
procedure machine_lt
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if vmint_to_vmsigned (x) < vmint_to_vmsigned (y) then
put_value (1);
else
put_value (0);
end if;
end machine_lt;
procedure machine_gt
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if vmint_to_vmsigned (x) > vmint_to_vmsigned (y) then
put_value (1);
else
put_value (0);
end if;
end machine_gt;
procedure machine_le
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if vmint_to_vmsigned (x) <= vmint_to_vmsigned (y) then
put_value (1);
else
put_value (0);
end if;
end machine_le;
procedure machine_ge
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if vmint_to_vmsigned (x) >= vmint_to_vmsigned (y) then
put_value (1);
else
put_value (0);
end if;
end machine_ge;
procedure machine_eq
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if x = y then
put_value (1);
else
put_value (0);
end if;
end machine_eq;
procedure machine_ne
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if x /= y then
put_value (1);
else
put_value (0);
end if;
end machine_ne;
procedure machine_and
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if x /= 0 and y /= 0 then
put_value (1);
else
put_value (0);
end if;
end machine_and;
procedure machine_or
is
x, y : vmint;
begin
pop_value (y);
get_value (x);
if x /= 0 or y /= 0 then
put_value (1);
else
put_value (0);
end if;
end machine_or;
procedure machine_neg
is
x : vmint;
begin
get_value (x);
put_value (twos_complement (x));
end machine_neg;
procedure machine_not
is
x : vmint;
begin
get_value (x);
if x = 0 then
put_value (1);
else
put_value (0);
end if;
end machine_not;
procedure machine_prtc
is
x : vmint;
begin
pop_value (x);
Character'Write (output_stream, Character'Val (x));
end machine_prtc;
procedure machine_prti
is
x : vmint;
begin
pop_value (x);
if 16#7FFF_FFFF# < x then
Character'Write (output_stream, '-');
String'Write
(output_stream,
To_String (vmint_to_digits (twos_complement (x))));
else
String'Write (output_stream, To_String (vmint_to_digits (x)));
end if;
end machine_prti;
procedure machine_prts
is
k : vmint;
begin
pop_value (k);
if strings_size <= k then
raise vm_runtime_error with "strings boundary exceeded";
end if;
String'Write (output_stream, To_String (strings (Integer (k))));
end machine_prts;
procedure machine_fetch
is
k : vmint;
x : vmint;
begin
immediate_value (k);
fetch_value (k, x);
push_value (x);
pc := pc + 4;
end machine_fetch;
procedure machine_store
is
k : vmint;
x : vmint;
begin
immediate_value (k);
pop_value (x);
store_value (k, x);
pc := pc + 4;
end machine_store;
procedure machine_push
is
x : vmint;
begin
immediate_value (x);
push_value (x);
pc := pc + 4;
end machine_push;
procedure machine_jmp
is
offset : vmint;
begin
immediate_value (offset);
pc := pc + offset;
end machine_jmp;
procedure machine_jz
is
x : vmint;
offset : vmint;
begin
pop_value (x);
if x = 0 then
immediate_value (offset);
pc := pc + offset;
else
pc := pc + 4;
end if;
end machine_jz;
procedure machine_step
(halt : out Boolean)
is
opcode : byte;
op_div_4, op_rem_4 : byte;
begin
if code_size <= pc then
raise vm_runtime_error with "code boundary exceeded";
end if;
opcode := code (Integer (pc));
pc := pc + 1;
halt := False;
op_div_4 := opcode / 4;
op_rem_4 := opcode rem 4;
if op_div_4 = 0 then
if op_rem_4 = 0 then
halt := True;
elsif op_rem_4 = 1 then
machine_add;
elsif op_rem_4 = 2 then
machine_sub;
else
machine_mul;
end if;
elsif op_div_4 = 1 then
if op_rem_4 = 0 then
machine_div;
elsif op_rem_4 = 1 then
machine_mod;
elsif op_rem_4 = 2 then
machine_lt;
else
machine_gt;
end if;
elsif op_div_4 = 2 then
if op_rem_4 = 0 then
machine_le;
elsif op_rem_4 = 1 then
machine_ge;
elsif op_rem_4 = 2 then
machine_eq;
else
machine_ne;
end if;
elsif op_div_4 = 3 then
if op_rem_4 = 0 then
machine_and;
elsif op_rem_4 = 1 then
machine_or;
elsif op_rem_4 = 2 then
machine_neg;
else
machine_not;
end if;
elsif op_div_4 = 4 then
if op_rem_4 = 0 then
machine_prtc;
elsif op_rem_4 = 1 then
machine_prti;
elsif op_rem_4 = 2 then
machine_prts;
else
machine_fetch;
end if;
elsif op_div_4 = 5 then
if op_rem_4 = 0 then
machine_store;
elsif op_rem_4 = 1 then
machine_push;
elsif op_rem_4 = 2 then
machine_jmp;
else
machine_jz;
end if;
else
-- Treat anything unrecognized as equivalent to a halt.
halt := True;
end if;
end machine_step;
procedure machine_continue
is
halt : Boolean;
begin
halt := False;
while not halt loop
machine_step (halt);
end loop;
end machine_continue;
procedure machine_run
is
begin
sp := 0;
pc := 0;
for i in data'Range loop
data (i) := 0;
end loop;
machine_continue;
end machine_run;
begin
status := 0;
input_file_name := To_Unbounded_String ("-");
if Argument_Count = 0 then
null;
elsif Argument_Count = 1 then
input_file_name := To_Unbounded_String (Argument (1));
else
Put ("Usage: ");
Put (Command_Name);
Put_Line (" [INPUTFILE]");
Put ("If either INPUTFILE is missing or ""-"",");
Put_Line (" standard input is used.");
Put_Line ("Output is always to standard output.");
status := 1;
end if;
if status = 0 then
if input_file_name /= "-" then
Open (input_file, In_File, To_String (input_file_name));
Set_Input (input_file);
end if;
output_stream := Stream (Current_Output);
read_parse_and_store_program;
machine_run;
if input_file_name /= "-" then
Set_Input (Standard_Input);
Close (input_file);
end if;
end if;
Set_Exit_Status (status);
end VM; |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #COBOL | COBOL | >>SOURCE FORMAT IS FREE
identification division.
*> this code is dedicated to the public domain
*> (GnuCOBOL) 2.3-dev.0
program-id. astinterpreter.
environment division.
configuration section.
repository. function all intrinsic.
data division.
working-storage section.
01 program-name pic x(32) value spaces global.
01 input-name pic x(32) value spaces global.
01 input-status pic xx global.
01 ast-record global.
03 ast-type pic x(14).
03 ast-value pic x(48).
03 filler redefines ast-value.
05 asl-left pic 999.
05 asl-right pic 999.
01 error-record pic x(64) value spaces global.
01 loadstack global.
03 l pic 99 value 0.
03 l-lim pic 99 value 64.
03 load-entry occurs 64.
05 l-node pic x(14).
05 l-left pic 999.
05 l-right pic 999.
05 l-link pic 999.
01 abstract-syntax-tree global.
03 t pic 999 value 0.
03 t1 pic 999.
03 n1 pic 999.
03 t-lim pic 999 value 998.
03 filler occurs 998.
05 leaf.
07 leaf-type pic x(14).
07 leaf-value pic x(48).
05 node redefines leaf.
07 node-type pic x(14).
07 node-left pic 999.
07 node-right pic 999.
01 interpreterstack global.
03 stack1 pic 99 value 2.
03 stack2 pic 99 value 1.
03 stack-lim pic 99 value 32.
03 stack-entry occurs 32.
05 stack-source pic 99.
05 stack usage binary-int.
01 variables global.
03 v pic 99.
03 v-max pic 99 value 0.
03 v-lim pic 99 value 16.
03 filler occurs 16.
05 variable-value binary-int.
05 variable-name pic x(48).
01 strings global.
03 s pic 99.
03 s-max pic 99 value 0.
03 s-lim pic 99 value 16.
03 filler occurs 16 value spaces.
05 string-value pic x(48).
01 string-fields global.
03 string-length pic 99.
03 string1 pic 99.
03 length1 pic 99.
03 count1 pic 99.
01 display-fields global.
03 display-number pic -(9)9.
03 display-pending pic x value 'n'.
03 character-value.
05 character-number usage binary-char.
procedure division chaining program-name.
start-astinterpreter.
call 'loadast'
if program-name <> spaces
call 'readinput' *> close the input-file
end-if
>>d perform print-ast
call 'runast' using t
if display-pending = 'y'
display space
end-if
stop run
.
print-ast.
call 'printast' using t
display 'ast:' upon syserr
display 't=' t
perform varying t1 from 1 by 1 until t1 > t
if leaf-type(t1) = 'Identifier' or 'Integer' or 'String'
display t1 space trim(leaf-type(t1)) space trim(leaf-value(t1)) upon syserr
else
display t1 space node-left(t1) space node-right(t1) space trim(node-type(t1))
upon syserr
end-if
end-perform
.
identification division.
program-id. runast common recursive.
data division.
working-storage section.
01 word-length constant as length of binary-int.
linkage section.
01 n pic 999.
procedure division using n.
start-runast.
if n = 0
exit program
end-if
evaluate node-type(n)
when 'Integer'
perform push-stack
move numval(leaf-value(n)) to stack(stack1)
when 'Identifier'
perform get-variable-index
perform push-stack
move v to stack-source(stack1)
move variable-value(v) to stack(stack1)
when 'String'
perform get-string-index
perform push-stack
move s to stack-source(stack1)
when 'Assign'
call 'runast' using node-left(n)
call 'runast' using node-right(n)
move stack-source(stack2) to v
move stack(stack1) to variable-value(v)
perform pop-stack
perform pop-stack
when 'If'
call 'runast' using node-left(n)
move node-right(n) to n1
if stack(stack1) <> 0
call 'runast' using node-left(n1)
else
call 'runast' using node-right(n1)
end-if
perform pop-stack
when 'While'
call 'runast' using node-left(n)
perform until stack(stack1) = 0
perform pop-stack
call 'runast' using node-right(n)
call 'runast' using node-left(n)
end-perform
perform pop-stack
when 'Add'
perform get-values
add stack(stack1) to stack(stack2)
perform pop-stack
when 'Subtract'
perform get-values
subtract stack(stack1) from stack(stack2)
perform pop-stack
when 'Multiply'
perform get-values
multiply stack(stack1) by stack(stack2)
perform pop-stack
when 'Divide'
perform get-values
divide stack(stack1) into stack(stack2)
perform pop-stack
when 'Mod'
perform get-values
move mod(stack(stack2),stack(stack1)) to stack(stack2)
perform pop-stack
when 'Less'
perform get-values
if stack(stack2) < stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when 'Greater'
perform get-values
if stack(stack2) > stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when 'LessEqual'
perform get-values
if stack(stack2) <= stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when 'GreaterEqual'
perform get-values
if stack(stack2) >= stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when 'Equal'
perform get-values
if stack(stack2) = stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when 'NotEqual'
perform get-values
if stack(stack2) <> stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when 'And'
perform get-values
call "CBL_AND" using stack(stack1) stack(stack2) by value word-length
perform pop-stack
when 'Or'
perform get-values
call "CBL_OR" using stack(stack1) stack(stack2) by value word-length
perform pop-stack
when 'Not'
call 'runast' using node-left(n)
if stack(stack1) = 0
move 1 to stack(stack1)
else
move 0 to stack(stack1)
end-if
when 'Negate'
call 'runast' using node-left(n)
compute stack(stack1) = - stack(stack1)
when 'Prtc'
call 'runast' using node-left(n)
move stack(stack1) to character-number
display character-value with no advancing
move 'y' to display-pending
perform pop-stack
when 'Prti'
call 'runast' using node-left(n)
move stack(stack1) to display-number
display trim(display-number) with no advancing
move 'y' to display-pending
perform pop-stack
when 'Prts'
call 'runast' using node-left(n)
move stack-source(stack1) to s
move length(trim(string-value(s))) to string-length
move 2 to string1
compute length1 = string-length - 2
perform until string1 >= string-length
move 0 to count1
inspect string-value(s)(string1:length1)
tallying count1 for characters before initial '\' *> ' (workaround Rosetta Code highlighter problem)
evaluate true
when string-value(s)(string1 + count1 + 1:1) = 'n' *> \n
display string-value(s)(string1:count1)
move 'n' to display-pending
compute string1 = string1 + 2 + count1
compute length1 = length1 - 2 - count1
when string-value(s)(string1 + count1 + 1:1) = '\' *> \\ '
display string-value(s)(string1:count1 + 1) with no advancing
move 'y' to display-pending
compute string1 = string1 + 2 + count1
compute length1 = length1 - 2 - count1
when other
display string-value(s)(string1:count1) with no advancing
move 'y' to display-pending
add count1 to string1
subtract count1 from length1
end-evaluate
end-perform
perform pop-stack
when 'Sequence'
call 'runast' using node-left(n)
call 'runast' using node-right(n)
when other
string 'in astinterpreter unknown node type ' node-type(n) into error-record
call 'reporterror'
end-evaluate
exit program
.
push-stack.
if stack1 >= s-lim
string 'in astinterpreter at ' n ' stack overflow' into error-record
call 'reporterror'
end-if
add 1 to stack1 stack2
initialize stack-entry(stack1)
.
pop-stack.
if stack1 < 2
string 'in astinterpreter at ' n ' stack underflow ' into error-record
call 'reporterror'
end-if
subtract 1 from stack1 stack2
.
get-variable-index.
perform varying v from 1 by 1 until v > v-max
or variable-name(v) = leaf-value(n)
continue
end-perform
if v > v-max
if v-max = v-lim
string 'in astinterpreter number of variables exceeds ' v-lim into error-record
call 'reporterror'
end-if
move v to v-max
move leaf-value(n) to variable-name(v)
move 0 to variable-value(v)
end-if
.
get-string-index.
perform varying s from 1 by 1 until s > s-max
or string-value(s) = leaf-value(n)
continue
end-perform
if s > s-max
if s-max = s-lim
string 'in astinterpreter number of strings exceeds ' s-lim into error-record
call 'reporterror'
end-if
move s to s-max
move leaf-value(n) to string-value(s)
end-if
.
get-values.
call 'runast' using node-left(n)
call 'runast' using node-right(n)
.
end program runast.
identification division.
program-id. loadast common recursive.
procedure division.
start-loadast.
if l >= l-lim
string 'in astinterpreter loadast l exceeds ' l-lim into error-record
call 'reporterror'
end-if
add 1 to l
call 'readinput'
evaluate true
when ast-record = ';'
when input-status = '10'
move 0 to return-code
when ast-type = 'Identifier'
when ast-type = 'Integer'
when ast-type = 'String'
call 'makeleaf' using ast-type ast-value
move t to return-code
when ast-type = 'Sequence'
move ast-type to l-node(l)
call 'loadast'
move return-code to l-left(l)
call 'loadast'
move t to l-right(l)
call 'makenode' using l-node(l) l-left(l) l-right(l)
move t to return-code
when other
move ast-type to l-node(l)
call 'loadast'
move return-code to l-left(l)
call 'loadast'
move return-code to l-right(l)
call 'makenode' using l-node(l) l-left(l) l-right(l)
move t to return-code
end-evaluate
subtract 1 from l
.
end program loadast.
identification division.
program-id. makenode common.
data division.
linkage section.
01 parm-type any length.
01 parm-l-left pic 999.
01 parm-l-right pic 999.
procedure division using parm-type parm-l-left parm-l-right.
start-makenode.
if t >= t-lim
string 'in astinterpreter makenode t exceeds ' t-lim into error-record
call 'reporterror'
end-if
add 1 to t
move parm-type to node-type(t)
move parm-l-left to node-left(t)
move parm-l-right to node-right(t)
.
end program makenode.
identification division.
program-id. makeleaf common.
data division.
linkage section.
01 parm-type any length.
01 parm-value pic x(48).
procedure division using parm-type parm-value.
start-makeleaf.
add 1 to t
if t >= t-lim
string 'in astinterpreter makeleaf t exceeds ' t-lim into error-record
call 'reporterror'
end-if
move parm-type to leaf-type(t)
move parm-value to leaf-value(t)
.
end program makeleaf.
identification division.
program-id. printast common recursive.
data division.
linkage section.
01 n pic 999.
procedure division using n.
start-printast.
if n = 0
display ';' upon syserr
exit program
end-if
display leaf-type(n) upon syserr
evaluate leaf-type(n)
when 'Identifier'
when 'Integer'
when 'String'
display leaf-type(n) space trim(leaf-value(n)) upon syserr
when other
display node-type(n) upon syserr
call 'printast' using node-left(n)
call 'printast' using node-right(n)
end-evaluate
.
end program printast.
identification division.
program-id. readinput common.
environment division.
input-output section.
file-control.
select input-file assign using input-name
status is input-status
organization is line sequential.
data division.
file section.
fd input-file.
01 input-record pic x(64).
procedure division.
start-readinput.
if program-name = spaces
move '00' to input-status
accept ast-record on exception move '10' to input-status end-accept
exit program
end-if
if input-name = spaces
string program-name delimited by space '.ast' into input-name
open input input-file
if input-status = '35'
string 'in astinterpreter ' trim(input-name) ' not found' into error-record
call 'reporterror'
end-if
end-if
read input-file into ast-record
evaluate input-status
when '00'
continue
when '10'
close input-file
when other
string 'in astinterpreter ' trim(input-name) ' unexpected input-status: ' input-status
into error-record
call 'reporterror'
end-evaluate
.
end program readinput.
program-id. reporterror common.
procedure division.
start-reporterror.
report-error.
display error-record upon syserr
stop run with error status -1
.
end program reporterror.
end program astinterpreter. |
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #ATS | ATS | (********************************************************************)
(* Usage: parse [INPUTFILE [OUTPUTFILE]]
If INPUTFILE or OUTPUTFILE is "-" or missing, then standard input
or standard output is used, respectively. *)
#include "share/atspre_staload.hats"
staload UN = "prelude/SATS/unsafe.sats"
#define NIL list_nil ()
#define :: list_cons
%{^
/* alloca(3) is needed for ATS exceptions. */
#include <alloca.h>
%}
(********************************************************************)
#define NUM_TOKENS 31
#define TOKEN_ELSE 0
#define TOKEN_IF 1
#define TOKEN_PRINT 2
#define TOKEN_PUTC 3
#define TOKEN_WHILE 4
#define TOKEN_MULTIPLY 5
#define TOKEN_DIVIDE 6
#define TOKEN_MOD 7
#define TOKEN_ADD 8
#define TOKEN_SUBTRACT 9
#define TOKEN_NEGATE 10
#define TOKEN_LESS 11
#define TOKEN_LESSEQUAL 12
#define TOKEN_GREATER 13
#define TOKEN_GREATEREQUAL 14
#define TOKEN_EQUAL 15
#define TOKEN_NOTEQUAL 16
#define TOKEN_NOT 17
#define TOKEN_ASSIGN 18
#define TOKEN_AND 19
#define TOKEN_OR 20
#define TOKEN_LEFTPAREN 21
#define TOKEN_RIGHTPAREN 22
#define TOKEN_LEFTBRACE 23
#define TOKEN_RIGHTBRACE 24
#define TOKEN_SEMICOLON 25
#define TOKEN_COMMA 26
#define TOKEN_IDENTIFIER 27
#define TOKEN_INTEGER 28
#define TOKEN_STRING 29
#define TOKEN_END_OF_INPUT 30
typedef token_t =
[i : int | TOKEN_ELSE <= i; i <= TOKEN_END_OF_INPUT]
int i
typedef tokentuple_t = (token_t, String, ullint, ullint)
fn
token_text (tok : token_t) : String =
case+ tok of
| TOKEN_ELSE => "else"
| TOKEN_IF => "if"
| TOKEN_PRINT => "print"
| TOKEN_PUTC => "putc"
| TOKEN_WHILE => "while"
| TOKEN_MULTIPLY => "*"
| TOKEN_DIVIDE => "/"
| TOKEN_MOD => "%"
| TOKEN_ADD => "+"
| TOKEN_SUBTRACT => "-"
| TOKEN_NEGATE => "-"
| TOKEN_LESS => "<"
| TOKEN_LESSEQUAL => "<="
| TOKEN_GREATER => ">"
| TOKEN_GREATEREQUAL => ">="
| TOKEN_EQUAL => "=="
| TOKEN_NOTEQUAL => "!="
| TOKEN_NOT => "!"
| TOKEN_ASSIGN => "="
| TOKEN_AND => "&&"
| TOKEN_OR => "||"
| TOKEN_LEFTPAREN => "("
| TOKEN_RIGHTPAREN => ")"
| TOKEN_LEFTBRACE => "{"
| TOKEN_RIGHTBRACE => "}"
| TOKEN_SEMICOLON => ";"
| TOKEN_COMMA => ","
| TOKEN_IDENTIFIER => "Ident"
| TOKEN_INTEGER => "Integer literal"
| TOKEN_STRING => "String literal"
| TOKEN_END_OF_INPUT => "EOI"
(********************************************************************)
(* A perfect hash for the lexical token names.
This hash was generated by GNU gperf and then translated to
reasonable ATS by hand. Note, though, that one could have embedded
the generated C code directly and used it. *)
#define MIN_WORD_LENGTH 5
#define MAX_WORD_LENGTH 15
#define MIN_HASH_VALUE 5
#define MAX_HASH_VALUE 64
#define HASH_TABLE_SIZE 65
local
extern castfn u : {n : nat | n < 256} int n -<> uint8 n
in
vtypedef asso_values_vt = @[[n : nat | n < 256] uint8 n][256]
var asso_values =
@[[n : nat | n < 256] uint8 n][256]
(u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 10, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 0, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 0, u 65, u 25,
u 5, u 5, u 0, u 15, u 65, u 0, u 65, u 65, u 10, u 65,
u 30, u 0, u 65, u 5, u 10, u 10, u 0, u 15, u 65, u 65,
u 65, u 5, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65, u 65,
u 65, u 65, u 65, u 65, u 65, u 65)
end
fn
get_asso_value {i : nat | i < 256}
(i : uint i) :<>
[n : nat | n < 256] uint n =
let
extern castfn u8ui : {n : nat} uint8 n -<> uint n
extern castfn mk_asso_values :<>
{p : addr} ptr p -<> (asso_values_vt @ p | ptr p)
val asso_values_tup = mk_asso_values (addr@ asso_values)
macdef asso_values = !(asso_values_tup.1)
val retval = asso_values[i]
val _ = $UN.castvwtp0{void} asso_values_tup
in
u8ui retval
end
fn
hash {n : int | MIN_WORD_LENGTH <= n; n <= MAX_WORD_LENGTH}
(str : string n,
len : size_t n) :<>
[key : nat] uint key =
let
extern castfn uc2ui : {n : nat} uchar n -<> uint n
val c1 = uc2ui (c2uc str[4])
val c2 = uc2ui (c2uc str[pred len])
in
sz2u len + get_asso_value c1 + get_asso_value c2
end
typedef wordlist_vt = @[(String, token_t)][HASH_TABLE_SIZE]
var wordlist =
@[(String, token_t)][HASH_TABLE_SIZE]
(("", 0), ("", 0), ("", 0), ("", 0), ("", 0),
("Comma", 26),
("Op_not", 17),
("", 0), ("", 0), ("", 0),
("Keyword_if", 1),
("Op_mod", 7),
("End_of_input", 30),
("Keyword_print", 2),
("Op_divide", 6),
("RightBrace", 24),
("Op_add", 8),
("Keyword_else", 0),
("Keyword_while", 4),
("Op_negate", 10),
("Identifier", 27),
("Op_notequal", 16),
("Op_less", 11),
("Op_equal", 15),
("LeftBrace", 23),
("Op_or", 20),
("Op_subtract", 9),
("Op_lessequal", 12),
("", 0), ("", 0),
("Op_greater", 13),
("Op_multiply", 5 ),
("Integer", 28),
("", 0), ("", 0),
("Op_greaterequal", 14),
("", 0),
("Keyword_putc", 3),
("", 0),
("LeftParen", 21),
("RightParen", 22),
("Op_and", 19),
("", 0), ("", 0), ("", 0), ("", 0), ("", 0), ("", 0), ("", 0),
("Op_assign", 18),
("", 0),
("String", 29),
("", 0), ("", 0), ("", 0), ("", 0), ("", 0), ("", 0), ("", 0),
("", 0), ("", 0), ("", 0), ("", 0), ("", 0),
("Semicolon", 25))
fn
get_wordlist_entry
{n : nat | n <= MAX_HASH_VALUE}
(key : uint n) :<> (String, token_t) =
let
extern castfn mk_wordlist_tup :<>
{p : addr} ptr p -<> (wordlist_vt @ p | ptr p)
val wordlist_tup = mk_wordlist_tup (addr@ wordlist)
macdef wordlist = !(wordlist_tup.1)
val retval = wordlist[key]
val _ = $UN.castvwtp0{void} wordlist_tup
in
retval
end
fn
string2token_t_opt
{n : int}
(str : string n) :<>
Option token_t =
let
val len = string_length str
in
if len < i2sz MIN_WORD_LENGTH then
None ()
else if i2sz MAX_WORD_LENGTH < len then
None ()
else
let
val key = hash (str, len)
in
if i2u MAX_HASH_VALUE < key then
None ()
else
let
val (s, tok) = get_wordlist_entry (key)
in
if str <> s then
None ()
else
Some tok
end
end
end
(********************************************************************)
exception bad_lex_integer of (String)
exception bad_lex_token_name of (String)
exception bad_string_literal of (String)
extern fun {}
skip_something$pred : char -<> bool
fn {}
skip_something {n : nat}
{i : nat | i <= n}
(s : string n,
n : size_t n,
i : size_t i) :<>
[j : nat | i <= j; j <= n]
size_t j =
let
fun
loop {k : nat | i <= k; k <= n} .<n - k>.
(k : size_t k) :<>
[j : nat | i <= j; j <= n]
size_t j =
if k = n then
k
else if ~(skip_something$pred<> s[k]) then
k
else
loop (succ k)
in
loop i
end
fn
skip_space {n : nat}
{i : nat | i <= n}
(s : string n,
n : size_t n,
i : size_t i) :<>
[j : nat | i <= j; j <= n]
size_t j =
let
implement skip_something$pred<> (c) = isspace c
in
skip_something (s, n, i)
end
fn
skip_nonspace {n : nat}
{i : nat | i <= n}
(s : string n,
n : size_t n,
i : size_t i) :<>
[j : nat | i <= j; j <= n]
size_t j =
let
implement skip_something$pred<> (c) = ~isspace c
in
skip_something (s, n, i)
end
fn
skip_nonquote {n : nat}
{i : nat | i <= n}
(s : string n,
n : size_t n,
i : size_t i) :<>
[j : nat | i <= j; j <= n]
size_t j =
let
implement skip_something$pred<> (c) = c <> '"'
in
skip_something (s, n, i)
end
fn
skip_string_literal
{n : nat}
{i : nat | i <= n}
(s : string n,
n : size_t n,
i : size_t i) :<>
[j : nat | i <= j; j <= n]
size_t j =
if i = n then
i
else if s[i] <> '"' then
i
else
let
val j = skip_nonquote (s, n, succ i)
in
if j = n then
i
else
succ j
end
fn
get_substr {n, i, j : nat | i <= j; j <= n}
(s : string n,
i : size_t i,
j : size_t j) :
[m : int | m == j - i] string m =
let
val s = string_make_substring (s, i, j - i)
in
strnptr2string s
end
fn
string2ullint
{n : nat}
(s : string n) : ullint =
let
val n = string_length s
in
if n = i2sz 0 then
$raise bad_lex_integer ("")
else
let
extern castfn u2ull : uint -<> ullint
fun
evaluate {k : nat | k <= n} .<n - k>.
(k : size_t k,
v : ullint) : ullint =
if k = n then
v
else if ~isdigit s[k] then
$raise bad_lex_integer (s)
else
let
val d = char2ui s[k] - char2ui '0'
in
evaluate (succ k, (10ULL * v) + u2ull d)
end
in
evaluate (i2sz 0, 0ULL)
end
end
fn
string2token {n : int}
(str : string n) : token_t =
case+ string2token_t_opt str of
| None () => $raise bad_lex_token_name (str)
| Some tok => tok
fn
read_lex_file (inpf : FILEref) : List0 tokentuple_t =
(* Convert the output of "lex" to a list of tokens. *)
(* This routine could stand to do more validation of the input. *)
let
fun
loop (lst : List0 tokentuple_t) : List0 tokentuple_t =
if fileref_is_eof inpf then
lst
else
let
val s = strptr2string (fileref_get_line_string inpf)
val n = string_length s
prval _ = lemma_g1uint_param n
val i0_line_no = skip_space (s, n, i2sz 0)
in
if i0_line_no = n then
(* Skip any blank lines, including end of file. *)
loop lst
else
let
val i1_line_no = skip_nonspace (s, n, i0_line_no)
val s_line_no = get_substr (s, i0_line_no, i1_line_no)
val line_no = string2ullint s_line_no
val i0_column_no = skip_space (s, n, i1_line_no)
val i1_column_no = skip_nonspace (s, n, i0_column_no)
val s_column_no = get_substr (s, i0_column_no,
i1_column_no)
val column_no = string2ullint s_column_no
val i0_tokname = skip_space (s, n, i1_column_no)
val i1_tokname = skip_nonspace (s, n, i0_tokname)
val tokname = get_substr (s, i0_tokname, i1_tokname)
val tok = string2token tokname
in
case+ tok of
| TOKEN_INTEGER =>
let
val i0 = skip_space (s, n, i1_tokname)
val i1 = skip_nonspace (s, n, i0)
val arg = get_substr (s, i0, i1)
val toktup = (tok, arg, line_no, column_no)
in
loop (toktup :: lst)
end
| TOKEN_IDENTIFIER =>
let
val i0 = skip_space (s, n, i1_tokname)
val i1 = skip_nonspace (s, n, i0)
val arg = get_substr (s, i0, i1)
val toktup = (tok, arg, line_no, column_no)
in
loop (toktup :: lst)
end
| TOKEN_STRING =>
let
val i0 = skip_space (s, n, i1_tokname)
val i1 = skip_string_literal (s, n, i0)
val arg = get_substr (s, i0, i1)
val toktup = (tok, arg, line_no, column_no)
in
loop (toktup :: lst)
end
| _ =>
let
val toktup = (tok, "", line_no, column_no)
in
loop (toktup :: lst)
end
end
end
in
list_vt2t (list_reverse (loop NIL))
end
(********************************************************************)
exception truncated_lexical of ()
exception unexpected_token of (tokentuple_t, token_t)
exception unexpected_primary of (tokentuple_t)
exception unterminated_statement_block of (ullint, ullint)
exception expected_a_statement of (tokentuple_t)
datatype node_t =
| node_t_nil of ()
| node_t_leaf of (String, String)
| node_t_cons of (String, node_t, node_t)
fn
right_assoc (tok : token_t) : bool =
(* None of the currently supported operators is right
associative. *)
false
fn
binary_op (tok : token_t) : bool =
case+ tok of
| TOKEN_ADD => true
| TOKEN_SUBTRACT => true
| TOKEN_MULTIPLY => true
| TOKEN_DIVIDE => true
| TOKEN_MOD => true
| TOKEN_LESS => true
| TOKEN_LESSEQUAL => true
| TOKEN_GREATER => true
| TOKEN_GREATEREQUAL => true
| TOKEN_EQUAL => true
| TOKEN_NOTEQUAL => true
| TOKEN_AND => true
| TOKEN_OR => true
| _ => false
fn
precedence (tok : token_t) : int =
case+ tok of
| TOKEN_MULTIPLY => 13
| TOKEN_DIVIDE => 13
| TOKEN_MOD => 13
| TOKEN_ADD => 12
| TOKEN_SUBTRACT => 12
| TOKEN_NEGATE => 14
| TOKEN_NOT => 14
| TOKEN_LESS => 10
| TOKEN_LESSEQUAL => 10
| TOKEN_GREATER => 10
| TOKEN_GREATEREQUAL => 10
| TOKEN_EQUAL => 9
| TOKEN_NOTEQUAL => 9
| TOKEN_AND => 5
| TOKEN_OR => 4
| _ => ~1
fn
opname (tok : token_t) : String =
case- tok of
| TOKEN_MULTIPLY => "Multiply"
| TOKEN_DIVIDE => "Divide"
| TOKEN_MOD => "Mod"
| TOKEN_ADD => "Add"
| TOKEN_SUBTRACT => "Subtract"
| TOKEN_NEGATE => "Negate"
| TOKEN_NOT => "Not"
| TOKEN_LESS => "Less"
| TOKEN_LESSEQUAL => "LessEqual"
| TOKEN_GREATER => "Greater"
| TOKEN_GREATEREQUAL => "GreaterEqual"
| TOKEN_EQUAL => "Equal"
| TOKEN_NOTEQUAL => "NotEqual"
| TOKEN_AND => "And"
| TOKEN_OR => "Or"
fn
parse (lex : List0 tokentuple_t) : node_t =
let
typedef toktups_t (n : int) = list (tokentuple_t, n)
typedef toktups_t = [n : nat] toktups_t n
fn
expect (expected : token_t,
lex : toktups_t) : toktups_t =
case+ lex of
| NIL => $raise truncated_lexical ()
| toktup :: tail =>
if toktup.0 = expected then
tail
else
$raise unexpected_token (toktup, expected)
fn
peek {n : int} (lex : toktups_t n) : [1 <= n] token_t =
case+ lex of
| NIL => $raise truncated_lexical ()
| (tok, _, _, _) :: _ => tok
fun
stmt (lex : toktups_t) : (node_t, toktups_t) =
case+ lex of
| NIL => $raise truncated_lexical ()
| (TOKEN_IF, _, _, _) :: lex =>
let
val (e, lex) = paren_expr lex
val (s, lex) = stmt lex
in
case+ lex of
| (TOKEN_ELSE, _, _, _) :: lex =>
let
val (t, lex) = stmt lex
in
(node_t_cons ("If", e, node_t_cons ("If", s, t)), lex)
end
| _ =>
let
(* There is no 'else' clause. *)
val t = node_t_nil ()
in
(node_t_cons ("If", e, node_t_cons ("If", s, t)), lex)
end
end
| (TOKEN_PUTC, _, _, _) :: lex =>
let
val (subtree, lex) = paren_expr lex
val subtree = node_t_cons ("Prtc", subtree, node_t_nil ())
val lex = expect (TOKEN_SEMICOLON, lex)
in
(subtree, lex)
end
| (TOKEN_PRINT, _, _, _) :: lex =>
let
val lex = expect (TOKEN_LEFTPAREN, lex)
fun
loop_over_args (subtree : node_t,
lex : toktups_t) : (node_t, toktups_t) =
case+ lex of
| (TOKEN_STRING, arg, _, _) ::
(TOKEN_COMMA, _, _, _) :: lex =>
let
val leaf = node_t_leaf ("String", arg)
val e = node_t_cons ("Prts", leaf, node_t_nil ())
in
loop_over_args
(node_t_cons ("Sequence", subtree, e), lex)
end
| (TOKEN_STRING, arg, _, _) :: lex =>
let
val lex = expect (TOKEN_RIGHTPAREN, lex)
val lex = expect (TOKEN_SEMICOLON, lex)
val leaf = node_t_leaf ("String", arg)
val e = node_t_cons ("Prts", leaf, node_t_nil ())
in
(node_t_cons ("Sequence", subtree, e), lex)
end
| _ :: _ =>
let
val (x, lex) = expr (0, lex)
val e = node_t_cons ("Prti", x, node_t_nil ())
val subtree = node_t_cons ("Sequence", subtree, e)
in
case+ peek lex of
| TOKEN_COMMA =>
let
val lex = expect (TOKEN_COMMA, lex)
in
loop_over_args (subtree, lex)
end
| _ =>
let
val lex = expect (TOKEN_RIGHTPAREN, lex)
val lex = expect (TOKEN_SEMICOLON, lex)
in
(subtree, lex)
end
end
| NIL => $raise truncated_lexical ()
in
loop_over_args (node_t_nil (), lex)
end
| (TOKEN_SEMICOLON, _, _, _) :: lex => (node_t_nil (), lex)
| (TOKEN_IDENTIFIER, arg, _, _) :: lex =>
let
val v = node_t_leaf ("Identifier", arg)
val lex = expect (TOKEN_ASSIGN, lex)
val (subtree, lex) = expr (0, lex)
val t = node_t_cons ("Assign", v, subtree)
val lex = expect (TOKEN_SEMICOLON, lex)
in
(t, lex)
end
| (TOKEN_WHILE, _, _, _) :: lex =>
let
val (e, lex) = paren_expr lex
val (t, lex) = stmt lex
in
(node_t_cons ("While", e, t), lex)
end
| (TOKEN_LEFTBRACE, _, _, _) :: lex =>
let
fun
loop_over_stmts (subtree : node_t,
lex : toktups_t) :
(node_t, toktups_t) =
case+ lex of
| (TOKEN_RIGHTBRACE, _, _, _) :: lex => (subtree, lex)
| (TOKEN_END_OF_INPUT, _, line_no, column_no) :: _ =>
$raise unterminated_statement_block (line_no, column_no)
| _ =>
let
val (e, lex) = stmt lex
in
loop_over_stmts
(node_t_cons ("Sequence", subtree, e), lex)
end
in
loop_over_stmts (node_t_nil (), lex)
end
| (TOKEN_END_OF_INPUT, _, _, _) :: lex => (node_t_nil (), lex)
| toktup :: _ => $raise expected_a_statement (toktup)
and
expr (prec : int,
lex : toktups_t) : (node_t, toktups_t) =
case+ lex of
| (TOKEN_LEFTPAREN, _, _, _) :: _ =>
(* '(' expr ')' *)
let
val (subtree, lex) = paren_expr lex
in
prec_climb (prec, subtree, lex)
end
| (TOKEN_ADD, _, _, _) :: lex =>
(* '+' expr *)
let
val (subtree, lex) = expr (precedence TOKEN_ADD, lex)
in
prec_climb (prec, subtree, lex)
end
| (TOKEN_SUBTRACT, _, _, _) :: lex =>
(* '-' expr *)
let
val (subtree, lex) = expr (precedence TOKEN_NEGATE, lex)
val subtree = node_t_cons ("Negate", subtree, node_t_nil ())
in
prec_climb (prec, subtree, lex)
end
| (TOKEN_NOT, _, _, _) :: lex =>
(* '!' expr *)
let
val (subtree, lex) = expr (precedence TOKEN_NOT, lex)
val subtree = node_t_cons ("Not", subtree, node_t_nil ())
in
prec_climb (prec, subtree, lex)
end
| (TOKEN_IDENTIFIER, arg, _, _) :: lex =>
let
val leaf = node_t_leaf ("Identifier", arg)
in
prec_climb (prec, leaf, lex)
end
| (TOKEN_INTEGER, arg, _, _) :: lex =>
let
val leaf = node_t_leaf ("Integer", arg)
in
prec_climb (prec, leaf, lex)
end
| toktup :: lex =>
$raise unexpected_primary (toktup)
| NIL =>
$raise truncated_lexical ()
and
prec_climb (prec : int,
subtree : node_t,
lex : toktups_t) : (node_t, toktups_t) =
case+ peek lex of
| tokval =>
if ~binary_op tokval then
(subtree, lex)
else if precedence tokval < prec then
(subtree, lex)
else
case+ lex of
| toktup :: lex =>
let
val q =
if right_assoc (toktup.0) then
precedence tokval
else
succ (precedence tokval)
val (e, lex) = expr (q, lex)
val subtree1 =
node_t_cons (opname (toktup.0), subtree, e)
in
prec_climb (prec, subtree1, lex)
end
and
paren_expr (lex : toktups_t) : (node_t, toktups_t) =
(* '(' expr ')' *)
let
val lex = expect (TOKEN_LEFTPAREN, lex)
val (subtree, lex) = expr (0, lex)
val lex = expect (TOKEN_RIGHTPAREN, lex)
in
(subtree, lex)
end
fun
main_loop (subtree : node_t,
lex : toktups_t) : node_t =
case+ peek lex of
| TOKEN_END_OF_INPUT => subtree
| _ =>
let
val (x, lex) = stmt lex
in
main_loop (node_t_cons ("Sequence", subtree, x), lex)
end
in
main_loop (node_t_nil (), lex)
end
fn
print_ast (outf : FILEref,
ast : node_t) : void =
let
fun
traverse (ast : node_t) : void =
case+ ast of
| node_t_nil () => fprintln! (outf, ";")
| node_t_leaf (str, arg) => fprintln! (outf, str, " ", arg)
| node_t_cons (str, left, right) =>
begin
fprintln! (outf, str);
traverse left;
traverse right
end
in
traverse ast
end
(********************************************************************)
fn
main_program (inpf : FILEref,
outf : FILEref) : int =
let
val toklst = read_lex_file inpf
val ast = parse toklst
val () = print_ast (outf, ast)
in
0
end
fn
error_start (line_no : ullint,
column_no : ullint) : void =
print! ("(", line_no, ", ", column_no, ") error: ")
implement
main (argc, argv) =
let
val inpfname =
if 2 <= argc then
$UN.cast{string} argv[1]
else
"-"
val outfname =
if 3 <= argc then
$UN.cast{string} argv[2]
else
"-"
in
try
let
val inpf =
if (inpfname : string) = "-" then
stdin_ref
else
fileref_open_exn (inpfname, file_mode_r)
val outf =
if (outfname : string) = "-" then
stdout_ref
else
fileref_open_exn (outfname, file_mode_w)
in
main_program (inpf, outf)
end
with
| ~ unexpected_primary @(tok, _, line_no, column_no) =>
begin
error_start (line_no, column_no);
println! ("Expecting a primary, found: ", token_text tok);
1
end
| ~ unexpected_token (@(tok, _, line_no, column_no), expected) =>
begin
error_start (line_no, column_no);
println! ("Expecting '", token_text expected,
"', found '", token_text tok, "'");
1
end
| ~ expected_a_statement @(tok, _, line_no, column_no) =>
begin
error_start (line_no, column_no);
println! ("expecting start of statement, found '",
token_text tok, "'");
1
end
| ~ unterminated_statement_block (line_no, column_no) =>
begin
error_start (line_no, column_no);
println! ("unterminated statement block");
1
end
| ~ truncated_lexical () =>
begin
println! ("truncated input token stream");
2
end
| ~ bad_lex_integer (s) =>
begin
println! ("bad integer literal in the token stream: '",
s, "'");
2
end
| ~ bad_string_literal (s) =>
begin
println! ("bad string literal in the token stream: '",
s, "'");
2
end
| ~ bad_lex_token_name (s) =>
begin
println! ("bad token name in the token stream: '",
s, "'");
2
end
end
(********************************************************************) |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #AWK | AWK |
BEGIN {
c=220; d=619; i=10000;
printf("\033[2J"); # Clear screen
while(i--) m[i]=0;
while(d--) m[int(rand()*1000)]=1;
while(c--){
for(i=52; i<=949; i++){
d=m[i-1]+m[i+1]+m[i-51]+m[i-50]+m[i-49]+m[i+49]+m[i+50]+m[i+51];
n[i]=m[i];
if(m[i]==0 && d==3) n[i]=1;
else if(m[i]==1 && d<2) n[i]=0;
else if(m[i]==1 && d>3) n[i]=0;
}
printf("\033[1;1H"); # Home cursor
for(i=1;i<=1000;i++) # gridsize 50x20
{
if(n[i]) printf("O"); else printf(".");
m[i]=n[i];
if(!(i%50)) printf("\n");
}
printf("%3d\n",c); # Countdown
x=30000; while(x--) ; # Delay
}
}
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #MAXScript | MAXScript | struct myPoint (x, y)
newPoint = myPoint x:3 y:4 |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #MiniScript | MiniScript | Point = {}
Point.x = 0
Point.y = 0 |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Smalltalk | Smalltalk | |s1 s2|
"bind the var s1 to the object string on the right"
s1 := 'i am a string'.
"bind the var s2 to the same object..."
s2 := s1.
"bind s2 to a copy of the object bound to s1"
s2 := (s1 copy). |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #SNOBOL4 | SNOBOL4 |
* copy a to b
b = a = "test"
output = a
output = b
* change the copy
b "t" = "T"
output = b
end |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #Racket | Racket | #lang racket
(require plot plot/utils)
(plot (points (for*/lists (result)
([_ (in-naturals)]
#:break (= 100 (length result))
[xy (in-value (v- (vector (random 31) (random 31))
#(15 15)))]
#:when (<= 10 (vmag xy) 15))
xy))) |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Sidef | Sidef | var a = <Enjoy Rosetta Code>
a.map{|str|
{ Sys.sleep(1.rand)
say str
}.fork
}.map{|thr| thr.wait } |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Swift | Swift | import Foundation
let myList = ["Enjoy", "Rosetta", "Code"]
for word in myList {
dispatch_async(dispatch_get_global_queue(0, 0)) {
NSLog(word)
}
}
dispatch_main() |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Standard_ML | Standard ML | structure TTd = Thread.Thread ;
structure TTm = Thread.Mutex ;
val threadedStringList = fn tasks:string list =>
let
val mx = TTm.mutex () ;
val taskstore = ref tasks ;
fun makeFastRand () = Real.rem (Time.toReal (Time.now ()),1.0)
val doTask = fn () =>
let
val mytask : string ref = ref "" ;
in
( TTm.lock mx ; mytask := hd ( !taskstore ) ; taskstore:= tl (!taskstore) ; TTm.unlock mx ;
Posix.Process.sleep (Time.fromReal (makeFastRand ())) ;
TTm.lock mx ; print ( !mytask ^ "\n") ; TTm.unlock mx ;
TTd.exit ()
)
end
in
List.tabulate ( length tasks , fn i => TTd.fork (doTask , []) )
end ;
|
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #ALGOL_60 | ALGOL 60 | expression::= if conditional_expression then expression else expression
K:=if X=Y then I else J
|
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #Aime | Aime | integer n, pc, sp;
file f;
text s;
index code, Data;
list l, stack, strings;
f.affix(argv(1));
f.list(l, 0);
n = atoi(l[-1]);
while (n) {
f.lead(s);
strings.append(erase(s, -1, 0));
n -= 1;
}
while (f.list(l, 0) ^ -1) {
code.put(atoi(lf_x_text(l)), l);
}
pc = sp = 0;
while (1) {
l = code[pc];
s = l[0];
if (s == "jz") {
if (lb_pick(stack)) {
isk_greater(code, pc, pc);
} else {
pc = atoi(l[-1]);
}
} elif (s == "jmp") {
pc = atoi(l[-1]);
} else {
if (s == "push") {
lb_push(stack, atoi(l[1]));
} elif (s == "fetch") {
lb_push(stack, Data[atoi(erase(l[1], -1, 0))]);
} elif (s == "neg") {
stack[-1] = -stack[-1];
} elif (s == "not") {
stack[-1] = !stack[-1];
} elif (s == "halt") {
break;
} else {
n = lb_pick(stack);
if (s == "store") {
Data[atoi(erase(l[1], -1, 0))] = n;
} elif (s == "add") {
stack[-1] = stack[-1] + n;
} elif (s == "sub") {
stack[-1] = stack[-1] - n;
} elif (s == "mul") {
stack[-1] = stack[-1] * n;
} elif (s == "div") {
stack[-1] = stack[-1] / n;
} elif (s == "mod") {
stack[-1] = stack[-1] % n;
} elif (s == "lt") {
stack[-1] = stack[-1] < n;
} elif (s == "gt") {
stack[-1] = stack[-1] > n;
} elif (s == "le") {
stack[-1] = stack[-1] <= n;
} elif (s == "ge") {
stack[-1] = stack[-1] >= n;
} elif (s == "eq") {
stack[-1] = stack[-1] == n;
} elif (s == "ne") {
stack[-1] = stack[-1] != n;
} elif (s == "and") {
stack[-1] = stack[-1] && n;
} elif (s == "or") {
stack[-1] = stack[-1] || n;
} elif (s == "prtc") {
o_byte(n);
} elif (s == "prti") {
o_(n);
} elif (s == "prts") {
o_(strings[n]);
} else {
}
}
isk_greater(code, pc, pc);
}
} |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #Forth | Forth | CREATE BUF 0 , \ single-character look-ahead buffer
: PEEK BUF @ 0= IF KEY BUF ! THEN BUF @ ;
: GETC PEEK 0 BUF ! ;
: SPACE? DUP BL = SWAP 9 14 WITHIN OR ;
: >SPACE BEGIN PEEK SPACE? WHILE GETC DROP REPEAT ;
: DIGIT? 48 58 WITHIN ;
: GETINT >SPACE 0
BEGIN PEEK DIGIT?
WHILE GETC [CHAR] 0 - SWAP 10 * + REPEAT ;
: GETNAM >SPACE PAD 1+
BEGIN PEEK SPACE? INVERT
WHILE GETC OVER C! CHAR+
REPEAT PAD TUCK - 1- PAD C! ;
: GETSTR ( -- c-addr u)
HERE >R 0 >SPACE GETC DROP \ skip leading "
BEGIN GETC DUP [CHAR] " <> WHILE C, 1+ REPEAT
DROP R> SWAP ;
: \TYPE BEGIN DUP 0> WHILE
OVER C@ [CHAR] \ = IF
1- >R CHAR+ R>
OVER C@ [CHAR] n = IF CR ELSE
OVER C@ [CHAR] \ = IF [CHAR] \ EMIT THEN THEN
ELSE OVER C@ EMIT THEN 1- >R CHAR+ R> REPEAT
DROP DROP ;
: . S>D SWAP OVER DABS <# #S ROT SIGN #> TYPE ;
: CONS ( v l -- l) HERE >R SWAP , , R> ;
: HEAD ( l -- v) @ ;
: TAIL ( l -- l) CELL+ @ ;
CREATE GLOBALS 0 ,
: DECLARE ( c-addr -- a-addr) HERE TUCK
OVER C@ CHAR+ DUP ALLOT CMOVE HERE SWAP 0 ,
GLOBALS @ CONS GLOBALS ! ;
: LOOKUP ( c-addr -- a-addr) DUP COUNT GLOBALS @ >R
BEGIN R@ 0<>
WHILE R@ HEAD COUNT 2OVER COMPARE 0=
IF 2DROP DROP R> HEAD DUP C@ CHAR+ + EXIT
THEN R> TAIL >R
REPEAT
2DROP RDROP DECLARE ;
DEFER GETAST
: >Identifier GETNAM LOOKUP 0 ;
: >Integer GETINT 0 ;
: >String GETSTR ;
: >; 0 0 ;
: NODE ( xt left right -- addr) HERE >R , , , R> ;
CREATE BUF' 12 ALLOT
: PREPEND ( c-addr c -- c-addr) BUF' 1+ C!
COUNT DUP 1+ BUF' C! BUF' 2 + SWAP CMOVE BUF' ;
: HANDLER ( c-addr -- xt) [CHAR] $ PREPEND FIND
0= IF ." No handler for AST node '" COUNT TYPE ." '" THEN ;
: READER ( c-addr -- xt t | f)
[CHAR] > PREPEND FIND DUP 0= IF NIP THEN ;
: READ ( c-addr -- left right) READER
IF EXECUTE ELSE GETAST GETAST THEN ;
: (GETAST) GETNAM DUP HANDLER SWAP READ NODE ;
' (GETAST) IS GETAST
: INTERP DUP 2@ ROT [ 2 CELLS ]L + @ EXECUTE ;
: $; DROP DROP ;
: $Identifier ( l r -- a-addr) DROP @ ;
: $Integer ( l r -- n) DROP ;
: $String ( l r -- c-addr u) ( noop) ;
: $Prtc ( l r --) DROP INTERP EMIT ;
: $Prti ( l r --) DROP INTERP . ;
: $Prts ( l r --) DROP INTERP \TYPE ;
: $Not ( l r --) DROP INTERP 0= ;
: $Negate ( l r --) DROP INTERP NEGATE ;
: $Sequence ( l r --) SWAP INTERP INTERP ;
: $Assign ( l r --) SWAP CELL+ @ >R INTERP R> ! ;
: $While ( l r --)
>R BEGIN DUP INTERP WHILE R@ INTERP REPEAT RDROP DROP ;
: $If ( l r --) SWAP INTERP 0<> IF CELL+ THEN @ INTERP ;
: $Subtract ( l r -- n) >R INTERP R> INTERP - ;
: $Add >R INTERP R> INTERP + ;
: $Mod >R INTERP R> INTERP MOD ;
: $Multiply >R INTERP R> INTERP * ;
: $Divide >R INTERP S>D R> INTERP SM/REM SWAP DROP ;
: $Less >R INTERP R> INTERP < ;
: $LessEqual >R INTERP R> INTERP <= ;
: $Greater >R INTERP R> INTERP > ;
: $GreaterEqual >R INTERP R> INTERP >= ;
: $Equal >R INTERP R> INTERP = ;
: $NotEqual >R INTERP R> INTERP <> ;
: $And >R INTERP IF R> INTERP 0<> ELSE RDROP 0 THEN ;
: $Or >R INTERP IF RDROP -1 ELSE R> INTERP 0<> THEN ;
GETAST INTERP
|
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #AWK | AWK |
function Token_assign(tk, attr, attr_array, n, i) {
n=split(attr, attr_array)
for(i=1; i<=n; i++)
Tokens[tk,i-1] = attr_array[i]
}
#*** show error and exit
function error(msg) {
printf("(%s, %s) %s\n", err_line, err_col, msg)
exit(1)
}
function gettok( line, n, i) {
getline line
if (line == "")
error("empty line")
n=split(line, line_list)
# line col Ident var_name
# 1 2 3 4
err_line = line_list[1]
err_col = line_list[2]
tok_text = line_list[3]
tok = all_syms[tok_text]
for (i=5; i<=n; i++)
line_list[4] = line_list[4] " " line_list[i]
if (tok == "")
error("Unknown token " tok_text)
tok_other = ""
if (tok == "tk_Integer" || tok == "tk_Ident" || tok =="tk_String")
tok_other = line_list[4]
}
function make_node(oper, left, right, value) {
node_type [next_free_node_index] = oper
node_left [next_free_node_index] = left
node_right[next_free_node_index] = right
node_value[next_free_node_index] = value
return next_free_node_index ++
}
function make_leaf(oper, n) {
return make_node(oper, 0, 0, n)
}
function expect(msg, s) {
if (tok == s) {
gettok()
return
}
error(msg ": Expecting '" Tokens[s,TK_NAME] "', found '" Tokens[tok,TK_NAME] "'")
}
function expr(p, x, op, node) {
x = 0
if (tok == "tk_Lparen") {
x = paren_expr()
} else if (tok == "tk_Sub" || tok == "tk_Add") {
if (tok == "tk_Sub")
op = "tk_Negate"
else
op = "tk_Add"
gettok()
node = expr(Tokens["tk_Negate",TK_PRECEDENCE]+0)
if (op == "tk_Negate")
x = make_node("nd_Negate", node)
else
x = node
} else if (tok == "tk_Not") {
gettok()
x = make_node("nd_Not", expr(Tokens["tk_Not",TK_PRECEDENCE]+0))
} else if (tok == "tk_Ident") {
x = make_leaf("nd_Ident", tok_other)
gettok()
} else if (tok == "tk_Integer") {
x = make_leaf("nd_Integer", tok_other)
gettok()
} else {
error("Expecting a primary, found: " Tokens[tok,TK_NAME])
}
while (((Tokens[tok,TK_IS_BINARY]+0) > 0) && ((Tokens[tok,TK_PRECEDENCE]+0) >= p)) {
op = tok
gettok()
q = Tokens[op,TK_PRECEDENCE]+0
if (! (Tokens[op,TK_RIGHT_ASSOC]+0 > 0))
q += 1
node = expr(q)
x = make_node(Tokens[op,TK_NODE], x, node)
}
return x
}
function paren_expr( node) {
expect("paren_expr", "tk_Lparen")
node = expr(0)
expect("paren_expr", "tk_Rparen")
return node
}
function stmt( t, e, s, s2, v) {
t = 0
if (tok == "tk_If") {
gettok()
e = paren_expr()
s = stmt()
s2 = 0
if (tok == "tk_Else") {
gettok()
s2 = stmt()
}
t = make_node("nd_If", e, make_node("nd_If", s, s2))
} else if (tok == "tk_Putc") {
gettok()
e = paren_expr()
t = make_node("nd_Prtc", e)
expect("Putc", "tk_Semi")
} else if (tok == "tk_Print") {
gettok()
expect("Print", "tk_Lparen")
while (1) {
if (tok == "tk_String") {
e = make_node("nd_Prts", make_leaf("nd_String", tok_other))
gettok()
} else {
e = make_node("nd_Prti", expr(0))
}
t = make_node("nd_Sequence", t, e)
if (tok != "tk_Comma")
break
gettok()
}
expect("Print", "tk_Rparen")
expect("Print", "tk_Semi")
} else if (tok == "tk_Semi") {
gettok()
} else if (tok == "tk_Ident") {
v = make_leaf("nd_Ident", tok_other)
gettok()
expect("assign", "tk_Assign")
e = expr(0)
t = make_node("nd_Assign", v, e)
expect("assign", "tk_Semi")
} else if (tok == "tk_While") {
gettok()
e = paren_expr()
s = stmt()
t = make_node("nd_While", e, s)
} else if (tok == "tk_Lbrace") {
gettok()
while (tok != "tk_Rbrace" && tok != "tk_EOI")
t = make_node("nd_Sequence", t, stmt())
expect("Lbrace", "tk_Rbrace")
} else if (tok == "tk_EOI") {
} else {
error("Expecting start of statement, found: " Tokens[tok,TK_NAME])
}
return t
}
function parse( t) {
t = 0 # None
gettok()
while (1) {
t = make_node("nd_Sequence", t, stmt())
if (tok == "tk_EOI" || t == 0)
break
}
return t
}
function prt_ast(t) {
if (t == 0) {
print(";")
} else {
printf("%-14s", Display_nodes[node_type[t]])
if ((node_type[t] == "nd_Ident") || (node_type[t] == "nd_Integer"))
printf("%s\n", node_value[t])
else if (node_type[t] == "nd_String") {
printf("%s\n", node_value[t])
} else {
print("")
prt_ast(node_left[t])
prt_ast(node_right[t])
}
}
}
BEGIN {
all_syms["End_of_input" ] = "tk_EOI"
all_syms["Op_multiply" ] = "tk_Mul"
all_syms["Op_divide" ] = "tk_Div"
all_syms["Op_mod" ] = "tk_Mod"
all_syms["Op_add" ] = "tk_Add"
all_syms["Op_subtract" ] = "tk_Sub"
all_syms["Op_negate" ] = "tk_Negate"
all_syms["Op_not" ] = "tk_Not"
all_syms["Op_less" ] = "tk_Lss"
all_syms["Op_lessequal" ] = "tk_Leq"
all_syms["Op_greater" ] = "tk_Gtr"
all_syms["Op_greaterequal" ] = "tk_Geq"
all_syms["Op_equal" ] = "tk_Eq"
all_syms["Op_notequal" ] = "tk_Neq"
all_syms["Op_assign" ] = "tk_Assign"
all_syms["Op_and" ] = "tk_And"
all_syms["Op_or" ] = "tk_Or"
all_syms["Keyword_if" ] = "tk_If"
all_syms["Keyword_else" ] = "tk_Else"
all_syms["Keyword_while" ] = "tk_While"
all_syms["Keyword_print" ] = "tk_Print"
all_syms["Keyword_putc" ] = "tk_Putc"
all_syms["LeftParen" ] = "tk_Lparen"
all_syms["RightParen" ] = "tk_Rparen"
all_syms["LeftBrace" ] = "tk_Lbrace"
all_syms["RightBrace" ] = "tk_Rbrace"
all_syms["Semicolon" ] = "tk_Semi"
all_syms["Comma" ] = "tk_Comma"
all_syms["Identifier" ] = "tk_Ident"
all_syms["Integer" ] = "tk_Integer"
all_syms["String" ] = "tk_String"
Display_nodes["nd_Ident" ] = "Identifier"
Display_nodes["nd_String" ] = "String"
Display_nodes["nd_Integer" ] = "Integer"
Display_nodes["nd_Sequence"] = "Sequence"
Display_nodes["nd_If" ] = "If"
Display_nodes["nd_Prtc" ] = "Prtc"
Display_nodes["nd_Prts" ] = "Prts"
Display_nodes["nd_Prti" ] = "Prti"
Display_nodes["nd_While" ] = "While"
Display_nodes["nd_Assign" ] = "Assign"
Display_nodes["nd_Negate" ] = "Negate"
Display_nodes["nd_Not" ] = "Not"
Display_nodes["nd_Mul" ] = "Multiply"
Display_nodes["nd_Div" ] = "Divide"
Display_nodes["nd_Mod" ] = "Mod"
Display_nodes["nd_Add" ] = "Add"
Display_nodes["nd_Sub" ] = "Subtract"
Display_nodes["nd_Lss" ] = "Less"
Display_nodes["nd_Leq" ] = "LessEqual"
Display_nodes["nd_Gtr" ] = "Greater"
Display_nodes["nd_Geq" ] = "GreaterEqual"
Display_nodes["nd_Eql" ] = "Equal"
Display_nodes["nd_Neq" ] = "NotEqual"
Display_nodes["nd_And" ] = "And"
Display_nodes["nd_Or" ] = "Or"
TK_NAME = 0
TK_RIGHT_ASSOC = 1
TK_IS_BINARY = 2
TK_IS_UNARY = 3
TK_PRECEDENCE = 4
TK_NODE = 5
Token_assign("tk_EOI" , "EOI 0 0 0 -1 -1 ")
Token_assign("tk_Mul" , "* 0 1 0 13 nd_Mul ")
Token_assign("tk_Div" , "/ 0 1 0 13 nd_Div ")
Token_assign("tk_Mod" , "% 0 1 0 13 nd_Mod ")
Token_assign("tk_Add" , "+ 0 1 0 12 nd_Add ")
Token_assign("tk_Sub" , "- 0 1 0 12 nd_Sub ")
Token_assign("tk_Negate" , "- 0 0 1 14 nd_Negate ")
Token_assign("tk_Not" , "! 0 0 1 14 nd_Not ")
Token_assign("tk_Lss" , "< 0 1 0 10 nd_Lss ")
Token_assign("tk_Leq" , "<= 0 1 0 10 nd_Leq ")
Token_assign("tk_Gtr" , "> 0 1 0 10 nd_Gtr ")
Token_assign("tk_Geq" , ">= 0 1 0 10 nd_Geq ")
Token_assign("tk_Eql" , "== 0 1 0 9 nd_Eql ")
Token_assign("tk_Neq" , "!= 0 1 0 9 nd_Neq ")
Token_assign("tk_Assign" , "= 0 0 0 -1 nd_Assign ")
Token_assign("tk_And" , "&& 0 1 0 5 nd_And ")
Token_assign("tk_Or" , "|| 0 1 0 4 nd_Or ")
Token_assign("tk_If" , "if 0 0 0 -1 nd_If ")
Token_assign("tk_Else" , "else 0 0 0 -1 -1 ")
Token_assign("tk_While" , "while 0 0 0 -1 nd_While ")
Token_assign("tk_Print" , "print 0 0 0 -1 -1 ")
Token_assign("tk_Putc" , "putc 0 0 0 -1 -1 ")
Token_assign("tk_Lparen" , "( 0 0 0 -1 -1 ")
Token_assign("tk_Rparen" , ") 0 0 0 -1 -1 ")
Token_assign("tk_Lbrace" , "{ 0 0 0 -1 -1 ")
Token_assign("tk_Rbrace" , "} 0 0 0 -1 -1 ")
Token_assign("tk_Semi" , "; 0 0 0 -1 -1 ")
Token_assign("tk_Comma" , ", 0 0 0 -1 -1 ")
Token_assign("tk_Ident" , "Ident 0 0 0 -1 nd_Ident ")
Token_assign("tk_Integer", "Integer 0 0 0 -1 nd_Integer")
Token_assign("tk_String" , "String 0 0 0 -1 nd_String ")
input_file = "-"
err_line = 0
err_col = 0
tok = ""
tok_text = ""
next_free_node_index = 1
if (ARGC > 1)
input_file = ARGV[1]
t = parse()
prt_ast(t)
}
|
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #Axe | Axe | Full
While getKey(0)
End
ClrDraw
.BLINKER
Pxl-On(45,45)
Pxl-On(46,45)
Pxl-On(47,45)
.GLIDER
Pxl-On(1,1)
Pxl-On(2,2)
Pxl-On(2,3)
Pxl-On(3,1)
Pxl-On(3,2)
Repeat getKey(0)
DispGraph
EVOLVE()
RecallPic
ClrDrawʳ
End
Return
Lbl EVOLVE
For(Y,0,63)
For(X,0,95)
0→N
For(B,Y-1,Y+1)
For(A,X-1,X+1)
pxl-Test(A,B)?N++
End
End
pxl_Test(X,Y)?N--
If N=3??(N=2?pxl-Test(X,Y))
Pxl-On(X,Y)ʳ
Else
Pxl-Off(X,Y)ʳ
End
End
End
Return |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Modula-2 | Modula-2 | TYPE Point = RECORD
x, y : INTEGER
END; |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Modula-3 | Modula-3 | TYPE Point = RECORD
x, y: INTEGER;
END; |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Standard_ML | Standard ML | val src = "Hello";
val srcCopy = CharArray.array (size src, #"x"); (* 'x' is just dummy character *)
CharArray.copyVec {src = src, dst = srcCopy, di = 0};
src = CharArray.vector srcCopy; (* evaluates to true *) |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Swift | Swift | var src = "Hello"
var dst = src |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #Raku | Raku | my @range = -15..16;
my @points = gather for @range X @range -> ($x, $y) {
take [$x,$y] if 10 <= sqrt($x*$x+$y*$y) <= 15
}
my @samples = @points.roll(100); # or .pick(100) to get distinct points
# format and print
my %matrix;
for @range X @range -> ($x, $y) { %matrix{$y}{$x} = ' ' }
%matrix{.[1]}{.[0]} = '*' for @samples;
%matrix{$_}{@range}.join(' ').say for @range; |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Tcl | Tcl | after [expr int(1000*rand())] {puts "Enjoy"}
after [expr int(1000*rand())] {puts "Rosetta"}
after [expr int(1000*rand())] {puts "Code"} |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #UnixPipes | UnixPipes | (echo "Enjoy" & echo "Rosetta"& echo "Code"&) |
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #ALGOL_68 | ALGOL 68 | begin
integer a, b, c;
a := 1; b := 2; c := 3;
% algol W has the traditional Algol if-the-else statement %
% there is no "elseif" contraction %
if a = b
then write( "a = b" )
else if a = c
then write( "a = c" )
else write( "a is ", a );
% if-then-else can also be used in an expression %
write( if a < 4 then "lt 4" else "ge 4" );
% algol W also has a "case" statement, an integer expression is used to %
% select the statement to execute. If the expression evaluates to 1, %
% the first statement is executed, if 2, the second is executed etc. %
% If the expression is less than 1 or greater than the number of %
% statements, a run time error occurs %
case a + b of
begin write( "a + b is one" )
; write( "a + b is two" )
; write( "a + b is three" )
; write( "a + b is four" )
end;
% there is also an expression form of the case: %
write( case c - a of ( "one", "two", "three", "four" ) )
end. |
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #ALGOL_W | ALGOL W | begin % virtual machine interpreter %
% string literals %
string(256) array stringValue ( 0 :: 256 );
integer array stringLength ( 0 :: 256 );
integer MAX_STRINGS;
% op codes %
integer oFetch, oStore, oPush
, oAdd, oSub, oMul, oDiv, oMod, oLt, oGt, oLe, oGe, oEq, oNe
, oAnd, oOr, oNeg, oNot, oJmp, oJz, oPrtc, oPrts, oPrti, oHalt
;
string(6) array opName ( 1 :: 24 );
integer OP_MAX;
% code %
string(1) array byteCode ( 0 :: 4096 );
integer nextLocation, MAX_LOCATION;
% data %
integer array data ( 0 :: 4096 );
integer dataSize, MAX_DATA, MAX_STACK;
% tracing %
logical trace;
% reports an error and stops %
procedure rtError( string(80) value message ); begin
integer errorPos;
write( s_w := 0, "**** Runtime error: " );
errorPos := 0;
while errorPos < 80 and message( errorPos // 1 ) not = "." do begin
writeon( s_w := 0, message( errorPos // 1 ) );
errorPos := errorPos + 1
end while_not_at_end_of_message ;
writeon( s_w := 0, "." );
assert( false )
end genError ;
oFetch := 1; opName( oFetch ) := "fetch"; oStore := 2; opName( oStore ) := "store"; oPush := 3; opName( oPush ) := "push";
oAdd := 4; opName( oAdd ) := "add"; oSub := 5; opName( oSub ) := "sub"; oMul := 6; opName( oMul ) := "mul";
oDiv := 7; opName( oDiv ) := "div"; oMod := 8; opName( oMod ) := "mod"; oLt := 9; opName( oLt ) := "lt";
oGt := 10; opName( oGt ) := "gt"; oLe := 11; opName( oLe ) := "le"; oGe := 12; opName( oGe ) := "ge";
oEq := 13; opName( oEq ) := "eq"; oNe := 14; opName( oNe ) := "ne"; oAnd := 15; opName( oAnd ) := "and";
oOr := 16; opName( oOr ) := "or"; oNeg := 17; opName( oNeg ) := "neg"; oNot := 18; opName( oNot ) := "not";
oJmp := 19; opName( oJmp ) := "jmp"; oJz := 20; opName( oJz ) := "jz"; oPrtc := 21; opName( oPrtc ) := "prtc";
oPrts := 22; opName( oPrts ) := "prts"; oPrti := 23; opName( oPrti ) := "prti"; oHalt := 24; opName( oHalt ) := "halt";
OP_MAX := oHalt;
trace := false;
MAX_STACK := 256;
MAX_LOCATION := 4096;
for pc := 0 until MAX_LOCATION do byteCode( pc ) := code( 0 );
MAX_DATA := 4096;
for dPos := 0 until MAX_DATA do data( dPos ) := 0;
MAX_STRINGS := 256;
for sPos := 0 until MAX_STRINGS do begin
stringValue( sPos ) := " ";
stringLength( sPos ) := 0
end for_sPos ;
% load thge output from syntaxc analyser %
begin % readCode %
% skips spaces on the source line %
procedure skipSpaces ; begin
while line( lPos // 1 ) = " " do lPos := lPos + 1
end skipSpaces ;
% parses a string from line and stores it in the string literals table %
procedure readString ( integer value stringNumber ) ; begin
string(256) str;
integer sLen;
str := " ";
sLen := 0;
lPos := lPos + 1; % skip the opening double-quote %
while lPos <= 255 and line( lPos // 1 ) not = """" do begin
str( sLen // 1 ) := line( lPos // 1 );
sLen := sLen + 1;
lPos := lPos + 1
end while_more_string ;
if lPos > 255 then rtError( "Unterminated String." );
% store the string %
stringValue( stringNumber ) := str;
stringLength( stringNumber ) := sLen
end readString ;
% gets an integer from the line - checks for valid digits %
integer procedure readInteger ; begin
integer n;
skipSpaces;
n := 0;
while line( lPos // 1 ) >= "0" and line( lPos // 1 ) <= "9" do begin
n := ( n * 10 ) + ( decode( line( lPos // 1 ) ) - decode( "0" ) );
lPos := lPos + 1
end while_not_end_of_integer ;
n
end readInteger ;
% reads the next line from standard input %
procedure readALine ; begin
lPos := 0;
readcard( line );
if trace then write( s_w := 0, ">> ", line( 0 // 32 ) )
end readALine ;
% loads an instruction from the current source line %
procedure loadCodeFromLine ; begin
integer pc, opCode, operand, oPos;
string(256) op;
logical haveOperand;
% get the code location %
pc := readInteger;
if pc > MAX_LOCATION then rtError( "Code too large." );
% get the opCode %
skipSpaces;
oPos := 0;
op := " ";
while lPos <= 255 and line( lPos // 1 ) not = " " do begin
op( oPos // 1 ) := line( lPos // 1 );
oPos := oPos + 1;
lPos := lPos + 1
end while_more_opName ;
% lookup the op code %
opCode := 0;
oPos := 1;
while oPos <= OP_MAX and opCode = 0 do begin
if opName( oPos ) = op then opCode := oPos
else oPos := oPos + 1
end while_op_not_found ;
if opCode = 0 then rtError( "Unknown op code." );
% get the operand if there is one %
operand := 0;
haveOperand := false;
if opCode = oFetch or opCode = oStore then begin
% fetch or store - operand is enclosed in square brackets %
skipSpaces;
if line( lPos // 1 ) not = "[" then rtError( """["" expected after fetch/store." );
lPos := lPos + 1;
operand := readInteger;
if operand > dataSize then rtError( "fetch/store address out of range." );
haveOperand := true
end
else if opCode = oPush then begin
% push integer literal instruction %
operand := readInteger;
haveOperand := true
end
else if opCode = oJmp or opCode = oJz then begin
% jump - the operand is the relative address enclosed in parenthesis %
% followed by the absolute address - we use the absolute address so %
% the opewrand will be >= 0 %
skipSpaces;
if line( lPos // 1 ) not = "(" then rtError( """("" expected after jmp/jz." );
lPos := lPos + 1;
if line( lPos // 1 ) = "-" then % negative relative address % lPos := lPos + 1;
operand := readInteger;
if line( lPos // 1 ) not = ")" then rtError( """)"" expected after jmp/jz." );
lPos := lPos + 1;
operand := readInteger;
haveOperand := true
end if_various_opcodes ;
% store the code %
byteCode( pc ) := code( opCode );
if haveOperand then begin
% have an operand for the op code %
if ( pc + 4 ) > MAX_LOCATION then rtError( "Code too large." );
for oPos := 1 until 4 do begin
pc := pc + 1;
byteCode( pc ) := code( operand rem 256 );
operand := operand div 256;
end for_oPos
end if_have_operand ;
end loadCodeFromLine ;
string(256) line;
string(16) name;
integer lPos, tPos, stringCount;
% allow us to detect EOF %
ENDFILE := EXCEPTION( false, 1, 0, false, "EOF" );
% first line should be "Datasize: d Strings: s" where d = number variables %
% and s = number of strings %
readALine;
if line = "trace" then begin
% extension - run in trace mode %
trace := true;
readALine
end if_line_eq_trace ;
if XCPNOTED(ENDFILE) then rtError( "Empty program file." );
if line( 0 // 10 ) not = "Datasize: " then rtError( "Header line missing." );
lPos := 10;
dataSize := readInteger;
if dataSize > MAX_DATA then rtError( "Datasize too large." );
skipSpaces;
if line( lPos // 9 ) not = "Strings: " then rtError( """Strings: "" missing on header line." );
lPos := lPos + 9;
stringCount := readInteger;
if stringCount > MAX_STRINGS then rtError( "Too many strings." );
% read the string table %
for stringNumber := 0 until stringCount - 1 do begin
string(256) str;
integer sLen, sPos;
readALine;
if XCPNOTED(ENDFILE) then rtError( "End-of-file in string table." );
if line( lPos // 1 ) not = """" then rtError( "String literal expected." );
str := " ";
sLen := 0;
lPos := lPos + 1; % skip the opening double-quote %
while lPos <= 255 and line( lPos // 1 ) not = """" do begin
str( sLen // 1 ) := line( lPos // 1 );
sLen := sLen + 1;
lPos := lPos + 1
end while_more_string ;
if lPos > 255 then rtError( "Unterminated String." );
% store the string %
stringValue( stringNumber ) := str;
stringLength( stringNumber ) := sLen
end for_sPos ;
% read the code %
readALine;
while not XCPNOTED(ENDFILE) do begin
if line not = " " then loadCodeFromLine;
readALine
end while_not_eof
end;
% run the program %
begin
integer pc, opCode, operand, sp;
integer array st ( 0 :: MAX_STACK );
logical halted;
% prints a string from the string pool, escape sequences are interpreted %
procedure writeOnString( integer value stringNumber ) ;
begin
integer cPos, sLen;
string(256) text;
if stringNumber < 0 or stringNumber > MAX_STRINGS then rtError( "Invalid string number." );
cPos := 0;
sLen := stringLength( stringNumber );
text := stringValue( stringNumber );
while cPos < stringLength( stringNumber ) do begin
string(1) ch;
ch := text( cPos // 1 );
if ch not = "\" then writeon( s_w := 0, ch )
else begin
% escaped character %
cPos := cPos + 1;
if cPos > sLen then rtError( "String terminates with ""\""." );
ch := text( cPos // 1 );
if ch = "n" then % newline % write()
else writeon( s_w := 0, ch )
end;
cPos := cPos + 1
end while_not_end_of_string
end writeOnString ;
pc := 0;
sp := -1;
halted := false;
while not halted do begin;
% get the next op code and operand %
opCode := decode( byteCode( pc ) );
pc := pc + 1;
operand := 0;
if opCode = oFetch or opCode = oStore or opCode = oPush or opCode = oJmp or opCode = oJz then begin
% this opCode has an operand %
pc := pc + 4;
for bPos := 1 until 4 do begin
operand := ( operand * 256 ) + decode( byteCode( pc - bPos ) );
end for_bPos
end if_opCode_with_an_operand ;
if trace then begin
write( i_w:= 1, s_w := 0, pc, " op(", opCode, "): ", opName( opCode ), " ", operand );
write()
end if_trace ;
% interpret the instruction %
if opCode = oFetch then begin sp := sp + 1; st( sp ) := data( operand ) end
else if opCode = oStore then begin data( operand ) := st( sp ); sp := sp - 1 end
else if opCode = oPush then begin sp := sp + 1; st( sp ) := operand end
else if opCode = oHalt then halted := true
else if opCode = oJmp then pc := operand
else if oPCode = oJz then begin
if st( sp ) = 0 then pc := operand;
sp := sp - 1
end
else if opCode = oPrtc then begin writeon( i_w := 1, s_w := 0, code( st( sp ) ) ); sp := sp - 1 end
else if opCode = oPrti then begin writeon( i_w := 1, s_w := 0, st( sp ) ); sp := sp - 1 end
else if opCode = oPrts then begin writeonString( st( sp ) ); sp := sp - 1 end
else if opCode = oNeg then st( sp ) := - st( sp )
else if opCode = oNot then st( sp ) := ( if st( sp ) = 0 then 1 else 0 )
else begin
operand := st( sp );
sp := sp - 1;
if opCode = oAdd then st( sp ) := st( sp ) + operand
else if opCode = oSub then st( sp ) := st( sp ) - operand
else if opCode = oMul then st( sp ) := st( sp ) * operand
else if opCode = oDiv then st( sp ) := st( sp ) div operand
else if opCode = oMod then st( sp ) := st( sp ) rem operand
else if opCode = oLt then st( sp ) := if st( sp ) < operand then 1 else 0
else if opCode = oGt then st( sp ) := if st( sp ) > operand then 1 else 0
else if opCode = oLe then st( sp ) := if st( sp ) <= operand then 1 else 0
else if opCode = oGe then st( sp ) := if st( sp ) >= operand then 1 else 0
else if opCode = oEq then st( sp ) := if st( sp ) = operand then 1 else 0
else if opCode = oNe then st( sp ) := if st( sp ) not = operand then 1 else 0
else if opCode = oAnd then st( sp ) := if st( sp ) not = 0 and operand not = 0 then 1 else 0
else if opCode = oOr then st( sp ) := if st( sp ) not = 0 or operand not = 0 then 1 else 0
else rtError( "Unknown opCode." )
end if_various_opCodes
end while_not_halted
end
end. |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #Fortran | Fortran | !!!
!!! An implementation of the Rosetta Code interpreter task:
!!! https://rosettacode.org/wiki/Compiler/AST_interpreter
!!!
!!! The implementation is based on the published pseudocode.
!!!
module compiler_type_kinds
use, intrinsic :: iso_fortran_env, only: int32
use, intrinsic :: iso_fortran_env, only: int64
implicit none
private
! Synonyms.
integer, parameter, public :: size_kind = int64
integer, parameter, public :: length_kind = size_kind
integer, parameter, public :: nk = size_kind
! Synonyms for character capable of storing a Unicode code point.
integer, parameter, public :: unicode_char_kind = selected_char_kind ('ISO_10646')
integer, parameter, public :: ck = unicode_char_kind
! Synonyms for integers capable of storing a Unicode code point.
integer, parameter, public :: unicode_ichar_kind = int32
integer, parameter, public :: ick = unicode_ichar_kind
! Synonyms for integers in the runtime code.
integer, parameter, public :: runtime_int_kind = int64
integer, parameter, public :: rik = runtime_int_kind
end module compiler_type_kinds
module helper_procedures
use, non_intrinsic :: compiler_type_kinds, only: nk, ck
implicit none
private
public :: new_storage_size
public :: next_power_of_two
public :: isspace
character(1, kind = ck), parameter :: horizontal_tab_char = char (9, kind = ck)
character(1, kind = ck), parameter :: linefeed_char = char (10, kind = ck)
character(1, kind = ck), parameter :: vertical_tab_char = char (11, kind = ck)
character(1, kind = ck), parameter :: formfeed_char = char (12, kind = ck)
character(1, kind = ck), parameter :: carriage_return_char = char (13, kind = ck)
character(1, kind = ck), parameter :: space_char = ck_' '
contains
elemental function new_storage_size (length_needed) result (size)
integer(kind = nk), intent(in) :: length_needed
integer(kind = nk) :: size
! Increase storage by orders of magnitude.
if (2_nk**32 < length_needed) then
size = huge (1_nk)
else
size = next_power_of_two (length_needed)
end if
end function new_storage_size
elemental function next_power_of_two (x) result (y)
integer(kind = nk), intent(in) :: x
integer(kind = nk) :: y
!
! It is assumed that no more than 64 bits are used.
!
! The branch-free algorithm is that of
! https://archive.is/nKxAc#RoundUpPowerOf2
!
! Fill in bits until one less than the desired power of two is
! reached, and then add one.
!
y = x - 1
y = ior (y, ishft (y, -1))
y = ior (y, ishft (y, -2))
y = ior (y, ishft (y, -4))
y = ior (y, ishft (y, -8))
y = ior (y, ishft (y, -16))
y = ior (y, ishft (y, -32))
y = y + 1
end function next_power_of_two
elemental function isspace (ch) result (bool)
character(1, kind = ck), intent(in) :: ch
logical :: bool
bool = (ch == horizontal_tab_char) .or. &
& (ch == linefeed_char) .or. &
& (ch == vertical_tab_char) .or. &
& (ch == formfeed_char) .or. &
& (ch == carriage_return_char) .or. &
& (ch == space_char)
end function isspace
end module helper_procedures
module string_buffers
use, intrinsic :: iso_fortran_env, only: error_unit
use, intrinsic :: iso_fortran_env, only: int64
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick
use, non_intrinsic :: helper_procedures
implicit none
private
public :: strbuf_t
public :: skip_whitespace
public :: skip_non_whitespace
public :: skip_whitespace_backwards
public :: at_end_of_line
type :: strbuf_t
integer(kind = nk), private :: len = 0
!
! ‘chars’ is made public for efficient access to the individual
! characters.
!
character(1, kind = ck), allocatable, public :: chars(:)
contains
procedure, pass, private :: ensure_storage => strbuf_t_ensure_storage
procedure, pass :: to_unicode_full_string => strbuf_t_to_unicode_full_string
procedure, pass :: to_unicode_substring => strbuf_t_to_unicode_substring
procedure, pass :: length => strbuf_t_length
procedure, pass :: set => strbuf_t_set
procedure, pass :: append => strbuf_t_append
generic :: to_unicode => to_unicode_full_string
generic :: to_unicode => to_unicode_substring
generic :: assignment(=) => set
end type strbuf_t
contains
function strbuf_t_to_unicode_full_string (strbuf) result (s)
class(strbuf_t), intent(in) :: strbuf
character(:, kind = ck), allocatable :: s
!
! This does not actually ensure that the string is valid Unicode;
! any 31-bit ‘character’ is supported.
!
integer(kind = nk) :: i
allocate (character(len = strbuf%len, kind = ck) :: s)
do i = 1, strbuf%len
s(i:i) = strbuf%chars(i)
end do
end function strbuf_t_to_unicode_full_string
function strbuf_t_to_unicode_substring (strbuf, i, j) result (s)
!
! ‘Extreme’ values of i and j are allowed, as shortcuts for ‘from
! the beginning’, ‘up to the end’, or ‘empty substring’.
!
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i, j
character(:, kind = ck), allocatable :: s
!
! This does not actually ensure that the string is valid Unicode;
! any 31-bit ‘character’ is supported.
!
integer(kind = nk) :: i1, j1
integer(kind = nk) :: n
integer(kind = nk) :: k
i1 = max (1_nk, i)
j1 = min (strbuf%len, j)
n = max (0_nk, (j1 - i1) + 1_nk)
allocate (character(n, kind = ck) :: s)
do k = 1, n
s(k:k) = strbuf%chars(i1 + (k - 1_nk))
end do
end function strbuf_t_to_unicode_substring
elemental function strbuf_t_length (strbuf) result (n)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk) :: n
n = strbuf%len
end function strbuf_t_length
subroutine strbuf_t_ensure_storage (strbuf, length_needed)
class(strbuf_t), intent(inout) :: strbuf
integer(kind = nk), intent(in) :: length_needed
integer(kind = nk) :: len_needed
integer(kind = nk) :: new_size
type(strbuf_t) :: new_strbuf
len_needed = max (length_needed, 1_nk)
if (.not. allocated (strbuf%chars)) then
! Initialize a new strbuf%chars array.
new_size = new_storage_size (len_needed)
allocate (strbuf%chars(1:new_size))
else if (ubound (strbuf%chars, 1) < len_needed) then
! Allocate a new strbuf%chars array, larger than the current
! one, but containing the same characters.
new_size = new_storage_size (len_needed)
allocate (new_strbuf%chars(1:new_size))
new_strbuf%chars(1:strbuf%len) = strbuf%chars(1:strbuf%len)
call move_alloc (new_strbuf%chars, strbuf%chars)
end if
end subroutine strbuf_t_ensure_storage
subroutine strbuf_t_set (dst, src)
class(strbuf_t), intent(inout) :: dst
class(*), intent(in) :: src
integer(kind = nk) :: n
integer(kind = nk) :: i
select type (src)
type is (character(*, kind = ck))
n = len (src, kind = nk)
call dst%ensure_storage(n)
do i = 1, n
dst%chars(i) = src(i:i)
end do
dst%len = n
type is (character(*))
n = len (src, kind = nk)
call dst%ensure_storage(n)
do i = 1, n
dst%chars(i) = src(i:i)
end do
dst%len = n
class is (strbuf_t)
n = src%len
call dst%ensure_storage(n)
dst%chars(1:n) = src%chars(1:n)
dst%len = n
class default
error stop
end select
end subroutine strbuf_t_set
subroutine strbuf_t_append (dst, src)
class(strbuf_t), intent(inout) :: dst
class(*), intent(in) :: src
integer(kind = nk) :: n_dst, n_src, n
integer(kind = nk) :: i
select type (src)
type is (character(*, kind = ck))
n_dst = dst%len
n_src = len (src, kind = nk)
n = n_dst + n_src
call dst%ensure_storage(n)
do i = 1, n_src
dst%chars(n_dst + i) = src(i:i)
end do
dst%len = n
type is (character(*))
n_dst = dst%len
n_src = len (src, kind = nk)
n = n_dst + n_src
call dst%ensure_storage(n)
do i = 1, n_src
dst%chars(n_dst + i) = src(i:i)
end do
dst%len = n
class is (strbuf_t)
n_dst = dst%len
n_src = src%len
n = n_dst + n_src
call dst%ensure_storage(n)
dst%chars((n_dst + 1):n) = src%chars(1:n_src)
dst%len = n
class default
error stop
end select
end subroutine strbuf_t_append
function skip_whitespace (strbuf, i) result (j)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
integer(kind = nk) :: j
logical :: done
j = i
done = .false.
do while (.not. done)
if (at_end_of_line (strbuf, j)) then
done = .true.
else if (.not. isspace (strbuf%chars(j))) then
done = .true.
else
j = j + 1
end if
end do
end function skip_whitespace
function skip_non_whitespace (strbuf, i) result (j)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
integer(kind = nk) :: j
logical :: done
j = i
done = .false.
do while (.not. done)
if (at_end_of_line (strbuf, j)) then
done = .true.
else if (isspace (strbuf%chars(j))) then
done = .true.
else
j = j + 1
end if
end do
end function skip_non_whitespace
function skip_whitespace_backwards (strbuf, i) result (j)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
integer(kind = nk) :: j
logical :: done
j = i
done = .false.
do while (.not. done)
if (j == -1) then
done = .true.
else if (.not. isspace (strbuf%chars(j))) then
done = .true.
else
j = j - 1
end if
end do
end function skip_whitespace_backwards
function at_end_of_line (strbuf, i) result (bool)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
logical :: bool
bool = (strbuf%length() < i)
end function at_end_of_line
end module string_buffers
module reading_one_line_from_a_stream
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick
use, non_intrinsic :: string_buffers
implicit none
private
! get_line_from_stream: read an entire input line from a stream into
! a strbuf_t.
public :: get_line_from_stream
character(1, kind = ck), parameter :: linefeed_char = char (10, kind = ck)
! The following is correct for Unix and its relatives.
character(1, kind = ck), parameter :: newline_char = linefeed_char
contains
subroutine get_line_from_stream (unit_no, eof, no_newline, strbuf)
integer, intent(in) :: unit_no
logical, intent(out) :: eof ! End of file?
logical, intent(out) :: no_newline ! There is a line but it has no
! newline? (Thus eof also must
! be .true.)
class(strbuf_t), intent(inout) :: strbuf
character(1, kind = ck) :: ch
strbuf = ''
call get_ch (unit_no, eof, ch)
do while (.not. eof .and. ch /= newline_char)
call strbuf%append (ch)
call get_ch (unit_no, eof, ch)
end do
no_newline = eof .and. (strbuf%length() /= 0)
end subroutine get_line_from_stream
subroutine get_ch (unit_no, eof, ch)
!
! Read a single code point from the stream.
!
! Currently this procedure simply inputs ‘ASCII’ bytes rather than
! Unicode code points.
!
integer, intent(in) :: unit_no
logical, intent(out) :: eof
character(1, kind = ck), intent(out) :: ch
integer :: stat
character(1) :: c = '*'
eof = .false.
if (unit_no == input_unit) then
call get_input_unit_char (c, stat)
else
read (unit = unit_no, iostat = stat) c
end if
if (stat < 0) then
ch = ck_'*'
eof = .true.
else if (0 < stat) then
write (error_unit, '("Input error with status code ", I0)') stat
stop 1
else
ch = char (ichar (c, kind = ick), kind = ck)
end if
end subroutine get_ch
!!!
!!! If you tell gfortran you want -std=f2008 or -std=f2018, you likely
!!! will need to add also -fall-intrinsics or -U__GFORTRAN__
!!!
!!! The first way, you get the FGETC intrinsic. The latter way, you
!!! get the C interface code that uses getchar(3).
!!!
#ifdef __GFORTRAN__
subroutine get_input_unit_char (c, stat)
!
! The following works if you are using gfortran.
!
! (FGETC is considered a feature for backwards compatibility with
! g77. However, I know of no way to reconfigure input_unit as a
! Fortran 2003 stream, for use with ordinary ‘read’.)
!
character, intent(inout) :: c
integer, intent(out) :: stat
call fgetc (input_unit, c, stat)
end subroutine get_input_unit_char
#else
subroutine get_input_unit_char (c, stat)
!
! An alternative implementation of get_input_unit_char. This
! actually reads input from the C standard input, which might not
! be the same as input_unit.
!
use, intrinsic :: iso_c_binding, only: c_int
character, intent(inout) :: c
integer, intent(out) :: stat
interface
!
! Use getchar(3) to read characters from standard input. This
! assumes there is actually such a function available, and that
! getchar(3) does not exist solely as a macro. (One could write
! one’s own getchar() if necessary, of course.)
!
function getchar () result (c) bind (c, name = 'getchar')
use, intrinsic :: iso_c_binding, only: c_int
integer(kind = c_int) :: c
end function getchar
end interface
integer(kind = c_int) :: i_char
i_char = getchar ()
!
! The C standard requires that EOF have a negative value. If the
! value returned by getchar(3) is not EOF, then it will be
! representable as an unsigned char. Therefore, to check for end
! of file, one need only test whether i_char is negative.
!
if (i_char < 0) then
stat = -1
else
stat = 0
c = char (i_char)
end if
end subroutine get_input_unit_char
#endif
end module reading_one_line_from_a_stream
module ast_reader
!
! The AST will be read into an array. Perhaps that will improve
! locality, compared to storing the AST as many linked heap nodes.
!
! In any case, implementing the AST this way is an interesting
! problem.
!
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: output_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick, rik
use, non_intrinsic :: helper_procedures, only: next_power_of_two
use, non_intrinsic :: helper_procedures, only: new_storage_size
use, non_intrinsic :: string_buffers
use, non_intrinsic :: reading_one_line_from_a_stream
implicit none
private
public :: symbol_table_t
public :: interpreter_ast_node_t
public :: interpreter_ast_t
public :: read_ast
integer, parameter, public :: node_Nil = 0
integer, parameter, public :: node_Identifier = 1
integer, parameter, public :: node_String = 2
integer, parameter, public :: node_Integer = 3
integer, parameter, public :: node_Sequence = 4
integer, parameter, public :: node_If = 5
integer, parameter, public :: node_Prtc = 6
integer, parameter, public :: node_Prts = 7
integer, parameter, public :: node_Prti = 8
integer, parameter, public :: node_While = 9
integer, parameter, public :: node_Assign = 10
integer, parameter, public :: node_Negate = 11
integer, parameter, public :: node_Not = 12
integer, parameter, public :: node_Multiply = 13
integer, parameter, public :: node_Divide = 14
integer, parameter, public :: node_Mod = 15
integer, parameter, public :: node_Add = 16
integer, parameter, public :: node_Subtract = 17
integer, parameter, public :: node_Less = 18
integer, parameter, public :: node_LessEqual = 19
integer, parameter, public :: node_Greater = 20
integer, parameter, public :: node_GreaterEqual = 21
integer, parameter, public :: node_Equal = 22
integer, parameter, public :: node_NotEqual = 23
integer, parameter, public :: node_And = 24
integer, parameter, public :: node_Or = 25
type :: symbol_table_element_t
character(:, kind = ck), allocatable :: str
end type symbol_table_element_t
type :: symbol_table_t
integer(kind = nk), private :: len = 0_nk
type(symbol_table_element_t), allocatable, private :: symbols(:)
contains
procedure, pass, private :: ensure_storage => symbol_table_t_ensure_storage
procedure, pass :: look_up_index => symbol_table_t_look_up_index
procedure, pass :: look_up_name => symbol_table_t_look_up_name
procedure, pass :: length => symbol_table_t_length
generic :: look_up => look_up_index
generic :: look_up => look_up_name
end type symbol_table_t
type :: interpreter_ast_node_t
integer :: node_variety
integer(kind = rik) :: int ! Runtime integer or symbol index.
character(:, kind = ck), allocatable :: str ! String value.
! The left branch begins at the next node. The right branch
! begins at the address of the left branch, plus the following.
integer(kind = nk) :: right_branch_offset
end type interpreter_ast_node_t
type :: interpreter_ast_t
integer(kind = nk), private :: len = 0_nk
type(interpreter_ast_node_t), allocatable, public :: nodes(:)
contains
procedure, pass, private :: ensure_storage => interpreter_ast_t_ensure_storage
end type interpreter_ast_t
contains
subroutine symbol_table_t_ensure_storage (symtab, length_needed)
class(symbol_table_t), intent(inout) :: symtab
integer(kind = nk), intent(in) :: length_needed
integer(kind = nk) :: len_needed
integer(kind = nk) :: new_size
type(symbol_table_t) :: new_symtab
len_needed = max (length_needed, 1_nk)
if (.not. allocated (symtab%symbols)) then
! Initialize a new symtab%symbols array.
new_size = new_storage_size (len_needed)
allocate (symtab%symbols(1:new_size))
else if (ubound (symtab%symbols, 1) < len_needed) then
! Allocate a new symtab%symbols array, larger than the current
! one, but containing the same symbols.
new_size = new_storage_size (len_needed)
allocate (new_symtab%symbols(1:new_size))
new_symtab%symbols(1:symtab%len) = symtab%symbols(1:symtab%len)
call move_alloc (new_symtab%symbols, symtab%symbols)
end if
end subroutine symbol_table_t_ensure_storage
elemental function symbol_table_t_length (symtab) result (len)
class(symbol_table_t), intent(in) :: symtab
integer(kind = nk) :: len
len = symtab%len
end function symbol_table_t_length
function symbol_table_t_look_up_index (symtab, symbol_name) result (index)
class(symbol_table_t), intent(inout) :: symtab
character(*, kind = ck), intent(in) :: symbol_name
integer(kind = rik) :: index
!
! This implementation simply stores the symbols sequentially into
! an array. Obviously, for large numbers of symbols, one might
! wish to do something more complex.
!
! Standard Fortran does not come, out of the box, with a massive
! runtime library for doing such things. They are, however, no
! longer nearly as challenging to implement in Fortran as they
! used to be.
!
integer(kind = nk) :: i
i = 1
index = 0
do while (index == 0)
if (i == symtab%len + 1) then
! The symbol is new and must be added to the table.
i = symtab%len + 1
if (huge (1_rik) < i) then
! Symbol indices are assumed to be storable as runtime
! integers.
write (error_unit, '("There are more symbols than can be handled.")')
stop 1
end if
call symtab%ensure_storage(i)
symtab%len = i
allocate (symtab%symbols(i)%str, source = symbol_name)
index = int (i, kind = rik)
else if (symtab%symbols(i)%str == symbol_name) then
index = int (i, kind = rik)
else
i = i + 1
end if
end do
end function symbol_table_t_look_up_index
function symbol_table_t_look_up_name (symtab, index) result (symbol_name)
class(symbol_table_t), intent(inout) :: symtab
integer(kind = rik), intent(in) :: index
character(:, kind = ck), allocatable :: symbol_name
!
! This is the reverse of symbol_table_t_look_up_index: given an
! index, it finds the symbol’s name.
!
if (index < 1 .or. symtab%len < index) then
! In correct code, this branch should never be reached.
error stop
else
allocate (symbol_name, source = symtab%symbols(index)%str)
end if
end function symbol_table_t_look_up_name
subroutine interpreter_ast_t_ensure_storage (ast, length_needed)
class(interpreter_ast_t), intent(inout) :: ast
integer(kind = nk), intent(in) :: length_needed
integer(kind = nk) :: len_needed
integer(kind = nk) :: new_size
type(interpreter_ast_t) :: new_ast
len_needed = max (length_needed, 1_nk)
if (.not. allocated (ast%nodes)) then
! Initialize a new ast%nodes array.
new_size = new_storage_size (len_needed)
allocate (ast%nodes(1:new_size))
else if (ubound (ast%nodes, 1) < len_needed) then
! Allocate a new ast%nodes array, larger than the current one,
! but containing the same nodes.
new_size = new_storage_size (len_needed)
allocate (new_ast%nodes(1:new_size))
new_ast%nodes(1:ast%len) = ast%nodes(1:ast%len)
call move_alloc (new_ast%nodes, ast%nodes)
end if
end subroutine interpreter_ast_t_ensure_storage
subroutine read_ast (unit_no, strbuf, ast, symtab)
integer, intent(in) :: unit_no
type(strbuf_t), intent(inout) :: strbuf
type(interpreter_ast_t), intent(inout) :: ast
type(symbol_table_t), intent(inout) :: symtab
logical :: eof
logical :: no_newline
integer(kind = nk) :: after_ast_address
symtab%len = 0
ast%len = 0
call build_subtree (1_nk, after_ast_address)
contains
recursive subroutine build_subtree (here_address, after_subtree_address)
integer(kind = nk), value :: here_address
integer(kind = nk), intent(out) :: after_subtree_address
integer :: node_variety
integer(kind = nk) :: i, j
integer(kind = nk) :: left_branch_address
integer(kind = nk) :: right_branch_address
! Get a line from the parser output.
call get_line_from_stream (unit_no, eof, no_newline, strbuf)
if (eof) then
call ast_error
else
! Prepare to store a new node.
call ast%ensure_storage(here_address)
ast%len = here_address
! What sort of node is it?
i = skip_whitespace (strbuf, 1_nk)
j = skip_non_whitespace (strbuf, i)
node_variety = strbuf_to_node_variety (strbuf, i, j - 1)
ast%nodes(here_address)%node_variety = node_variety
select case (node_variety)
case (node_Nil)
after_subtree_address = here_address + 1
case (node_Identifier)
i = skip_whitespace (strbuf, j)
j = skip_non_whitespace (strbuf, i)
ast%nodes(here_address)%int = &
& strbuf_to_symbol_index (strbuf, i, j - 1, symtab)
after_subtree_address = here_address + 1
case (node_String)
i = skip_whitespace (strbuf, j)
j = skip_whitespace_backwards (strbuf, strbuf%length())
ast%nodes(here_address)%str = strbuf_to_string (strbuf, i, j)
after_subtree_address = here_address + 1
case (node_Integer)
i = skip_whitespace (strbuf, j)
j = skip_non_whitespace (strbuf, i)
ast%nodes(here_address)%int = strbuf_to_int (strbuf, i, j - 1)
after_subtree_address = here_address + 1
case default
! The node is internal, and has left and right branches.
! The left branch will start at left_branch_address; the
! right branch will start at left_branch_address +
! right_side_offset.
left_branch_address = here_address + 1
! Build the left branch.
call build_subtree (left_branch_address, right_branch_address)
! Build the right_branch.
call build_subtree (right_branch_address, after_subtree_address)
ast%nodes(here_address)%right_branch_offset = &
& right_branch_address - left_branch_address
end select
end if
end subroutine build_subtree
end subroutine read_ast
function strbuf_to_node_variety (strbuf, i, j) result (node_variety)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i, j
integer :: node_variety
!
! This function has not been optimized in any way, unless the
! Fortran compiler can optimize it.
!
! Something like a ‘radix tree search’ could be done on the
! characters of the strbuf. Or a perfect hash function. Or a
! binary search. Etc.
!
if (j == i - 1) then
call ast_error
else
select case (strbuf%to_unicode(i, j))
case (ck_";")
node_variety = node_Nil
case (ck_"Identifier")
node_variety = node_Identifier
case (ck_"String")
node_variety = node_String
case (ck_"Integer")
node_variety = node_Integer
case (ck_"Sequence")
node_variety = node_Sequence
case (ck_"If")
node_variety = node_If
case (ck_"Prtc")
node_variety = node_Prtc
case (ck_"Prts")
node_variety = node_Prts
case (ck_"Prti")
node_variety = node_Prti
case (ck_"While")
node_variety = node_While
case (ck_"Assign")
node_variety = node_Assign
case (ck_"Negate")
node_variety = node_Negate
case (ck_"Not")
node_variety = node_Not
case (ck_"Multiply")
node_variety = node_Multiply
case (ck_"Divide")
node_variety = node_Divide
case (ck_"Mod")
node_variety = node_Mod
case (ck_"Add")
node_variety = node_Add
case (ck_"Subtract")
node_variety = node_Subtract
case (ck_"Less")
node_variety = node_Less
case (ck_"LessEqual")
node_variety = node_LessEqual
case (ck_"Greater")
node_variety = node_Greater
case (ck_"GreaterEqual")
node_variety = node_GreaterEqual
case (ck_"Equal")
node_variety = node_Equal
case (ck_"NotEqual")
node_variety = node_NotEqual
case (ck_"And")
node_variety = node_And
case (ck_"Or")
node_variety = node_Or
case default
call ast_error
end select
end if
end function strbuf_to_node_variety
function strbuf_to_symbol_index (strbuf, i, j, symtab) result (int)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i, j
type(symbol_table_t), intent(inout) :: symtab
integer(kind = rik) :: int
if (j == i - 1) then
call ast_error
else
int = symtab%look_up(strbuf%to_unicode (i, j))
end if
end function strbuf_to_symbol_index
function strbuf_to_int (strbuf, i, j) result (int)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i, j
integer(kind = rik) :: int
integer :: stat
character(:, kind = ck), allocatable :: str
if (j < i) then
call ast_error
else
allocate (character(len = (j - i) + 1_nk, kind = ck) :: str)
str = strbuf%to_unicode (i, j)
read (str, *, iostat = stat) int
if (stat /= 0) then
call ast_error
end if
end if
end function strbuf_to_int
function strbuf_to_string (strbuf, i, j) result (str)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i, j
character(:, kind = ck), allocatable :: str
character(1, kind = ck), parameter :: linefeed_char = char (10, kind = ck)
character(1, kind = ck), parameter :: backslash_char = char (92, kind = ck)
! The following is correct for Unix and its relatives.
character(1, kind = ck), parameter :: newline_char = linefeed_char
integer(kind = nk) :: k
integer(kind = nk) :: count
if (strbuf%chars(i) /= ck_'"' .or. strbuf%chars(j) /= ck_'"') then
call ast_error
else
! Count how many characters are needed.
count = 0
k = i + 1
do while (k < j)
count = count + 1
if (strbuf%chars(k) == backslash_char) then
k = k + 2
else
k = k + 1
end if
end do
allocate (character(len = count, kind = ck) :: str)
count = 0
k = i + 1
do while (k < j)
if (strbuf%chars(k) == backslash_char) then
if (k == j - 1) then
call ast_error
else
select case (strbuf%chars(k + 1))
case (ck_'n')
count = count + 1
str(count:count) = newline_char
case (backslash_char)
count = count + 1
str(count:count) = backslash_char
case default
call ast_error
end select
k = k + 2
end if
else
count = count + 1
str(count:count) = strbuf%chars(k)
k = k + 1
end if
end do
end if
end function strbuf_to_string
subroutine ast_error
!
! It might be desirable to give more detail.
!
write (error_unit, '("The AST input seems corrupted.")')
stop 1
end subroutine ast_error
end module ast_reader
module ast_interpreter
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: output_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds
use, non_intrinsic :: ast_reader
implicit none
private
public :: value_t
public :: variable_table_t
public :: nil_value
public :: interpret_ast_node
integer, parameter, public :: v_Nil = 0
integer, parameter, public :: v_Integer = 1
integer, parameter, public :: v_String = 2
type :: value_t
integer :: tag = v_Nil
integer(kind = rik) :: int_val = -(huge (1_rik))
character(:, kind = ck), allocatable :: str_val
end type value_t
type :: variable_table_t
type(value_t), allocatable :: vals(:)
contains
procedure, pass :: initialize => variable_table_t_initialize
end type variable_table_t
! The canonical nil value.
type(value_t), parameter :: nil_value = value_t ()
contains
elemental function int_value (int_val) result (val)
integer(kind = rik), intent(in) :: int_val
type(value_t) :: val
val%tag = v_Integer
val%int_val = int_val
end function int_value
elemental function str_value (str_val) result (val)
character(*, kind = ck), intent(in) :: str_val
type(value_t) :: val
val%tag = v_String
allocate (val%str_val, source = str_val)
end function str_value
subroutine variable_table_t_initialize (vartab, symtab)
class(variable_table_t), intent(inout) :: vartab
type(symbol_table_t), intent(in) :: symtab
allocate (vartab%vals(1:symtab%length()), source = nil_value)
end subroutine variable_table_t_initialize
recursive subroutine interpret_ast_node (outp, ast, symtab, vartab, address, retval)
integer, intent(in) :: outp
type(interpreter_ast_t), intent(in) :: ast
type(symbol_table_t), intent(in) :: symtab
type(variable_table_t), intent(inout) :: vartab
integer(kind = nk) :: address
type(value_t), intent(inout) :: retval
integer(kind = rik) :: variable_index
type(value_t) :: val1, val2, val3
select case (ast%nodes(address)%node_variety)
case (node_Nil)
retval = nil_value
case (node_Integer)
retval = int_value (ast%nodes(address)%int)
case (node_Identifier)
variable_index = ast%nodes(address)%int
retval = vartab%vals(variable_index)
case (node_String)
retval = str_value (ast%nodes(address)%str)
case (node_Assign)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val1)
variable_index = ast%nodes(left_branch (address))%int
vartab%vals(variable_index) = val1
retval = nil_value
case (node_Multiply)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call multiply (val1, val2, val3)
retval = val3
case (node_Divide)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call divide (val1, val2, val3)
retval = val3
case (node_Mod)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call pseudo_remainder (val1, val2, val3)
retval = val3
case (node_Add)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call add (val1, val2, val3)
retval = val3
case (node_Subtract)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call subtract (val1, val2, val3)
retval = val3
case (node_Less)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call less_than (val1, val2, val3)
retval = val3
case (node_LessEqual)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call less_than_or_equal_to (val1, val2, val3)
retval = val3
case (node_Greater)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call greater_than (val1, val2, val3)
retval = val3
case (node_GreaterEqual)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call greater_than_or_equal_to (val1, val2, val3)
retval = val3
case (node_Equal)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call equal_to (val1, val2, val3)
retval = val3
case (node_NotEqual)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call not_equal_to (val1, val2, val3)
retval = val3
case (node_Negate)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
retval = int_value (-(rik_cast (val1, ck_'unary ''-''')))
case (node_Not)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
retval = int_value (bool2int (rik_cast (val1, ck_'unary ''!''') == 0_rik))
case (node_And)
! For similarity to C, we make this a ‘short-circuiting AND’,
! which is really a branching construct rather than a binary
! operation.
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
if (rik_cast (val1, ck_'''&&''') == 0_rik) then
retval = int_value (0_rik)
else
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
retval = int_value (bool2int (rik_cast (val2, ck_'''&&''') /= 0_rik))
end if
case (node_Or)
! For similarity to C, we make this a ‘short-circuiting OR’,
! which is really a branching construct rather than a binary
! operation.
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
if (rik_cast (val1, ck_'''||''') /= 0_rik) then
retval = int_value (1_rik)
else
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
retval = int_value (bool2int (rik_cast (val2, ck_'''||''') /= 0_rik))
end if
case (node_If)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
if (rik_cast (val1, ck_'''if-else'' construct') /= 0_rik) then
call interpret_ast_node (outp, ast, symtab, vartab, &
& left_branch (right_branch (address)), &
& val2)
else
call interpret_ast_node (outp, ast, symtab, vartab, &
& right_branch (right_branch (address)), &
& val2)
end if
retval = nil_value
case (node_While)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
do while (rik_cast (val1, ck_'''while'' construct') /= 0_rik)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
end do
retval = nil_value
case (node_Prtc)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
write (outp, '(A1)', advance = 'no') &
& char (rik_cast (val1, ck_'''putc'''), kind = ck)
retval = nil_value
case (node_Prti, node_Prts)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
select case (val1%tag)
case (v_Integer)
write (outp, '(I0)', advance = 'no') val1%int_val
case (v_String)
write (outp, '(A)', advance = 'no') val1%str_val
case (v_Nil)
write (outp, '("(no value)")', advance = 'no')
case default
error stop
end select
retval = nil_value
case (node_Sequence)
call interpret_ast_node (outp, ast, symtab, vartab, left_branch (address), val1)
call interpret_ast_node (outp, ast, symtab, vartab, right_branch (address), val2)
retval = nil_value
case default
write (error_unit, '("unknown node type")')
stop 1
end select
contains
elemental function left_branch (here_addr) result (left_addr)
integer(kind = nk), intent(in) :: here_addr
integer(kind = nk) :: left_addr
left_addr = here_addr + 1
end function left_branch
elemental function right_branch (here_addr) result (right_addr)
integer(kind = nk), intent(in) :: here_addr
integer(kind = nk) :: right_addr
right_addr = here_addr + 1 + ast%nodes(here_addr)%right_branch_offset
end function right_branch
end subroutine interpret_ast_node
subroutine multiply (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'*'
z = int_value (rik_cast (x, op) * rik_cast (y, op))
end subroutine multiply
subroutine divide (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'/'
! Fortran integer division truncates towards zero, as C’s does.
z = int_value (rik_cast (x, op) / rik_cast (y, op))
end subroutine divide
subroutine pseudo_remainder (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
!
! I call this ‘pseudo-remainder’ because I consider ‘remainder’ to
! mean the *non-negative* remainder in A = (B * Quotient) +
! Remainder. See https://doi.org/10.1145%2F128861.128862
!
! The pseudo-remainder gives the actual remainder, if both
! operands are positive.
!
character(*, kind = ck), parameter :: op = ck_'binary ''%'''
! Fortran’s MOD intrinsic, when given integer arguments, works
! like C ‘%’.
z = int_value (mod (rik_cast (x, op), rik_cast (y, op)))
end subroutine pseudo_remainder
subroutine add (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''+'''
z = int_value (rik_cast (x, op) + rik_cast (y, op))
end subroutine add
subroutine subtract (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''-'''
z = int_value (rik_cast (x, op) - rik_cast (y, op))
end subroutine subtract
subroutine less_than (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''<'''
z = int_value (bool2int (rik_cast (x, op) < rik_cast (y, op)))
end subroutine less_than
subroutine less_than_or_equal_to (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''<='''
z = int_value (bool2int (rik_cast (x, op) <= rik_cast (y, op)))
end subroutine less_than_or_equal_to
subroutine greater_than (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''>'''
z = int_value (bool2int (rik_cast (x, op) > rik_cast (y, op)))
end subroutine greater_than
subroutine greater_than_or_equal_to (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''>='''
z = int_value (bool2int (rik_cast (x, op) >= rik_cast (y, op)))
end subroutine greater_than_or_equal_to
subroutine equal_to (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''=='''
z = int_value (bool2int (rik_cast (x, op) == rik_cast (y, op)))
end subroutine equal_to
subroutine not_equal_to (x, y, z)
type(value_t), intent(in) :: x, y
type(value_t), intent(out) :: z
character(*, kind = ck), parameter :: op = ck_'binary ''!='''
z = int_value (bool2int (rik_cast (x, op) /= rik_cast (y, op)))
end subroutine not_equal_to
function rik_cast (val, operation_name) result (i_val)
class(*), intent(in) :: val
character(*, kind = ck), intent(in) :: operation_name
integer(kind = rik) :: i_val
select type (val)
class is (value_t)
if (val%tag == v_Integer) then
i_val = val%int_val
else
call type_error (operation_name)
end if
type is (integer(kind = rik))
i_val = val
class default
call type_error (operation_name)
end select
end function rik_cast
elemental function bool2int (bool) result (int)
logical, intent(in) :: bool
integer(kind = rik) :: int
if (bool) then
int = 1_rik
else
int = 0_rik
end if
end function bool2int
subroutine type_error (operation_name)
character(*, kind = ck), intent(in) :: operation_name
write (error_unit, '("type error in ", A)') operation_name
stop 1
end subroutine type_error
end module ast_interpreter
program Interp
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: output_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds
use, non_intrinsic :: string_buffers
use, non_intrinsic :: ast_reader
use, non_intrinsic :: ast_interpreter
implicit none
integer, parameter :: inp_unit_no = 100
integer, parameter :: outp_unit_no = 101
integer :: arg_count
character(200) :: arg
integer :: inp
integer :: outp
type(strbuf_t) :: strbuf
type(interpreter_ast_t) :: ast
type(symbol_table_t) :: symtab
type(variable_table_t) :: vartab
type(value_t) :: retval
arg_count = command_argument_count ()
if (3 <= arg_count) then
call print_usage
else
if (arg_count == 0) then
inp = input_unit
outp = output_unit
else if (arg_count == 1) then
call get_command_argument (1, arg)
inp = open_for_input (trim (arg))
outp = output_unit
else if (arg_count == 2) then
call get_command_argument (1, arg)
inp = open_for_input (trim (arg))
call get_command_argument (2, arg)
outp = open_for_output (trim (arg))
end if
call read_ast (inp, strbuf, ast, symtab)
if (1 <= ubound (ast%nodes, 1)) then
call vartab%initialize(symtab)
call interpret_ast_node (outp, ast, symtab, vartab, 1_nk, retval)
end if
end if
contains
function open_for_input (filename) result (unit_no)
character(*), intent(in) :: filename
integer :: unit_no
integer :: stat
open (unit = inp_unit_no, file = filename, status = 'old', &
& action = 'read', access = 'stream', form = 'unformatted', &
& iostat = stat)
if (stat /= 0) then
write (error_unit, '("Error: failed to open ", 1A, " for input")') filename
stop 1
end if
unit_no = inp_unit_no
end function open_for_input
function open_for_output (filename) result (unit_no)
character(*), intent(in) :: filename
integer :: unit_no
integer :: stat
open (unit = outp_unit_no, file = filename, action = 'write', iostat = stat)
if (stat /= 0) then
write (error_unit, '("Error: failed to open ", 1A, " for output")') filename
stop 1
end if
unit_no = outp_unit_no
end function open_for_output
subroutine print_usage
character(200) :: progname
call get_command_argument (0, progname)
write (output_unit, '("Usage: ", 1A, " [INPUT_FILE [OUTPUT_FILE]]")') &
& trim (progname)
end subroutine print_usage
end program Interp |
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #C | C | #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <stdbool.h>
#include <ctype.h>
#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
typedef enum {
tk_EOI, tk_Mul, tk_Div, tk_Mod, tk_Add, tk_Sub, tk_Negate, tk_Not, tk_Lss, tk_Leq, tk_Gtr,
tk_Geq, tk_Eql, tk_Neq, tk_Assign, tk_And, tk_Or, tk_If, tk_Else, tk_While, tk_Print,
tk_Putc, tk_Lparen, tk_Rparen, tk_Lbrace, tk_Rbrace, tk_Semi, tk_Comma, tk_Ident,
tk_Integer, tk_String
} TokenType;
typedef enum {
nd_Ident, nd_String, nd_Integer, nd_Sequence, nd_If, nd_Prtc, nd_Prts, nd_Prti, nd_While,
nd_Assign, nd_Negate, nd_Not, nd_Mul, nd_Div, nd_Mod, nd_Add, nd_Sub, nd_Lss, nd_Leq,
nd_Gtr, nd_Geq, nd_Eql, nd_Neq, nd_And, nd_Or
} NodeType;
typedef struct {
TokenType tok;
int err_ln;
int err_col;
char *text; /* ident or string literal or integer value */
} tok_s;
typedef struct Tree {
NodeType node_type;
struct Tree *left;
struct Tree *right;
char *value;
} Tree;
// dependency: Ordered by tok, must remain in same order as TokenType enum
struct {
char *text, *enum_text;
TokenType tok;
bool right_associative, is_binary, is_unary;
int precedence;
NodeType node_type;
} atr[] = {
{"EOI", "End_of_input" , tk_EOI, false, false, false, -1, -1 },
{"*", "Op_multiply" , tk_Mul, false, true, false, 13, nd_Mul },
{"/", "Op_divide" , tk_Div, false, true, false, 13, nd_Div },
{"%", "Op_mod" , tk_Mod, false, true, false, 13, nd_Mod },
{"+", "Op_add" , tk_Add, false, true, false, 12, nd_Add },
{"-", "Op_subtract" , tk_Sub, false, true, false, 12, nd_Sub },
{"-", "Op_negate" , tk_Negate, false, false, true, 14, nd_Negate },
{"!", "Op_not" , tk_Not, false, false, true, 14, nd_Not },
{"<", "Op_less" , tk_Lss, false, true, false, 10, nd_Lss },
{"<=", "Op_lessequal" , tk_Leq, false, true, false, 10, nd_Leq },
{">", "Op_greater" , tk_Gtr, false, true, false, 10, nd_Gtr },
{">=", "Op_greaterequal", tk_Geq, false, true, false, 10, nd_Geq },
{"==", "Op_equal" , tk_Eql, false, true, false, 9, nd_Eql },
{"!=", "Op_notequal" , tk_Neq, false, true, false, 9, nd_Neq },
{"=", "Op_assign" , tk_Assign, false, false, false, -1, nd_Assign },
{"&&", "Op_and" , tk_And, false, true, false, 5, nd_And },
{"||", "Op_or" , tk_Or, false, true, false, 4, nd_Or },
{"if", "Keyword_if" , tk_If, false, false, false, -1, nd_If },
{"else", "Keyword_else" , tk_Else, false, false, false, -1, -1 },
{"while", "Keyword_while" , tk_While, false, false, false, -1, nd_While },
{"print", "Keyword_print" , tk_Print, false, false, false, -1, -1 },
{"putc", "Keyword_putc" , tk_Putc, false, false, false, -1, -1 },
{"(", "LeftParen" , tk_Lparen, false, false, false, -1, -1 },
{")", "RightParen" , tk_Rparen, false, false, false, -1, -1 },
{"{", "LeftBrace" , tk_Lbrace, false, false, false, -1, -1 },
{"}", "RightBrace" , tk_Rbrace, false, false, false, -1, -1 },
{";", "Semicolon" , tk_Semi, false, false, false, -1, -1 },
{",", "Comma" , tk_Comma, false, false, false, -1, -1 },
{"Ident", "Identifier" , tk_Ident, false, false, false, -1, nd_Ident },
{"Integer literal", "Integer" , tk_Integer, false, false, false, -1, nd_Integer},
{"String literal", "String" , tk_String, false, false, false, -1, nd_String },
};
char *Display_nodes[] = {"Identifier", "String", "Integer", "Sequence", "If", "Prtc",
"Prts", "Prti", "While", "Assign", "Negate", "Not", "Multiply", "Divide", "Mod",
"Add", "Subtract", "Less", "LessEqual", "Greater", "GreaterEqual", "Equal",
"NotEqual", "And", "Or"};
static tok_s tok;
static FILE *source_fp, *dest_fp;
Tree *paren_expr();
void error(int err_line, int err_col, const char *fmt, ... ) {
va_list ap;
char buf[1000];
va_start(ap, fmt);
vsprintf(buf, fmt, ap);
va_end(ap);
printf("(%d, %d) error: %s\n", err_line, err_col, buf);
exit(1);
}
char *read_line(int *len) {
static char *text = NULL;
static int textmax = 0;
for (*len = 0; ; (*len)++) {
int ch = fgetc(source_fp);
if (ch == EOF || ch == '\n') {
if (*len == 0)
return NULL;
break;
}
if (*len + 1 >= textmax) {
textmax = (textmax == 0 ? 128 : textmax * 2);
text = realloc(text, textmax);
}
text[*len] = ch;
}
text[*len] = '\0';
return text;
}
char *rtrim(char *text, int *len) { // remove trailing spaces
for (; *len > 0 && isspace(text[*len - 1]); --(*len))
;
text[*len] = '\0';
return text;
}
TokenType get_enum(const char *name) { // return internal version of name
for (size_t i = 0; i < NELEMS(atr); i++) {
if (strcmp(atr[i].enum_text, name) == 0)
return atr[i].tok;
}
error(0, 0, "Unknown token %s\n", name);
return 0;
}
tok_s gettok() {
int len;
tok_s tok;
char *yytext = read_line(&len);
yytext = rtrim(yytext, &len);
// [ ]*{lineno}[ ]+{colno}[ ]+token[ ]+optional
// get line and column
tok.err_ln = atoi(strtok(yytext, " "));
tok.err_col = atoi(strtok(NULL, " "));
// get the token name
char *name = strtok(NULL, " ");
tok.tok = get_enum(name);
// if there is extra data, get it
char *p = name + strlen(name);
if (p != &yytext[len]) {
for (++p; isspace(*p); ++p)
;
tok.text = strdup(p);
}
return tok;
}
Tree *make_node(NodeType node_type, Tree *left, Tree *right) {
Tree *t = calloc(sizeof(Tree), 1);
t->node_type = node_type;
t->left = left;
t->right = right;
return t;
}
Tree *make_leaf(NodeType node_type, char *value) {
Tree *t = calloc(sizeof(Tree), 1);
t->node_type = node_type;
t->value = strdup(value);
return t;
}
void expect(const char msg[], TokenType s) {
if (tok.tok == s) {
tok = gettok();
return;
}
error(tok.err_ln, tok.err_col, "%s: Expecting '%s', found '%s'\n", msg, atr[s].text, atr[tok.tok].text);
}
Tree *expr(int p) {
Tree *x = NULL, *node;
TokenType op;
switch (tok.tok) {
case tk_Lparen:
x = paren_expr();
break;
case tk_Sub: case tk_Add:
op = tok.tok;
tok = gettok();
node = expr(atr[tk_Negate].precedence);
x = (op == tk_Sub) ? make_node(nd_Negate, node, NULL) : node;
break;
case tk_Not:
tok = gettok();
x = make_node(nd_Not, expr(atr[tk_Not].precedence), NULL);
break;
case tk_Ident:
x = make_leaf(nd_Ident, tok.text);
tok = gettok();
break;
case tk_Integer:
x = make_leaf(nd_Integer, tok.text);
tok = gettok();
break;
default:
error(tok.err_ln, tok.err_col, "Expecting a primary, found: %s\n", atr[tok.tok].text);
}
while (atr[tok.tok].is_binary && atr[tok.tok].precedence >= p) {
TokenType op = tok.tok;
tok = gettok();
int q = atr[op].precedence;
if (!atr[op].right_associative)
q++;
node = expr(q);
x = make_node(atr[op].node_type, x, node);
}
return x;
}
Tree *paren_expr() {
expect("paren_expr", tk_Lparen);
Tree *t = expr(0);
expect("paren_expr", tk_Rparen);
return t;
}
Tree *stmt() {
Tree *t = NULL, *v, *e, *s, *s2;
switch (tok.tok) {
case tk_If:
tok = gettok();
e = paren_expr();
s = stmt();
s2 = NULL;
if (tok.tok == tk_Else) {
tok = gettok();
s2 = stmt();
}
t = make_node(nd_If, e, make_node(nd_If, s, s2));
break;
case tk_Putc:
tok = gettok();
e = paren_expr();
t = make_node(nd_Prtc, e, NULL);
expect("Putc", tk_Semi);
break;
case tk_Print: /* print '(' expr {',' expr} ')' */
tok = gettok();
for (expect("Print", tk_Lparen); ; expect("Print", tk_Comma)) {
if (tok.tok == tk_String) {
e = make_node(nd_Prts, make_leaf(nd_String, tok.text), NULL);
tok = gettok();
} else
e = make_node(nd_Prti, expr(0), NULL);
t = make_node(nd_Sequence, t, e);
if (tok.tok != tk_Comma)
break;
}
expect("Print", tk_Rparen);
expect("Print", tk_Semi);
break;
case tk_Semi:
tok = gettok();
break;
case tk_Ident:
v = make_leaf(nd_Ident, tok.text);
tok = gettok();
expect("assign", tk_Assign);
e = expr(0);
t = make_node(nd_Assign, v, e);
expect("assign", tk_Semi);
break;
case tk_While:
tok = gettok();
e = paren_expr();
s = stmt();
t = make_node(nd_While, e, s);
break;
case tk_Lbrace: /* {stmt} */
for (expect("Lbrace", tk_Lbrace); tok.tok != tk_Rbrace && tok.tok != tk_EOI;)
t = make_node(nd_Sequence, t, stmt());
expect("Lbrace", tk_Rbrace);
break;
case tk_EOI:
break;
default: error(tok.err_ln, tok.err_col, "expecting start of statement, found '%s'\n", atr[tok.tok].text);
}
return t;
}
Tree *parse() {
Tree *t = NULL;
tok = gettok();
do {
t = make_node(nd_Sequence, t, stmt());
} while (t != NULL && tok.tok != tk_EOI);
return t;
}
void prt_ast(Tree *t) {
if (t == NULL)
printf(";\n");
else {
printf("%-14s ", Display_nodes[t->node_type]);
if (t->node_type == nd_Ident || t->node_type == nd_Integer || t->node_type == nd_String) {
printf("%s\n", t->value);
} else {
printf("\n");
prt_ast(t->left);
prt_ast(t->right);
}
}
}
void init_io(FILE **fp, FILE *std, const char mode[], const char fn[]) {
if (fn[0] == '\0')
*fp = std;
else if ((*fp = fopen(fn, mode)) == NULL)
error(0, 0, "Can't open %s\n", fn);
}
int main(int argc, char *argv[]) {
init_io(&source_fp, stdin, "r", argc > 1 ? argv[1] : "");
init_io(&dest_fp, stdout, "wb", argc > 2 ? argv[2] : "");
prt_ast(parse());
} |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #BASIC | BASIC | # Conway's_Game_of_Life
X = 59 : Y = 35 : H = 4
fastgraphics
graphsize X*H,Y*H
dim c(X,Y) : dim cn(X,Y) : dim cl(X,Y)
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #NetRexx | NetRexx | /* NetRexx */
options replace format comments java crossref symbols nobinary
class RCompoundDataType
method main(args = String[]) public static
pp = Point(2, 4)
say pp
return
class RCompoundDataType.Point -- inner class "Point"
properties indirect -- have NetRexx create getters & setters
x = Integer
y = Integer
method Point(x_ = 0, y_ = 0) public -- providing default values for x_ & y_ lets NetRexx generate intermediate constructors Point() & Point(x_)
this.x = Integer(x_)
this.y = Integer(y_)
return
method toString() public returns String
res = 'X='getX()',Y='getY()
return res
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Nim | Nim | type Point = tuple[x, y: int]
var p: Point = (12, 13)
var p2: Point = (x: 100, y: 200) |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Tcl | Tcl | set src "Rosetta Code"
set dst $src |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #TI-83_BASIC | TI-83 BASIC | :"Rosetta Code"→Str1
:Str1→Str2 |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #REXX | REXX | /*REXX program generates 100 random points in an annulus: 10 ≤ √(x²≤y²) ≤ 15 */
parse arg pts LO HI . /*obtain optional args from the C.L. */
if pts=='' then pts= 100 /*Not specified? Then use the default.*/
if LO=='' then LO= 10; LO2= LO**2 /*define a shortcut for squaring LO. */
if HI=='' then HI= 15; HI2= HI**2 /* " " " " " HI. */
$=
do x=-HI; xx= x*x /*generate all possible annulus points.*/
if x>0 & xx>HI2 then leave /*end of annulus points generation ? */
do y=-HI; s= xx + y*y
if (y<0 & s>HI2) | s<LO2 then iterate
if y>0 & s>HI2 then leave
$= $ x','y /*add a point─set to the $ list. */
end /*y*/
end /*x*/
#= words($); @.= /*def: plotchr; #pts; lines*/
do pts; parse value word($, random(1,#)) with x ',' y /*get rand point in annulus*/
@.y= overlay('☼', @.y, x+x + HI+HI + 1) /*put a plot char on a line*/
end /*pts*/ /* [↑] maintain aspect ratio on X axis*/
/*stick a fork in it, we're all done. */
do y=-HI to HI; say @.y; end /*display the annulus to the terminal. */ |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #VBA | VBA | Private Sub Enjoy()
Debug.Print "Enjoy"
End Sub
Private Sub Rosetta()
Debug.Print "Rosetta"
End Sub
Private Sub Code()
Debug.Print "Code"
End Sub
Public Sub concurrent()
when = Now + TimeValue("00:00:01")
Application.OnTime when, "Enjoy"
Application.OnTime when, "Rosetta"
Application.OnTime when, "Code"
End Sub |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Visual_Basic_.NET | Visual Basic .NET | Imports System.Threading
Module Module1
Public rnd As New Random
Sub Main()
Dim t1 As New Thread(AddressOf Foo)
Dim t2 As New Thread(AddressOf Foo)
Dim t3 As New Thread(AddressOf Foo)
t1.Start("Enjoy")
t2.Start("Rosetta")
t3.Start("Code")
t1.Join()
t2.Join()
t3.Join()
End Sub
Sub Foo(ByVal state As Object)
Thread.Sleep(rnd.Next(1000))
Console.WriteLine(state)
End Sub
End Module |
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #ALGOL_W | ALGOL W | begin
integer a, b, c;
a := 1; b := 2; c := 3;
% algol W has the traditional Algol if-the-else statement %
% there is no "elseif" contraction %
if a = b
then write( "a = b" )
else if a = c
then write( "a = c" )
else write( "a is ", a );
% if-then-else can also be used in an expression %
write( if a < 4 then "lt 4" else "ge 4" );
% algol W also has a "case" statement, an integer expression is used to %
% select the statement to execute. If the expression evaluates to 1, %
% the first statement is executed, if 2, the second is executed etc. %
% If the expression is less than 1 or greater than the number of %
% statements, a run time error occurs %
case a + b of
begin write( "a + b is one" )
; write( "a + b is two" )
; write( "a + b is three" )
; write( "a + b is four" )
end;
% there is also an expression form of the case: %
write( case c - a of ( "one", "two", "three", "four" ) )
end. |
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #ATS | ATS | (*
Usage: vm [INPUTFILE [OUTPUTFILE]]
If INPUTFILE or OUTPUTFILE is "-" or missing, then standard input
or standard output is used, respectively.
The Rosetta Code virtual machine task in ATS2 (also known as
Postiats).
Some implementation notes:
* Values are stored as uint32, and it is checked that uint32
really is 32 bits, two’s-complement. Addition and subtraction
are allowed to roll around, and so can be done without casting
to int32. (The C standard specifies that unsigned integer values
will roll around, rather than signal an overflow.)
* Where it matters, the uint32 are stored in little-endian
order. I have *not* optimized the code for x86/AMD64 (which are
little-endian and also can address unaligned data).
* Here I am often writing out code instead of using some library
function. Partly this is to improve code safety (proof at
compile-time that buffers are not overrun, proof of loop
termination, etc.). Partly this is because I do not feel like
using the C library (or ATS interfaces to it) all that much.
* I am using linear types and so forth, because I think it
interesting to do so. It is unnecessary to use a garbage
collector, because there (hopefully) are no memory leaks. (Not
that we couldn’t simply let memory leak, for this little program
with no REPL.)
*)
#define ATS_EXTERN_PREFIX "rosettacode_vm_"
#define ATS_DYNLOADFLAG 0 (* No initialization is needed. *)
#include "share/atspre_define.hats"
#include "share/atspre_staload.hats"
staload UN = "prelude/SATS/unsafe.sats"
#define NIL list_vt_nil ()
#define :: list_vt_cons
(* The stack has a fixed size but is very large. (Alternatively, one
could make the stack double in size whenever it overflows. Design
options such as using a linked list for the stack come with a
performance penalty.) *)
#define VMSTACK_SIZE 65536
macdef vmstack_size = (i2sz VMSTACK_SIZE)
(* In this program, exceptions are not meant to be caught, unless
the catcher terminates the program. Linear types and
general exception-catching do not go together well. *)
exception bad_vm of string
exception vm_runtime_error of string
(********************************************************************)
(* *)
(* Some string functions that are safe against buffer overruns. *)
(* *)
fn
skip_whitespace {n, i : int | 0 <= i; i <= n}
(s : string n,
n : size_t n,
i : size_t i) :
[j : int | i <= j; j <= n]
size_t j =
let
fun
loop {k : int | i <= k; k <= n} .<n - k>.
(k : size_t k) :
[j : int | i <= j; j <= n]
size_t j =
if k = n then
k
else if isspace (s[k]) then
loop (succ k)
else
k
in
loop (i)
end
fn
skip_non_whitespace {n, i : int | 0 <= i; i <= n}
(s : string n,
n : size_t n,
i : size_t i) :
[j : int | i <= j; j <= n]
size_t j =
let
fun
loop {k : int | i <= k; k <= n} .<n - k>.
(k : size_t k) :
[j : int | i <= j; j <= n]
size_t j =
if k = n then
k
else if isspace (s[k]) then
k
else
loop (succ k)
in
loop (i)
end
fn
substr_equal {n, i, j : int | 0 <= i; i <= j; j <= n}
{m : int | 0 <= m}
(s : string n,
i : size_t i,
j : size_t j,
t : string m) : bool =
(* Is s[i .. j-1] equal to t? *)
let
val m = string_length t
in
if m <> j - i then
false
else
let
fun
loop {k : int | 0 <= k; k <= m} .<m - k>.
(k : size_t k) : bool =
if k = m then
true
else if s[i + k] <> t[k] then
false
else
loop (succ k)
in
loop (i2sz 0)
end
end
(********************************************************************)
(* *)
(* vmint = 32-bit two’s-complement numbers. *)
(* *)
stadef vmint_kind = uint32_kind
typedef vmint = uint32
extern castfn i2vm : int -<> vmint
extern castfn u2vm : uint -<> vmint
extern castfn byte2vm : byte -<> vmint
extern castfn vm2i : vmint -<> int
extern castfn vm2sz : vmint -<> size_t
extern castfn vm2byte : vmint -<> byte
%{^
/*
* The ATS prelude might not have C implementations of all the
* operations we would like to have, so here are some.
*/
typedef uint32_t vmint_t;
ATSinline() vmint_t
rosettacode_vm_g0uint_add_vmint (vmint_t x, vmint_t y)
{
return (x + y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_sub_vmint (vmint_t x, vmint_t y)
{
return (x - y);
}
ATSinline() int
rosettacode_vm_g0uint_eq_vmint (vmint_t x, vmint_t y)
{
return (x == y);
}
ATSinline() int
rosettacode_vm_g0uint_neq_vmint (vmint_t x, vmint_t y)
{
return (x != y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_equality_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) (x == y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_inequality_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) (x != y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_lt_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x < (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_gt_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x > (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_lte_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x <= (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_gte_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x >= (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_mul_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x * (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_div_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x / (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_signed_mod_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((int32_t) x % (int32_t) y);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_logical_not_vmint (vmint_t x)
{
return (vmint_t) (!x);
}
ATSinline() vmint_t
rosettacode_vm_g0uint_logical_and_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) ((!!x) * (!!y));
}
ATSinline() vmint_t
rosettacode_vm_g0uint_logical_or_vmint (vmint_t x, vmint_t y)
{
return (vmint_t) (1 - ((!x) * (!y)));
}
%}
extern fn g0uint_add_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn g0uint_sub_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn g0uint_eq_vmint (x : vmint, y : vmint) :<> bool = "mac#%"
extern fn g0uint_neq_vmint (x : vmint, y : vmint) :<> bool = "mac#%"
implement g0uint_add<vmint_kind> (x, y) = g0uint_add_vmint (x, y)
implement g0uint_sub<vmint_kind> (x, y) = g0uint_sub_vmint (x, y)
implement g0uint_eq<vmint_kind> (x, y) = g0uint_eq_vmint (x, y)
implement g0uint_neq<vmint_kind> (x, y) = g0uint_neq_vmint (x, y)
extern fn
g0uint_signed_mul_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_signed_div_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_signed_mod_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_equality_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_inequality_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_signed_lt_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_signed_gt_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_signed_lte_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_signed_gte_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_logical_not_vmint (x : vmint) :<> vmint = "mac#%"
extern fn
g0uint_logical_and_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
extern fn
g0uint_logical_or_vmint (x : vmint, y : vmint) :<> vmint = "mac#%"
overload signed_mul with g0uint_signed_mul_vmint
overload signed_div with g0uint_signed_div_vmint
overload signed_mod with g0uint_signed_mod_vmint
overload equality with g0uint_equality_vmint
overload inequality with g0uint_inequality_vmint
overload signed_lt with g0uint_signed_lt_vmint
overload signed_gt with g0uint_signed_gt_vmint
overload signed_lte with g0uint_signed_lte_vmint
overload signed_gte with g0uint_signed_gte_vmint
overload logical_not with g0uint_logical_not_vmint
overload logical_and with g0uint_logical_and_vmint
overload logical_or with g0uint_logical_or_vmint
fn {}
twos_complement (x : vmint) :<>
vmint =
(~x) + i2vm 1
fn
ensure_that_vmint_is_suitable () : void =
{
val _ = assertloc (u2vm (0xFFFFFFFFU) + u2vm 1U = u2vm 0U)
val _ = assertloc (u2vm 0U - u2vm 1U = u2vm (0xFFFFFFFFU))
val _ = assertloc (i2vm (~1234) = twos_complement (i2vm 1234))
}
fn
parse_digits {n, i, j : int | 0 <= i; i <= j; j <= n}
(s : string n,
i : size_t i,
j : size_t j) :
vmint =
let
val bad_integer = "Bad integer."
fun
loop {k : int | i <= k; k <= j} .<j - k>.
(k : size_t k,
x : vmint) : vmint =
if k = j then
x
else if ~isdigit (s[k]) then
$raise bad_vm (bad_integer)
else
(* The result is allowed to overflow freely. *)
loop (succ k, (i2vm 10 * x) + i2vm (char2i s[k] - char2i '0'))
in
if j = i then
$raise bad_vm (bad_integer)
else
loop (i, i2vm 0)
end
fn
parse_integer {n, i, j : int | 0 <= i; i <= j; j <= n}
(s : string n,
i : size_t i,
j : size_t j) :
vmint =
let
val bad_integer = "Bad integer."
in
if j = i then
$raise bad_vm (bad_integer)
else if j = succ i && ~isdigit (s[i]) then
$raise bad_vm (bad_integer)
else if s[i] <> '-' then
parse_digits (s, i, j)
else if succ i = j then
$raise bad_vm (bad_integer)
else
twos_complement (parse_digits (s, succ i, j))
end
(********************************************************************)
(* *)
(* A linear array type for elements of vmint, byte, etc. *)
(* *)
vtypedef vmarray_vt (t : t@ype+, n : int, p : addr) =
@{
pf = @[t][n] @ p,
pfgc = mfree_gc_v p |
n = size_t n,
p = ptr p
}
vtypedef vmarray_vt (t : t@ype+, n : int) =
[p : addr] vmarray_vt (t, n, p)
fn {t : t@ype}
vmarray_vt_alloc {n : int}
(n : size_t n,
fill : t) :
[p : addr | null < p]
vmarray_vt (t, n, p) =
let
val @(pf, pfgc | p) = array_ptr_alloc<t> (n)
val _ = array_initize_elt (!p, n, fill)
in
@{
pf = pf,
pfgc = pfgc |
n = n,
p = p
}
end
fn {t : t@ype}
vmarray_vt_free {n : int}
{p : addr}
(arr : vmarray_vt (t, n, p)) :
void =
let
val @{
pf = pf,
pfgc = pfgc |
n = n,
p = p
} = arr
in
array_ptr_free (pf, pfgc | p)
end
fn {t : t@ype}
vmarray_vt_fill {n : int}
{p : addr}
(arr : !vmarray_vt (t, n, p),
fill : t) :
void =
array_initize_elt (!(arr.p), (arr.n), fill)
fn {t : t@ype}
{tk : tkind}
vmarray_vt_get_at_g1int {n, i : int | 0 <= i; i < n}
(arr : !vmarray_vt (t, n),
i : g1int (tk, i)) :
t =
array_get_at (!(arr.p), i)
fn {t : t@ype}
{tk : tkind}
vmarray_vt_get_at_g1uint {n, i : int | 0 <= i; i < n}
(arr : !vmarray_vt (t, n),
i : g1uint (tk, i)) :
t =
array_get_at (!(arr.p), i)
overload [] with vmarray_vt_get_at_g1int
overload [] with vmarray_vt_get_at_g1uint
fn {t : t@ype}
{tk : tkind}
vmarray_vt_set_at_g1int {n, i : int | 0 <= i; i < n}
(arr : !vmarray_vt (t, n),
i : g1int (tk, i),
x : t) :
void =
array_set_at (!(arr.p), i, x)
fn {t : t@ype}
{tk : tkind}
vmarray_vt_set_at_g1uint {n, i : int | 0 <= i; i < n}
(arr : !vmarray_vt (t, n),
i : g1uint (tk, i),
x : t) :
void =
array_set_at (!(arr.p), i, x)
overload [] with vmarray_vt_set_at_g1int
overload [] with vmarray_vt_set_at_g1uint
fn {t : t@ype}
vmarray_vt_length {n : int}
(arr : !vmarray_vt (t, n)) :<>
size_t n =
arr.n
(********************************************************************)
(* *)
(* Storage for the strings section. *)
(* *)
vtypedef vmstring_vt (n : int, p : addr) =
@{
(* A vmstring_vt is NUL-terminated, and thus there is [n + 1]
instead of [n] in the following declaration. *)
pf = @[char][n + 1] @ p,
pfgc = mfree_gc_v p |
length = size_t n,
p = ptr p
}
vtypedef vmstring_vt (n : int) = [p : addr] vmstring_vt (n, p)
vtypedef vmstring_vt = [n : int | 0 <= n] vmstring_vt (n)
vtypedef vmstrings_section_vt (n : int, p : addr) =
@{
pf = @[vmstring_vt][n] @ p,
pfgc = mfree_gc_v p |
n = size_t n,
p = ptr p
}
vtypedef vmstrings_section_vt (n : int) =
[p : addr] vmstrings_section_vt (n, p)
fn {t : t@ype}
vmstrings_section_vt_length {n : int}
(arr : !vmstrings_section_vt (n)) :<>
size_t n =
arr.n
fn
vmstring_vt_free {n : int}
{p : addr}
(s : vmstring_vt (n, p)) :
void =
array_ptr_free (s.pf, s.pfgc | s.p)
fn
vmstrings_section_vt_free {n : int}
{p : addr}
(strings : vmstrings_section_vt (n, p)) :
void =
{
fun
free_the_strings {n : int | 0 <= n}
{p : addr} .<n>.
(pf : !(@[vmstring_vt][n] @ p) >>
@[vmstring_vt?][n] @ p |
n : size_t n,
p : ptr p) : void =
if n = 0 then
{
prval _ = pf :=
array_v_unnil_nil {vmstring_vt, vmstring_vt?} pf
}
else
{
prval @(pf_element, pf_rest) = array_v_uncons pf
val _ = vmstring_vt_free (!p)
val p_next = ptr_succ<vmstring_vt> (p)
val _ = free_the_strings (pf_rest | pred n, p_next)
prval _ = pf := array_v_cons (pf_element, pf_rest)
}
val @{
pf = pf,
pfgc = pfgc |
n = n,
p = p
} = strings
prval _ = lemma_g1uint_param n
val _ = free_the_strings (pf | n, p)
val _ = array_ptr_free (pf, pfgc | p)
}
fn
quoted_string_length {n : int | 0 <= n}
(s : string n,
n : size_t n) :
[m : int | 0 <= m; m <= n - 2]
size_t m =
let
val bad_quoted_string = "Bad quoted string."
fun
loop {i : int | 1 <= i; i <= n - 1}
{j : int | 0 <= j; j <= i - 1} .<n - i>.
(i : size_t i,
j : size_t j) :
[k : int | 0 <= k; k <= n - 2]
size_t k =
if i = pred n then
j
else if s[i] <> '\\' then
loop (succ i, succ j)
else if succ i = pred n then
$raise bad_vm (bad_quoted_string)
else if s[succ i] = 'n' || s[succ i] = '\\' then
loop (succ (succ i), succ j)
else
$raise bad_vm (bad_quoted_string)
in
if n < i2sz 2 then
$raise bad_vm (bad_quoted_string)
else if s[0] <> '"' then
$raise bad_vm (bad_quoted_string)
else if s[pred n] <> '"' then
$raise bad_vm (bad_quoted_string)
else
loop (i2sz 1, i2sz 0)
end
fn
dequote_string {m, n : int | 0 <= m; m <= n - 2}
(s : string n,
n : size_t n,
t : !vmstring_vt m) :
void =
let
fun
loop {i : int | 1 <= i; i <= n - 1}
{j : int | 0 <= j; j <= i - 1} .<n - i>.
(t : !vmstring_vt m,
i : size_t i,
j : size_t j) : void =
let
macdef t_str = !(t.p)
in
if i = pred n then
()
else if (t.length) < j then
assertloc (false)
else if s[i] <> '\\' then
begin
t_str[j] := s[i];
loop (t, succ i, succ j)
end
else if succ i = pred n then
assertloc (false)
else if s[succ i] = 'n' then
begin
t_str[j] := '\n';
loop (t, succ (succ i), succ j)
end
else
begin
t_str[j] := s[succ i];
loop (t, succ (succ i), succ j)
end
end
in
loop (t, i2sz 1, i2sz 0)
end
fn
read_vmstrings {strings_size : int}
{strings_addr : addr}
(pf_strings :
!(@[vmstring_vt?][strings_size] @ strings_addr) >>
@[vmstring_vt][strings_size] @ strings_addr |
f : FILEref,
strings_size : size_t strings_size,
strings : ptr strings_addr) :
void =
let
prval _ = lemma_g1uint_param strings_size
fun
loop {k : int | 0 <= k; k <= strings_size} .<strings_size - k>.
(lst : list_vt (vmstring_vt, k),
k : size_t k) :
list_vt (vmstring_vt, strings_size) =
if k = strings_size then
list_vt_reverse (lst)
else
let
val bad_quoted_string = "Bad quoted string."
val line = fileref_get_line_string (f)
val s = $UN.strptr2string (line)
val n = string_length s
val str_length = quoted_string_length (s, n)
val (pf, pfgc | p) =
array_ptr_alloc<char> (succ str_length)
val _ = array_initize_elt (!p, succ str_length, '\0')
val vmstring =
@{
pf = pf,
pfgc = pfgc |
length = str_length,
p = p
}
in
dequote_string (s, n, vmstring);
free line;
loop (vmstring :: lst, succ k)
end
val lst = loop (NIL, i2sz 0)
in
array_initize_list_vt<vmstring_vt>
(!strings, sz2i strings_size, lst)
end
fn
vmstrings_section_vt_read {strings_size : int}
(f : FILEref,
strings_size : size_t strings_size) :
[p : addr]
vmstrings_section_vt (strings_size, p) =
let
val @(pf, pfgc | p) = array_ptr_alloc<vmstring_vt> strings_size
val _ = read_vmstrings (pf | f, strings_size, p)
in
@{
pf = pf,
pfgc = pfgc |
n = strings_size,
p = p
}
end
fn
vmstring_fprint {n, i : int | i < n}
(f : FILEref,
strings : !vmstrings_section_vt n,
i : size_t i) :
void =
{
(*
* The following code does some ‘unsafe’ tricks. For instance, it
* is assumed each stored string is NUL-terminated.
*)
fn
print_it (str : !vmstring_vt) : void =
fileref_puts (f, $UN.cast{string} (str.p))
prval _ = lemma_g1uint_param i
val p_element = array_getref_at (!(strings.p), i)
val @(pf_element | p_element) =
$UN.castvwtp0
{[n : int; p : addr] @(vmstring_vt @ p | ptr p)}
(p_element)
val _ = print_it (!p_element)
prval _ = $UN.castview0{void} pf_element
}
(********************************************************************)
(* *)
(* vm_vt: the dataviewtype for a virtual machine. *)
(* *)
datavtype instruction_vt =
| instruction_vt_1 of (byte)
| instruction_vt_5 of (byte, byte, byte, byte, byte)
#define OPCODE_COUNT 24
#define OP_HALT 0x0000 // 00000
#define OP_ADD 0x0001 // 00001
#define OP_SUB 0x0002 // 00010
#define OP_MUL 0x0003 // 00011
#define OP_DIV 0x0004 // 00100
#define OP_MOD 0x0005 // 00101
#define OP_LT 0x0006 // 00110
#define OP_GT 0x0007 // 00111
#define OP_LE 0x0008 // 01000
#define OP_GE 0x0009 // 01001
#define OP_EQ 0x000A // 01010
#define OP_NE 0x000B // 01011
#define OP_AND 0x000C // 01100
#define OP_OR 0x000D // 01101
#define OP_NEG 0x000E // 01110
#define OP_NOT 0x000F // 01111
#define OP_PRTC 0x0010 // 10000
#define OP_PRTI 0x0011 // 10001
#define OP_PRTS 0x0012 // 10010
#define OP_FETCH 0x0013 // 10011
#define OP_STORE 0x0014 // 10100
#define OP_PUSH 0x0015 // 10101
#define OP_JMP 0x0016 // 10110
#define OP_JZ 0x0017 // 10111
#define REGISTER_PC 0
#define REGISTER_SP 1
#define MAX_REGISTER REGISTER_SP
vtypedef vm_vt (strings_size : int,
strings_addr : addr,
code_size : int,
code_addr : addr,
data_size : int,
data_addr : addr,
stack_size : int,
stack_addr : addr) =
@{
strings = vmstrings_section_vt (strings_size, strings_addr),
code = vmarray_vt (byte, code_size, code_addr),
data = vmarray_vt (vmint, data_size, data_addr),
stack = vmarray_vt (vmint, stack_size, stack_addr),
registers = vmarray_vt (vmint, MAX_REGISTER + 1)
}
vtypedef vm_vt (strings_size : int,
code_size : int,
data_size : int,
stack_size : int) =
[strings_addr : addr]
[code_addr : addr]
[data_addr : addr]
[stack_addr : addr]
vm_vt (strings_size, strings_addr,
code_size, code_addr,
data_size, data_addr,
stack_size, stack_addr)
vtypedef vm_vt =
[strings_size : int]
[code_size : int]
[data_size : int]
[stack_size : int]
vm_vt (strings_size, code_size, data_size, stack_size)
fn
vm_vt_free (vm : vm_vt) :
void =
let
val @{
strings = strings,
code = code,
data = data,
stack = stack,
registers = registers
} = vm
in
vmstrings_section_vt_free strings;
vmarray_vt_free<byte> code;
vmarray_vt_free<vmint> data;
vmarray_vt_free<vmint> stack;
vmarray_vt_free<vmint> registers
end
fn
opcode_name_to_byte {n, i, j : int | 0 <= i; i <= j; j <= n}
(arr : &(@[String0][OPCODE_COUNT]),
str : string n,
i : size_t i,
j : size_t j) :
byte =
let
fun
loop {k : int | 0 <= k; k <= OPCODE_COUNT} .<OPCODE_COUNT - k>.
(arr : &(@[String0][OPCODE_COUNT]),
k : int k) : byte =
if k = OPCODE_COUNT then
$raise bad_vm ("Unrecognized opcode name.")
else if substr_equal (str, i, j, arr[k]) then
i2byte k
else
loop (arr, succ k)
in
loop (arr, 0)
end
fn {}
vmint_byte0 (i : vmint) :<>
byte =
vm2byte (i land (u2vm 0xFFU))
fn {}
vmint_byte1 (i : vmint) :<>
byte =
vm2byte ((i >> 8) land (u2vm 0xFFU))
fn {}
vmint_byte2 (i : vmint) :<>
byte =
vm2byte ((i >> 16) land (u2vm 0xFFU))
fn {}
vmint_byte3 (i : vmint) :<>
byte =
vm2byte (i >> 24)
fn
parse_instruction {n : int | 0 <= n}
(arr : &(@[String0][OPCODE_COUNT]),
line : string n) :
instruction_vt =
let
val bad_instruction = "Bad VM instruction."
val n = string_length (line)
val i = skip_whitespace (line, n, i2sz 0)
(* Skip the address field*)
val i = skip_non_whitespace (line, n, i)
val i = skip_whitespace (line, n, i)
val j = skip_non_whitespace (line, n, i)
val opcode = opcode_name_to_byte (arr, line, i, j)
val start_of_argument = j
fn
finish_push () :
instruction_vt =
let
val i1 = skip_whitespace (line, n, start_of_argument)
val j1 = skip_non_whitespace (line, n, i1)
val arg = parse_integer (line, i1, j1)
in
(* Little-endian storage. *)
instruction_vt_5 (opcode, vmint_byte0 arg, vmint_byte1 arg,
vmint_byte2 arg, vmint_byte3 arg)
end
fn
finish_fetch_or_store () :
instruction_vt =
let
val i1 = skip_whitespace (line, n, start_of_argument)
val j1 = skip_non_whitespace (line, n, i1)
in
if j1 - i1 < i2sz 3 then
$raise bad_vm (bad_instruction)
else if line[i1] <> '\[' || line[pred j1] <> ']' then
$raise bad_vm (bad_instruction)
else
let
val arg = parse_integer (line, succ i1, pred j1)
in
(* Little-endian storage. *)
instruction_vt_5 (opcode, vmint_byte0 arg, vmint_byte1 arg,
vmint_byte2 arg, vmint_byte3 arg)
end
end
fn
finish_jmp_or_jz () :
instruction_vt =
let
val i1 = skip_whitespace (line, n, start_of_argument)
val j1 = skip_non_whitespace (line, n, i1)
in
if j1 - i1 < i2sz 3 then
$raise bad_vm (bad_instruction)
else if line[i1] <> '\(' || line[pred j1] <> ')' then
$raise bad_vm (bad_instruction)
else
let
val arg = parse_integer (line, succ i1, pred j1)
in
(* Little-endian storage. *)
instruction_vt_5 (opcode, vmint_byte0 arg, vmint_byte1 arg,
vmint_byte2 arg, vmint_byte3 arg)
end
end
in
case+ byte2int0 opcode of
| OP_PUSH => finish_push ()
| OP_FETCH => finish_fetch_or_store ()
| OP_STORE => finish_fetch_or_store ()
| OP_JMP => finish_jmp_or_jz ()
| OP_JZ => finish_jmp_or_jz ()
| _ => instruction_vt_1 (opcode)
end
fn
read_instructions (f : FILEref,
arr : &(@[String0][OPCODE_COUNT])) :
(List_vt (instruction_vt), Size_t) =
(* Read the instructions from the input, producing a list of
instruction_vt objects, and also calculating the total
number of bytes in the instructions. *)
let
fun
loop (arr : &(@[String0][OPCODE_COUNT]),
lst : List_vt (instruction_vt),
bytes_needed : Size_t) :
@(List_vt (instruction_vt), Size_t) =
if fileref_is_eof f then
@(list_vt_reverse lst, bytes_needed)
else
let
val line = fileref_get_line_string (f)
in
if fileref_is_eof f then
begin
free line;
@(list_vt_reverse lst, bytes_needed)
end
else
let
val instruction =
parse_instruction (arr, $UN.strptr2string line)
val _ = free line
prval _ = lemma_list_vt_param lst
in
case+ instruction of
| instruction_vt_1 _ =>
loop (arr, instruction :: lst, bytes_needed + i2sz 1)
| instruction_vt_5 _ =>
loop (arr, instruction :: lst, bytes_needed + i2sz 5)
end
end
in
loop (arr, NIL, i2sz 0)
end
fn
list_of_instructions_to_code {bytes_needed : int}
(lst : List_vt (instruction_vt),
bytes_needed : size_t bytes_needed) :
[bytes_needed : int]
vmarray_vt (byte, bytes_needed) =
(* This routine consumes and destroys lst. *)
let
fun
loop {n : int | 0 <= n} .<n>.
(code : &vmarray_vt (byte, bytes_needed),
lst : list_vt (instruction_vt, n),
i : Size_t) : void =
case+ lst of
| ~ NIL => ()
| ~ head :: tail =>
begin
case head of
| ~ instruction_vt_1 (byte1) =>
let
val _ = assertloc (i < bytes_needed)
in
code[i] := byte1;
loop (code, tail, i + i2sz 1)
end
| ~ instruction_vt_5 (byte1, byte2, byte3, byte4, byte5) =>
let
val _ = assertloc (i + i2sz 4 < bytes_needed)
in
code[i] := byte1;
code[i + i2sz 1] := byte2;
code[i + i2sz 2] := byte3;
code[i + i2sz 3] := byte4;
code[i + i2sz 4] := byte5;
loop (code, tail, i + i2sz 5)
end
end
var code = vmarray_vt_alloc<byte> (bytes_needed, i2byte OP_HALT)
prval _ = lemma_list_vt_param lst
prval _ = lemma_g1uint_param bytes_needed
val _ = loop (code, lst, i2sz 0)
in
code
end
fn
read_and_parse_code (f : FILEref,
arr : &(@[String0][OPCODE_COUNT])) :
[bytes_needed : int]
vmarray_vt (byte, bytes_needed) =
let
val @(instructions, bytes_needed) = read_instructions (f, arr)
in
list_of_instructions_to_code (instructions, bytes_needed)
end
fn
parse_header_line {n : int | 0 <= n}
(line : string n) :
@(vmint, vmint) =
let
val bad_vm_header_line = "Bad VM header line."
val n = string_length (line)
val i = skip_whitespace (line, n, i2sz 0)
val j = skip_non_whitespace (line, n, i)
val _ = if ~substr_equal (line, i, j, "Datasize:") then
$raise bad_vm (bad_vm_header_line)
val i = skip_whitespace (line, n, j)
val j = skip_non_whitespace (line, n, i)
val data_size = parse_integer (line, i, j)
val i = skip_whitespace (line, n, j)
val j = skip_non_whitespace (line, n, i)
val _ = if ~substr_equal (line, i, j, "Strings:") then
$raise bad_vm (bad_vm_header_line)
val i = skip_whitespace (line, n, j)
val j = skip_non_whitespace (line, n, i)
val strings_size = parse_integer (line, i, j)
in
@(data_size, strings_size)
end
fn
read_vm (f : FILEref,
opcode_names_arr : &(@[String0][OPCODE_COUNT])) :
vm_vt =
let
val line = fileref_get_line_string (f)
val @(data_size, strings_size) =
parse_header_line ($UN.strptr2string line)
val _ = free line
val [data_size : int] data_size =
g1ofg0 (vm2sz data_size)
val [strings_size : int] strings_size =
g1ofg0 (vm2sz strings_size)
prval _ = lemma_g1uint_param data_size
prval _ = lemma_g1uint_param strings_size
prval _ = prop_verify {0 <= data_size} ()
prval _ = prop_verify {0 <= strings_size} ()
val strings = vmstrings_section_vt_read (f, strings_size)
val code = read_and_parse_code (f, opcode_names_arr)
val data = vmarray_vt_alloc<vmint> (data_size, i2vm 0)
val stack = vmarray_vt_alloc<vmint> (vmstack_size, i2vm 0)
val registers = vmarray_vt_alloc<vmint> (i2sz (MAX_REGISTER + 1),
i2vm 0)
in
@{
strings = strings,
code = code,
data = data,
stack = stack,
registers = registers
}
end
fn {}
pop (vm : &vm_vt) :
vmint =
let
macdef registers = vm.registers
macdef stack = vm.stack
val sp_before = registers[REGISTER_SP]
in
if sp_before = i2vm 0 then
$raise vm_runtime_error ("Stack underflow.")
else
let
val sp_after = sp_before - i2vm 1
val _ = registers[REGISTER_SP] := sp_after
val i = g1ofg0 (vm2sz sp_after)
(* What follows is a runtime assertion that the upper stack
boundary is not gone past, even though it certainly will
not. This is necessary (assuming one does not use something
such as $UN.prop_assert) because the stack pointer is a
vmint, whose bounds cannot be proven at compile time.
If you comment out the assertloc, the program will not pass
typechecking.
Compilers for many other languages will just insert such
checks willy-nilly, leading programmers to turn off such
instrumentation in the very code they provide to users.
One might be tempted to use Size_t instead for the stack
pointer, but what if the instruction set were later
augmented with ways to read from or write into the stack
pointer? *)
val _ = assertloc (i < vmarray_vt_length stack)
in
stack[i]
end
end
fn {}
push (vm : &vm_vt,
x : vmint) :
void =
let
macdef registers = vm.registers
macdef stack = vm.stack
val sp_before = registers[REGISTER_SP]
val i = g1ofg0 (vm2sz sp_before)
in
if vmarray_vt_length stack <= i then
$raise vm_runtime_error ("Stack overflow.")
else
let
val sp_after = sp_before + i2vm 1
in
registers[REGISTER_SP] := sp_after;
stack[i] := x
end
end
fn {}
fetch_data (vm : &vm_vt,
index : vmint) :
vmint =
let
macdef data = vm.data
val i = g1ofg0 (vm2sz index)
in
if vmarray_vt_length data <= i then
$raise vm_runtime_error ("Fetch from outside the data section.")
else
data[i]
end
fn {}
store_data (vm : &vm_vt,
index : vmint,
x : vmint) :
void =
let
macdef data = vm.data
val i = g1ofg0 (vm2sz index)
in
if vmarray_vt_length data <= i then
$raise vm_runtime_error ("Store to outside the data section.")
else
data[i] := x
end
fn {}
get_argument (vm : &vm_vt) :
vmint =
let
macdef code = vm.code
macdef registers = vm.registers
val pc = registers[REGISTER_PC]
val i = g1ofg0 (vm2sz pc)
in
if vmarray_vt_length code <= i + i2sz 4 then
$raise (vm_runtime_error
("The program counter is out of bounds."))
else
let
(* The data is stored little-endian. *)
val byte0 = byte2vm code[i]
val byte1 = byte2vm code[i + i2sz 1]
val byte2 = byte2vm code[i + i2sz 2]
val byte3 = byte2vm code[i + i2sz 3]
in
(byte0) lor (byte1 << 8) lor (byte2 << 16) lor (byte3 << 24)
end
end
fn {}
skip_argument (vm : &vm_vt) :
void =
let
macdef registers = vm.registers
val pc = registers[REGISTER_PC]
in
registers[REGISTER_PC] := pc + i2vm 4
end
extern fun {}
unary_operation$inner : vmint -<> vmint
fn {}
unary_operation (vm : &vm_vt) :
void =
let
macdef registers = vm.registers
macdef stack = vm.stack
val sp = registers[REGISTER_SP]
val i = g1ofg0 (vm2sz (sp))
prval _ = lemma_g1uint_param i
in
if i = i2sz 0 then
$raise vm_runtime_error ("Stack underflow.")
else
let
val _ = assertloc (i < vmarray_vt_length stack)
(* The actual unary operation is inserted here during
template expansion. *)
val result = unary_operation$inner<> (stack[i - 1])
in
stack[i - 1] := result
end
end
extern fun {}
binary_operation$inner : (vmint, vmint) -<> vmint
fn {}
binary_operation (vm : &vm_vt) :
void =
let
macdef registers = vm.registers
macdef stack = vm.stack
val sp_before = registers[REGISTER_SP]
val i = g1ofg0 (vm2sz (sp_before))
prval _ = lemma_g1uint_param i
in
if i <= i2sz 1 then
$raise vm_runtime_error ("Stack underflow.")
else
let
val _ = registers[REGISTER_SP] := sp_before - i2vm 1
val _ = assertloc (i < vmarray_vt_length stack)
(* The actual binary operation is inserted here during
template expansion. *)
val result =
binary_operation$inner<> (stack[i - 2], stack[i - 1])
in
stack[i - 2] := result
end
end
fn {}
uop_neg (vm : &vm_vt) :
void =
let
implement {}
unary_operation$inner (x) =
twos_complement x
in
unary_operation (vm)
end
fn {}
uop_not (vm : &vm_vt) :
void =
let
implement {}
unary_operation$inner (x) =
logical_not x
in
unary_operation (vm)
end
fn {}
binop_add (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x + y
in
binary_operation (vm)
end
fn {}
binop_sub (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x - y
in
binary_operation (vm)
end
fn {}
binop_mul (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_mul y
in
binary_operation (vm)
end
fn {}
binop_div (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_div y
in
binary_operation (vm)
end
fn {}
binop_mod (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_mod y
in
binary_operation (vm)
end
fn {}
binop_eq (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \equality y
in
binary_operation (vm)
end
fn {}
binop_ne (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \inequality y
in
binary_operation (vm)
end
fn {}
binop_lt (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_lt y
in
binary_operation (vm)
end
fn {}
binop_gt (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_gt y
in
binary_operation (vm)
end
fn {}
binop_le (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_lte y
in
binary_operation (vm)
end
fn {}
binop_ge (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \signed_gte y
in
binary_operation (vm)
end
fn {}
binop_and (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \logical_and y
in
binary_operation (vm)
end
fn {}
binop_or (vm : &vm_vt) :
void =
let
implement {}
binary_operation$inner (x, y) =
x \logical_or y
in
binary_operation (vm)
end
fn {}
do_push (vm : &vm_vt) :
void =
let
val arg = get_argument (vm)
in
push (vm, arg);
skip_argument (vm)
end
fn {}
do_fetch (vm : &vm_vt) :
void =
let
val i = get_argument (vm)
val x = fetch_data (vm, i)
in
push (vm, x);
skip_argument (vm)
end
fn {}
do_store (vm : &vm_vt) :
void =
let
val i = get_argument (vm)
val x = pop (vm)
in
store_data (vm, i, x);
skip_argument (vm)
end
fn {}
do_jmp (vm : &vm_vt) :
void =
let
macdef registers = vm.registers
val arg = get_argument (vm)
val pc = registers[REGISTER_PC]
in
registers[REGISTER_PC] := pc + arg
end
fn {}
do_jz (vm : &vm_vt) :
void =
let
val x = pop (vm)
in
if x = i2vm 0 then
do_jmp (vm)
else
skip_argument (vm)
end
fn {}
do_prtc (f_output : FILEref,
vm : &vm_vt) :
void =
let
val x = pop (vm)
in
fileref_putc (f_output, vm2i x)
end
fn {}
do_prti (f_output : FILEref,
vm : &vm_vt) :
void =
let
val x = pop (vm)
in
fprint! (f_output, vm2i x)
end
fn {}
do_prts (f_output : FILEref,
vm : &vm_vt) :
void =
let
val i = g1ofg0 (vm2sz (pop (vm)))
in
if vmstrings_section_vt_length (vm.strings) <= i then
$raise vm_runtime_error ("String index out of bounds.")
else
vmstring_fprint (f_output, vm.strings, i)
end
fn
vm_step (f_output : FILEref,
vm : &vm_vt,
machine_halt : &bool,
bad_opcode : &bool) :
void =
let
macdef code = vm.code
macdef registers = vm.registers
val pc = registers[REGISTER_PC]
val i = g1ofg0 (vm2sz (pc))
prval _ = lemma_g1uint_param i
in
if vmarray_vt_length (code) <= i then
$raise (vm_runtime_error
("The program counter is out of bounds."))
else
let
val _ = registers[REGISTER_PC] := pc + i2vm 1
val opcode = code[i]
val u_opcode = byte2uint0 opcode
in
(* Dispatch by bifurcation on the bit pattern of the
opcode. This method is logarithmic in the number
of opcode values. *)
machine_halt := false;
bad_opcode := false;
if (u_opcode land (~(0x1FU))) = 0U then
begin
if (u_opcode land 0x10U) = 0U then
begin
if (u_opcode land 0x08U) = 0U then
begin
if (u_opcode land 0x04U) = 0U then
begin
if (u_opcode land 0x02U) = 0U then
begin
if (u_opcode land 0x01U) = 0U then
(* OP_HALT *)
machine_halt := true
else
binop_add (vm)
end
else
begin
if (u_opcode land 0x01U) = 0U then
binop_sub (vm)
else
binop_mul (vm)
end
end
else
begin
if (u_opcode land 0x02U) = 0U then
begin
if (u_opcode land 0x01U) = 0U then
binop_div (vm)
else
binop_mod (vm)
end
else
begin
if (u_opcode land 0x01U) = 0U then
binop_lt (vm)
else
binop_gt (vm)
end
end
end
else
begin
if (u_opcode land 0x04U) = 0U then
begin
if (u_opcode land 0x02U) = 0U then
begin
if (u_opcode land 0x01U) = 0U then
binop_le (vm)
else
binop_ge (vm)
end
else
begin
if (u_opcode land 0x01U) = 0U then
binop_eq (vm)
else
binop_ne (vm)
end
end
else
begin
if (u_opcode land 0x02U) = 0U then
begin
if (u_opcode land 0x01U) = 0U then
binop_and (vm)
else
binop_or (vm)
end
else
begin
if (u_opcode land 0x01U) = 0U then
uop_neg (vm)
else
uop_not (vm)
end
end
end
end
else
begin
if (u_opcode land 0x08U) = 0U then
begin
if (u_opcode land 0x04U) = 0U then
begin
if (u_opcode land 0x02U) = 0U then
begin
if (u_opcode land 0x01U) = 0U then
do_prtc (f_output, vm)
else
do_prti (f_output, vm)
end
else
begin
if (u_opcode land 0x01U) = 0U then
do_prts (f_output, vm)
else
do_fetch (vm)
end
end
else
begin
if (u_opcode land 0x02U) = 0U then
begin
if (u_opcode land 0x01U) = 0U then
do_store (vm)
else
do_push (vm)
end
else
begin
if (u_opcode land 0x01U) = 0U then
do_jmp (vm)
else
do_jz (vm)
end
end
end
else
bad_opcode := true
end
end
else
bad_opcode := true
end
end
fn
vm_continue (f_output : FILEref,
vm : &vm_vt) :
void =
let
fun
loop (vm : &vm_vt,
machine_halt : &bool,
bad_opcode : &bool) : void =
if ~machine_halt && ~bad_opcode then
begin
vm_step (f_output, vm, machine_halt, bad_opcode);
loop (vm, machine_halt, bad_opcode)
end
var machine_halt : bool = false
var bad_opcode : bool = false
in
loop (vm, machine_halt, bad_opcode);
if bad_opcode then
$raise vm_runtime_error ("Unrecognized opcode at runtime.")
end
fn
vm_initialize (vm : &vm_vt) :
void =
let
macdef data = vm.data
macdef registers = vm.registers
in
vmarray_vt_fill (data, i2vm 0);
registers[REGISTER_PC] := i2vm 0;
registers[REGISTER_SP] := i2vm 0
end
fn
vm_run (f_output : FILEref,
vm : &vm_vt) :
void =
begin
vm_initialize (vm);
vm_continue (f_output, vm)
end
(********************************************************************)
implement
main0 (argc, argv) =
{
val inpfname =
if 2 <= argc then
$UN.cast{string} argv[1]
else
"-"
val outfname =
if 3 <= argc then
$UN.cast{string} argv[2]
else
"-"
val inpf =
if (inpfname : string) = "-" then
stdin_ref
else
fileref_open_exn (inpfname, file_mode_r)
val outf =
if (outfname : string) = "-" then
stdout_ref
else
fileref_open_exn (outfname, file_mode_w)
(* The following order must match that established by
OP_HALT, OP_ADD, OP_SUB, etc. *)
var opcode_order =
@[String0][OPCODE_COUNT] ("halt", // 00000 bit pattern
"add", // 00001
"sub", // 00010
"mul", // 00011
"div", // 00100
"mod", // 00101
"lt", // 00110
"gt", // 00111
"le", // 01000
"ge", // 01001
"eq", // 01010
"ne", // 01011
"and", // 01100
"or", // 01101
"neg", // 01110
"not", // 01111
"prtc", // 10000
"prti", // 10001
"prts", // 10010
"fetch", // 10011
"store", // 10100
"push", // 10101
"jmp", // 10110
"jz") // 10111
val _ = ensure_that_vmint_is_suitable ()
var vm = read_vm (inpf, opcode_order)
val _ = vm_run (outf, vm)
val _ = vm_vt_free vm
}
(********************************************************************) |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #Go | Go | package main
import (
"bufio"
"fmt"
"log"
"os"
"strconv"
"strings"
)
type NodeType int
const (
ndIdent NodeType = iota
ndString
ndInteger
ndSequence
ndIf
ndPrtc
ndPrts
ndPrti
ndWhile
ndAssign
ndNegate
ndNot
ndMul
ndDiv
ndMod
ndAdd
ndSub
ndLss
ndLeq
ndGtr
ndGeq
ndEql
ndNeq
ndAnd
ndOr
)
type Tree struct {
nodeType NodeType
left *Tree
right *Tree
value int
}
// dependency: Ordered by NodeType, must remain in same order as NodeType enum
type atr struct {
enumText string
nodeType NodeType
}
var atrs = []atr{
{"Identifier", ndIdent},
{"String", ndString},
{"Integer", ndInteger},
{"Sequence", ndSequence},
{"If", ndIf},
{"Prtc", ndPrtc},
{"Prts", ndPrts},
{"Prti", ndPrti},
{"While", ndWhile},
{"Assign", ndAssign},
{"Negate", ndNegate},
{"Not", ndNot},
{"Multiply", ndMul},
{"Divide", ndDiv},
{"Mod", ndMod},
{"Add", ndAdd},
{"Subtract", ndSub},
{"Less", ndLss},
{"LessEqual", ndLeq},
{"Greater", ndGtr},
{"GreaterEqual", ndGeq},
{"Equal", ndEql},
{"NotEqual", ndNeq},
{"And", ndAnd},
{"Or", ndOr},
}
var (
stringPool []string
globalNames []string
globalValues = make(map[int]int)
)
var (
err error
scanner *bufio.Scanner
)
func reportError(msg string) {
log.Fatalf("error : %s\n", msg)
}
func check(err error) {
if err != nil {
log.Fatal(err)
}
}
func btoi(b bool) int {
if b {
return 1
}
return 0
}
func itob(i int) bool {
if i == 0 {
return false
}
return true
}
func makeNode(nodeType NodeType, left *Tree, right *Tree) *Tree {
return &Tree{nodeType, left, right, 0}
}
func makeLeaf(nodeType NodeType, value int) *Tree {
return &Tree{nodeType, nil, nil, value}
}
func interp(x *Tree) int { // interpret the parse tree
if x == nil {
return 0
}
switch x.nodeType {
case ndInteger:
return x.value
case ndIdent:
return globalValues[x.value]
case ndString:
return x.value
case ndAssign:
n := interp(x.right)
globalValues[x.left.value] = n
return n
case ndAdd:
return interp(x.left) + interp(x.right)
case ndSub:
return interp(x.left) - interp(x.right)
case ndMul:
return interp(x.left) * interp(x.right)
case ndDiv:
return interp(x.left) / interp(x.right)
case ndMod:
return interp(x.left) % interp(x.right)
case ndLss:
return btoi(interp(x.left) < interp(x.right))
case ndGtr:
return btoi(interp(x.left) > interp(x.right))
case ndLeq:
return btoi(interp(x.left) <= interp(x.right))
case ndEql:
return btoi(interp(x.left) == interp(x.right))
case ndNeq:
return btoi(interp(x.left) != interp(x.right))
case ndAnd:
return btoi(itob(interp(x.left)) && itob(interp(x.right)))
case ndOr:
return btoi(itob(interp(x.left)) || itob(interp(x.right)))
case ndNegate:
return -interp(x.left)
case ndNot:
if interp(x.left) == 0 {
return 1
}
return 0
case ndIf:
if interp(x.left) != 0 {
interp(x.right.left)
} else {
interp(x.right.right)
}
return 0
case ndWhile:
for interp(x.left) != 0 {
interp(x.right)
}
return 0
case ndPrtc:
fmt.Printf("%c", interp(x.left))
return 0
case ndPrti:
fmt.Printf("%d", interp(x.left))
return 0
case ndPrts:
fmt.Print(stringPool[interp(x.left)])
return 0
case ndSequence:
interp(x.left)
interp(x.right)
return 0
default:
reportError(fmt.Sprintf("interp: unknown tree type %d\n", x.nodeType))
}
return 0
}
func getEnumValue(name string) NodeType {
for _, atr := range atrs {
if atr.enumText == name {
return atr.nodeType
}
}
reportError(fmt.Sprintf("Unknown token %s\n", name))
return -1
}
func fetchStringOffset(s string) int {
var d strings.Builder
s = s[1 : len(s)-1]
for i := 0; i < len(s); i++ {
if s[i] == '\\' && (i+1) < len(s) {
if s[i+1] == 'n' {
d.WriteByte('\n')
i++
} else if s[i+1] == '\\' {
d.WriteByte('\\')
i++
}
} else {
d.WriteByte(s[i])
}
}
s = d.String()
for i := 0; i < len(stringPool); i++ {
if s == stringPool[i] {
return i
}
}
stringPool = append(stringPool, s)
return len(stringPool) - 1
}
func fetchVarOffset(name string) int {
for i := 0; i < len(globalNames); i++ {
if globalNames[i] == name {
return i
}
}
globalNames = append(globalNames, name)
return len(globalNames) - 1
}
func loadAst() *Tree {
var nodeType NodeType
var s string
if scanner.Scan() {
line := strings.TrimRight(scanner.Text(), " \t")
tokens := strings.Fields(line)
first := tokens[0]
if first[0] == ';' {
return nil
}
nodeType = getEnumValue(first)
le := len(tokens)
if le == 2 {
s = tokens[1]
} else if le > 2 {
idx := strings.Index(line, `"`)
s = line[idx:]
}
}
check(scanner.Err())
if s != "" {
var n int
switch nodeType {
case ndIdent:
n = fetchVarOffset(s)
case ndInteger:
n, err = strconv.Atoi(s)
check(err)
case ndString:
n = fetchStringOffset(s)
default:
reportError(fmt.Sprintf("Unknown node type: %s\n", s))
}
return makeLeaf(nodeType, n)
}
left := loadAst()
right := loadAst()
return makeNode(nodeType, left, right)
}
func main() {
ast, err := os.Open("ast.txt")
check(err)
defer ast.Close()
scanner = bufio.NewScanner(ast)
x := loadAst()
interp(x)
} |
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Ada | Ada | with ada.command_line, ada.containers.indefinite_vectors, ada.text_io;
procedure compare_lengths is
package string_vector is new ada.containers.indefinite_vectors
(index_type => Positive, element_type => String);
function "<" (left, right : String) return Boolean is
begin
return left'length > right'length;
end "<";
package string_vector_sorting is new string_vector.generic_sorting;
list : string_vector.Vector;
begin
for i in 1 .. ada.command_line.argument_count loop
list.append (ada.command_line.argument (i));
end loop;
string_vector_sorting.sort (list);
for elem of list loop
ada.text_io.put_line (elem'length'image & ": " & elem);
end loop;
end compare_lengths;
|
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #COBOL | COBOL | >>SOURCE FORMAT IS FREE
identification division.
*> this code is dedicated to the public domain
*> (GnuCOBOL) 2.3-dev.0
*> for extra credit, generate this program directly from the EBNF
program-id. parser.
environment division.
configuration section.
repository. function all intrinsic.
input-output section.
file-control.
select input-file assign using input-name
status is input-status
organization is line sequential.
data division.
file section.
fd input-file global.
01 input-record global.
03 input-line pic zzzz9.
03 input-column pic zzzzzz9.
03 filler pic x(3).
03 input-token pic x(16).
03 input-value pic x(48).
working-storage section.
01 program-name pic x(32) value spaces global.
01 input-name pic x(32) value spaces global.
01 input-status pic xx global.
01 line-no pic 999 value 0.
01 col-no pic 99 value 0.
01 error-record global.
03 error-line-no pic zzzz9.
03 error-col-no pic zzzzzz9.
03 filler pic x value space.
03 error-message pic x(64) value spaces.
01 token global.
03 token-type pic x(16).
03 token-line pic 999.
03 token-column pic 99.
03 token-value pic x(48).
01 parse-stack global.
03 p pic 999 value 0.
03 p-lim pic 999 value 200.
03 p-zero pic 999 value 0.
03 parse-entry occurs 200.
05 parse-name pic x(24).
05 parse-token pic x(16).
05 parse-left pic 999.
05 parse-right pic 999.
05 parse-work pic 999.
05 parse-work1 pic 999.
01 abstract-syntax-tree global.
03 t pic 999 value 0.
03 t1 pic 999.
03 t-lim pic 999 value 998.
03 filler occurs 998.
05 leaf.
07 leaf-type pic x(14).
07 leaf-value pic x(48).
05 node redefines leaf.
07 node-type pic x(14).
07 node-left pic 999.
07 node-right pic 999.
01 indent pic x(200) value all '| ' global.
procedure division chaining program-name.
start-parser.
if program-name <> spaces
string program-name delimited by space '.lex' into input-name
open input input-file
if input-status <> '00'
string 'in parser ' trim(input-name) ' open status ' input-status
into error-message
call 'reporterror'
end-if
end-if
call 'gettoken'
call 'stmt_list'
if input-name <> spaces
close input-file
end-if
call 'printast' using t
>>d perform dump-ast
stop run
.
dump-ast.
display '==========' upon syserr
display 'ast:' upon syserr
display 't=' t upon syserr
perform varying t1 from 1 by 1 until t1 > t
if leaf-type(t1) = 'Identifier' or 'Integer' or 'String'
display t1 space trim(leaf-type(t1)) space trim(leaf-value(t1)) upon syserr
else
display t1 space node-left(t1) space node-right(t1) space trim(node-type(t1))
upon syserr
end-if
end-perform
.
identification division.
program-id. stmt_list common recursive.
data division.
procedure division.
start-stmt_list.
call 'push' using module-id
move p-zero to parse-left(p)
perform forever
call 'stmt'
move return-code to parse-right(p)
call 'makenode' using 'Sequence' parse-left(p) parse-right(p)
move return-code to parse-left(p)
if parse-right(p) = 0
or token-type = 'End_of_input'
exit perform
end-if
end-perform
call 'pop'
.
end program stmt_list.
identification division.
program-id. stmt common recursive.
procedure division.
start-stmt.
call 'push' using module-id
move p-zero to parse-left(p)
evaluate token-type
when 'Semicolon'
call 'gettoken'
when 'Identifier'
*>Identifier '=' expr ';'
call 'makeleaf' using 'Identifier' token-value
move return-code to parse-left(p)
call 'gettoken'
call 'expect' using 'Op_assign'
call 'expr'
move return-code to parse-right(p)
call 'expect' using 'Semicolon'
call 'makenode' using 'Assign' parse-left(p) parse-right(p)
move return-code to parse-left(p)
when 'Keyword_while'
*>'while' paren_expr '{' stmt '}'
call 'gettoken'
call 'paren_expr'
move return-code to parse-work(p)
call 'stmt'
move return-code to parse-right(p)
call 'makenode' using 'While' parse-work(p) parse-right(p)
move return-code to parse-left(p)
when 'Keyword_if'
*>'if' paren_expr stmt ['else' stmt]
call 'gettoken'
call 'paren_expr'
move return-code to parse-left(p)
call 'stmt'
move return-code to parse-work(p)
move p-zero to parse-work1(p)
if token-type = 'Keyword_else'
call 'gettoken'
call 'stmt'
move return-code to parse-work1(p)
end-if
call 'makenode' using 'If' parse-work(p) parse-work1(p)
move return-code to parse-right(p)
call 'makenode' using 'If' parse-left(p) parse-right(p)
move return-code to parse-left(p)
when 'Keyword_print'
*>'print' '(' prt_list ')' ';'
call 'gettoken'
call 'expect' using 'LeftParen'
call 'prt_list'
move return-code to parse-left(p)
call 'expect' using 'RightParen'
call 'expect' using 'Semicolon'
when 'Keyword_putc'
*>'putc' paren_expr ';'
call 'gettoken'
call 'paren_expr'
move return-code to parse-left(p)
call 'makenode' using 'Prtc' parse-left(p) p-zero
move return-code to parse-left(p)
call 'expect' using 'Semicolon'
when 'LeftBrace'
*>'{' stmt '}'
call 'gettoken'
move p-zero to parse-left(p)
perform until token-type = 'RightBrace' or 'End_of_input'
call 'stmt'
move return-code to parse-right(p)
call 'makenode' using 'Sequence' parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-perform
if token-type <> 'End_of_input'
call 'gettoken'
end-if
when other
move 0 to parse-left(p)
end-evaluate
move parse-left(p) to return-code
call 'pop'
.
end program stmt.
identification division.
program-id. paren_expr common recursive.
procedure division.
start-paren_expr.
*>'(' expr ')' ;
call 'push' using module-id
call 'expect' using 'LeftParen'
call 'expr'
call 'expect' using 'RightParen'
call 'pop'
.
end program paren_expr.
identification division.
program-id. prt_list common.
procedure division.
start-prt_list.
*>(string | expr) {',' (String | expr)} ;
call 'push' using module-id
move p-zero to parse-work(p)
perform prt_entry
perform until token-type <> 'Comma'
call 'gettoken'
perform prt_entry
end-perform
call 'pop'
exit program
.
prt_entry.
if token-type = 'String'
call 'makeleaf' using token-type token-value
move return-code to parse-left(p)
call 'makenode' using 'Prts' parse-left(p) p-zero
call 'gettoken'
else
call 'expr'
move return-code to parse-left(p)
call 'makenode' using 'Prti' parse-left(p) p-zero
end-if
move return-code to parse-right(p)
call 'makenode' using 'Sequence' parse-work(p) parse-right(p)
move return-code to parse-work(p)
.
end program prt_list.
identification division.
program-id. expr common recursive.
procedure division.
start-expr.
*>and_expr {'||' and_expr} ;
call 'push' using module-id
call 'and_expr'
move return-code to parse-left(p)
perform forever
if token-type <> 'Op_or'
exit perform
end-if
call 'gettoken'
call 'and_expr'
move return-code to parse-right(p)
call 'makenode' using 'Or' parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-perform
move parse-left(p) to return-code
call 'pop'
.
end program expr.
identification division.
program-id. and_expr common recursive.
procedure division.
start-and_expr.
*>equality_expr {'&&' equality_expr} ;
call 'push' using module-id
call 'equality_expr'
move return-code to parse-left(p)
perform forever
if token-type <> 'Op_and'
exit perform
end-if
call 'gettoken'
call 'equality_expr'
move return-code to parse-right(p)
call 'makenode' using 'And' parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-perform
call 'pop'
.
end program and_expr.
identification division.
program-id. equality_expr common recursive.
procedure division.
start-equality_expr.
*>relational_expr [('==' | '!=') relational_expr] ;
call 'push' using module-id
call 'relational_expr'
move return-code to parse-left(p)
evaluate token-type
when 'Op_equal'
move 'Equal' to parse-token(p)
when 'Op_notequal'
move 'NotEqual' to parse-token(p)
end-evaluate
if parse-token(p) <> spaces
call 'gettoken'
call 'relational_expr'
move return-code to parse-right(p)
call 'makenode' using parse-token(p) parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-if
call 'pop'
.
end program equality_expr.
identification division.
program-id. relational_expr common recursive.
procedure division.
start-relational_expr.
*>addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
call 'push' using module-id
call 'addition_expr'
move return-code to parse-left(p)
evaluate token-type
when 'Op_less'
move 'Less' to parse-token(p)
when 'Op_lessequal'
move 'LessEqual' to parse-token(p)
when 'Op_greater'
move 'Greater' to parse-token(p)
when 'Op_greaterequal'
move 'GreaterEqual' to parse-token(p)
end-evaluate
if parse-token(p) <> spaces
call 'gettoken'
call 'addition_expr'
move return-code to parse-right(p)
call 'makenode' using parse-token(p) parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-if
call 'pop'
.
end program relational_expr.
identification division.
program-id. addition_expr common recursive.
procedure division.
start-addition_expr.
*>multiplication_expr {('+' | '-') multiplication_expr} ;
call 'push' using module-id
call 'multiplication_expr'
move return-code to parse-left(p)
perform forever
evaluate token-type
when 'Op_add'
move 'Add' to parse-token(p)
when 'Op_subtract'
move 'Subtract' to parse-token(p)
when other
exit perform
end-evaluate
call 'gettoken'
call 'multiplication_expr'
move return-code to parse-right(p)
call 'makenode' using parse-token(p) parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-perform
call 'pop'
.
end program addition_expr.
identification division.
program-id. multiplication_expr common recursive.
procedure division.
start-multiplication_expr.
*>primary {('*' | '/' | '%') primary } ;
call 'push' using module-id
call 'primary'
move return-code to parse-left(p)
perform forever
evaluate token-type
when 'Op_multiply'
move 'Multiply' to parse-token(p)
when 'Op_divide'
move 'Divide' to parse-token(p)
when 'Op_mod'
move 'Mod' to parse-token(p)
when other
exit perform
end-evaluate
call 'gettoken'
call 'primary'
move return-code to parse-right(p)
call 'makenode' using parse-token(p) parse-left(p) parse-right(p)
move return-code to parse-left(p)
end-perform
call 'pop'
.
end program multiplication_expr.
identification division.
program-id. primary common recursive.
procedure division.
start-primary.
*> Identifier
*>| Integer
*>| 'LeftParen' expr 'RightParen'
*>| ('+' | '-' | '!') primary
*>;
call 'push' using module-id
evaluate token-type
when 'Identifier'
call 'makeleaf' using 'Identifier' token-value
call 'gettoken'
when 'Integer'
call 'makeleaf' using 'Integer' token-value
call 'gettoken'
when 'LeftParen'
call 'gettoken'
call 'expr'
call 'expect' using 'RightParen'
move t to return-code
when 'Op_add'
call 'gettoken'
call 'primary'
when 'Op_subtract'
call 'gettoken'
call 'primary'
move return-code to parse-left(p)
call 'makenode' using 'Negate' parse-left(p) p-zero
when 'Op_not'
call 'gettoken'
call 'primary'
move return-code to parse-left(p)
call 'makenode' using 'Not' parse-left(p) p-zero
when other
move 0 to return-code
end-evaluate
call 'pop'
.
end program primary.
program-id. reporterror common.
procedure division.
start-reporterror.
report-error.
move token-line to error-line-no
move token-column to error-col-no
display error-record upon syserr
stop run with error status -1
.
end program reporterror.
identification division.
program-id. gettoken common.
procedure division.
start-gettoken.
if program-name = spaces
move '00' to input-status
accept input-record on exception move '10' to input-status end-accept
else
read input-file
end-if
evaluate input-status
when '00'
move input-token to token-type
move input-value to token-value
move numval(input-line) to token-line
move numval(input-column) to token-column
>>d display indent(1:min(4 * p,length(indent))) 'new token: ' token-type upon syserr
when '10'
string 'in parser ' trim(input-name) ' unexpected end of input'
into error-message
call 'reporterror'
when other
string 'in parser ' trim(input-name) ' unexpected input-status ' input-status
into error-message
call 'reporterror'
end-evaluate
.
end program gettoken.
identification division.
program-id. expect common.
data division.
linkage section.
01 what any length.
procedure division using what.
start-expect.
if token-type <> what
string 'in parser expected ' what ' found ' token-type into error-message
call 'reporterror'
end-if
>>d display indent(1:min(4 * p,length(indent))) 'match: ' token-type upon syserr
call 'gettoken'
.
end program expect.
identification division.
program-id. push common.
data division.
linkage section.
01 what any length.
procedure division using what.
start-push.
>>d display indent(1:min(4 * p,length(indent))) 'push ' what upon syserr
if p >= p-lim
move 'in parser stack overflow' to error-message
call 'reporterror'
end-if
add 1 to p
initialize parse-entry(p)
move what to parse-name(p)
.
end program push.
identification division.
program-id. pop common.
procedure division.
start-pop.
if p < 1
move 'in parser stack underflow' to error-message
call 'reporterror'
end-if
>>d display indent(1:4 * p - 4) 'pop ' parse-name(p) upon syserr
subtract 1 from p
.
end program pop.
identification division.
program-id. makenode common.
data division.
linkage section.
01 parm-type any length.
01 parm-left pic 999.
01 parm-right pic 999.
procedure division using parm-type parm-left parm-right.
start-makenode.
if t >= t-lim
string 'in parser makenode tree index t exceeds ' t-lim into error-message
call 'reporterror'
end-if
add 1 to t
move parm-type to node-type(t)
move parm-left to node-left(t)
move parm-right to node-right(t)
move t to return-code
.
end program makenode.
identification division.
program-id. makeleaf common.
data division.
linkage section.
01 parm-type any length.
01 parm-value pic x(48).
procedure division using parm-type parm-value.
start-makeleaf.
if t >= t-lim
string 'in parser makeleaf tree index t exceeds ' t-lim into error-message
call 'reporterror'
end-if
add 1 to t
move parm-type to leaf-type(t)
move parm-value to leaf-value(t)
move t to return-code
.
end program makeleaf.
identification division.
program-id. printast recursive.
data division.
linkage section.
01 n pic 999.
procedure division using n.
start-printast.
if n = 0
display ';'
exit program
end-if
evaluate leaf-type(n)
when 'Identifier'
when 'Integer'
when 'String'
display leaf-type(n) trim(leaf-value(n))
when other
display node-type(n)
call 'printast' using node-left(n)
call 'printast' using node-right(n)
end-evaluate
.
end program printast.
end program parser. |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #Batch_File | Batch File |
@echo off
setlocal enabledelayedexpansion
if "%1"=="" (
call:_blinkerArray
) else (
call:_randomArray %*
)
for /l %%i in (1,1,%iterations%) do (
call:_setStatus
call:_display
for /l %%m in (1,1,%m%) do (
for /l %%n in (1,1,%m%) do (
call:_evolution %%m %%n
)
)
)
:_blinkerArray
for /l %%m in (0,1,4) do (
for /l %%n in (0,1,4) do (
set cell[%%m][%%n]=0
)
)
set cell[2][1]=1
set cell[2][2]=1
set cell[2][3]=1
set iterations=5
set m=3
set cellsaddone=4
exit /b
:_randomArray
set cellsaddone=%1+1
for /l %%m in (0,1,%cellsaddone%) do for /l %%n in (0,1,%cellsaddone%) do set cell[%%m][%%n]=0
for /l %%m in (1,1,%1) do (
for /l %%n in (1,1,%1) do (
set /a cellrandom=!random! %% 101
set cell[%%m][%%n]=0
if !cellrandom! leq %2 set cell[%%m][%%n]=1
)
)
set iterations=%3
set m=%1
exit /b
:_setStatus
for /l %%m in (0,1,%cellsaddone%) do (
for /l %%n in (0,1,%cellsaddone%) do (
if !cell[%%m][%%n]!==1 set cellstatus[%%m][%%n]=alive
if !cell[%%m][%%n]!==0 set cellstatus[%%m][%%n]=dead
)
)
exit /b
:_evolution
set /a lowerm=%1-1
set /a upperm=%1+1
set /a lowern=%2-1
set /a uppern=%2+1
set numm=%1
set numn=%2
set sum=0
for /l %%m in (%lowerm%,1,%upperm%) do (
for /l %%n in (%lowern%,1,%uppern%) do (
if %%m==%numm% (
if %%n==%numn% (
set /a sum=!sum!
) else (
if !cellstatus[%%m][%%n]!==alive set /a sum+=1
)
) else (
if !cellstatus[%%m][%%n]!==alive set /a sum+=1
)
)
)
goto:!cell[%numm%][%numn%]!
exit /b
:0
set alive=3
set death=0 1 2 4 5 6 7 8
for %%i in (%alive%) do if %sum%==%%i set cell[%numm%][%numn%]=1
for %%i in (%death%) do if %sum%==%%i set cell[%numm%][%numn%]=0
exit /b
:1
set alive=2 3
set death=0 1 4 5 6 7 8
for %%i in (%alive%) do if %sum%==%%i set cell[%1][%2]=1
for %%i in (%death%) do if %sum%==%%i set cell[%1][%2]=0
exit /b
:_display
echo.
for /l %%m in (1,1,%m%) do (
set m%%m=
for /l %%n in (1,1,%m%) do set m%%m=!m%%m! !cell[%%m][%%n]!
echo !m%%m!
)
exit /b
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Oberon-2 | Oberon-2 |
MODULE Point;
TYPE
Object* = POINTER TO ObjectDesc;
ObjectDesc* = RECORD
x-,y-: INTEGER;
END;
PROCEDURE (p: Object) Init(x,y: INTEGER);
BEGIN
p.x := x; p.y := y
END Init;
PROCEDURE New*(x,y: INTEGER): Object;
VAR
p: Object;
BEGIN
NEW(p);p.Init(x,y);RETURN p;
END New;
END Point.
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Objeck | Objeck |
class Point {
@x : Int;
@y : Int;
New() {
@x := 0;
@y := 0;
}
New(x : Int, y : Int) {
@x := x;
@y := y;
}
New(p : Point) {
@x := p->GetX();
@y := p->GetY();
}
method : public : GetX() ~ Int {
return @x;
}
method : public : GetY() ~ Int {
return @y;
}
method : public : SetX(x : Int) ~ Nil {
@x := x;
}
method : public : SetY(y : Int) ~ Nil {
@y := y;
}
}
|
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #TI-89_BASIC | TI-89 BASIC | :"Rosetta Code"→str1
:str1→str2 |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Toka | Toka | " hello" is-data a
a string.clone is-data b |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #Ring | Ring |
load "guilib.ring"
new qapp
{
win1 = new qwidget() {
setwindowtitle("drawing using qpainter")
setgeometry(100,100,500,500)
label1 = new qlabel(win1) {
setgeometry(10,10,400,400)
settext("")
}
new qpushbutton(win1) {
setgeometry(200,400,100,30)
settext("draw")
setclickevent("draw()")
}
show()
}
exec()
}
func draw
p1 = new qpicture()
color = new qcolor() {
setrgb(0,0,255,255)
}
pen = new qpen() {
setcolor(color)
setwidth(1)
}
new qpainter() {
begin(p1)
setpen(pen)
for i = 1 to 1000
x = random(31)-16
y = random(31)-16
r = sqrt (pow(x,2) + pow(y,2))
if r >= 10 if r <= 15 drawpoint(x*2, y*2) ok ok
next
endpaint()
}
label1 { setpicture(p1) show() }
|
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Vlang | Vlang | import time
import rand
import rand.pcg32
import rand.seed
fn main() {
words := ['Enjoy', 'Rosetta', 'Code']
seed_u64 := u64(time.now().unix_time_milli())
q := chan string{}
for i, w in words {
go fn (q chan string, w string, seed_u64 u64) {
mut rng := pcg32.PCG32RNG{}
time_seed := seed.time_seed_array(2)
seed_arr := [u32(seed_u64), u32(seed_u64 >> 32), time_seed[0], time_seed[1]]
rng.seed(seed_arr)
time.sleep(time.Duration(rng.i64n(1_000_000_000)))
q <- w
}(q, w, seed_u64 + u64(i))
}
for _ in 0 .. words.len {
println(<-q)
}
} |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #Wren | Wren | import "random" for Random
var words = ["Enjoy", "Rosetta", "Code"]
var rand = Random.new()
for (h in 1..3) {
var fibers = List.filled(3, null)
for (i in 0..2) fibers[i] = Fiber.new { System.print(words[i]) }
var called = List.filled(3, false)
var j = 0
while (j < 3) {
var k = rand.int(3)
if (!called[k]) {
fibers[k].call()
called[k] = true
j = j + 1
}
}
System.print()
} |
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #AmbientTalk | AmbientTalk |
if: condition then: {
// condition is true...
} else: {
// condition is false...
}
|
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #AWK | AWK |
function error(msg) {
printf("%s\n", msg)
exit(1)
}
function bytes_to_int(bstr, i, sum) {
sum = 0
for (i=word_size-1; i>=0; i--) {
sum *= 256
sum += code[bstr+i]
}
return sum
}
function emit_byte(x) {
code[next_free_code_index++] = x
}
function emit_word(x, i) {
for (i=0; i<word_size; i++) {
emit_byte(int(x)%256);
x = int(x/256)
}
}
function run_vm(data_size) {
sp = data_size + 1
pc = 0
while (1) {
op = code[pc++]
if (op == FETCH) {
stack[sp++] = stack[bytes_to_int(pc)]
pc += word_size
} else if (op == STORE) {
stack[bytes_to_int(pc)] = stack[--sp]
pc += word_size
} else if (op == PUSH) {
stack[sp++] = bytes_to_int(pc)
pc += word_size
} else if (op == ADD ) { stack[sp-2] += stack[sp-1]; sp--
} else if (op == SUB ) { stack[sp-2] -= stack[sp-1]; sp--
} else if (op == MUL ) { stack[sp-2] *= stack[sp-1]; sp--
} else if (op == DIV ) { stack[sp-2] = int(stack[sp-2] / stack[sp-1]); sp--
} else if (op == MOD ) { stack[sp-2] %= stack[sp-1]; sp--
} else if (op == LT ) { stack[sp-2] = stack[sp-2] < stack[sp-1]; sp--
} else if (op == GT ) { stack[sp-2] = stack[sp-2] > stack[sp-1]; sp--
} else if (op == LE ) { stack[sp-2] = stack[sp-2] <= stack[sp-1]; sp--
} else if (op == GE ) { stack[sp-2] = stack[sp-2] >= stack[sp-1]; sp--
} else if (op == EQ ) { stack[sp-2] = stack[sp-2] == stack[sp-1]; sp--
} else if (op == NE ) { stack[sp-2] = stack[sp-2] != stack[sp-1]; sp--
} else if (op == AND ) { stack[sp-2] = stack[sp-2] && stack[sp-1]; sp--
} else if (op == OR ) { stack[sp-2] = stack[sp-2] || stack[sp-1]; sp--
} else if (op == NEG ) { stack[sp-1] = - stack[sp-1]
} else if (op == NOT ) { stack[sp-1] = ! stack[sp-1]
} else if (op == JMP ) { pc += bytes_to_int(pc)
} else if (op == JZ ) { if (stack[--sp]) { pc += word_size } else { pc += bytes_to_int(pc) }
} else if (op == PRTC) { printf("%c", stack[--sp])
} else if (op == PRTS) { printf("%s", string_pool[stack[--sp]])
} else if (op == PRTI) { printf("%d", stack[--sp])
} else if (op == HALT) { break
}
} # while
}
function str_trans(srce, dest, i) {
dest = ""
for (i=1; i <= length(srce); ) {
if (substr(srce, i, 1) == "\\" && i < length(srce)) {
if (substr(srce, i+1, 1) == "n") {
dest = dest "\n"
i += 2
} else if (substr(srce, i+1, 1) == "\\") {
dest = dest "\\"
i += 2
}
} else {
dest = dest substr(srce, i, 1)
i += 1
}
}
return dest
}
function load_code( n, i) {
getline line
if (line == "")
error("empty line")
n=split(line, line_list)
data_size = line_list[2]
n_strings = line_list[4]
for (i=0; i<n_strings; i++) {
getline line
gsub(/\n/, "", line)
gsub(/"/ , "", line)
string_pool[i] = str_trans(line)
}
while (getline) {
offset = int($1)
instr = $2
opcode = code_map[instr]
if (opcode == "")
error("Unknown instruction " instr " at " offset)
emit_byte(opcode)
if (opcode == JMP || opcode == JZ) {
p = int($4)
emit_word(p - (offset + 1))
} else if (opcode == PUSH) {
value = int($3)
emit_word(value)
} else if (opcode == FETCH || opcode == STORE) {
gsub(/\[/, "", $3)
gsub(/\]/, "", $3)
value = int($3)
emit_word(value)
}
}
return data_size
}
BEGIN {
code_map["fetch"] = FETCH = 1
code_map["store"] = STORE = 2
code_map["push" ] = PUSH = 3
code_map["add" ] = ADD = 4
code_map["sub" ] = SUB = 5
code_map["mul" ] = MUL = 6
code_map["div" ] = DIV = 7
code_map["mod" ] = MOD = 8
code_map["lt" ] = LT = 9
code_map["gt" ] = GT = 10
code_map["le" ] = LE = 11
code_map["ge" ] = GE = 12
code_map["eq" ] = EQ = 13
code_map["ne" ] = NE = 14
code_map["and" ] = AND = 15
code_map["or" ] = OR = 16
code_map["neg" ] = NEG = 17
code_map["not" ] = NOT = 18
code_map["jmp" ] = JMP = 19
code_map["jz" ] = JZ = 20
code_map["prtc" ] = PRTC = 21
code_map["prts" ] = PRTS = 22
code_map["prti" ] = PRTI = 23
code_map["halt" ] = HALT = 24
next_free_node_index = 1
next_free_code_index = 0
word_size = 4
input_file = "-"
if (ARGC > 1)
input_file = ARGV[1]
data_size = load_code()
run_vm(data_size)
}
|
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #J | J | outbuf=: ''
emit=:{{
outbuf=: outbuf,y
if.LF e. outbuf do.
ndx=. outbuf i:LF
echo ndx{.outbuf
outbuf=: }.ndx}.outbuf
end.
}}
load_ast=: {{
'node_types node_values'=: 2{.|:(({.,&<&<}.@}.)~ i.&' ');._2 y
1{::0 load_ast ''
:
node_type=. x{::node_types
if. node_type-:,';' do. x;a: return.end.
node_value=. x{::node_values
if. -.''-:node_value do.x;<node_type make_leaf node_value return.end.
'x left'=.(x+1) load_ast''
'x right'=.(x+1) load_ast''
x;<node_type make_node left right
}}
make_leaf=: ;
typ=: 0&{::
val=: left=: 1&{::
right=: 2&{::
make_node=: {{m;n;<y}}
id2var=: 'var_',rplc&('z';'zz';'_';'_z')
interp=:{{
if.y-:'' do.'' return.end.
V=. val y
W=. ;2}.y
select.typ y
case.'Integer'do._".V
case.'String'do.rplc&('\\';'\';'\n';LF) V-.'"'
case.'Identifier'do.".id2var V
case.'Assign'do.''[(id2var left V)=: interp W
case.'Multiply'do.V *&interp W
case.'Divide'do.V (*&* * <.@%&|)&interp W
case.'Mod'do.V (*&* * |~&|)&interp W
case.'Add'do.V +&interp W
case.'Subtract'do.V -&interp W
case.'Negate'do.-interp V
case.'Less'do.V <&interp W
case.'LessEqual'do.V <:&interp W
case.'Greater'do.V >&interp W
case.'GreaterEqual'do.V >&interp W
case.'Equal'do.V =&interp W
case.'NotEqual'do.V ~:&interp W
case.'Not'do.0=interp V
case.'And'do.V *.&interp W
case.'Or' do.V +.&interp W
case.'If'do.if.interp V do.interp left W else.interp right W end.''
case.'While'do.while.interp V do.interp W end.''
case.'Prtc'do.emit u:interp V
case.'Prti'do.emit rplc&'_-'":interp V
case.'Prts'do.emit interp V
case.'Sequence'do.
interp V
interp W
''
case.do.error'unknown node type ',typ y
end.
}}
|
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #ALGOL_68 | ALGOL 68 | BEGIN # compare string lengths #
# returns the length of s using the builtin UPB and LWB operators #
OP LENGTH = ( STRING s )INT: ( UPB s + 1 ) - LWB s;
# prints s and its length #
PROC print string = ( STRING s )VOID:
print( ( """", s, """ has length: ", whole( LENGTH s, 0 ), " bytes.", newline ) );
STRING shorter = "short";
STRING not shorter = "longer";
IF LENGTH shorter > LENGTH not shorter THEN print string( shorter ) FI;
print string( not shorter );
IF LENGTH shorter <= LENGTH not shorter THEN print string( shorter ) FI
END |
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #APL | APL |
sv ← 'defg' 'hijklm' 'abc' 'abcd'
⍉(⍴¨sv[⍒sv]),[0.5]sv[⍒sv]
6 hijklm
4 defg
4 abcd
3 abc
|
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #Common_Lisp | Common Lisp | #!/bin/sh
#|-*- mode:lisp -*-|#
#|
exec ros -Q -- $0 "$@"
|#
(progn ;;init forms
(ros:ensure-asdf)
#+quicklisp(ql:quickload '() :silent t))
(defpackage :ros.script.parse.3859374047
(:use :cl))
(in-package :ros.script.parse.3859374047)
;;;
;;; The Rosetta Code Tiny-Language Parser, in Common Lisp.
;;;
(require "cl-ppcre")
(require "trivia")
(defstruct tokstruc line-no column-no tok tokval)
(defconstant re-blank-line
(ppcre:create-scanner "^\\s*$"))
(defconstant re-token-1
(ppcre:create-scanner
"^\\s*(\\d+)\\s+(\\d+)\\s+(\\S+)\\s*$"))
(defconstant re-token-2
(ppcre:create-scanner
"^\\s*(\\d+)\\s+(\\d+)\\s+(\\S+)\\s+(\\S(.*\\S)?)\\s*$"))
(defun string-to-tok (s)
(trivia:match s
("Keyword_else" 'TOK-ELSE)
("Keyword_if" 'TOK-IF)
("Keyword_print" 'TOK-PRINT)
("Keyword_putc" 'TOK-PUTC)
("Keyword_while" 'TOK-WHILE)
("Op_multiply" 'TOK-MULTIPLY)
("Op_divide" 'TOK-DIVIDE)
("Op_mod" 'TOK-MOD)
("Op_add" 'TOK-ADD)
("Op_subtract" 'TOK-SUBTRACT)
("Op_negate" 'TOK-NEGATE)
("Op_less" 'TOK-LESS)
("Op_lessequal" 'TOK-LESSEQUAL)
("Op_greater" 'TOK-GREATER)
("Op_greaterequal" 'TOK-GREATEREQUAL)
("Op_equal" 'TOK-EQUAL)
("Op_notequal" 'TOK-NOTEQUAL)
("Op_not" 'TOK-NOT)
("Op_assign" 'TOK-ASSIGN)
("Op_and" 'TOK-AND)
("Op_or" 'TOK-OR)
("LeftParen" 'TOK-LEFTPAREN)
("RightParen" 'TOK-RIGHTPAREN)
("LeftBrace" 'TOK-LEFTBRACE)
("RightBrace" 'TOK-RIGHTBRACE)
("Semicolon" 'TOK-SEMICOLON)
("Comma" 'TOK-COMMA)
("Identifier" 'TOK-IDENTIFIER)
("Integer" 'TOK-INTEGER)
("String" 'TOK-STRING)
("End_of_input" 'TOK-END-OF-INPUT)
(_ (warn "unparseable token line")
(uiop:quit 1))))
(defun precedence (tok)
(case tok
(TOK-MULTIPLY 13)
(TOK-DIVIDE 13)
(TOK-MOD 13)
(TOK-ADD 12)
(TOK-SUBTRACT 12)
(TOK-NEGATE 14)
(TOK-NOT 14)
(TOK-LESS 10)
(TOK-LESSEQUAL 10)
(TOK-GREATER 10)
(TOK-GREATEREQUAL 10)
(TOK-EQUAL 9)
(TOK-NOTEQUAL 9)
(TOK-AND 5)
(TOK-OR 4)
(otherwise -1)))
(defun binary-p (tok)
(case tok
(TOK-ADD t)
(TOK-SUBTRACT t)
(TOK-MULTIPLY t)
(TOK-DIVIDE t)
(TOK-MOD t)
(TOK-LESS t)
(TOK-LESSEQUAL t)
(TOK-GREATER t)
(TOK-GREATEREQUAL t)
(TOK-EQUAL t)
(TOK-NOTEQUAL t)
(TOK-AND t)
(TOK-OR t)
(otherwise nil)))
(defun right-associative-p (tok)
(declare (ignorable tok))
nil) ; None of the current operators is right associative.
(defun tok-text (tok)
(ecase tok
(TOK-ELSE "else")
(TOK-IF "if")
(TOK-PRINT "print")
(TOK-PUTC "putc")
(TOK-WHILE "while")
(TOK-MULTIPLY "*")
(TOK-DIVIDE "/")
(TOK-MOD "%")
(TOK-ADD "+")
(TOK-SUBTRACT "-")
(TOK-NEGATE "-")
(TOK-LESS "<")
(TOK-LESSEQUAL "<=")
(TOK-GREATER ">")
(TOK-GREATEREQUAL ">=")
(TOK-EQUAL "==")
(TOK-NOTEQUAL "!=")
(TOK-NOT "!")
(TOK-ASSIGN "=")
(TOK-AND "&&")
(TOK-OR "((")
(TOK-LEFTPAREN "(")
(TOK-RIGHTPAREN ")")
(TOK-LEFTBRACE "{")
(TOK-RIGHTBRACE "}")
(TOK-SEMICOLON ";")
(TOK-COMMA ",")
(TOK-IDENTIFIER "Ident")
(TOK-INTEGER "Integer literal")
(TOK-STRING "String literal")
(TOK-END_OF_INPUT "EOI")))
(defun operator (tok)
(ecase tok
(TOK-MULTIPLY "Multiply")
(TOK-DIVIDE "Divide")
(TOK-MOD "Mod")
(TOK-ADD "Add")
(TOK-SUBTRACT "Subtract")
(TOK-NEGATE "Negate")
(TOK-NOT "Not")
(TOK-LESS "Less")
(TOK-LESSEQUAL "LessEqual")
(TOK-GREATER "Greater")
(TOK-GREATEREQUAL "GreaterEqual")
(TOK-EQUAL "Equal")
(TOK-NOTEQUAL "NotEqual")
(TOK-AND "And")
(TOK-OR "Or")))
(defun join (&rest args)
(apply #'concatenate 'string args))
(defun nxt (gettok)
(funcall gettok :nxt))
(defun curr (gettok)
(funcall gettok :curr))
(defun err (token msg)
(format t "(~A, ~A) error: ~A~%"
(tokstruc-line-no token)
(tokstruc-column-no token)
msg)
(uiop:quit 1))
(defun prt-ast (outf ast)
;;
;; For fun, let us do prt-ast *non*-recursively, with a stack and a
;; loop.
;;
(let ((stack `(,ast)))
(loop while stack
do (let ((x (car stack)))
(setf stack (cdr stack))
(cond ((not x) (format outf ";~%"))
((or (string= (car x) "Identifier")
(string= (car x) "Integer")
(string= (car x) "String"))
(format outf "~A ~A~%" (car x) (cadr x)))
(t (format outf "~A~%" (car x))
(setf stack (cons (caddr x) stack))
(setf stack (cons (cadr x) stack))))))))
(defun accept (gettok tok)
(if (eq (tokstruc-tok (curr gettok)) tok)
(nxt gettok)
nil))
(defun expect (gettok msg tok)
(let ((curr-tok (tokstruc-tok (curr gettok))))
(if (eq curr-tok tok)
(nxt gettok)
(err (curr gettok)
(join msg ": Expecting '"
(tok-text tok) "', found '"
(tok-text curr-tok) "'")))))
(defun parse (gettok)
(defun paren-expr (gettok)
(expect gettok "paren_expr" 'TOK-LEFTPAREN)
(let ((x (expr gettok 0)))
(expect gettok "paren_expr" 'TOK-RIGHTPAREN)
x))
(defun expr (gettok p)
(let* ((tok (curr gettok))
(x (case (tokstruc-tok tok)
(TOK-LEFTPAREN (paren-expr gettok))
(TOK-SUBTRACT
(nxt gettok)
(let ((y (expr gettok (precedence 'TOK-NEGATE))))
`("Negate" ,y ())))
(TOK-ADD
(nxt gettok)
(expr gettok (precedence 'TOK-NEGATE)))
(TOK-NOT
(nxt gettok)
(let ((y (expr gettok (precedence 'TOK-NOT))))
`("Not" ,y ())))
(TOK-IDENTIFIER
(let ((y `("Identifier" ,(tokstruc-tokval tok))))
(nxt gettok)
y))
(TOK-INTEGER
(let ((y `("Integer" ,(tokstruc-tokval tok))))
(nxt gettok)
y))
(otherwise
(err tok (join "Expecting a primary, found: "
(tok-text (tokstruc-tok tok))))))))
;;
;; Precedence climbing for binary operators.
;;
(loop for tok = (curr gettok)
for toktok = (tokstruc-tok tok)
while (and (binary-p toktok) (<= p (precedence toktok)))
do (progn (nxt gettok)
(let ((q (if (right-associative-p toktok)
(precedence toktok)
(1+ (precedence toktok)))))
(setf x `(,(operator toktok) ,x
,(expr gettok q))))))
x))
(defun stmt (gettok)
(cond ((accept gettok 'TOK-IF)
(let* ((e (paren-expr gettok))
(s (stmt gettok))
(x (if (accept gettok 'TOK-ELSE)
`("If" ,s ,(stmt gettok))
`("If" ,s ()))))
`("If" ,e ,x)))
((accept gettok 'TOK-PUTC)
(let ((x `("Prtc" ,(paren-expr gettok) ())))
(expect gettok "Putc" 'TOK-SEMICOLON)
x))
((accept gettok 'TOK-PRINT)
(expect gettok "Print" 'TOK-LEFTPAREN)
(let ((x '()))
(loop for tok = (curr gettok)
for toktok = (tokstruc-tok tok)
for e = (if (eq toktok 'TOK-STRING)
(let* ((tokval (tokstruc-tokval tok))
(leaf `("String" ,tokval))
(e `("Prts" ,leaf ())))
(nxt gettok)
e)
`("Prti" ,(expr gettok 0) ()))
do (setf x `("Sequence" ,x ,e))
while (accept gettok 'TOK-COMMA))
(expect gettok "Print" 'TOK-RIGHTPAREN)
(expect gettok "Print" 'TOK-SEMICOLON)
x))
((eq (tokstruc-tok (curr gettok)) 'TOK-SEMICOLON)
(nxt gettok))
((eq (tokstruc-tok (curr gettok)) 'TOK-IDENTIFIER)
(let ((v `("Identifier" ,(tokstruc-tokval (curr gettok)))))
(nxt gettok)
(expect gettok "assign" 'TOK-ASSIGN)
(let ((x `("Assign" ,v ,(expr gettok 0))))
(expect gettok "assign" 'TOK-SEMICOLON)
x)))
((accept gettok 'TOK-WHILE)
(let ((e (paren-expr gettok)))
`("While" ,e ,(stmt gettok))))
((accept gettok 'TOK-LEFTBRACE)
(let ((x '()))
(loop for tok = (curr gettok)
for toktok = (tokstruc-tok tok)
until (or (eq toktok 'TOK-RIGHTBRACE)
(eq toktok 'TOK-END-OF-INPUT))
do (setf x `("Sequence" ,x ,(stmt gettok))))
(expect gettok "Lbrace" 'TOK-RIGHTBRACE)
x))
((eq (tokstruc-tok (curr gettok)) 'TOK-END-OF-INPUT)
'())
(t (let* ((tok (curr gettok))
(toktok (tokstruc-tok tok)))
(err tok (join "expecting start of statement, found '"
(tok-text toktok) "'"))))))
;;
;; Parsing of the top-level statement sequence.
;;
(let ((x '()))
(nxt gettok)
(loop do (setf x `("Sequence" ,x ,(stmt gettok)))
until (eq (tokstruc-tok (curr gettok)) 'TOK-END-OF-INPUT))
x))
(defun string-to-tokstruc (s)
(let ((strings
(nth-value 1 (ppcre:scan-to-strings re-token-1 s))))
(if strings
(make-tokstruc :line-no (elt strings 0)
:column-no (elt strings 1)
:tok (string-to-tok (elt strings 2))
:tokval nil)
(let ((strings
(nth-value 1 (ppcre:scan-to-strings re-token-2 s))))
(if strings
(make-tokstruc :line-no (elt strings 0)
:column-no (elt strings 1)
:tok (string-to-tok (elt strings 2))
:tokval (elt strings 3))
(progn
(warn "unparseable token line")
(uiop:quit 1)))))))
(defun read-token-line (inpf)
(loop for line = (read-line inpf nil "End_of_input")
while (ppcre:scan re-blank-line line)
finally (return line)))
(defun open-inpf (inpf-filename)
(if (string= inpf-filename "-")
*standard-input*
(open inpf-filename :direction :input)))
(defun open-outf (outf-filename)
(if (string= outf-filename "-")
*standard-output*
(open outf-filename :direction :output
:if-exists :overwrite
:if-does-not-exist :create)))
(defun usage-error ()
(princ "Usage: parse [INPUTFILE [OUTPUTFILE]]" *standard-output*)
(terpri *standard-output*)
(princ "If either INPUTFILE or OUTPUTFILE is \"-\", the respective"
*standard-output*)
(princ " standard I/O is used." *standard-output*)
(terpri *standard-output*)
(uiop:quit 1))
(defun get-filenames (argv)
(trivia:match argv
((list) '("-" "-"))
((list inpf-filename) `(,inpf-filename "-"))
((list inpf-filename outf-filename) `(,inpf-filename
,outf-filename))
(_ (usage-error))))
(defun main (&rest argv)
(let* ((filenames (get-filenames argv))
(inpf-filename (car filenames))
(inpf (open-inpf inpf-filename))
(outf-filename (cadr filenames))
(outf (open-outf outf-filename)))
(let* ((current-token (list nil))
(gettok-curr (lambda () (elt current-token 0)))
(gettok-nxt (lambda ()
(let* ((s (read-token-line inpf))
(tok (string-to-tokstruc s)))
(setf (elt current-token 0) tok)
tok)))
(gettok (lambda (instruction)
(trivia:match instruction
(:curr (funcall gettok-curr))
(:nxt (funcall gettok-nxt)))))
(ast (parse gettok)))
(prt-ast outf ast))
(unless (string= inpf-filename "-")
(close inpf))
(unless (string= outf-filename "-")
(close outf))
(uiop:quit 0)))
;;; vim: set ft=lisp lisp: |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #Befunge | Befunge | 00p10p20p30p&>40p&>50p60p>$#v~>:55+-vv+`1:%3:+*g04p03< >3/"P"%\56v>p\56*8*/8+:v
v5\`\"~"::-*3p06!:!-+67:_^#!<*<!g06!<>1+70g*\:3/"P"%v^ ^::+*g04%<*0v`1:%3\gp08<
>6*`*#v_55+-#v_p10g1+10p>^pg08g07+gp08:+8/*8*65\p07:<^ >/10g-50g^87>+1+:01p/8/v
>%#74#<-!!70p 00g::1+00p:20g\-:0`*+20p10g::30g\-:0`*+^ ^2+2+g03*<*:v+g06p09:%2<
.v,:*93"[2J"0<>"H["39*,,,50g0v!:-1,+55$_:40g3*20g+2+2/\-40g%50g3^/%\ >:3-\3-90v
O>"l52?[">:#,_^v/3+2:*g05g04$_>:10p40g0^!:-1,g+4\0%2/+1+`1:%3\g+8<^: $v10!*-g<<
g+70g80gp:#v_$^>1-:::"P"%\"P"/8+:10v >/10g+1-50g+50g%40g*+::3/"P"^>!|>g*70g80g
:p00%g04:-1<<$_^#!:pg01%"P"\*8%8gp<< ^3\%g04+g04-1+g00%3:%9+4:-1p06\<90p01/g04 |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #OCaml | OCaml | type tree = Empty
| Leaf of int
| Node of tree * tree
let t1 = Node (Leaf 1, Node (Leaf 2, Leaf 3)) |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Oforth | Oforth | Object Class new: Point(x, y) |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Transd | Transd | #lang transd
MainModule : {
_start: (λ
(with s "Hello!" s1 "" s2 ""
(= s1 s) // duplication of 's' content
(rebind s2 s) // another reference to 's'
(= s "Good bye!")
(lout s)
(lout s1)
(lout s2)
)
)
} |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Trith | Trith | "Hello" dup |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #Ruby | Ruby | points = (1..100).map do
# choose a random radius and angle
angle = rand * 2.0 * Math::PI
rad = rand * 5.0 + 10.0
# convert back from polar to cartesian coordinates
[rad * Math::cos(angle), rad * Math::sin(angle)].map(&:round)
end
(-15..15).each do |row|
puts (-15..15).map { |col| points.include?([row, col]) ? "X" : " " }.join
end
load 'raster_graphics.rb'
pixmap = Pixmap.new(321,321)
pixmap.draw_circle(Pixel.new(160,160),90,RGBColour::BLACK)
pixmap.draw_circle(Pixel.new(160,160),160,RGBColour::BLACK)
points.each {|(x,y)| pixmap[10*(x+16),10*(y+16)] = RGBColour::BLACK}
pngfile = __FILE__
pngfile[/\.rb/] = ".png"
pixmap.save_as_png(pngfile) |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #XPL0 | XPL0 | int Key, Process;
[Key:= SharedMem(4); \allocate 4 bytes of memory common to all processes
Process:= Fork(2); \start 2 child processes
case Process of
0: [Lock(Key); Text(0, "Enjoy"); CrLf(0); Unlock(Key)]; \parent process
1: [Lock(Key); Text(0, "Rosetta"); CrLf(0); Unlock(Key)]; \child process
2: [Lock(Key); Text(0, "Code"); CrLf(0); Unlock(Key)] \child process
other [Lock(Key); Text(0, "Error"); CrLf(0); Unlock(Key)];
Join(Process); \wait for all child processes to finish
] |
http://rosettacode.org/wiki/Concurrent_computing | Concurrent computing | Task
Using either native language concurrency syntax or freely available libraries, write a program to display the strings "Enjoy" "Rosetta" "Code", one string per line, in random order.
Concurrency syntax must use threads, tasks, co-routines, or whatever concurrency is called in your language.
| #zkl | zkl | fcn{println("Enjoy")}.launch(); // thread
fcn{println("Rosetta")}.strand(); // co-op thread
fcn{println("Code")}.future(); // another thread type |
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #AmigaE | AmigaE | IF condition
-> if condition is true...
ELSEIF condition2
-> else if condition2 is true...
ELSE
-> if all other conditions are not true...
ENDIF |
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #C | C | #include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <stdint.h>
#include <ctype.h>
#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
#define da_dim(name, type) type *name = NULL; \
int _qy_ ## name ## _p = 0; \
int _qy_ ## name ## _max = 0
#define da_redim(name) do {if (_qy_ ## name ## _p >= _qy_ ## name ## _max) \
name = realloc(name, (_qy_ ## name ## _max += 32) * sizeof(name[0]));} while (0)
#define da_rewind(name) _qy_ ## name ## _p = 0
#define da_append(name, x) do {da_redim(name); name[_qy_ ## name ## _p++] = x;} while (0)
typedef unsigned char uchar;
typedef uchar code;
typedef enum { FETCH, STORE, PUSH, ADD, SUB, MUL, DIV, MOD, LT, GT, LE, GE, EQ, NE, AND,
OR, NEG, NOT, JMP, JZ, PRTC, PRTS, PRTI, HALT
} Code_t;
typedef struct Code_map {
char *text;
Code_t op;
} Code_map;
Code_map code_map[] = {
{"fetch", FETCH},
{"store", STORE},
{"push", PUSH },
{"add", ADD },
{"sub", SUB },
{"mul", MUL },
{"div", DIV },
{"mod", MOD },
{"lt", LT },
{"gt", GT },
{"le", LE },
{"ge", GE },
{"eq", EQ },
{"ne", NE },
{"and", AND },
{"or", OR },
{"neg", NEG },
{"not", NOT },
{"jmp", JMP },
{"jz", JZ },
{"prtc", PRTC },
{"prts", PRTS },
{"prti", PRTI },
{"halt", HALT },
};
FILE *source_fp;
da_dim(object, code);
void error(const char *fmt, ... ) {
va_list ap;
char buf[1000];
va_start(ap, fmt);
vsprintf(buf, fmt, ap);
va_end(ap);
printf("error: %s\n", buf);
exit(1);
}
/*** Virtual Machine interpreter ***/
void run_vm(const code obj[], int32_t data[], int g_size, char **string_pool) {
int32_t *sp = &data[g_size + 1];
const code *pc = obj;
again:
switch (*pc++) {
case FETCH: *sp++ = data[*(int32_t *)pc]; pc += sizeof(int32_t); goto again;
case STORE: data[*(int32_t *)pc] = *--sp; pc += sizeof(int32_t); goto again;
case PUSH: *sp++ = *(int32_t *)pc; pc += sizeof(int32_t); goto again;
case ADD: sp[-2] += sp[-1]; --sp; goto again;
case SUB: sp[-2] -= sp[-1]; --sp; goto again;
case MUL: sp[-2] *= sp[-1]; --sp; goto again;
case DIV: sp[-2] /= sp[-1]; --sp; goto again;
case MOD: sp[-2] %= sp[-1]; --sp; goto again;
case LT: sp[-2] = sp[-2] < sp[-1]; --sp; goto again;
case GT: sp[-2] = sp[-2] > sp[-1]; --sp; goto again;
case LE: sp[-2] = sp[-2] <= sp[-1]; --sp; goto again;
case GE: sp[-2] = sp[-2] >= sp[-1]; --sp; goto again;
case EQ: sp[-2] = sp[-2] == sp[-1]; --sp; goto again;
case NE: sp[-2] = sp[-2] != sp[-1]; --sp; goto again;
case AND: sp[-2] = sp[-2] && sp[-1]; --sp; goto again;
case OR: sp[-2] = sp[-2] || sp[-1]; --sp; goto again;
case NEG: sp[-1] = -sp[-1]; goto again;
case NOT: sp[-1] = !sp[-1]; goto again;
case JMP: pc += *(int32_t *)pc; goto again;
case JZ: pc += (*--sp == 0) ? *(int32_t *)pc : (int32_t)sizeof(int32_t); goto again;
case PRTC: printf("%c", sp[-1]); --sp; goto again;
case PRTS: printf("%s", string_pool[sp[-1]]); --sp; goto again;
case PRTI: printf("%d", sp[-1]); --sp; goto again;
case HALT: break;
default: error("Unknown opcode %d\n", *(pc - 1));
}
}
char *read_line(int *len) {
static char *text = NULL;
static int textmax = 0;
for (*len = 0; ; (*len)++) {
int ch = fgetc(source_fp);
if (ch == EOF || ch == '\n') {
if (*len == 0)
return NULL;
break;
}
if (*len + 1 >= textmax) {
textmax = (textmax == 0 ? 128 : textmax * 2);
text = realloc(text, textmax);
}
text[*len] = ch;
}
text[*len] = '\0';
return text;
}
char *rtrim(char *text, int *len) { // remove trailing spaces
for (; *len > 0 && isspace(text[*len - 1]); --(*len))
;
text[*len] = '\0';
return text;
}
char *translate(char *st) {
char *p, *q;
if (st[0] == '"') // skip leading " if there
++st;
p = q = st;
while ((*p++ = *q++) != '\0') {
if (q[-1] == '\\') {
if (q[0] == 'n') {
p[-1] = '\n';
++q;
} else if (q[0] == '\\') {
++q;
}
}
if (q[0] == '"' && q[1] == '\0') // skip trialing " if there
++q;
}
return st;
}
/* convert an opcode string into its byte value */
int findit(const char text[], int offset) {
for (size_t i = 0; i < sizeof(code_map) / sizeof(code_map[0]); i++) {
if (strcmp(code_map[i].text, text) == 0)
return code_map[i].op;
}
error("Unknown instruction %s at %d\n", text, offset);
return -1;
}
void emit_byte(int c) {
da_append(object, (uchar)c);
}
void emit_int(int32_t n) {
union {
int32_t n;
unsigned char c[sizeof(int32_t)];
} x;
x.n = n;
for (size_t i = 0; i < sizeof(x.n); ++i) {
emit_byte(x.c[i]);
}
}
/*
Datasize: 5 Strings: 3
" is prime\n"
"Total primes found: "
"\n"
154 jmp (-73) 82
164 jz (32) 197
175 push 0
159 fetch [4]
149 store [3]
*/
/* Load code into global array object, return the string pool and data size */
char **load_code(int *ds) {
int line_len, n_strings;
char **string_pool;
char *text = read_line(&line_len);
text = rtrim(text, &line_len);
strtok(text, " "); // skip "Datasize:"
*ds = atoi(strtok(NULL, " ")); // get actual data_size
strtok(NULL, " "); // skip "Strings:"
n_strings = atoi(strtok(NULL, " ")); // get number of strings
string_pool = malloc(n_strings * sizeof(char *));
for (int i = 0; i < n_strings; ++i) {
text = read_line(&line_len);
text = rtrim(text, &line_len);
text = translate(text);
string_pool[i] = strdup(text);
}
for (;;) {
int len;
text = read_line(&line_len);
if (text == NULL)
break;
text = rtrim(text, &line_len);
int offset = atoi(strtok(text, " ")); // get the offset
char *instr = strtok(NULL, " "); // get the instruction
int opcode = findit(instr, offset);
emit_byte(opcode);
char *operand = strtok(NULL, " ");
switch (opcode) {
case JMP: case JZ:
operand++; // skip the '('
len = strlen(operand);
operand[len - 1] = '\0'; // remove the ')'
emit_int(atoi(operand));
break;
case PUSH:
emit_int(atoi(operand));
break;
case FETCH: case STORE:
operand++; // skip the '['
len = strlen(operand);
operand[len - 1] = '\0'; // remove the ']'
emit_int(atoi(operand));
break;
}
}
return string_pool;
}
void init_io(FILE **fp, FILE *std, const char mode[], const char fn[]) {
if (fn[0] == '\0')
*fp = std;
else if ((*fp = fopen(fn, mode)) == NULL)
error(0, 0, "Can't open %s\n", fn);
}
int main(int argc, char *argv[]) {
init_io(&source_fp, stdin, "r", argc > 1 ? argv[1] : "");
int data_size;
char **string_pool = load_code(&data_size);
int data[1000 + data_size];
run_vm(object, data, data_size, string_pool);
} |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #Java | Java |
import java.util.Scanner;
import java.io.File;
import java.util.List;
import java.util.ArrayList;
import java.util.Map;
import java.util.HashMap;
class Interpreter {
static Map<String, Integer> globals = new HashMap<>();
static Scanner s;
static List<Node> list = new ArrayList<>();
static Map<String, NodeType> str_to_nodes = new HashMap<>();
static class Node {
public NodeType nt;
public Node left, right;
public String value;
Node() {
this.nt = null;
this.left = null;
this.right = null;
this.value = null;
}
Node(NodeType node_type, Node left, Node right, String value) {
this.nt = node_type;
this.left = left;
this.right = right;
this.value = value;
}
public static Node make_node(NodeType nodetype, Node left, Node right) {
return new Node(nodetype, left, right, "");
}
public static Node make_node(NodeType nodetype, Node left) {
return new Node(nodetype, left, null, "");
}
public static Node make_leaf(NodeType nodetype, String value) {
return new Node(nodetype, null, null, value);
}
}
static enum NodeType {
nd_None(";"), nd_Ident("Identifier"), nd_String("String"), nd_Integer("Integer"),
nd_Sequence("Sequence"), nd_If("If"),
nd_Prtc("Prtc"), nd_Prts("Prts"), nd_Prti("Prti"), nd_While("While"),
nd_Assign("Assign"), nd_Negate("Negate"), nd_Not("Not"), nd_Mul("Multiply"), nd_Div("Divide"),
nd_Mod("Mod"), nd_Add("Add"),
nd_Sub("Subtract"), nd_Lss("Less"), nd_Leq("LessEqual"),
nd_Gtr("Greater"), nd_Geq("GreaterEqual"), nd_Eql("Equal"), nd_Neq("NotEqual"), nd_And("And"), nd_Or("Or");
private final String name;
NodeType(String name) { this.name = name; }
@Override
public String toString() { return this.name; }
}
static String str(String s) {
String result = "";
int i = 0;
s = s.replace("\"", "");
while (i < s.length()) {
if (s.charAt(i) == '\\' && i + 1 < s.length()) {
if (s.charAt(i + 1) == 'n') {
result += '\n';
i += 2;
} else if (s.charAt(i) == '\\') {
result += '\\';
i += 2;
}
} else {
result += s.charAt(i);
i++;
}
}
return result;
}
static boolean itob(int i) {
return i != 0;
}
static int btoi(boolean b) {
return b ? 1 : 0;
}
static int fetch_var(String name) {
int result;
if (globals.containsKey(name)) {
result = globals.get(name);
} else {
globals.put(name, 0);
result = 0;
}
return result;
}
static Integer interpret(Node n) throws Exception {
if (n == null) {
return 0;
}
switch (n.nt) {
case nd_Integer:
return Integer.parseInt(n.value);
case nd_Ident:
return fetch_var(n.value);
case nd_String:
return 1;//n.value;
case nd_Assign:
globals.put(n.left.value, interpret(n.right));
return 0;
case nd_Add:
return interpret(n.left) + interpret(n.right);
case nd_Sub:
return interpret(n.left) - interpret(n.right);
case nd_Mul:
return interpret(n.left) * interpret(n.right);
case nd_Div:
return interpret(n.left) / interpret(n.right);
case nd_Mod:
return interpret(n.left) % interpret(n.right);
case nd_Lss:
return btoi(interpret(n.left) < interpret(n.right));
case nd_Leq:
return btoi(interpret(n.left) <= interpret(n.right));
case nd_Gtr:
return btoi(interpret(n.left) > interpret(n.right));
case nd_Geq:
return btoi(interpret(n.left) >= interpret(n.right));
case nd_Eql:
return btoi(interpret(n.left) == interpret(n.right));
case nd_Neq:
return btoi(interpret(n.left) != interpret(n.right));
case nd_And:
return btoi(itob(interpret(n.left)) && itob(interpret(n.right)));
case nd_Or:
return btoi(itob(interpret(n.left)) || itob(interpret(n.right)));
case nd_Not:
if (interpret(n.left) == 0) {
return 1;
} else {
return 0;
}
case nd_Negate:
return -interpret(n.left);
case nd_If:
if (interpret(n.left) != 0) {
interpret(n.right.left);
} else {
interpret(n.right.right);
}
return 0;
case nd_While:
while (interpret(n.left) != 0) {
interpret(n.right);
}
return 0;
case nd_Prtc:
System.out.printf("%c", interpret(n.left));
return 0;
case nd_Prti:
System.out.printf("%d", interpret(n.left));
return 0;
case nd_Prts:
System.out.print(str(n.left.value));//interpret(n.left));
return 0;
case nd_Sequence:
interpret(n.left);
interpret(n.right);
return 0;
default:
throw new Exception("Error: '" + n.nt + "' found, expecting operator");
}
}
static Node load_ast() throws Exception {
String command, value;
String line;
Node left, right;
while (s.hasNext()) {
line = s.nextLine();
value = null;
if (line.length() > 16) {
command = line.substring(0, 15).trim();
value = line.substring(15).trim();
} else {
command = line.trim();
}
if (command.equals(";")) {
return null;
}
if (!str_to_nodes.containsKey(command)) {
throw new Exception("Command not found: '" + command + "'");
}
if (value != null) {
return Node.make_leaf(str_to_nodes.get(command), value);
}
left = load_ast(); right = load_ast();
return Node.make_node(str_to_nodes.get(command), left, right);
}
return null; // for the compiler, not needed
}
public static void main(String[] args) {
Node n;
str_to_nodes.put(";", NodeType.nd_None);
str_to_nodes.put("Sequence", NodeType.nd_Sequence);
str_to_nodes.put("Identifier", NodeType.nd_Ident);
str_to_nodes.put("String", NodeType.nd_String);
str_to_nodes.put("Integer", NodeType.nd_Integer);
str_to_nodes.put("If", NodeType.nd_If);
str_to_nodes.put("While", NodeType.nd_While);
str_to_nodes.put("Prtc", NodeType.nd_Prtc);
str_to_nodes.put("Prts", NodeType.nd_Prts);
str_to_nodes.put("Prti", NodeType.nd_Prti);
str_to_nodes.put("Assign", NodeType.nd_Assign);
str_to_nodes.put("Negate", NodeType.nd_Negate);
str_to_nodes.put("Not", NodeType.nd_Not);
str_to_nodes.put("Multiply", NodeType.nd_Mul);
str_to_nodes.put("Divide", NodeType.nd_Div);
str_to_nodes.put("Mod", NodeType.nd_Mod);
str_to_nodes.put("Add", NodeType.nd_Add);
str_to_nodes.put("Subtract", NodeType.nd_Sub);
str_to_nodes.put("Less", NodeType.nd_Lss);
str_to_nodes.put("LessEqual", NodeType.nd_Leq);
str_to_nodes.put("Greater", NodeType.nd_Gtr);
str_to_nodes.put("GreaterEqual", NodeType.nd_Geq);
str_to_nodes.put("Equal", NodeType.nd_Eql);
str_to_nodes.put("NotEqual", NodeType.nd_Neq);
str_to_nodes.put("And", NodeType.nd_And);
str_to_nodes.put("Or", NodeType.nd_Or);
if (args.length > 0) {
try {
s = new Scanner(new File(args[0]));
n = load_ast();
interpret(n);
} catch (Exception e) {
System.out.println("Ex: "+e.getMessage());
}
}
}
}
|
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Arturo | Arturo | sortByLength: function [strs][
map sort.descending.by:'v
map strs 'str -> #[s: str, v: size str]
'z -> z\s
]
A: "I am string"
B: "I am string too"
sA: size A
sB: size B
if? sA < sB ->
print ["string ->" A "(" sA ") is smaller than string ->" B "(" sB ")"]
else [
if? sA > sB ->
print ["string ->" A "(" sA ") is larger than string ->" B "(" sB ")"]
else ->
print ["string ->" A "(" sA ") and string ->" B "(" sB ") are of equal length"]
]
print ["sorted strings (by length):" sortByLength ["abcd" "123456789" "abcdef" "1234567"]] |
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Asymptote | Asymptote | string A, B, t = '\t';
void comp(string A, string B) {
if (length(A) >= length(B)) {
write(A+t, length(A));
write(B+t, length(B));
} else {
write(B+t, length(B));
write(A+t, length(A));
}
}
comp("abcd", "123456789"); |
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #Forth | Forth | CREATE BUF 0 , \ single-character look-ahead buffer
: PEEK BUF @ 0= IF KEY BUF ! THEN BUF @ ;
: GETC PEEK 0 BUF ! ;
: SPACE? DUP BL = SWAP 9 14 WITHIN OR ;
: >SPACE BEGIN PEEK SPACE? WHILE GETC DROP REPEAT ;
: DIGIT? 48 58 WITHIN ;
: GETINT >SPACE 0
BEGIN PEEK DIGIT?
WHILE GETC [CHAR] 0 - SWAP 10 * +
REPEAT ;
: GETNAM >SPACE PAD 1+
BEGIN PEEK SPACE? INVERT
WHILE GETC OVER C! CHAR+
REPEAT PAD TUCK - 1- PAD C! ;
: GETSTR >SPACE PAD 1+ GETC DROP \ skip leading "
BEGIN GETC DUP [CHAR] " <>
WHILE OVER C! CHAR+
REPEAT DROP PAD TUCK - 1- PAD C! ;
: INTERN HERE SWAP DUP C@ 1+ BOUNDS DO I C@ C, LOOP ALIGN ;
CREATE #TK 0 ,
: TK: CREATE #TK @ , 1 #TK +! DOES> @ ;
TK: End_of_input TK: Keyword_if TK: Keyword_else
TK: Keyword_while TK: Keyword_print TK: Keyword_putc
TK: String TK: Integer TK: Identifier
TK: LeftParen TK: RightParen
TK: LeftBrace TK: RightBrace
TK: Semicolon TK: Comma
TK: Op_assign TK: Op_not
: (BINARY?) [ #TK @ ] literal >= ;
TK: Op_subtract TK: Op_add
TK: Op_mod TK: Op_multiply TK: Op_divide
TK: Op_equal TK: Op_notequal
TK: Op_less TK: Op_lessequal
TK: Op_greater TK: Op_greaterequal
TK: Op_and TK: Op_or
CREATE TOKEN 0 , 0 , 0 , 0 ,
: TOKEN-TYPE TOKEN 2 CELLS + @ ;
: TOKEN-VALUE TOKEN 3 CELLS + @ ;
: GETTOK GETINT GETINT TOKEN 2!
GETNAM FIND DROP EXECUTE
DUP Integer = IF GETINT ELSE
DUP String = IF GETSTR INTERN ELSE
DUP Identifier = IF GETNAM INTERN ELSE
0 THEN THEN THEN
TOKEN 3 CELLS + ! TOKEN 2 CELLS + ! ;
: BINARY? TOKEN-TYPE (BINARY?) ;
CREATE PREC #TK @ CELLS ALLOT PREC #TK @ CELLS -1 FILL
: PREC! CELLS PREC + ! ;
14 Op_not PREC! 13 Op_multiply PREC!
13 Op_divide PREC! 13 Op_mod PREC!
12 Op_add PREC! 12 Op_subtract PREC!
10 Op_less PREC! 10 Op_greater PREC!
10 Op_lessequal PREC! 10 Op_greaterequal PREC!
9 Op_equal PREC! 9 Op_notequal PREC!
5 Op_and PREC! 4 Op_or PREC!
: PREC@ CELLS PREC + @ ;
\ Each AST Node is a sequence of cells in data space consisting
\ of the execution token of a printing word, followed by that
\ node's data. Each printing word receives the address of the
\ node's data, and is responsible for printing that data
\ appropriately.
DEFER .NODE
: .NULL DROP ." ;" CR ;
CREATE $NULL ' .NULL ,
: .IDENTIFIER ." Identifier " @ COUNT TYPE CR ;
: $IDENTIFIER ( a-addr --) HERE SWAP ['] .IDENTIFIER , , ;
: .INTEGER ." Integer " @ . CR ;
: $INTEGER ( n --) HERE SWAP ['] .INTEGER , , ;
: "TYPE" [CHAR] " EMIT TYPE [CHAR] " EMIT ;
: .STRING ." String " @ COUNT "TYPE" CR ;
: $STRING ( a-addr --) HERE SWAP ['] .STRING , , ;
: .LEAF DUP @ COUNT TYPE CR CELL+ @ .NODE 0 .NULL ;
: LEAF CREATE HERE CELL+ , BL WORD INTERN .
DOES> HERE >R ['] .LEAF , @ , , R> ;
LEAF $PRTC Prtc LEAF $PRTS Prts LEAF $PRTI Prti
LEAF $NOT Not LEAF $NEGATE Negate
: .BINARY DUP @ COUNT TYPE CR
CELL+ DUP @ .NODE CELL+ @ .NODE ;
: BINARY CREATE HERE CELL+ , BL WORD INTERN .
DOES> HERE >R ['] .BINARY , @ , SWAP 2, R> ;
BINARY $SEQUENCE Sequence BINARY $ASSIGN Assign
BINARY $WHILE While BINARY $IF If
BINARY $SUBTRACT Subtract BINARY $ADD Add
BINARY $MOD Mod BINARY $MULTIPLY Multiply
BINARY $DIVIDE Divide
BINARY $LESS Less BINARY $LESSEQUAL LessEqual
BINARY $GREATER Greater BINARY $GREATEREQUAL GreaterEqual
BINARY $EQUAL Equal BINARY $NOTEQUAL NotEqual
BINARY $AND And BINARY $OR Or
: TOK-CONS ( x* -- node-xt) TOKEN-TYPE CASE
Op_subtract OF ['] $SUBTRACT ENDOF
Op_add OF ['] $ADD ENDOF
op_mod OF ['] $MOD ENDOF
op_multiply OF ['] $MULTIPLY ENDOF
Op_divide OF ['] $DIVIDE ENDOF
Op_equal OF ['] $EQUAL ENDOF
Op_notequal OF ['] $NOTEQUAL ENDOF
Op_less OF ['] $LESS ENDOF
Op_lessequal OF ['] $LESSEQUAL ENDOF
Op_greater OF ['] $GREATER ENDOF
Op_greaterequal OF ['] $GREATEREQUAL ENDOF
Op_and OF ['] $AND ENDOF
Op_or OF ['] $OR ENDOF
ENDCASE ;
: (.NODE) DUP CELL+ SWAP @ EXECUTE ;
' (.NODE) IS .NODE
: .- ( n --) 0 <# #S #> TYPE ;
: EXPECT ( tk --) DUP TOKEN-TYPE <>
IF CR ." stdin:" TOKEN 2@ SWAP .- ." :" .-
." : unexpected token, expecting " . CR BYE
THEN DROP GETTOK ;
: '(' LeftParen EXPECT ;
: ')' RightParen EXPECT ;
: '}' RightBrace EXPECT ;
: ';' Semicolon EXPECT ;
: ',' Comma EXPECT ;
: '=' Op_assign EXPECT ;
DEFER *EXPR DEFER EXPR DEFER STMT
: PAREN-EXPR '(' EXPR ')' ;
: PRIMARY
TOKEN-TYPE LeftParen = IF PAREN-EXPR EXIT THEN
TOKEN-TYPE Op_add = IF GETTOK 12 *EXPR EXIT THEN
TOKEN-TYPE Op_subtract = IF GETTOK 14 *EXPR $NEGATE EXIT THEN
TOKEN-TYPE Op_not = IF GETTOK 14 *EXPR $NOT EXIT THEN
TOKEN-TYPE Identifier = IF TOKEN-VALUE $IDENTIFIER ELSE
TOKEN-TYPE Integer = IF TOKEN-VALUE $INTEGER THEN THEN
GETTOK ;
: (*EXPR) ( n -- node)
PRIMARY ( n node)
BEGIN OVER TOKEN-TYPE PREC@ SWAP OVER <= BINARY? AND
WHILE ( n node prec) 1+ TOK-CONS SWAP GETTOK *EXPR SWAP EXECUTE
REPEAT ( n node prec) DROP NIP ( node) ;
: (EXPR) 0 *EXPR ;
: -)? TOKEN-TYPE RightParen <> ;
: -}? TOKEN-TYPE RightBrace <> ;
: (STMT)
TOKEN-TYPE Semicolon = IF GETTOK STMT EXIT THEN
TOKEN-TYPE Keyword_while =
IF GETTOK PAREN-EXPR STMT $WHILE EXIT THEN
TOKEN-TYPE Keyword_if =
IF GETTOK PAREN-EXPR STMT
TOKEN-TYPE Keyword_else = IF GETTOK STMT ELSE $NULL THEN
$IF $IF EXIT
THEN
TOKEN-TYPE Keyword_putc =
IF GETTOK PAREN-EXPR ';' $PRTC EXIT THEN
TOKEN-TYPE Keyword_print =
IF GETTOK '(' $NULL
BEGIN TOKEN-TYPE String =
IF TOKEN-VALUE $STRING $PRTS GETTOK
ELSE EXPR $PRTI THEN $SEQUENCE -)?
WHILE ',' REPEAT ')' ';' EXIT THEN
TOKEN-TYPE Identifier =
IF TOKEN-VALUE $IDENTIFIER GETTOK '=' EXPR ';' $ASSIGN
EXIT THEN
TOKEN-TYPE LeftBrace =
IF $NULL GETTOK BEGIN -}? WHILE STMT $SEQUENCE REPEAT
'}' EXIT THEN
TOKEN-TYPE End_of_input = IF EXIT THEN EXPR ;
' (*EXPR) IS *EXPR ' (EXPR) IS EXPR ' (STMT) IS STMT
: -EOI? TOKEN-TYPE End_of_input <> ;
: PARSE $NULL GETTOK BEGIN -EOI? WHILE STMT $SEQUENCE REPEAT ;
PARSE .NODE |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #Brainf.2A.2A.2A | Brainf*** | width = 3
height = 3
rounds = 3
universe = [[0 1 0]
[0 1 0]
[0 1 0]]
next = height.of({width.of(0)})
cell = { x, y |
true? x < width && { x >= 0 && { y >= 0 && { y < height }}}
{
universe[y][x]
}
{ 0 }
}
neighbors = { x, y |
cell(x - 1, y - 1) +
cell(x, y - 1) +
cell(x + 1, y - 1) +
cell(x + 1, y) +
cell(x + 1, y + 1) +
cell(x, y + 1) +
cell(x - 1, y + 1) +
cell(x - 1, y)
}
set_next = { x, y, v |
next[y][x] = v
}
step = {
universe.each_with_index { row, y |
row.each_with_index { c, x |
n = neighbors(x, y)
when { n < 2 } { set_next x,y, 0 }
{ n > 3 } { set_next x, y, 0 }
{ n == 3 } { set_next x, y, 1 }
{ true } { set_next x, y, c }
}
}
u2 = universe
universe = next
next = u2
}
display = {
p universe.map({ r |
r.map({ n | true? n == 0, '-', "O" }).join
}).join("\n")
}
rounds.times {
display
p
step
} |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #ooRexx | ooRexx |
p = .point~new(3,4)
say "x =" p~x
say "y =" p~y
::class point
::method init
expose x y
use strict arg x = 0, y = 0 -- defaults to 0 for any non-specified coordinates
::attribute x
::attribute y
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #OpenEdge.2FProgress | OpenEdge/Progress | DEF TEMP-TABLE point
FIELD X AS INT
FIELD Y AS INT
. |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #TUSCRIPT | TUSCRIPT | $$ MODE TUSCRIPT
str="Hello"
dst=str |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #UNIX_Shell | UNIX Shell | foo="Hello"
bar=$foo # This is a copy of the string |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #Run_BASIC | Run BASIC | w = 320
h = 320
dim canvas(w,h)
for pts = 1 to 1000
x = (rnd(1) * 31) - 15
y = (rnd(1) * 31) - 15
r = x * x + y * y
if (r > 100) and (r < 225) then
x = int(x * 10 + w/2)
y = int(y * 10 + h/2)
canvas(x,y) = 1
end if
next pts
' -----------------------------
' display the graphic
' -----------------------------
graphic #g, w,h
for x = 1 to w
for y = 1 to h
if canvas(x,y) = 1 then #g "color green ; set "; x; " "; y else #g "color blue ; set "; x; " "; y
next y
next x
render #g
#g "flush" |
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #Apex | Apex | if (s == 'Hello World') {
foo();
} else if (s == 'Bye World') {
bar();
} else {
deusEx();
} |
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #COBOL | COBOL | >>SOURCE FORMAT IS FREE
identification division.
*> this code is dedicated to the public domain
*> (GnuCOBOL) 2.3-dev.0
program-id. vminterpreter.
environment division.
configuration section.
repository. function all intrinsic.
input-output section.
file-control.
select input-file assign using input-name
status is input-status
organization is line sequential.
data division.
file section.
fd input-file.
01 input-record pic x(64).
working-storage section.
01 program-name pic x(32).
01 input-name pic x(32).
01 input-status pic xx.
01 error-record pic x(64) value spaces global.
01 v-max pic 99.
01 parameters.
03 offset pic 999.
03 opcode pic x(8).
03 parm0 pic x(16).
03 parm1 pic x(16).
03 parm2 pic x(16).
01 opcodes.
03 opFETCH pic x value x'00'.
03 opSTORE pic x value x'01'.
03 opPUSH pic x value x'02'.
03 opADD pic x value x'03'.
03 opSUB pic x value x'04'.
03 opMUL pic x value x'05'.
03 opDIV pic x value x'06'.
03 opMOD pic x value x'07'.
03 opLT pic x value x'08'.
03 opGT pic x value x'09'.
03 opLE pic x value x'0A'.
03 opGE pic x value x'0B'.
03 opEQ pic x value x'0C'.
03 opNE pic x value x'0D'.
03 opAND pic x value x'0E'.
03 opOR pic x value x'0F'.
03 opNEG pic x value x'10'.
03 opNOT pic x value x'11'.
03 opJMP pic x value x'13'.
03 opJZ pic x value x'14'.
03 opPRTC pic x value x'15'.
03 opPRTS pic x value x'16'.
03 opPRTI pic x value x'17'.
03 opHALT pic x value x'18'.
01 filler.
03 s pic 99.
03 s-max pic 99 value 0.
03 s-lim pic 99 value 16.
03 filler occurs 16.
05 string-length pic 99.
05 string-entry pic x(48).
01 filler.
03 v pic 99.
03 v-lim pic 99 value 16.
03 variables occurs 16 usage binary-int.
01 generated-code global.
03 c pic 999 value 1.
03 pc pic 999.
03 c-lim pic 999 value 512.
03 kode pic x(512).
01 filler.
03 stack1 pic 999 value 2.
03 stack2 pic 999 value 1.
03 stack-lim pic 999 value 998.
03 stack occurs 998 usage binary-int.
01 display-definitions global.
03 ascii-character.
05 numeric-value usage binary-char.
03 display-integer pic -(9)9.
03 word-x.
05 word usage binary-int.
03 word-length pic 9.
03 string1 pic 99.
03 length1 pic 99.
03 count1 pic 99.
03 display-pending pic x.
procedure division.
start-vminterpreter.
display 1 upon command-line *> get arg(1)
accept program-name from argument-value
move length(word) to word-length
perform load-code
perform run-code
stop run
.
run-code.
move 1 to pc
perform until pc >= c
evaluate kode(pc:1)
when opFETCH
perform push-stack
move kode(pc + 1:word-length) to word-x
add 1 to word *> convert offset to subscript
move variables(word) to stack(stack1)
add word-length to pc
when opPUSH
perform push-stack
move kode(pc + 1:word-length) to word-x
move word to stack(stack1)
add word-length to pc
when opNEG
compute stack(stack1) = -stack(stack1)
when opNOT
if stack(stack1) = 0
move 1 to stack(stack1)
else
move 0 to stack(stack1)
end-if
when opJMP
move kode(pc + 1:word-length) to word-x
move word to pc
when opHALT
if display-pending = 'Y'
display space
end-if
exit perform
when opJZ
if stack(stack1) = 0
move kode(pc + 1:word-length) to word-x
move word to pc
else
add word-length to pc
end-if
perform pop-stack
when opSTORE
move kode(pc + 1:word-length) to word-x
add 1 to word *> convert offset to subscript
move stack(stack1) to variables(word)
add word-length to pc
perform pop-stack
when opADD
add stack(stack1) to stack(stack2)
perform pop-stack
when opSUB
subtract stack(stack1) from stack(stack2)
perform pop-stack
when opMUL
multiply stack(stack1) by stack(stack2)
*>rounded mode nearest-toward-zero *> doesn't match python
perform pop-stack
when opDIV
divide stack(stack1) into stack(stack2)
*>rounded mode nearest-toward-zero *> doesn't match python
perform pop-stack
when opMOD
move mod(stack(stack2),stack(stack1)) to stack(stack2)
perform pop-stack
when opLT
if stack(stack2) < stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opGT
if stack(stack2) > stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opLE
if stack(stack2) <= stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opGE
if stack(stack2) >= stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opEQ
if stack(stack2) = stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opNE
if stack(stack2) <> stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opAND
call "CBL_AND" using stack(stack1) stack(stack2) by value word-length
perform pop-stack
when opOR
call "CBL_OR" using stack(stack1) stack(stack2) by value word-length
perform pop-stack
when opPRTC
move stack(stack1) to numeric-value
if numeric-value = 10
display space
move 'N' to display-pending
else
display ascii-character with no advancing
move 'Y' to display-pending
end-if
perform pop-stack
when opPRTS
add 1 to word *> convert offset to subscript
move 1 to string1
move string-length(word) to length1
perform until string1 > string-length(word)
move 0 to count1
inspect string-entry(word)(string1:length1)
tallying count1 for characters before initial '\' *> ' workaround code highlighter problem
evaluate true
when string-entry(word)(string1 + count1 + 1:1) = 'n' *> \n
display string-entry(word)(string1:count1)
move 'N' to display-pending
compute string1 = string1 + 2 + count1
compute length1 = length1 - 2 - count1
when string-entry(word)(string1 + count1 + 1:1) = '\' *> ' \\
display string-entry(word)(string1:count1 + 1) with no advancing
move 'Y' to display-pending
compute string1 = string1 + 2 + count1
compute length1 = length1 - 2 - count1
when other
display string-entry(word)(string1:count1) with no advancing
move 'Y' to display-pending
add count1 to string1
subtract count1 from length1
end-evaluate
end-perform
perform pop-stack
when opPRTI
move stack(stack1) to display-integer
display trim(display-integer) with no advancing
move 'Y' to display-pending
perform pop-stack
end-evaluate
add 1 to pc
end-perform
.
push-stack.
if stack1 >= stack-lim
string 'in vminterpreter at ' pc ' stack overflow at ' stack-lim into error-record
perform report-error
end-if
add 1 to stack1 stack2
>>d display ' push at ' pc space stack1 space stack2
.
pop-stack.
if stack1 < 2
string 'in vminterpreter at ' pc ' stack underflow' into error-record
perform report-error
end-if
>>d display ' pop at ' pc space stack1 space stack2
subtract 1 from stack1 stack2
.
load-code.
perform read-input
if input-status <> '00'
string 'in vminterpreter no input data' into error-record
perform report-error
end-if
unstring input-record delimited by all spaces into parm1 v-max parm2 s-max
if v-max > v-lim
string 'in vminterpreter datasize exceeds ' v-lim into error-record
perform report-error
end-if
if s-max > s-lim
string 'in vminterpreter number of strings exceeds ' s-lim into error-record
perform report-error
end-if
perform read-input
perform varying s from 1 by 1 until s > s-max
or input-status <> '00'
compute string-length(s) string-length(word) = length(trim(input-record)) - 2
move input-record(2:string-length(word)) to string-entry(s)
perform read-input
end-perform
if s <= s-max
string 'in vminterpreter not all strings found' into error-record
perform report-error
end-if
perform until input-status <> '00'
initialize parameters
unstring input-record delimited by all spaces into
parm0 offset opcode parm1 parm2
evaluate opcode
when 'fetch'
call 'emitbyte' using opFETCH
call 'emitword' using parm1
when 'store'
call 'emitbyte' using opSTORE
call 'emitword' using parm1
when 'push'
call 'emitbyte' using opPUSH
call 'emitword' using parm1
when 'add' call 'emitbyte' using opADD
when 'sub' call 'emitbyte' using opSUB
when 'mul' call 'emitbyte' using opMUL
when 'div' call 'emitbyte' using opDIV
when 'mod' call 'emitbyte' using opMOD
when 'lt' call 'emitbyte' using opLT
when 'gt' call 'emitbyte' using opGT
when 'le' call 'emitbyte' using opLE
when 'ge' call 'emitbyte' using opGE
when 'eq' call 'emitbyte' using opEQ
when 'ne' call 'emitbyte' using opNE
when 'and' call 'emitbyte' using opAND
when 'or' call 'emitbyte' using opOR
when 'not' call 'emitbyte' using opNOT
when 'neg' call 'emitbyte' using opNEG
when 'jmp'
call 'emitbyte' using opJMP
call 'emitword' using parm2
when 'jz'
call 'emitbyte' using opJZ
call 'emitword' using parm2
when 'prtc' call 'emitbyte' using opPRTC
when 'prts' call 'emitbyte' using opPRTS
when 'prti' call 'emitbyte' using opPRTI
when 'halt' call 'emitbyte' using opHALT
when other
string 'in vminterpreter unknown opcode ' trim(opcode) ' at ' offset into error-record
perform report-error
end-evaluate
perform read-input
end-perform
.
read-input.
if program-name = spaces
move '00' to input-status
accept input-record on exception move '10' to input-status end-accept
exit paragraph
end-if
if input-name = spaces
string program-name delimited by space '.gen' into input-name
open input input-file
if input-status <> '00'
string 'in vminterpreter ' trim(input-name) ' file open status ' input-status
into error-record
perform report-error
end-if
end-if
read input-file into input-record
evaluate input-status
when '00'
continue
when '10'
close input-file
when other
string 'in vminterpreter unexpected input-status: ' input-status into error-record
perform report-error
end-evaluate
.
report-error.
display error-record upon syserr
stop run with error status -1
.
identification division.
program-id. emitbyte.
data division.
linkage section.
01 opcode pic x.
procedure division using opcode.
start-emitbyte.
if c >= c-lim
string 'in vminterpreter emitbyte c exceeds ' c-lim into error-record
call 'reporterror'
end-if
move opcode to kode(c:1)
add 1 to c
.
end program emitbyte.
identification division.
program-id. emitword.
data division.
working-storage section.
01 word-temp pic x(8).
linkage section.
01 word-value any length.
procedure division using word-value.
start-emitword.
if c + word-length >= c-lim
string 'in vminterpreter emitword c exceeds ' c-lim into error-record
call 'reporterror'
end-if
move word-value to word-temp
inspect word-temp converting '[' to ' '
inspect word-temp converting ']' to ' '
move numval(trim(word-temp)) to word
move word-x to kode(c:word-length)
add word-length to c
.
end program emitword.
end program vminterpreter. |
http://rosettacode.org/wiki/Compiler/code_generator | Compiler/code generator | A code generator translates the output of the syntax analyzer and/or semantic analyzer
into lower level code, either assembly, object, or virtual.
Task[edit]
Take the output of the Syntax analyzer task - which is a flattened Abstract Syntax Tree (AST) - and convert it to virtual machine code, that can be run by the
Virtual machine interpreter. The output is in text format, and represents virtual assembly code.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
while.ast can be input into the code generator.
The following table shows the input to lex, lex output, the AST produced by the parser, and the generated virtual assembly code.
Run as: lex < while.t | parse | gen
Input to lex
Output from lex, input to parse
Output from parse
Output from gen, input to VM
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
Input format
As shown in the table, above, the output from the syntax analyzer is a flattened AST.
In the AST, Identifier, Integer, and String, are terminal nodes, e.g, they do not have child nodes.
Loading this data into an internal parse tree should be as simple as:
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";"
return None
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Output format - refer to the table above
The first line is the header: Size of data, and number of constant strings.
size of data is the number of 32-bit unique variables used. In this example, one variable, count
number of constant strings is just that - how many there are
After that, the constant strings
Finally, the assembly code
Registers
sp: the stack pointer - points to the next top of stack. The stack is a 32-bit integer array.
pc: the program counter - points to the current instruction to be performed. The code is an array of bytes.
Data
32-bit integers and strings
Instructions
Each instruction is one byte. The following instructions also have a 32-bit integer operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
prtc
Print the word at stack top as a character.
prti
Print the word at stack top as an integer.
prts
Stack top points to an index into the string pool. Print that entry.
halt
Unconditional stop.
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Virtual Machine Interpreter task
AST Interpreter task
| #ALGOL_68 | ALGOL 68 | # RC Compiler code generator #
COMMENT
this writes a .NET IL assembler source to standard output.
If the output is stored in a file called "rcsample.il",
it could be compiled the command:
ilasm /opt /out:rcsample.exe rcsample.il
(Note ilasm may not be in the PATH by default(
Note: The generated IL is *very* naive
COMMENT
# parse tree nodes #
MODE NODE = STRUCT( INT type, REF NODE left, right, INT value );
INT nidentifier = 1, nstring = 2, ninteger = 3, nsequence = 4, nif = 5, nprtc = 6, nprts = 7
, nprti = 8, nwhile = 9, nassign = 10, nnegate = 11, nnot = 12, nmultiply = 13, ndivide = 14
, nmod = 15, nadd = 16, nsubtract = 17, nless = 18, nlessequal = 19, ngreater = 20
, ngreaterequal = 21, nequal = 22, nnotequal = 23, nand = 24, nor = 25
;
# op codes #
INT ofetch = 1, ostore = 2, opush = 3, oadd = 4, osub = 5, omul = 6, odiv = 7, omod = 8
, olt = 9, ogt = 10, ole = 11, oge = 12, oeq = 13, one = 14, oand = 15, oor = 16
, oneg = 17, onot = 18, ojmp = 19, ojz = 20, oprtc = 21, oprts = 22, oprti = 23, opushstr = 24
;
[]INT ndop
= ( -1 , -1 , -1 , -1 , -1 , -1 , -1
, -1 , -1 , -1 , oneg , -1 , omul , odiv
, omod , oadd , osub , olt , -1 , ogt
, -1 , oeq , -1 , oand , oor
) ;
[]STRING ndname
= ( "Identifier" , "String" , "Integer" , "Sequence" , "If" , "Prtc" , "Prts"
, "Prti" , "While" , "Assign" , "Negate" , "Not" , "Multiply" , "Divide"
, "Mod" , "Add" , "Subtract" , "Less" , "LessEqual" , "Greater"
, "GreaterEqual" , "Equal" , "NotEqual" , "And" , "Or"
) ;
[]STRING opname
= ( "ldloc ", "stloc ", "ldc.i4 ", "add ", "sub ", "mul ", "div ", "rem "
, "clt ", "cgt ", "?le ", "?ge ", "ceq ", "?ne ", "and ", "or "
, "neg ", "?not ", "br ", "brfalse", "?prtc ", "?prts ", "?prti ", "ldstr "
) ;
# string and identifier arrays - a hash table might be better... #
INT max string number = 1024;
[ 0 : max string number ]STRING identifiers, strings;
FOR s pos FROM 0 TO max string number DO
identifiers[ s pos ] := "";
strings [ s pos ] := ""
OD;
# label number for label generation #
INT next label number := 0;
# returns the next free label number #
PROC new label = INT: next label number +:= 1;
# returns a new node with left and right branches #
PROC op node = ( INT op type, REF NODE left, right )REF NODE: HEAP NODE := NODE( op type, left, right, 0 );
# returns a new operand node #
PROC operand node = ( INT op type, value )REF NODE: HEAP NODE := NODE( op type, NIL, NIL, value );
# reports an error and stops #
PROC gen error = ( STRING message )VOID:
BEGIN
print( ( message, newline ) );
stop
END # gen error # ;
# reads a node from standard input #
PROC read node = REF NODE:
BEGIN
REF NODE result := NIL;
# parses a string from line and stores it in a string in the text array #
# - if it is not already present in the specified textElement list. #
# returns the position of the string in the text array #
PROC read string = ( REF[]STRING text list, CHAR terminator )INT:
BEGIN
# get the text of the string #
STRING str := line[ l pos ];
l pos +:= 1;
WHILE IF l pos <= UPB line THEN line[ l pos ] /= terminator ELSE FALSE FI DO
str +:= line[ l pos ];
l pos +:= 1
OD;
IF l pos > UPB line THEN gen error( "Unterminated String in node file: (" + line + ")." ) FI;
# attempt to find the text in the list of strings/identifiers #
INT t pos := LWB text list;
BOOL found := FALSE;
INT result := LWB text list - 1;
FOR t pos FROM LWB text list TO UPB text list WHILE NOT found DO
IF found := text list[ t pos ] = str THEN
# found the string #
result := t pos
ELIF text list[ t pos ] = "" THEN
# have an empty slot for ther string #
found := TRUE;
text list[ t pos ] := str;
result := t pos
FI
OD;
IF NOT found THEN gen error( "Out of string space." ) FI;
result
END # read string # ;
# gets an integer from the line - no checks for valid digits #
PROC read integer = INT:
BEGIN
INT n := 0;
WHILE line[ l pos ] /= " " DO
( n *:= 10 ) +:= ( ABS line[ l pos ] - ABS "0" );
l pos +:= 1
OD;
n
END # read integer # ;
STRING line, name;
INT l pos := 1, nd type := -1;
read( ( line, newline ) );
line +:= " ";
# get the node type name #
WHILE line[ l pos ] = " " DO l pos +:= 1 OD;
name := "";
WHILE IF l pos > UPB line THEN FALSE ELSE line[ l pos ] /= " " FI DO
name +:= line[ l pos ];
l pos +:= 1
OD;
# determine the node type #
nd type := LWB nd name;
IF name /= ";" THEN
# not a null node #
WHILE IF nd type <= UPB nd name THEN name /= nd name[ nd type ] ELSE FALSE FI DO nd type +:= 1 OD;
IF nd type > UPB nd name THEN gen error( "Malformed node: (" + line + ")." ) FI;
# handle the additional parameter for identifier/string/integer, or sub-nodes for operator nodes #
IF nd type = ninteger OR nd type = nidentifier OR nd type = nstring THEN
WHILE line[ l pos ] = " " DO l pos +:= 1 OD;
IF nd type = ninteger THEN result := operand node( nd type, read integer )
ELIF nd type = nidentifier THEN result := operand node( nd type, read string( identifiers, " " ) )
ELSE # nd type = nString # result := operand node( nd type, read string( strings, """" ) )
FI
ELSE
# operator node #
REF NODE left node = read node;
result := op node( nd type, left node, read node )
FI
FI;
result
END # read node # ;
# returns a formatted op code for code generation #
PROC operation = ( INT op code )STRING: " " + op name[ op code ] + " ";
# defines the specified label #
PROC define label = ( INT label number )VOID: print( ( "lbl_", whole( label number, 0 ), ":", newline ) );
# generates code to load a string value #
PROC gen load string = ( INT value )VOID:
BEGIN
print( ( operation( opushstr ), " ", strings[ value ], """", newline ) )
END # push string # ;
# generates code to load a constant value #
PROC gen load constant = ( INT value )VOID: print( ( operation( opush ), " ", whole( value, 0 ), newline ) );
# generates an operation acting on an address #
PROC gen data op = ( INT op, address )VOID: print( ( operation( op ), " l_", identifiers[ address ], newline ) );
# generates a nullary operation #
PROC gen op 0 = ( INT op )VOID: print( ( operation( op ), newline ) );
# generates a "not" instruction sequence #
PROC gen not = VOID:
BEGIN
gen load constant( 0 );
print( ( operation( oeq ), newline ) )
END # gen not # ;
# generates a negated condition #
PROC gen not op = ( INT op, REF NODE n )VOID:
BEGIN
gen( left OF n );
gen( right OF n );
gen op 0( op );
gen not
END # gen not op # ;
# generates a jump operation #
PROC gen jump = ( INT op, label )VOID: print( ( operation( op ), " lbl_", whole( label, 0 ), newline ) );
# generates code to output something to System.Console.Out #
PROC gen output = ( REF NODE n, STRING output type )VOID:
BEGIN
print( ( " call " ) );
print( ( "class [mscorlib]System.IO.TextWriter [mscorlib]System.Console::get_Out()", newline ) );
gen( left OF n );
print( ( " callvirt " ) );
print( ( "instance void [mscorlib]System.IO.TextWriter::Write(", output type, ")", newline ) )
END # gen output # ;
# generates the code header - assembly info, namespace, class and start of the Main method #
PROC code header = VOID:
BEGIN
print( ( ".assembly extern mscorlib { auto }", newline ) );
print( ( ".assembly RccSample {}", newline ) );
print( ( ".module RccSample.exe", newline ) );
print( ( ".namespace Rcc.Sample", newline ) );
print( ( "{", newline ) );
print( ( " .class public auto ansi Program extends [mscorlib]System.Object", newline ) );
print( ( " {", newline ) );
print( ( " .method public static void Main() cil managed", newline ) );
print( ( " {", newline ) );
print( ( " .entrypoint", newline ) );
# output the local variables #
BOOL have locals := FALSE;
STRING local prefix := " .locals init (int32 l_";
FOR s pos FROM LWB identifiers TO UPB identifiers WHILE identifiers[ s pos ] /= "" DO
print( ( local prefix, identifiers[ s pos ], newline ) );
local prefix := " ,int32 l_";
have locals := TRUE
OD;
IF have locals THEN
# there were some local variables defined - output the terminator #
print( ( " )", newline ) )
FI
END # code header # ;
# generates code for the node n #
PROC gen = ( REF NODE n )VOID:
IF n IS REF NODE( NIL ) THEN # null node #
SKIP
ELIF type OF n = nidentifier THEN # load identifier #
gen data op( ofetch, value OF n )
ELIF type OF n = nstring THEN # load string #
gen load string( value OF n )
ELIF type OF n = ninteger THEN # load integer #
gen load constant( value OF n )
ELIF type OF n = nsequence THEN # list #
gen( left OF n );
gen( right OF n )
ELIF type OF n = nif THEN # if-else #
INT else label := new label;
gen( left OF n );
gen jump( ojz, else label );
gen( left OF right OF n );
IF right OF right OF n IS REF NODE( NIL ) THEN
# no "else" part #
define label( else label )
ELSE
# have an "else" part #
INT end if label := new label;
gen jump( ojmp, end if label );
define label( else label );
gen( right OF right OF n );
define label( end if label )
FI
ELIF type OF n = nwhile THEN # while-loop #
INT loop label := new label;
INT exit label := new label;
define label( loop label );
gen( left OF n );
gen jump( ojz, exit label );
gen( right OF n );
gen jump( ojmp, loop label );
define label( exit label )
ELIF type OF n = nassign THEN # assignment #
gen( right OF n );
gen data op( ostore, value OF left OF n )
ELIF type OF n = nnot THEN # bolean not #
gen( left OF n );
gen not
ELIF type OF n = ngreaterequal THEN # compare >= #
gen not op( olt, n )
ELIF type OF n = nnotequal THEN # compare not = #
gen not op( oeq, n )
ELIF type OF n = nlessequal THEN # compare <= #
gen not op( ogt, n )
ELIF type OF n = nprts THEN # print string #
gen output( n, "string" )
ELIF type OF n = nprtc THEN # print character #
gen output( n, "char" )
ELIF type OF n = nprti THEN # print integer #
gen output( n, "int32" )
ELSE # everything else #
gen( left OF n );
gen( right OF n ); # right will be null for a unary op so no code will be generated #
print( ( operation( ndop( type OF n ) ), newline ) )
FI # gen # ;
# generates the code trailer - return instruction, end of Main method, end of class and end of namespace #
PROC code trailer = VOID:
BEGIN
print( ( " ret", newline ) );
print( ( " } // Main method", newline ) );
print( ( " } // Program class", newline ) );
print( ( "} // Rcc.Sample namespace", newline ) )
END # code trailer # ;
# parse the output from the syntax analyser and generate code from the parse tree #
REF NODE code = read node;
code header;
gen( code );
code trailer |
http://rosettacode.org/wiki/Compare_sorting_algorithms%27_performance | Compare sorting algorithms' performance |
Sorting Algorithm
This is a sorting algorithm. It may be applied to a set of data in order to sort it.
For comparing various sorts, see compare sorts.
For other sorting algorithms, see sorting algorithms, or:
O(n logn) sorts
Heap sort |
Merge sort |
Patience sort |
Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort
Measure a relative performance of sorting algorithms implementations.
Plot execution time vs. input sequence length dependencies for various implementation of sorting algorithm and different input sequence types (example figures).
Consider three type of input sequences:
ones: sequence of all 1's. Example: {1, 1, 1, 1, 1}
range: ascending sequence, i.e. already sorted. Example: {1, 2, 3, 10, 15}
shuffled range: sequence with elements randomly distributed. Example: {5, 3, 9, 6, 8}
Consider at least two different sorting functions (different algorithms or/and different implementation of the same algorithm).
For example, consider Bubble Sort, Insertion sort, Quicksort or/and implementations of Quicksort with different pivot selection mechanisms. Where possible, use existing implementations.
Preliminary subtask:
Bubble Sort, Insertion sort, Quicksort, Radix sort, Shell sort
Query Performance
Write float arrays to a text file
Plot x, y arrays
Polynomial Fitting
General steps:
Define sorting routines to be considered.
Define appropriate sequence generators and write timings.
Plot timings.
What conclusions about relative performance of the sorting routines could be made based on the plots?
| #AutoHotkey | AutoHotkey | ; BUGGY - FIX
#Persistent
#SingleInstance OFF
SetBatchLines, -1
SortMethods := "Bogo,Bubble,Cocktail,Counting,Gnome,Insertion,Merge,Permutation,Quick,Selection,Shell,BuiltIn"
Gui, Add, Edit, vInput, numbers,separated,by,commas,without,spaces,afterwards
Loop, PARSE, SortMethods, `,
Gui, Add, CheckBox, v%A_LoopField%, %A_LoopField% Sort
Gui, Add, Button, gTest, Test!
Gui, Show,, SortTest!
Return
Test:
SplashTextOn,,, Test Commencing
Sleep 2500
SplashTextOff
Gui, +OwnDialogs
Gui, Submit, NoHide
Loop, PARSE, SortMethods, `,
{
If (%A_LoopField%)
{
DllCall("QueryPerformanceCounter", "Int64 *", %A_LoopField%Begin)
%A_LoopField%Out := %A_LoopField%Sort(Input)
DllCall("QueryPerformanceCounter", "Int64 *", %A_LoopField%Time)
%A_LoopField%End := %A_LoopField%Begin + %A_LoopField%Time
%A_LoopField%Time -= %A_LoopField%Begin
}
}
Time := ""
Loop, PARSE, SortMethods, `,
If (%A_LoopField%)
Time .= A_LoopField . " Sort: " . %A_LoopField%Time . "`t`t" . %A_LoopField%Out . "`r`n"
MsgBox,, Results!, %Time%
Return
; Sorting funtions (Bogo, Bubble, Cocktail, Counting, Gnome, Insertion, Merge, Permutation, Quick, Selection, Shell, BuiltIn):
BogoSort(var)
{
sorted := 1
Loop, Parse, var
{
current := A_LoopField
rest := SubStr(var, A_Index)
Loop, Parse, rest
{
If (current > A_LoopField)
sorted := 0
}
}
While !sorted {
sorted := 1
Loop, Parse, var, `,
{
current := A_LoopField
rest := SubStr(var, A_Index)
Loop, Parse, rest, `,
{
If (current > A_LoopField)
sorted := 0
}
}
Sort, var, D`, Random
}
Return var
}
BubbleSort(var)
{
StringSplit, array, var, `,
hasChanged = 1
size := array0
While hasChanged
{
hasChanged = 0
Loop, % (size - 1)
{
i := array%A_Index%
aj := A_Index + 1
j := array%aj%
If (j < i)
{
temp := array%A_Index%
array%A_Index% := array%aj%
array%aj% := temp
hasChanged = 1
}
}
}
Loop, % size
sorted .= "," . array%A_Index%
Return substr(sorted,2)
}
CocktailSort(var)
{
StringSplit array, var, `,
i0 := 1, i1 := array0
Loop
{
Changed =
Loop % i1-- -i0 {
j := i0+A_Index, i := j-1
If (array%j% < array%i%)
t := array%i%, array%i% := array%j%, array%j% := t
,Changed = 1
}
IfEqual Changed,, Break
Loop % i1-i0++
{
i := i1-A_Index, j := i+1
If (array%j% < array%i%)
t := array%i%, array%i% := array%j%, array%j% := t
,Changed = 1
}
IfEqual Changed,, Break
}
Loop % array0
sorted .= "," . array%A_Index%
Return SubStr(sorted,2)
}
CountingSort(var)
{
max := min := substr(var, 1, instr(var, ","))
Loop, parse, var, `,
{
If (A_LoopField > max)
max := A_LoopField
Else If (A_LoopField < min)
min := A_LoopField
}
Loop % max-min+1
i := A_Index-1, a%i% := 0
Loop, Parse, var, `,
i := A_LoopField-min, a%i%++
Loop % max-min+1
{
i := A_Index-1, v := i+min
Loop % a%i%
t .= "," v
}
Return SubStr(t,2)
}
GnomeSort(var) {
StringSplit, a, var, `,
i := 2, j := 3
While i <= a0 {
u := i-1
If (a%u% < a%i%)
i := j, j := j+1
Else {
t := a%u%, a%u% := a%i%, a%i% := t
If (--i = 1)
i := j, j++
}
}
Loop % a0
sorted .= "," . a%A_Index%
Return SubStr(sorted,2)
}
InsertionSort(var) {
StringSplit, a, var, `,
Loop % a0-1 {
i := A_Index+1, v := a%i%, j := i-1
While j>0 and a%j%>v
u := j+1, a%u% := a%j%, j--
u := j+1, a%u% := v
}
Loop % a0
sorted .= "," . a%A_Index%
Return SubStr(sorted,2)
}
MergeSort(var) {
StringReplace, t, var, `,,, UseErrorLevel
L := ((t = "") ? 0 : ErrorLevel+1)
If (2 > L)
Return var
StringGetPos, p, var, `,, % "L" L//2
list0 := MergeSort(SubStr(var,1,p))
list1 := MergeSort(SubStr(var,p+2))
If (list0 = "")
Return list1
Else If (list1 = "")
Return list0
list := list0
i0 := (p0 := InStr(list,",",0,i:=p0+1)) ? SubStr(list,i,p0-i) : SubStr(list,i)
list := list1
i1 := (p1 := InStr(list,",",0,i:=p1+1)) ? SubStr(list,i,p1-i) : SubStr(list,i)
Loop {
i := i0>i1
list .= "," i%i%
If (p%i%) {
list := list%i%
i%i% := (p%i% := InStr(list,",",0,i:=p%i%+1)) ? SubStr(list,i,p%i%-i) : SubStr(list,i)
}
Else {
i ^= 1
rtv := SubStr(list "," i%i% (p%i% ? "," SubStr(list%i%,p%i%+1) : ""), 2)
}
}
Return rtv
}
PermutationSort(var) {
static a:="a",v:="v"
StringSplit, a, var, `,
v0 := a0
Loop %v0%
v%A_Index% := A_Index
unsorted := 0
Loop % %a%0-1 {
i := %v%%A_Index%, j := A_Index+1, j := %v%%j%
If (%a%%i% > %a%%j%)
unSorted := 1
}
While unSorted {
i := %v%0, i1 := i-1
While %v%%i1% >= %v%%i% {
--i, --i1
IfLess i1,1, Return 1
}
j := %v%0
While %v%%j% <= %v%%i1%
--j
t := %v%%i1%, %v%%i1% := %v%%j%, %v%%j% := t, j := %v%0
While i < j
t := %v%%i%, %v%%i% := %v%%j%, %v%%j% := t, ++i, --j
unsorted := 0
Loop % %a%0-1 {
i := %v%%A_Index%, j := A_Index+1, j := %v%%j%
If (%a%%i% > %a%%j%)
unSorted := 1
}
}
Loop % a0
i := v%A_Index%, sorted .= "," . a%i%
Return SubStr(sorted,2)
}
QuickSort(var)
{
StringSplit, list, var, `,
If (list0 <= 1)
Return list
pivot := list1
Loop, Parse, var, `,
{
If (A_LoopField < pivot)
less .= "," . A_LoopField
Else If (A_LoopField > pivot)
more .= "," . A_LoopField
Else
pivotlist .= "," . A_LoopField
}
less := QuickSort(substr(less,2))
more := QuickSort(substr(more,2))
Return substr(less,2) . pivotList . more
}
SelectionSort(var) {
StringSplit, a, var, `,
Loop % a0-1 {
i := A_Index, mn := a%i%, j := m := i
Loop % a0-i {
j++
If (a%j% < mn)
mn := a%j%, m := j
}
t := a%i%, a%i% := a%m%, a%m% := t
}
Loop % a0
sorted .= "," . a%A_Index%
Return SubStr(sorted,2)
}
ShellSort(var) {
StringSplit, a, var, `,
inc := a0
While inc:=round(inc/2.2)
Loop % a0-inc {
i := A_Index+inc, t := a%i%, j := i, k := j-inc
While j > inc && a%k% > t
a%j% := a%k%, j := k, k -= inc
a%j% := t
}
Loop % a0
s .= "," . a%A_Index%
Return SubStr(s,2)
}
BuiltInSort(var) {
Sort, var, N D`,
Return var
} |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #Julia | Julia | struct Anode
node_type::String
left::Union{Nothing, Anode}
right::Union{Nothing, Anode}
value::Union{Nothing, String}
end
make_leaf(t, v) = Anode(t, nothing, nothing, v)
make_node(t, l, r) = Anode(t, l, r, nothing)
const OP2 = Dict("Multiply" => "*", "Divide" => "/", "Mod" => "%", "Add" => "+", "Subtract" => "-",
"Less" => "<", "Greater" => ">", "LessEqual" => "<=", "GreaterEqual" => ">=",
"Equal" => "==", "NotEqual" => "!=", "And" => "&&", "Or" => "||")
const OP1 = Dict("Not" => "!", "Minus" => "-")
tobool(i::Bool) = i
tobool(i::Int) = (i != 0)
tobool(s::String) = eval(Symbol(s)) != 0
const stac = Vector{Any}()
function call2(op, x, y)
if op in ["And", "Or"]
x, y = tobool(x), tobool(y)
end
eval(Meta.parse("push!(stac, $(x) $(OP2[op]) $(y))"))
return Int(floor(pop!(stac)))
end
call1(op, x) = (if op in ["Not"] x = tobool(x) end; eval(Meta.parse("$(OP1[op]) $(x)")))
evalpn(op, x, y = nothing) = (haskey(OP2, op) ? call2(op, x, y) : call1(op, x))
function load_ast(io)
line = strip(readline(io))
line_list = filter(x -> x != nothing, match(r"(?:(\w+)\s+(\d+|\w+|\".*\")|(\w+|;))", line).captures)
text = line_list[1]
if text == ";"
return nothing
end
node_type = text
if length(line_list) > 1
return make_leaf(line_list[1], line_list[2])
end
left = load_ast(io)
right = load_ast(io)
return make_node(line_list[1], left, right)
end
function interp(x)
if x == nothing return nothing
elseif x.node_type == "Integer" return parse(Int, x.value)
elseif x.node_type == "Identifier" return "_" * x.value
elseif x.node_type == "String" return replace(replace(x.value, "\"" => ""), "\\n" => "\n")
elseif x.node_type == "Assign" s = "$(interp(x.left)) = $(interp(x.right))"; eval(Meta.parse(s)); return nothing
elseif x.node_type in keys(OP2) return evalpn(x.node_type, interp(x.left), interp(x.right))
elseif x.node_type in keys(OP1) return evalpn(x.node_type, interp(x.left))
elseif x.node_type == "If" tobool(eval(interp(x.left))) ? interp(x.right.left) : interp(x.right.right); return nothing
elseif x.node_type == "While" while tobool(eval(interp(x.left))) interp(x.right) end; return nothing
elseif x.node_type == "Prtc" print(Char(eval(interp(x.left)))); return nothing
elseif x.node_type == "Prti" s = interp(x.left); print((i = tryparse(Int, s)) == nothing ? eval(Symbol(s)) : i); return nothing
elseif x.node_type == "Prts" print(eval(interp(x.left))); return nothing
elseif x.node_type == "Sequence" interp(x.left); interp(x.right); return nothing
else
throw("unknown node type: $x")
end
end
const testparsed = """
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String \" is prime\\n\"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String \"Total primes found: \"
;
Prti
Identifier count
;
Prts
String \"\\n\"
; """
const lio = IOBuffer(testparsed)
interp(load_ast(lio))
|
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #AutoHotkey | AutoHotkey | list := ["abcd","123456789","abcdef","1234567"]
sorted := []
for i, s in list
sorted[0-StrLen(s), s] := s
for l, obj in sorted
{
i := A_Index
for s, v in obj
{
if (i = 1)
result .= """" s """ has length " 0-l " and is the longest string.`n"
else if (i < sorted.Count())
result .= """"s """ has length " 0-l " and is neither the longest nor the shortest string.`n"
else
result .= """"s """ has length " 0-l " and is the shorted string.`n"
}
}
MsgBox % result |
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #AWK | AWK |
# syntax: GAWK -f COMPARE_LENGTH_OF_TWO_STRINGS.AWK
BEGIN {
main("abcd","123456789")
main("longer","short")
main("hello","world")
exit(0)
}
function main(Sa,Sb, La,Lb) {
La = length(Sa)
Lb = length(Sb)
if (La > Lb) {
printf("a>b\n%3d %s\n%3d %s\n\n",La,Sa,Lb,Sb)
}
else if (La < Lb) {
printf("a<b\n%3d %s\n%3d %s\n\n",Lb,Sb,La,Sa)
}
else {
printf("a=b\n%3d %s\n%3d %s\n\n",Lb,Sb,La,Sa)
}
}
|
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #Fortran | Fortran | !!!
!!! An implementation of the Rosetta Code parser task:
!!! https://rosettacode.org/wiki/Compiler/syntax_analyzer
!!!
!!! The implementation is based on the published pseudocode.
!!!
module compiler_type_kinds
use, intrinsic :: iso_fortran_env, only: int32
use, intrinsic :: iso_fortran_env, only: int64
implicit none
private
! Synonyms.
integer, parameter, public :: size_kind = int64
integer, parameter, public :: length_kind = size_kind
integer, parameter, public :: nk = size_kind
! Synonyms for character capable of storing a Unicode code point.
integer, parameter, public :: unicode_char_kind = selected_char_kind ('ISO_10646')
integer, parameter, public :: ck = unicode_char_kind
! Synonyms for integers capable of storing a Unicode code point.
integer, parameter, public :: unicode_ichar_kind = int32
integer, parameter, public :: ick = unicode_ichar_kind
end module compiler_type_kinds
module string_buffers
use, intrinsic :: iso_fortran_env, only: error_unit
use, intrinsic :: iso_fortran_env, only: int64
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick
implicit none
private
public :: strbuf_t
type :: strbuf_t
integer(kind = nk), private :: len = 0
!
! ‘chars’ is made public for efficient access to the individual
! characters.
!
character(1, kind = ck), allocatable, public :: chars(:)
contains
procedure, pass, private :: ensure_storage => strbuf_t_ensure_storage
procedure, pass :: to_unicode_full_string => strbuf_t_to_unicode_full_string
procedure, pass :: to_unicode_substring => strbuf_t_to_unicode_substring
procedure, pass :: length => strbuf_t_length
procedure, pass :: set => strbuf_t_set
procedure, pass :: append => strbuf_t_append
generic :: to_unicode => to_unicode_full_string
generic :: to_unicode => to_unicode_substring
generic :: assignment(=) => set
end type strbuf_t
contains
function strbuf_t_to_unicode_full_string (strbuf) result (s)
class(strbuf_t), intent(in) :: strbuf
character(:, kind = ck), allocatable :: s
!
! This does not actually ensure that the string is valid Unicode;
! any 31-bit ‘character’ is supported.
!
integer(kind = nk) :: i
allocate (character(len = strbuf%len, kind = ck) :: s)
do i = 1, strbuf%len
s(i:i) = strbuf%chars(i)
end do
end function strbuf_t_to_unicode_full_string
function strbuf_t_to_unicode_substring (strbuf, i, j) result (s)
!
! ‘Extreme’ values of i and j are allowed, as shortcuts for ‘from
! the beginning’, ‘up to the end’, or ‘empty substring’.
!
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i, j
character(:, kind = ck), allocatable :: s
!
! This does not actually ensure that the string is valid Unicode;
! any 31-bit ‘character’ is supported.
!
integer(kind = nk) :: i1, j1
integer(kind = nk) :: n
integer(kind = nk) :: k
i1 = max (1_nk, i)
j1 = min (strbuf%len, j)
n = max (0_nk, (j1 - i1) + 1_nk)
allocate (character(n, kind = ck) :: s)
do k = 1, n
s(k:k) = strbuf%chars(i1 + (k - 1_nk))
end do
end function strbuf_t_to_unicode_substring
elemental function strbuf_t_length (strbuf) result (n)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk) :: n
n = strbuf%len
end function strbuf_t_length
elemental function next_power_of_two (x) result (y)
integer(kind = nk), intent(in) :: x
integer(kind = nk) :: y
!
! It is assumed that no more than 64 bits are used.
!
! The branch-free algorithm is that of
! https://archive.is/nKxAc#RoundUpPowerOf2
!
! Fill in bits until one less than the desired power of two is
! reached, and then add one.
!
y = x - 1
y = ior (y, ishft (y, -1))
y = ior (y, ishft (y, -2))
y = ior (y, ishft (y, -4))
y = ior (y, ishft (y, -8))
y = ior (y, ishft (y, -16))
y = ior (y, ishft (y, -32))
y = y + 1
end function next_power_of_two
elemental function new_storage_size (length_needed) result (size)
integer(kind = nk), intent(in) :: length_needed
integer(kind = nk) :: size
! Increase storage by orders of magnitude.
if (2_nk**32 < length_needed) then
size = huge (1_nk)
else
size = next_power_of_two (length_needed)
end if
end function new_storage_size
subroutine strbuf_t_ensure_storage (strbuf, length_needed)
class(strbuf_t), intent(inout) :: strbuf
integer(kind = nk), intent(in) :: length_needed
integer(kind = nk) :: new_size
type(strbuf_t) :: new_strbuf
if (.not. allocated (strbuf%chars)) then
! Initialize a new strbuf%chars array.
new_size = new_storage_size (length_needed)
allocate (strbuf%chars(1:new_size))
else if (ubound (strbuf%chars, 1) < length_needed) then
! Allocate a new strbuf%chars array, larger than the current
! one, but containing the same characters.
new_size = new_storage_size (length_needed)
allocate (new_strbuf%chars(1:new_size))
new_strbuf%chars(1:strbuf%len) = strbuf%chars(1:strbuf%len)
call move_alloc (new_strbuf%chars, strbuf%chars)
end if
end subroutine strbuf_t_ensure_storage
subroutine strbuf_t_set (dst, src)
class(strbuf_t), intent(inout) :: dst
class(*), intent(in) :: src
integer(kind = nk) :: n
integer(kind = nk) :: i
select type (src)
type is (character(*, kind = ck))
n = len (src, kind = nk)
call dst%ensure_storage(n)
do i = 1, n
dst%chars(i) = src(i:i)
end do
dst%len = n
type is (character(*))
n = len (src, kind = nk)
call dst%ensure_storage(n)
do i = 1, n
dst%chars(i) = src(i:i)
end do
dst%len = n
class is (strbuf_t)
n = src%len
call dst%ensure_storage(n)
dst%chars(1:n) = src%chars(1:n)
dst%len = n
class default
error stop
end select
end subroutine strbuf_t_set
subroutine strbuf_t_append (dst, src)
class(strbuf_t), intent(inout) :: dst
class(*), intent(in) :: src
integer(kind = nk) :: n_dst, n_src, n
integer(kind = nk) :: i
select type (src)
type is (character(*, kind = ck))
n_dst = dst%len
n_src = len (src, kind = nk)
n = n_dst + n_src
call dst%ensure_storage(n)
do i = 1, n_src
dst%chars(n_dst + i) = src(i:i)
end do
dst%len = n
type is (character(*))
n_dst = dst%len
n_src = len (src, kind = nk)
n = n_dst + n_src
call dst%ensure_storage(n)
do i = 1, n_src
dst%chars(n_dst + i) = src(i:i)
end do
dst%len = n
class is (strbuf_t)
n_dst = dst%len
n_src = src%len
n = n_dst + n_src
call dst%ensure_storage(n)
dst%chars((n_dst + 1):n) = src%chars(1:n_src)
dst%len = n
class default
error stop
end select
end subroutine strbuf_t_append
end module string_buffers
module reading_one_line_from_a_stream
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick
use, non_intrinsic :: string_buffers
implicit none
private
! get_line_from_stream: read an entire input line from a stream into
! a strbuf_t.
public :: get_line_from_stream
character(1, kind = ck), parameter :: linefeed_char = char (10, kind = ck)
! The following is correct for Unix and its relatives.
character(1, kind = ck), parameter :: newline_char = linefeed_char
contains
subroutine get_line_from_stream (unit_no, eof, no_newline, strbuf)
integer, intent(in) :: unit_no
logical, intent(out) :: eof ! End of file?
logical, intent(out) :: no_newline ! There is a line but it has no
! newline? (Thus eof also must
! be .true.)
class(strbuf_t), intent(inout) :: strbuf
character(1, kind = ck) :: ch
strbuf = ''
call get_ch (unit_no, eof, ch)
do while (.not. eof .and. ch /= newline_char)
call strbuf%append (ch)
call get_ch (unit_no, eof, ch)
end do
no_newline = eof .and. (strbuf%length() /= 0)
end subroutine get_line_from_stream
subroutine get_ch (unit_no, eof, ch)
!
! Read a single code point from the stream.
!
! Currently this procedure simply inputs ‘ASCII’ bytes rather than
! Unicode code points.
!
integer, intent(in) :: unit_no
logical, intent(out) :: eof
character(1, kind = ck), intent(out) :: ch
integer :: stat
character(1) :: c = '*'
eof = .false.
if (unit_no == input_unit) then
call get_input_unit_char (c, stat)
else
read (unit = unit_no, iostat = stat) c
end if
if (stat < 0) then
ch = ck_'*'
eof = .true.
else if (0 < stat) then
write (error_unit, '("Input error with status code ", I0)') stat
stop 1
else
ch = char (ichar (c, kind = ick), kind = ck)
end if
end subroutine get_ch
!!!
!!! If you tell gfortran you want -std=f2008 or -std=f2018, you likely
!!! will need to add also -fall-intrinsics or -U__GFORTRAN__
!!!
!!! The first way, you get the FGETC intrinsic. The latter way, you
!!! get the C interface code that uses getchar(3).
!!!
#ifdef __GFORTRAN__
subroutine get_input_unit_char (c, stat)
!
! The following works if you are using gfortran.
!
! (FGETC is considered a feature for backwards compatibility with
! g77. However, I know of no way to reconfigure input_unit as a
! Fortran 2003 stream, for use with ordinary ‘read’.)
!
character, intent(inout) :: c
integer, intent(out) :: stat
call fgetc (input_unit, c, stat)
end subroutine get_input_unit_char
#else
subroutine get_input_unit_char (c, stat)
!
! An alternative implementation of get_input_unit_char. This
! actually reads input from the C standard input, which might not
! be the same as input_unit.
!
use, intrinsic :: iso_c_binding, only: c_int
character, intent(inout) :: c
integer, intent(out) :: stat
interface
!
! Use getchar(3) to read characters from standard input. This
! assumes there is actually such a function available, and that
! getchar(3) does not exist solely as a macro. (One could write
! one’s own getchar() if necessary, of course.)
!
function getchar () result (c) bind (c, name = 'getchar')
use, intrinsic :: iso_c_binding, only: c_int
integer(kind = c_int) :: c
end function getchar
end interface
integer(kind = c_int) :: i_char
i_char = getchar ()
!
! The C standard requires that EOF have a negative value. If the
! value returned by getchar(3) is not EOF, then it will be
! representable as an unsigned char. Therefore, to check for end
! of file, one need only test whether i_char is negative.
!
if (i_char < 0) then
stat = -1
else
stat = 0
c = char (i_char)
end if
end subroutine get_input_unit_char
#endif
end module reading_one_line_from_a_stream
module lexer_token_facts
implicit none
private
integer, parameter, public :: tk_EOI = 0
integer, parameter, public :: tk_Mul = 1
integer, parameter, public :: tk_Div = 2
integer, parameter, public :: tk_Mod = 3
integer, parameter, public :: tk_Add = 4
integer, parameter, public :: tk_Sub = 5
integer, parameter, public :: tk_Negate = 6
integer, parameter, public :: tk_Not = 7
integer, parameter, public :: tk_Lss = 8
integer, parameter, public :: tk_Leq = 9
integer, parameter, public :: tk_Gtr = 10
integer, parameter, public :: tk_Geq = 11
integer, parameter, public :: tk_Eq = 12
integer, parameter, public :: tk_Neq = 13
integer, parameter, public :: tk_Assign = 14
integer, parameter, public :: tk_And = 15
integer, parameter, public :: tk_Or = 16
integer, parameter, public :: tk_If = 17
integer, parameter, public :: tk_Else = 18
integer, parameter, public :: tk_While = 19
integer, parameter, public :: tk_Print = 20
integer, parameter, public :: tk_Putc = 21
integer, parameter, public :: tk_Lparen = 22
integer, parameter, public :: tk_Rparen = 23
integer, parameter, public :: tk_Lbrace = 24
integer, parameter, public :: tk_Rbrace = 25
integer, parameter, public :: tk_Semi = 26
integer, parameter, public :: tk_Comma = 27
integer, parameter, public :: tk_Ident = 28
integer, parameter, public :: tk_Integer = 29
integer, parameter, public :: tk_String = 30
integer, parameter, public :: tk_Positive = 31
character(16), parameter, public :: lexer_token_string(0:31) = &
(/ "EOI ", &
& "* ", &
& "/ ", &
& "% ", &
& "+ ", &
& "- ", &
& "- ", &
& "! ", &
& "< ", &
& "<= ", &
& "> ", &
& ">= ", &
& "== ", &
& "!= ", &
& "= ", &
& "&& ", &
& "|| ", &
& "if ", &
& "else ", &
& "while ", &
& "print ", &
& "putc ", &
& "( ", &
& ") ", &
& "{ ", &
& "} ", &
& "; ", &
& ", ", &
& "Ident ", &
& "Integer literal ", &
& "String literal ", &
& "+ " /)
integer, parameter, public :: lexer_token_arity(0:31) = &
& (/ -1, & ! EOI
& 2, 2, 2, 2, 2, & ! * / % + -
& 1, 1, & ! negate !
& 2, 2, 2, 2, 2, 2, & ! < <= > >= == !=
& -1, & ! =
& 2, 2, & ! && ||
& -1, -1, -1, -1, -1, & !
& -1, -1, -1, -1, -1, & !
& -1, -1, -1, -1, & !
& 1 /) ! positive
integer, parameter, public :: lexer_token_precedence(0:31) = &
& (/ -1, & ! EOI
& 13, 13, 13, & ! * / %
& 12, 12, & ! + -
& 14, 14, & ! negate !
& 10, 10, 10, 10, & ! < <= > >=
& 9, 9, & ! == !=
& -1, & ! =
& 5, & ! &&
& 4, & ! ||
& -1, -1, -1, -1, -1, & !
& -1, -1, -1, -1, -1, & !
& -1, -1, -1, -1, & !
& 14 /) ! positive
integer, parameter, public :: left_associative = 0
integer, parameter, public :: right_associative = 1
! All current operators are left associative. (The values in the
! array for things that are not operators are unimportant.)
integer, parameter, public :: lexer_token_associativity(0:31) = left_associative
end module lexer_token_facts
module reading_of_lexer_tokens
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick
use, non_intrinsic :: string_buffers
use, non_intrinsic :: reading_one_line_from_a_stream
use, non_intrinsic :: lexer_token_facts
implicit none
private
public :: lexer_token_t
public :: get_lexer_token
character(1, kind = ck), parameter :: horizontal_tab_char = char (9, kind = ck)
character(1, kind = ck), parameter :: linefeed_char = char (10, kind = ck)
character(1, kind = ck), parameter :: vertical_tab_char = char (11, kind = ck)
character(1, kind = ck), parameter :: formfeed_char = char (12, kind = ck)
character(1, kind = ck), parameter :: carriage_return_char = char (13, kind = ck)
character(1, kind = ck), parameter :: space_char = ck_' '
type :: lexer_token_t
integer :: token_no = -(huge (1))
character(:, kind = ck), allocatable :: val
integer(nk) :: line_no = -(huge (1_nk))
integer(nk) :: column_no = -(huge (1_nk))
end type lexer_token_t
contains
subroutine get_lexer_token (unit_no, lex_line_no, eof, token)
!
! Lines that are empty or contain only whitespace are tolerated.
!
! Also tolerated are comment lines, whose first character is a
! '!'. It is convenient for debugging to be able to comment out
! lines.
!
! A last line be without a newline is *not* tolerated, unless it
! contains only whitespace.
!
! Letting there be some whitespace is partly for the sake of
! reading cut-and-paste from a browser display.
!
integer, intent(in) :: unit_no
integer(kind = nk), intent(inout) :: lex_line_no
logical, intent(out) :: eof
type(lexer_token_t), intent(out) :: token
type(strbuf_t) :: strbuf
logical :: no_newline
logical :: input_found
! Let a negative setting initialize the line number.
lex_line_no = max (0_nk, lex_line_no)
strbuf = ''
eof = .false.
input_found = .false.
do while (.not. eof .and. .not. input_found)
call get_line_from_stream (unit_no, eof, no_newline, strbuf)
if (eof) then
if (no_newline) then
lex_line_no = lex_line_no + 1
if (.not. strbuf_is_all_whitespace (strbuf)) then
call start_error_message (lex_line_no)
write (error_unit, '("lexer line ends without a newline")')
stop 1
end if
end if
else
lex_line_no = lex_line_no + 1
input_found = .true.
if (strbuf_is_all_whitespace (strbuf)) then
! A blank line.
input_found = .false.
else if (0 < strbuf%length()) then
if (strbuf%chars(1) == ck_'!') then
! A comment line.
input_found = .false.
end if
end if
end if
end do
token = lexer_token_t ()
if (.not. eof) then
token = strbuf_to_token (lex_line_no, strbuf)
end if
end subroutine get_lexer_token
function strbuf_to_token (lex_line_no, strbuf) result (token)
integer(kind = nk), intent(in) :: lex_line_no
class(strbuf_t), intent(in) :: strbuf
type(lexer_token_t) :: token
character(:, kind = ck), allocatable :: line_no
character(:, kind = ck), allocatable :: column_no
character(:, kind = ck), allocatable :: token_name
character(:, kind = ck), allocatable :: val_string
integer :: stat
integer(kind = nk) :: n
call split_line (lex_line_no, strbuf, line_no, column_no, token_name, val_string)
read (line_no, *, iostat = stat) token%line_no
if (stat /= 0) then
call start_error_message (lex_line_no)
write (error_unit, '("line number field is unreadable or too large")')
stop 1
end if
read (column_no, *, iostat = stat) token%column_no
if (stat /= 0) then
call start_error_message (lex_line_no)
write (error_unit, '("column number field is unreadable or too large")')
stop 1
end if
token%token_no = token_name_to_token_no (lex_line_no, token_name)
select case (token%token_no)
case (tk_Ident)
! I do no checking of identifier names.
allocate (token%val, source = val_string)
case (tk_Integer)
call check_is_all_digits (lex_line_no, val_string)
allocate (token%val, source = val_string)
case (tk_String)
n = len (val_string, kind = nk)
if (n < 2) then
call string_literal_missing_or_no_good
else if (val_string(1:1) /= ck_'"' .or. val_string(n:n) /= ck_'"') then
call string_literal_missing_or_no_good
else
allocate (token%val, source = val_string)
end if
case default
if (len (val_string, kind = nk) /= 0) then
call start_error_message (lex_line_no)
write (error_unit, '("token should not have a value")')
stop 1
end if
end select
contains
subroutine string_literal_missing_or_no_good
call start_error_message (lex_line_no)
write (error_unit, '("""String"" token requires a string literal")')
stop 1
end subroutine string_literal_missing_or_no_good
end function strbuf_to_token
subroutine split_line (lex_line_no, strbuf, line_no, column_no, token_name, val_string)
integer(kind = nk), intent(in) :: lex_line_no
class(strbuf_t), intent(in) :: strbuf
character(:, kind = ck), allocatable, intent(out) :: line_no
character(:, kind = ck), allocatable, intent(out) :: column_no
character(:, kind = ck), allocatable, intent(out) :: token_name
character(:, kind = ck), allocatable, intent(out) :: val_string
integer(kind = nk) :: i, j
i = skip_whitespace (strbuf, 1_nk)
j = skip_non_whitespace (strbuf, i)
line_no = strbuf%to_unicode(i, j - 1)
call check_is_all_digits (lex_line_no, line_no)
i = skip_whitespace (strbuf, j)
j = skip_non_whitespace (strbuf, i)
column_no = strbuf%to_unicode(i, j - 1)
call check_is_all_digits (lex_line_no, column_no)
i = skip_whitespace (strbuf, j)
j = skip_non_whitespace (strbuf, i)
token_name = strbuf%to_unicode(i, j - 1)
i = skip_whitespace (strbuf, j)
if (strbuf%length() < i) then
val_string = ck_''
else if (strbuf%chars(i) == ck_'"') then
j = skip_whitespace_backwards (strbuf, strbuf%length())
if (strbuf%chars(j) == ck_'"') then
val_string = strbuf%to_unicode(i, j)
else
call start_error_message (lex_line_no)
write (error_unit, '("string literal does not end in a double quote")')
stop 1
end if
else
j = skip_non_whitespace (strbuf, i)
val_string = strbuf%to_unicode(i, j - 1)
i = skip_whitespace (strbuf, j)
if (i <= strbuf%length()) then
call start_error_message (lex_line_no)
write (error_unit, '("token line contains unexpected text")')
stop 1
end if
end if
end subroutine split_line
function token_name_to_token_no (lex_line_no, token_name) result (token_no)
integer(kind = nk), intent(in) :: lex_line_no
character(*, kind = ck), intent(in) :: token_name
integer :: token_no
!!
!! This implementation is not optimized in any way, unless the
!! Fortran compiler can optimize the SELECT CASE.
!!
select case (token_name)
case (ck_"End_of_input")
token_no = tk_EOI
case (ck_"Op_multiply")
token_no = tk_Mul
case (ck_"Op_divide")
token_no = tk_Div
case (ck_"Op_mod")
token_no = tk_Mod
case (ck_"Op_add")
token_no = tk_Add
case (ck_"Op_subtract")
token_no = tk_Sub
case (ck_"Op_negate")
token_no = tk_Negate
case (ck_"Op_not")
token_no = tk_Not
case (ck_"Op_less")
token_no = tk_Lss
case (ck_"Op_lessequal ")
token_no = tk_Leq
case (ck_"Op_greater")
token_no = tk_Gtr
case (ck_"Op_greaterequal")
token_no = tk_Geq
case (ck_"Op_equal")
token_no = tk_Eq
case (ck_"Op_notequal")
token_no = tk_Neq
case (ck_"Op_assign")
token_no = tk_Assign
case (ck_"Op_and")
token_no = tk_And
case (ck_"Op_or")
token_no = tk_Or
case (ck_"Keyword_if")
token_no = tk_If
case (ck_"Keyword_else")
token_no = tk_Else
case (ck_"Keyword_while")
token_no = tk_While
case (ck_"Keyword_print")
token_no = tk_Print
case (ck_"Keyword_putc")
token_no = tk_Putc
case (ck_"LeftParen")
token_no = tk_Lparen
case (ck_"RightParen")
token_no = tk_Rparen
case (ck_"LeftBrace")
token_no = tk_Lbrace
case (ck_"RightBrace")
token_no = tk_Rbrace
case (ck_"Semicolon")
token_no = tk_Semi
case (ck_"Comma")
token_no = tk_Comma
case (ck_"Identifier")
token_no = tk_Ident
case (ck_"Integer")
token_no = tk_Integer
case (ck_"String")
token_no = tk_String
case default
call start_error_message (lex_line_no)
write (error_unit, '("unrecognized token name: ", A)') token_name
stop 1
end select
end function token_name_to_token_no
function skip_whitespace (strbuf, i) result (j)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
integer(kind = nk) :: j
logical :: done
j = i
done = .false.
do while (.not. done)
if (at_end_of_line (strbuf, j)) then
done = .true.
else if (.not. isspace (strbuf%chars(j))) then
done = .true.
else
j = j + 1
end if
end do
end function skip_whitespace
function skip_non_whitespace (strbuf, i) result (j)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
integer(kind = nk) :: j
logical :: done
j = i
done = .false.
do while (.not. done)
if (at_end_of_line (strbuf, j)) then
done = .true.
else if (isspace (strbuf%chars(j))) then
done = .true.
else
j = j + 1
end if
end do
end function skip_non_whitespace
function skip_whitespace_backwards (strbuf, i) result (j)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
integer(kind = nk) :: j
logical :: done
j = i
done = .false.
do while (.not. done)
if (j == -1) then
done = .true.
else if (.not. isspace (strbuf%chars(j))) then
done = .true.
else
j = j - 1
end if
end do
end function skip_whitespace_backwards
function at_end_of_line (strbuf, i) result (bool)
class(strbuf_t), intent(in) :: strbuf
integer(kind = nk), intent(in) :: i
logical :: bool
bool = (strbuf%length() < i)
end function at_end_of_line
elemental function strbuf_is_all_whitespace (strbuf) result (bool)
class(strbuf_t), intent(in) :: strbuf
logical :: bool
integer(kind = nk) :: n
integer(kind = nk) :: i
n = strbuf%length()
if (n == 0) then
bool = .true.
else
i = 1
bool = .true.
do while (bool .and. i /= n + 1)
bool = isspace (strbuf%chars(i))
i = i + 1
end do
end if
end function strbuf_is_all_whitespace
elemental function isspace (ch) result (bool)
character(1, kind = ck), intent(in) :: ch
logical :: bool
bool = (ch == horizontal_tab_char) .or. &
& (ch == linefeed_char) .or. &
& (ch == vertical_tab_char) .or. &
& (ch == formfeed_char) .or. &
& (ch == carriage_return_char) .or. &
& (ch == space_char)
end function isspace
elemental function isdigit (ch) result (bool)
character(1, kind = ck), intent(in) :: ch
logical :: bool
integer(kind = ick), parameter :: zero = ichar (ck_'0', kind = ick)
integer(kind = ick), parameter :: nine = ichar (ck_'9', kind = ick)
integer(kind = ick) :: i_ch
i_ch = ichar (ch, kind = ick)
bool = (zero <= i_ch .and. i_ch <= nine)
end function isdigit
subroutine check_is_all_digits (lex_line_no, str)
integer(kind = nk), intent(in) :: lex_line_no
character(*, kind = ck), intent(in) :: str
integer(kind = nk) :: n
integer(kind = nk) :: i
n = len (str, kind = nk)
if (n == 0_nk) then
call start_error_message (lex_line_no)
write (error_unit, '("a required field is missing")')
stop 1
else
do i = 1, n
if (.not. isdigit (str(i:i))) then
call start_error_message (lex_line_no)
write (error_unit, '("a numeric field contains a non-digit")')
stop 1
end if
end do
end if
end subroutine check_is_all_digits
subroutine start_error_message (lex_line_no)
integer(kind = nk), intent(in) :: lex_line_no
write (error_unit, '("Token stream error at line ", I0, ": ")', advance = 'no') &
& lex_line_no
end subroutine start_error_message
end module reading_of_lexer_tokens
module syntactic_analysis
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: output_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: compiler_type_kinds, only: nk, ck, ick
use, non_intrinsic :: string_buffers
use, non_intrinsic :: lexer_token_facts
use, non_intrinsic :: reading_of_lexer_tokens
implicit none
private
public :: ast_node_t
public :: ast_t
public :: parse_token_stream
public :: output_ast_flattened
integer, parameter, public :: tk_start_of_statement = -1
integer, parameter, public :: tk_primary = -2
integer, parameter :: node_Identifier = 1
integer, parameter :: node_String = 2
integer, parameter :: node_Integer = 3
integer, parameter :: node_Sequence = 4
integer, parameter :: node_If = 5
integer, parameter :: node_Prtc = 6
integer, parameter :: node_Prts = 7
integer, parameter :: node_Prti = 8
integer, parameter :: node_While = 9
integer, parameter :: node_Assign = 10
integer, parameter :: node_Negate = 11
integer, parameter :: node_Not = 12
integer, parameter :: node_Multiply = 13
integer, parameter :: node_Divide = 14
integer, parameter :: node_Mod = 15
integer, parameter :: node_Add = 16
integer, parameter :: node_Subtract = 17
integer, parameter :: node_Less = 18
integer, parameter :: node_LessEqual = 19
integer, parameter :: node_Greater = 20
integer, parameter :: node_GreaterEqual = 21
integer, parameter :: node_Equal = 22
integer, parameter :: node_NotEqual = 23
integer, parameter :: node_And = 24
integer, parameter :: node_Or = 25
character(16), parameter :: node_variety_string(1:25) = &
(/ "Identifier ", &
& "String ", &
& "Integer ", &
& "Sequence ", &
& "If ", &
& "Prtc ", &
& "Prts ", &
& "Prti ", &
& "While ", &
& "Assign ", &
& "Negate ", &
& "Not ", &
& "Multiply ", &
& "Divide ", &
& "Mod ", &
& "Add ", &
& "Subtract ", &
& "Less ", &
& "LessEqual ", &
& "Greater ", &
& "GreaterEqual ", &
& "Equal ", &
& "NotEqual ", &
& "And ", &
& "Or " /)
type :: ast_node_t
integer :: node_variety
character(:, kind = ck), allocatable :: val
type(ast_node_t), pointer :: left => null ()
type(ast_node_t), pointer :: right => null ()
contains
procedure, pass :: assign => ast_node_t_assign
generic :: assignment(=) => assign
final :: ast_node_t_finalize
end type ast_node_t
! ast_t phases.
integer, parameter :: building = 1
integer, parameter :: completed = 2
type :: ast_t
!
! This type is used to build the subtrees, as well as for the
! completed AST. The difference is in the setting of ‘phase’.
!
type(ast_node_t), pointer :: node => null ()
integer, private :: phase = building
contains
procedure, pass :: assign => ast_t_assign
generic :: assignment(=) => assign
final :: ast_t_finalize
end type ast_t
type(ast_t), parameter :: ast_nil = ast_t (null ())
contains
recursive subroutine ast_node_t_assign (node, other)
class(ast_node_t), intent(out) :: node
class(*), intent(in) :: other
select type (other)
class is (ast_node_t)
node%node_variety = other%node_variety
if (allocated (other%val)) allocate (node%val, source = other%val)
if (associated (other%left)) allocate (node%left, source = other%left)
if (associated (other%right)) allocate (node%right, source = other%right)
class default
! This branch should never be reached.
error stop
end select
end subroutine ast_node_t_assign
recursive subroutine ast_node_t_finalize (node)
type(ast_node_t), intent(inout) :: node
if (associated (node%left)) deallocate (node%left)
if (associated (node%right)) deallocate (node%right)
end subroutine ast_node_t_finalize
recursive subroutine ast_t_assign (ast, other)
class(ast_t), intent(out) :: ast
class(*), intent(in) :: other
select type (other)
class is (ast_t)
if (associated (other%node)) allocate (ast%node, source = other%node)
!
! Whether it is better to set phase to ‘building’ or to set it
! to ‘other%phase’ is unclear to me. Probably ‘building’ is the
! better choice. Which variable controls memory recovery is
! clear and unchanging, in that case: it is the original,
! ‘other’, that does.
!
ast%phase = building
class default
! This should not happen.
error stop
end select
end subroutine ast_t_assign
subroutine ast_t_finalize (ast)
type(ast_t), intent(inout) :: ast
!
! When we are building the tree, the tree’s nodes should not be
! deallocated when the ast_t variable temporarily holding them
! goes out of scope.
!
! However, once the AST is completed, we do want the memory
! recovered when the variable goes out of scope.
!
! (Elsewhere I have written a primitive garbage collector for
! Fortran programs, but in this case it would be a lot of overhead
! for little gain. In fact, we could reasonably just let the
! memory leak, in this program.
!
! Fortran runtimes *are* allowed by the standard to have garbage
! collectors built in. To my knowledge, at the time of this
! writing, only NAG Fortran has a garbage collector option.)
!
if (ast%phase == completed) then
if (associated (ast%node)) deallocate (ast%node)
end if
end subroutine ast_t_finalize
function parse_token_stream (unit_no) result (ast)
integer, intent(in) :: unit_no
type(ast_t) :: ast
integer(kind = nk) :: lex_line_no
type(ast_t) :: statement
type(lexer_token_t) :: token
lex_line_no = -1_nk
call get_token (unit_no, lex_line_no, token)
call parse_statement (unit_no, lex_line_no, token, statement)
ast = make_internal_node (node_Sequence, ast, statement)
do while (token%token_no /= tk_EOI)
call parse_statement (unit_no, lex_line_no, token, statement)
ast = make_internal_node (node_Sequence, ast, statement)
end do
ast%phase = completed
end function parse_token_stream
recursive subroutine parse_statement (unit_no, lex_line_no, token, ast)
integer, intent(in) :: unit_no
integer(kind = nk), intent(inout) :: lex_line_no
type(lexer_token_t), intent(inout) :: token
type(ast_t), intent(out) :: ast
ast = ast_nil
select case (token%token_no)
case (tk_If)
call parse_ifelse_construct
case (tk_Putc)
call parse_putc
case (tk_Print)
call parse_print
case (tk_Semi)
call get_token (unit_no, lex_line_no, token)
case (tk_Ident)
call parse_identifier
case (tk_While)
call parse_while_construct
case (tk_Lbrace)
call parse_lbrace_construct
case (tk_EOI)
continue
case default
call syntax_error_message ("", tk_start_of_statement, token)
stop 1
end select
contains
recursive subroutine parse_ifelse_construct
type(ast_t) :: predicate
type(ast_t) :: statement_for_predicate_true
type(ast_t) :: statement_for_predicate_false
call expect_token ("If", tk_If, token)
call get_token (unit_no, lex_line_no, token)
call parse_parenthesized_expression (unit_no, lex_line_no, token, predicate)
call parse_statement (unit_no, lex_line_no, token, statement_for_predicate_true)
if (token%token_no == tk_Else) then
call get_token (unit_no, lex_line_no, token)
call parse_statement (unit_no, lex_line_no, token, statement_for_predicate_false)
ast = make_internal_node (node_If, statement_for_predicate_true, &
& statement_for_predicate_false)
else
ast = make_internal_node (node_If, statement_for_predicate_true, ast_nil)
end if
ast = make_internal_node (node_If, predicate, ast)
end subroutine parse_ifelse_construct
recursive subroutine parse_putc
type(ast_t) :: arguments
call expect_token ("Putc", tk_Putc, token)
call get_token (unit_no, lex_line_no, token)
call parse_parenthesized_expression (unit_no, lex_line_no, token, arguments)
ast = make_internal_node (node_Prtc, arguments, ast_nil)
call expect_token ("Putc", tk_Semi, token)
call get_token (unit_no, lex_line_no, token)
end subroutine parse_putc
recursive subroutine parse_print
logical :: done
type(ast_t) :: arg
type(ast_t) :: printer
call expect_token ("Print", tk_Print, token)
call get_token (unit_no, lex_line_no, token)
call expect_token ("Print", tk_Lparen, token)
done = .false.
do while (.not. done)
call get_token (unit_no, lex_line_no, token)
select case (token%token_no)
case (tk_String)
arg = make_leaf_node (node_String, token%val)
printer = make_internal_node (node_Prts, arg, ast_nil)
call get_token (unit_no, lex_line_no, token)
case default
call parse_expression (unit_no, 0, lex_line_no, token, arg)
printer = make_internal_node (node_Prti, arg, ast_nil)
end select
ast = make_internal_node (node_Sequence, ast, printer)
done = (token%token_no /= tk_Comma)
end do
call expect_token ("Print", tk_Rparen, token)
call get_token (unit_no, lex_line_no, token)
call expect_token ("Print", tk_Semi, token)
call get_token (unit_no, lex_line_no, token)
end subroutine parse_print
recursive subroutine parse_identifier
type(ast_t) :: left_side
type(ast_t) :: right_side
left_side = make_leaf_node (node_Identifier, token%val)
call get_token (unit_no, lex_line_no, token)
call expect_token ("assign", tk_Assign, token)
call get_token (unit_no, lex_line_no, token)
call parse_expression (unit_no, 0, lex_line_no, token, right_side)
ast = make_internal_node (node_Assign, left_side, right_side)
call expect_token ("assign", tk_Semi, token)
call get_token (unit_no, lex_line_no, token)
end subroutine parse_identifier
recursive subroutine parse_while_construct
type(ast_t) :: predicate
type(ast_t) :: statement_to_be_repeated
call expect_token ("While", tk_While, token)
call get_token (unit_no, lex_line_no, token)
call parse_parenthesized_expression (unit_no, lex_line_no, token, predicate)
call parse_statement (unit_no, lex_line_no, token, statement_to_be_repeated)
ast = make_internal_node (node_While, predicate, statement_to_be_repeated)
end subroutine parse_while_construct
recursive subroutine parse_lbrace_construct
type(ast_t) :: statement
call expect_token ("Lbrace", tk_Lbrace, token)
call get_token (unit_no, lex_line_no, token)
do while (token%token_no /= tk_Rbrace .and. token%token_no /= tk_EOI)
call parse_statement (unit_no, lex_line_no, token, statement)
ast = make_internal_node (node_Sequence, ast, statement)
end do
call expect_token ("Lbrace", tk_Rbrace, token)
call get_token (unit_no, lex_line_no, token)
end subroutine parse_lbrace_construct
end subroutine parse_statement
recursive subroutine parse_expression (unit_no, p, lex_line_no, token, ast)
integer, intent(in) :: unit_no
integer, intent(in) :: p
integer(kind = nk), intent(inout) :: lex_line_no
type(lexer_token_t), intent(inout) :: token
type(ast_t), intent(out) :: ast
integer :: precedence
type(ast_t) :: expression
select case (token%token_no)
case (tk_Lparen)
call parse_parenthesized_expression (unit_no, lex_line_no, token, ast)
case (tk_Sub)
token%token_no = tk_Negate
precedence = lexer_token_precedence(token%token_no)
call get_token (unit_no, lex_line_no, token)
call parse_expression (unit_no, precedence, lex_line_no, token, expression)
ast = make_internal_node (node_Negate, expression, ast_nil)
case (tk_Add)
token%token_no = tk_Positive
precedence = lexer_token_precedence(token%token_no)
call get_token (unit_no, lex_line_no, token)
call parse_expression (unit_no, precedence, lex_line_no, token, expression)
ast = expression
case (tk_Not)
precedence = lexer_token_precedence(token%token_no)
call get_token (unit_no, lex_line_no, token)
call parse_expression (unit_no, precedence, lex_line_no, token, expression)
ast = make_internal_node (node_Not, expression, ast_nil)
case (tk_Ident)
ast = make_leaf_node (node_Identifier, token%val)
call get_token (unit_no, lex_line_no, token)
case (tk_Integer)
ast = make_leaf_node (node_Integer, token%val)
call get_token (unit_no, lex_line_no, token)
case default
call syntax_error_message ("", tk_primary, token)
stop 1
end select
do while (lexer_token_arity(token%token_no) == 2 .and. &
& p <= lexer_token_precedence(token%token_no))
block
type(ast_t) :: right_expression
integer :: q
integer :: node_variety
if (lexer_token_associativity(token%token_no) == right_associative) then
q = lexer_token_precedence(token%token_no)
else
q = lexer_token_precedence(token%token_no) + 1
end if
node_variety = binary_operator_node_variety (token%token_no)
call get_token (unit_no, lex_line_no, token)
call parse_expression (unit_no, q, lex_line_no, token, right_expression)
ast = make_internal_node (node_variety, ast, right_expression)
end block
end do
end subroutine parse_expression
recursive subroutine parse_parenthesized_expression (unit_no, lex_line_no, token, ast)
integer, intent(in) :: unit_no
integer(kind = nk), intent(inout) :: lex_line_no
type(lexer_token_t), intent(inout) :: token
type(ast_t), intent(out) :: ast
call expect_token ("paren_expr", tk_Lparen, token)
call get_token (unit_no, lex_line_no, token)
call parse_expression (unit_no, 0, lex_line_no, token, ast)
call expect_token ("paren_expr", tk_Rparen, token)
call get_token (unit_no, lex_line_no, token)
end subroutine parse_parenthesized_expression
elemental function binary_operator_node_variety (token_no) result (node_variety)
integer, intent(in) :: token_no
integer :: node_variety
select case (token_no)
case (tk_Mul)
node_variety = node_Multiply
case (tk_Div)
node_variety = node_Divide
case (tk_Mod)
node_variety = node_Mod
case (tk_Add)
node_variety = node_Add
case (tk_Sub)
node_variety = node_Subtract
case (tk_Lss)
node_variety = node_Less
case (tk_Leq)
node_variety = node_LessEqual
case (tk_Gtr)
node_variety = node_Greater
case (tk_Geq)
node_variety = node_GreaterEqual
case (tk_Eq)
node_variety = node_Equal
case (tk_Neq)
node_variety = node_NotEqual
case (tk_And)
node_variety = node_And
case (tk_Or)
node_variety = node_Or
case default
! This branch should never be reached.
error stop
end select
end function binary_operator_node_variety
function make_internal_node (node_variety, left, right) result (ast)
integer, intent(in) :: node_variety
class(ast_t), intent(in) :: left, right
type(ast_t) :: ast
type(ast_node_t), pointer :: node
allocate (node)
node%node_variety = node_variety
node%left => left%node
node%right => right%node
ast%node => node
end function make_internal_node
function make_leaf_node (node_variety, val) result (ast)
integer, intent(in) :: node_variety
character(*, kind = ck), intent(in) :: val
type(ast_t) :: ast
type(ast_node_t), pointer :: node
allocate (node)
node%node_variety = node_variety
node%val = val
ast%node => node
end function make_leaf_node
subroutine get_token (unit_no, lex_line_no, token)
integer, intent(in) :: unit_no
integer(kind = nk), intent(inout) :: lex_line_no
type(lexer_token_t), intent(out) :: token
logical :: eof
call get_lexer_token (unit_no, lex_line_no, eof, token)
if (eof) then
write (error_unit, '("Parser error: the stream of input tokens is incomplete")')
stop 1
end if
end subroutine get_token
subroutine expect_token (message, token_no, token)
character(*), intent(in) :: message
integer, intent (in) :: token_no
class(lexer_token_t), intent(in) :: token
if (token%token_no /= token_no) then
call syntax_error_message (message, token_no, token)
stop 1
end if
end subroutine expect_token
subroutine syntax_error_message (message, expected_token_no, token)
character(*), intent(in) :: message
integer, intent(in) :: expected_token_no
class(lexer_token_t), intent(in) :: token
! Write a message to an output unit dedicated to printing
! errors. The message could, of course, be more detailed than what
! we are doing here.
write (error_unit, '("Syntax error at ", I0, ".", I0)') &
& token%line_no, token%column_no
!
! For the sake of the exercise, also write, to output_unit, a
! message in the style of the C reference program.
!
write (output_unit, '("(", I0, ", ", I0, ") error: ")', advance = 'no') &
& token%line_no, token%column_no
select case (expected_token_no)
case (tk_start_of_statement)
write (output_unit, '("expecting start of statement, found ''", 1A, "''")') &
& trim (lexer_token_string(token%token_no))
case (tk_primary)
write (output_unit, '("Expecting a primary, found ''", 1A, "''")') &
& trim (lexer_token_string(token%token_no))
case default
write (output_unit, '(1A, ": Expecting ''", 1A, "'', found ''", 1A, "''")') &
& trim (message), trim (lexer_token_string(expected_token_no)), &
& trim (lexer_token_string(token%token_no))
end select
end subroutine syntax_error_message
subroutine output_ast_flattened (unit_no, ast)
integer, intent(in) :: unit_no
type(ast_t), intent(in) :: ast
call output_ast_node_flattened (unit_no, ast%node)
end subroutine output_ast_flattened
recursive subroutine output_ast_node_flattened (unit_no, node)
integer, intent(in) :: unit_no
type(ast_node_t), pointer, intent(in) :: node
if (.not. associated (node)) then
write (unit_no, '(";")')
else
if (allocated (node%val)) then
write (unit_no, '(1A16, 2X, 1A)') &
& node_variety_string(node%node_variety), node%val
else
write (unit_no, '(1A)') &
& trim (node_variety_string(node%node_variety))
call output_ast_node_flattened (unit_no, node%left)
call output_ast_node_flattened (unit_no, node%right)
end if
end if
end subroutine output_ast_node_flattened
end module syntactic_analysis
program parse
use, intrinsic :: iso_fortran_env, only: input_unit
use, intrinsic :: iso_fortran_env, only: output_unit
use, intrinsic :: iso_fortran_env, only: error_unit
use, non_intrinsic :: syntactic_analysis
implicit none
integer, parameter :: inp_unit_no = 100
integer, parameter :: outp_unit_no = 101
integer :: arg_count
character(200) :: arg
integer :: inp
integer :: outp
arg_count = command_argument_count ()
if (3 <= arg_count) then
call print_usage
else
if (arg_count == 0) then
inp = input_unit
outp = output_unit
else if (arg_count == 1) then
call get_command_argument (1, arg)
inp = open_for_input (trim (arg))
outp = output_unit
else if (arg_count == 2) then
call get_command_argument (1, arg)
inp = open_for_input (trim (arg))
call get_command_argument (2, arg)
outp = open_for_output (trim (arg))
end if
block
type(ast_t) :: ast
ast = parse_token_stream (inp)
call output_ast_flattened (outp, ast)
end block
end if
contains
function open_for_input (filename) result (unit_no)
character(*), intent(in) :: filename
integer :: unit_no
integer :: stat
open (unit = inp_unit_no, file = filename, status = 'old', &
& action = 'read', access = 'stream', form = 'unformatted', &
& iostat = stat)
if (stat /= 0) then
write (error_unit, '("Error: failed to open ", 1A, " for input")') filename
stop 1
end if
unit_no = inp_unit_no
end function open_for_input
function open_for_output (filename) result (unit_no)
character(*), intent(in) :: filename
integer :: unit_no
integer :: stat
open (unit = outp_unit_no, file = filename, action = 'write', iostat = stat)
if (stat /= 0) then
write (error_unit, '("Error: failed to open ", 1A, " for output")') filename
stop 1
end if
unit_no = outp_unit_no
end function open_for_output
subroutine print_usage
character(200) :: progname
call get_command_argument (0, progname)
write (output_unit, '("Usage: ", 1A, " [INPUT_FILE [OUTPUT_FILE]]")') &
& trim (progname)
end subroutine print_usage
end program parse |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #Brat | Brat | width = 3
height = 3
rounds = 3
universe = [[0 1 0]
[0 1 0]
[0 1 0]]
next = height.of({width.of(0)})
cell = { x, y |
true? x < width && { x >= 0 && { y >= 0 && { y < height }}}
{
universe[y][x]
}
{ 0 }
}
neighbors = { x, y |
cell(x - 1, y - 1) +
cell(x, y - 1) +
cell(x + 1, y - 1) +
cell(x + 1, y) +
cell(x + 1, y + 1) +
cell(x, y + 1) +
cell(x - 1, y + 1) +
cell(x - 1, y)
}
set_next = { x, y, v |
next[y][x] = v
}
step = {
universe.each_with_index { row, y |
row.each_with_index { c, x |
n = neighbors(x, y)
when { n < 2 } { set_next x,y, 0 }
{ n > 3 } { set_next x, y, 0 }
{ n == 3 } { set_next x, y, 1 }
{ true } { set_next x, y, c }
}
}
u2 = universe
universe = next
next = u2
}
display = {
p universe.map({ r |
r.map({ n | true? n == 0, '-', "O" }).join
}).join("\n")
}
rounds.times {
display
p
step
} |
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #OxygenBasic | OxygenBasic |
'SHORT FORM
type point float x,y
'FULL FORM
type point
float x
float y
end type
point p
'WITH DEFAULT VALUES
type point
float x = 1.0
float y = 1.0
end type
point p = {} 'assigns the set of default values
print p.x " " p.y
|
http://rosettacode.org/wiki/Compound_data_type | Compound data type |
Data Structure
This illustrates a data structure, a means of storing data within a program.
You may see other such structures in the Data Structures category.
Task
Create a compound data type:
Point(x,y)
A compound data type is one that holds multiple independent values.
Related task
Enumeration
See also
Array
Associative array: Creation, Iteration
Collections
Compound data type
Doubly-linked list: Definition, Element definition, Element insertion, List Traversal, Element Removal
Linked list
Queue: Definition, Usage
Set
Singly-linked list: Element definition, Element insertion, List Traversal, Element Removal
Stack
| #Oz | Oz | P = point(x:1 y:2) |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #Ursa | Ursa | decl string a b
set a "hello"
set b a |
http://rosettacode.org/wiki/Copy_a_string | Copy a string | This task is about copying a string.
Task
Where it is relevant, distinguish between copying the contents of a string
versus making an additional reference to an existing string.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #V | V | "hello" dup |
http://rosettacode.org/wiki/Constrained_random_points_on_a_circle | Constrained random points on a circle | Task
Generate 100 <x,y> coordinate pairs such that x and y are integers sampled from the uniform distribution with the condition that
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
Then display/plot them. The outcome should be a "fuzzy" circle. The actual number of points plotted may be less than 100, given that some pairs may be generated more than once.
There are several possible approaches to accomplish this. Here are two possible algorithms.
1) Generate random pairs of integers and filter out those that don't satisfy this condition:
10
≤
x
2
+
y
2
≤
15
{\displaystyle 10\leq {\sqrt {x^{2}+y^{2}}}\leq 15}
.
2) Precalculate the set of all possible points (there are 404 of them) and select randomly from this set.
| #Rust | Rust | extern crate rand;
use rand::Rng;
const POINTS_N: usize = 100;
fn generate_point<R: Rng>(rng: &mut R) -> (i32, i32) {
loop {
let x = rng.gen_range(-15, 16); // exclusive
let y = rng.gen_range(-15, 16);
let r2 = x * x + y * y;
if r2 >= 100 && r2 <= 225 {
return (x, y);
}
}
}
fn filtering_method<R: Rng>(rng: &mut R) {
let mut rows = [[" "; 62]; 31];
// Generate points
for _ in 0..POINTS_N {
let (x, y) = generate_point(rng);
rows[(y + 15) as usize][(x + 15) as usize * 2] = "*";
}
// draw the points
for row in &rows {
println!("{}", row.concat());
}
}
fn precalculating_method<R: Rng>(rng: &mut R) {
// Generate all possible points
let mut possible_points = Vec::with_capacity(404);
for y in -15..=15 {
for x in -15..=15 {
let r2 = x * x + y * y;
if r2 >= 100 && r2 <= 225 {
possible_points.push((x, y));
}
}
}
// A truncated Fisher-Yates shuffle
let len = possible_points.len();
for i in (len - POINTS_N..len).rev() {
let j = rng.gen_range(0, i + 1);
possible_points.swap(i, j);
}
// turn the selected points into "pixels"
let mut rows = [[" "; 62]; 31];
for &(x, y) in &possible_points[len - POINTS_N..] {
rows[(y + 15) as usize][(x + 15) as usize * 2] = "*";
}
// draw the "pixels"
for row in &rows {
println!("{}", row.concat());
}
}
fn main() {
let mut rng = rand::weak_rng();
filtering_method(&mut rng);
precalculating_method(&mut rng);
} |
http://rosettacode.org/wiki/Conditional_structures | Conditional structures | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Task
List the conditional structures offered by a programming language. See Wikipedia: conditionals for descriptions.
Common conditional structures include if-then-else and switch.
Less common are arithmetic if, ternary operator and Hash-based conditionals.
Arithmetic if allows tight control over computed gotos, which optimizers have a hard time to figure out.
| #AppleScript | AppleScript | if myVar is "ok" then return true
set i to 0
if i is 0 then
return "zero"
else if i mod 2 is 0 then
return "even"
else
return "odd"
end if |
http://rosettacode.org/wiki/Commatizing_numbers | Commatizing numbers | Commatizing numbers (as used here, is a handy expedient made-up word) is the act of adding commas to a number (or string), or to the numeric part of a larger string.
Task
Write a function that takes a string as an argument with optional arguments or parameters (the format of parameters/options is left to the programmer) that in general, adds commas (or some
other characters, including blanks or tabs) to the first numeric part of a string (if it's suitable for commatizing as per the rules below), and returns that newly commatized string.
Some of the commatizing rules (specified below) are arbitrary, but they'll be a part of this task requirements, if only to make the results consistent amongst national preferences and other disciplines.
The number may be part of a larger (non-numeric) string such as:
«US$1744 millions» ──or──
±25000 motes.
The string may possibly not have a number suitable for commatizing, so it should be untouched and no error generated.
If any argument (option) is invalid, nothing is changed and no error need be generated (quiet execution, no fail execution). Error message generation is optional.
The exponent part of a number is never commatized. The following string isn't suitable for commatizing: 9.7e+12000
Leading zeroes are never commatized. The string 0000000005714.882 after commatization is: 0000000005,714.882
Any period (.) in a number is assumed to be a decimal point.
The original string is never changed except by the addition of commas [or whatever character(s) is/are used for insertion], if at all.
To wit, the following should be preserved:
leading signs (+, -) ── even superfluous signs
leading/trailing/embedded blanks, tabs, and other whitespace
the case (upper/lower) of the exponent indicator, e.g.: 4.8903d-002
Any exponent character(s) should be supported:
1247e12
57256.1D-4
4444^60
7500∙10**35
8500x10**35
9500↑35
+55000↑3
1000**100
2048²
409632
10000pow(pi)
Numbers may be terminated with any non-digit character, including subscripts and/or superscript: 41421356243 or 7320509076(base 24).
The character(s) to be used for the comma can be specified, and may contain blanks, tabs, and other whitespace characters, as well as multiple characters. The default is the comma (,) character.
The period length can be specified (sometimes referred to as "thousands" or "thousands separators"). The period length can be defined as the length (or number) of the decimal digits between commas. The default period length is 3.
E.G.: in this example, the period length is five: 56789,12340,14148
The location of where to start the scanning for the target field (the numeric part) should be able to be specified. The default is 1.
The character strings below may be placed in a file (and read) or stored as simple strings within the program.
Strings to be used as a minimum
The value of pi (expressed in base 10) should be separated with blanks every 5 places past the decimal point,
the Zimbabwe dollar amount should use a decimal point for the "comma" separator:
pi=3.14159265358979323846264338327950288419716939937510582097494459231
The author has two Z$100000000000000 Zimbabwe notes (100 trillion).
"-in Aus$+1411.8millions"
===US$0017440 millions=== (in 2000 dollars)
123.e8000 is pretty big.
The land area of the earth is 57268900(29% of the surface) square miles.
Ain't no numbers in this here words, nohow, no way, Jose.
James was never known as 0000000007
Arthur Eddington wrote: I believe there are 15747724136275002577605653961181555468044717914527116709366231425076185631031296 protons in the universe.
␢␢␢$-140000±100 millions.
6/9/1946 was a good year for some.
where the penultimate string has three leading blanks (real blanks are to be used).
Also see
The Wiki entry: (sir) Arthur Eddington's number of protons in the universe.
| #11l | 11l | F commatize(s, period = 3, sep = ‘,’)
V m = re:‘(\.[0-9]+|[1-9]([0-9]+)?(\.[0-9]+)?)’.search(s)
I !m
R s
V match = m.group()
V splits = match.split(‘.’)
V ip = splits[0]
I ip.len > period
V inserted = 0
L(i) ((ip.len - 1) % period + 1 .< ip.len).step(period)
ip = ip[0 .< i + inserted]‘’sep‘’ip[i + inserted ..]
inserted += sep.len
I splits.len > 1
V dp = splits[1]
I dp.len > period
L(i) ((dp.len - 1) I/ period * period .< period - 1).step(-period)
dp = dp[0 .< i]‘’sep‘’dp[i..]
ip ‘’= ‘.’dp
R s[0 .< m.start()]‘’ip‘’s[m.end()..]
V tests = [‘123456789.123456789’,
‘.123456789’,
‘57256.1D-4’,
‘pi=3.14159265358979323846264338327950288419716939937510582097494459231’,
‘The author has two Z$100000000000000 Zimbabwe notes (100 trillion).’,
‘-in Aus$+1411.8millions’,
‘===US$0017440 millions=== (in 2000 dollars)’,
‘123.e8000 is pretty big.’,
‘The land area of the earth is 57268900(29% of the surface) square miles.’,
‘Ain't no numbers in this here words, nohow, no way, Jose.’,
‘James was never known as 0000000007’,
‘Arthur Eddington wrote: I believe there are ’""
‘15747724136275002577605653961181555468044717914527116709366231425076185631031296’""
‘ protons in the universe.’,
‘ $-140000±100 millions.’,
‘6/9/1946 was a good year for some.’]
print(commatize(tests[0], period' 2, sep' ‘*’))
print(commatize(tests[1], period' 3, sep' ‘-’))
print(commatize(tests[2], period' 4, sep' ‘__’))
print(commatize(tests[3], period' 5, sep' ‘ ’))
print(commatize(tests[4], sep' ‘.’))
L(test) tests[5..]
print(commatize(test)) |
http://rosettacode.org/wiki/Compiler/virtual_machine_interpreter | Compiler/virtual machine interpreter | A virtual machine implements a computer in software.
Task[edit]
Write a virtual machine interpreter. This interpreter should be able to run virtual
assembly language programs created via the task. This is a
byte-coded, 32-bit word stack based virtual machine.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Input format:
Given the following program:
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
The output from the Code generator is a virtual assembly code program:
Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
The first line of the input specifies the datasize required and the number of constant
strings, in the order that they are reference via the code.
The data can be stored in a separate array, or the data can be stored at the beginning of
the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if
referenced at address 2.
If there are one or more constant strings, they come next. The code refers to these
strings by their index. The index starts at 0. So if there are 3 strings, and the code
wants to reference the 3rd string, 2 will be used.
Next comes the actual virtual assembly code. The first number is the code address of that
instruction. After that is the instruction mnemonic, followed by optional operands,
depending on the instruction.
Registers:
sp:
the stack pointer - points to the next top of stack. The stack is a 32-bit integer
array.
pc:
the program counter - points to the current instruction to be performed. The code is an
array of bytes.
Data:
data
string pool
Instructions:
Each instruction is one byte. The following instructions also have a 32-bit integer
operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
Print the word at stack top as a character.
prtc
Print the word at stack top as an integer.
prti
Stack top points to an index into the string pool. Print that entry.
prts
Unconditional stop.
halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
AST Interpreter task
| #Common_Lisp | Common Lisp | #!/bin/sh
#|-*- mode:lisp -*-|#
#|
exec ros -Q -- $0 "$@"
|#
(progn ;;init forms
(ros:ensure-asdf)
#+quicklisp(ql:quickload '() :silent t)
)
(defpackage :ros.script.vm.3858678051
(:use :cl))
(in-package :ros.script.vm.3858678051)
;;;
;;; The Rosetta Code Virtual Machine, in Common Lisp.
;;;
;;; Notes:
;;;
;;; * I have tried not to use foreign types or similar means of
;;; optimization.
;;;
;;; * Integers are stored in the VM's executable memory in
;;; big-endian order. Not because I prefer it, but because I do
;;; not want to get myself into a little-endian rut.
;;;
(require "cl-ppcre")
(require "trivia")
;;; Yes, I could compute how much memory is needed, or I could assume
;;; that the instructions are in address order. However, for *this*
;;; implementation I am going to use a large fixed-size memory and use
;;; the address fields of instructions to place the instructions.
(defconstant executable-memory-size 65536
"The size of memory for executable code, in 8-bit words.")
;;; Similarly, I am going to have fixed size data and stack memory.
(defconstant data-memory-size 2048
"The size of memory for stored data, in 32-bit words.")
(defconstant stack-memory-size 2048
"The size of memory for the stack, in 32-bit words.")
;;; And so I am going to have specialized types for the different
;;; kinds of memory the platform contains. Also for its "word" and
;;; register types.
(deftype word ()
'(unsigned-byte 32))
(deftype register ()
'(simple-array word (1)))
(deftype executable-memory ()
`(simple-array (unsigned-byte 8) ,(list executable-memory-size)))
(deftype data-memory ()
`(simple-array word ,(list data-memory-size)))
(deftype stack-memory ()
`(simple-array word ,(list stack-memory-size)))
(defconstant re-blank-line
(ppcre:create-scanner "^\\s*$"))
(defconstant re-parse-instr-1
(ppcre:create-scanner "^\\s*(\\d+)\\s*(.*\\S)"))
(defconstant re-parse-instr-2
(ppcre:create-scanner "(?i)^(\\S+)\\s*(.*)"))
(defconstant re-parse-instr-3
(ppcre:create-scanner "^[[(]?([0-9-]+)"))
(defconstant opcode-names
#("halt"
"add"
"sub"
"mul"
"div"
"mod"
"lt"
"gt"
"le"
"ge"
"eq"
"ne"
"and"
"or"
"neg"
"not"
"prtc"
"prti"
"prts"
"fetch"
"store"
"push"
"jmp"
"jz"))
(defun blank-line-p (s)
(not (not (ppcre:scan re-blank-line s))))
(defun opcode-from-name (s)
(position-if (lambda (name)
(string= s name))
opcode-names))
(defun create-executable-memory ()
(coerce (make-list executable-memory-size
:initial-element (opcode-from-name "halt"))
'executable-memory))
(defun create-data-memory ()
(coerce (make-list data-memory-size :initial-element 0)
'data-memory))
(defun create-stack-memory ()
(coerce (make-list stack-memory-size :initial-element 0)
'stack-memory))
(defun create-register ()
(coerce (make-list 1 :initial-element 0) 'register))
(defstruct machine
(sp (create-register) :type register) ; Stack pointer.
(ip (create-register) :type register) ; Instruction pointer (same
; thing as program counter).
(code (create-executable-memory) :type executable-memory)
(data (create-data-memory) :type data-memory)
(stack (create-stack-memory) :type stack-memory)
(strings nil)
output *standard-output*)
(defun insert-instruction (memory instr)
(declare (type executable-memory memory))
(trivia:match instr
((list address opcode arg)
(let ((instr-size (if arg 5 1)))
(unless (<= (+ address instr-size) executable-memory-size)
(warn "the VM's executable memory size is exceeded")
(uiop:quit 1))
(setf (elt memory address) opcode)
(when arg
;; Big-endian order.
(setf (elt memory (+ address 1)) (ldb (byte 8 24) arg))
(setf (elt memory (+ address 2)) (ldb (byte 8 16) arg))
(setf (elt memory (+ address 3)) (ldb (byte 8 8) arg))
(setf (elt memory (+ address 4)) (ldb (byte 8 0) arg)))))))
(defun load-executable-memory (memory instr-lst)
(declare (type executable-memory memory))
(loop for instr in instr-lst
do (insert-instruction memory instr)))
(defun parse-instruction (s)
(if (blank-line-p s)
nil
(let* ((strings (nth-value 1 (ppcre:scan-to-strings
re-parse-instr-1 s)))
(address (parse-integer (elt strings 0)))
(split (nth-value 1 (ppcre:scan-to-strings
re-parse-instr-2 (elt strings 1))))
(opcode-name (string-downcase (elt split 0)))
(opcode (opcode-from-name opcode-name))
(arguments (elt split 1))
(has-arg (trivia:match opcode-name
((or "fetch" "store" "push" "jmp" "jz") t)
(_ nil))))
(if has-arg
(let* ((argstr-lst
(nth-value 1 (ppcre:scan-to-strings
re-parse-instr-3 arguments)))
(argstr (elt argstr-lst 0)))
`(,address ,opcode ,(parse-integer argstr)))
`(,address ,opcode ())))))
(defun read-instructions (inpf)
(loop for line = (read-line inpf nil 'eoi)
until (eq line 'eoi)
for instr = (parse-instruction line)
when instr collect instr))
(defun read-datasize-and-strings-count (inpf)
(let ((line (read-line inpf)))
(multiple-value-bind (_whole-match strings)
;; This is a permissive implementation.
(ppcre:scan-to-strings
"(?i)^\\s*Datasize\\s*:\\s*(\\d+)\\s*Strings\\s*:\\s*(\\d+)"
line)
(declare (ignore _whole-match))
`(,(parse-integer (elt strings 0))
,(parse-integer (elt strings 1))))))
(defun parse-string-literal (s)
;; This is a permissive implementation, but only in that it skips
;; any leading space. It does not check carefully for outright
;; mistakes.
(let* ((s (ppcre:regex-replace "^\\s*" s ""))
(quote-mark (elt s 0))
(i 1)
(lst
(loop until (char= (elt s i) quote-mark)
collect (let ((c (elt s i)))
(if (char= c #\\)
(let ((c0 (trivia:match (elt s (1+ i))
(#\n #\newline)
(c1 c1))))
(setq i (+ i 2))
c0)
(progn
(setq i (1+ i))
c))))))
(coerce lst 'string)))
(defun read-string-literals (inpf strings-count)
(loop for i from 1 to strings-count
collect (parse-string-literal (read-line inpf))))
(defun open-inpf (inpf-filename)
(if (string= inpf-filename "-")
*standard-input*
(open inpf-filename :direction :input)))
(defun open-outf (outf-filename)
(if (string= outf-filename "-")
*standard-output*
(open outf-filename :direction :output
:if-exists :overwrite
:if-does-not-exist :create)))
(defun word-signbit-p (x)
"True if and only if the sign bit is set."
(declare (type word x))
(/= 0 (logand x #x80000000)))
(defun word-add (x y)
"Addition with overflow freely allowed."
(declare (type word x))
(declare (type word y))
(coerce (logand (+ x y) #xFFFFFFFF) 'word))
(defun word-neg (x)
"The two's complement."
(declare (type word x))
(word-add (logxor x #xFFFFFFFF) 1))
(defun word-sub (x y)
"Subtraction with overflow freely allowed."
(declare (type word x))
(declare (type word y))
(word-add x (word-neg y)))
(defun word-mul (x y)
"Signed multiplication."
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(let ((abs-x (if x<0 (word-neg x) x))
(abs-y (if y<0 (word-neg y) y)))
(let* ((abs-xy (the word
(logand (* abs-x abs-y) #xFFFFFFFF))))
(if x<0
(if y<0 abs-xy (word-neg abs-xy))
(if y<0 (word-neg abs-xy) abs-xy))))))
(defun word-div (x y)
"The quotient after signed integer division with truncation towards
zero."
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(let ((abs-x (if x<0 (word-neg x) x))
(abs-y (if y<0 (word-neg y) y)))
(let* ((abs-x/y (the word
(logand (floor abs-x abs-y) #xFFFFFFFF))))
(if x<0
(if y<0 abs-x/y (word-neg abs-x/y))
(if y<0 (word-neg abs-x/y) abs-x/y))))))
(defun word-mod (x y)
"The remainder after signed integer division with truncation towards
zero."
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(let ((abs-x (if x<0 (word-neg x) x))
(abs-y (if y<0 (word-neg y) y)))
(let* ((abs-x%y (the word
(logand (nth-value 1 (floor abs-x abs-y))
#xFFFFFFFF))))
(if x<0 (word-neg abs-x%y) abs-x%y)))))
(defun b2i (b)
(declare (type boolean b))
(if b 1 0))
(defun word-lt (x y)
"Signed comparison: is x less than y?"
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(b2i (if x<0
(if y<0 (< x y) t)
(if y<0 nil (< x y))))))
(defun word-le (x y)
"Signed comparison: is x less than or equal to y?"
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(b2i (if x<0
(if y<0 (<= x y) t)
(if y<0 nil (<= x y))))))
(defun word-gt (x y)
"Signed comparison: is x greater than y?"
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(b2i (if x<0
(if y<0 (> x y) nil)
(if y<0 t (> x y))))))
(defun word-ge (x y)
"Signed comparison: is x greater than or equal to y?"
(declare (type word x))
(declare (type word y))
(let ((x<0 (word-signbit-p x))
(y<0 (word-signbit-p y)))
(b2i (if x<0
(if y<0 (>= x y) nil)
(if y<0 t (>= x y))))))
(defun word-eq (x y)
"Is x equal to y?"
(declare (type word x))
(declare (type word y))
(b2i (= x y)))
(defun word-ne (x y)
"Is x not equal to y?"
(declare (type word x))
(declare (type word y))
(b2i (/= x y)))
(defun word-cmp (x)
"The logical complement."
(declare (type word x))
(b2i (= x 0)))
(defun word-and (x y)
"The logical conjunction."
(declare (type word x))
(declare (type word y))
(b2i (and (/= x 0) (/= y 0))))
(defun word-or (x y)
"The logical disjunction."
(declare (type word x))
(declare (type word y))
(b2i (or (/= x 0) (/= y 0))))
(defun unop (stack sp operation)
"Perform a unary operation on the stack."
(declare (type stack-memory stack))
(declare (type register sp))
(declare (type (function (word) word) operation))
(let ((i (elt sp 0)))
(unless (<= 1 i)
(warn "stack underflow")
(uiop:quit 1))
(let ((x (elt stack (1- i))))
(setf (elt stack (1- i)) (funcall operation x)))))
(defun binop (stack sp operation)
"Perform a binary operation on the stack."
(declare (type stack-memory stack))
(declare (type register sp))
(declare (type (function (word word) word) operation))
(let ((i (elt sp 0)))
(unless (<= 2 i)
(warn "stack underflow")
(uiop:quit 1))
(let ((x (elt stack (- i 2)))
(y (elt stack (1- i))))
(setf (elt stack (- i 2)) (funcall operation x y)))
(setf (elt sp 0) (1- i))))
(defun jri (code ip)
"Jump relative immediate."
(declare (type executable-memory code))
(declare (type register ip))
;; Big-endian order.
(let ((j (elt ip 0)))
(unless (<= (+ j 4) executable-memory-size)
(warn "address past end of executable memory")
(uiop:quit 1))
(let* ((offset (elt code (+ j 3)))
(offset (dpb (elt code (+ j 2)) (byte 8 8) offset))
(offset (dpb (elt code (+ j 1)) (byte 8 16) offset))
(offset (dpb (elt code j) (byte 8 24) offset)))
(setf (elt ip 0) (word-add j offset)))))
(defun jriz (stack sp code ip)
"Jump relative immediate, if zero."
(declare (type stack-memory stack))
(declare (type register sp))
(declare (type executable-memory code))
(declare (type register ip))
(let ((i (elt sp 0)))
(unless (<= 1 i)
(warn "stack underflow")
(uiop:quit 1))
(let ((x (elt stack (1- i))))
(setf (elt sp 0) (1- i))
(if (= x 0)
(jri code ip)
(setf (elt ip 0) (+ (elt ip 0) 4))))))
(defun get-immediate-value (code ip)
(declare (type executable-memory code))
(declare (type register ip))
;; Big-endian order.
(let ((j (elt ip 0)))
(unless (<= (+ j 4) executable-memory-size)
(warn "address past end of executable memory")
(uiop:quit 1))
(let* ((x (elt code (+ j 3)))
(x (dpb (elt code (+ j 2)) (byte 8 8) x))
(x (dpb (elt code (+ j 1)) (byte 8 16) x))
(x (dpb (elt code j) (byte 8 24) x)))
(setf (elt ip 0) (+ j 4))
x)))
(defun pushi (stack sp code ip)
"Push-immediate a value from executable memory onto the stack."
(declare (type stack-memory stack))
(declare (type register sp))
(declare (type executable-memory code))
(declare (type register ip))
(let ((i (elt sp 0)))
(unless (< i stack-memory-size)
(warn "stack overflow")
(uiop:quit 1))
(setf (elt stack i) (get-immediate-value code ip))
(setf (elt sp 0) (1+ i))))
(defun fetch (stack sp code ip data)
"Fetch data to the stack, using the storage location given in
executable memory."
(declare (type stack-memory stack))
(declare (type register sp))
(declare (type executable-memory code))
(declare (type register ip))
(declare (type data-memory data))
(let ((i (elt sp 0)))
(unless (< i stack-memory-size)
(warn "stack overflow")
(uiop:quit 1))
(let* ((k (get-immediate-value code ip))
(x (elt data k)))
(setf (elt stack i) x)
(setf (elt sp 0) (1+ i)))))
(defun pop-one (stack sp)
(let ((i (elt sp 0)))
(unless (<= 1 i)
(warn "stack underflow")
(uiop:quit 1))
(let* ((x (elt stack (1- i))))
(setf (elt sp 0) (1- i))
x)))
(defun store (stack sp code ip data)
"Store data from the stack, using the storage location given in
executable memory."
(declare (type stack-memory stack))
(declare (type register sp))
(declare (type executable-memory code))
(declare (type register ip))
(declare (type data-memory data))
(let ((i (elt sp 0)))
(unless (<= 1 i)
(warn "stack underflow")
(uiop:quit 1))
(let ((k (get-immediate-value code ip))
(x (pop-one stack sp)))
(setf (elt data k) x))))
(defun prti (stack sp outf)
"Print the top value of the stack, as a signed decimal value."
(declare (type stack-memory stack))
(declare (type register sp))
(let* ((n (pop-one stack sp))
(n<0 (word-signbit-p n)))
(if n<0
(format outf "-~D" (word-neg n))
(format outf "~D" n))))
(defun prtc (stack sp outf)
"Print the top value of the stack, as a character."
(declare (type stack-memory stack))
(declare (type register sp))
(let* ((c (pop-one stack sp)))
(format outf "~C" (code-char c))))
(defun prts (stack sp strings outf)
"Print the string specified by the top of the stack."
(declare (type stack-memory stack))
(declare (type register sp))
(let* ((k (pop-one stack sp))
(s (elt strings k)))
(format outf "~A" s)))
(defmacro defun-machine-binop (op)
(let ((machine-op (read-from-string
(concatenate 'string "machine-" (string op))))
(word-op (read-from-string
(concatenate 'string "word-" (string op)))))
`(defun ,machine-op (mach)
(declare (type machine mach))
(binop (machine-stack mach)
(machine-sp mach)
#',word-op))))
(defmacro defun-machine-unop (op)
(let ((machine-op (read-from-string
(concatenate 'string "machine-" (string op))))
(word-op (read-from-string
(concatenate 'string "word-" (string op)))))
`(defun ,machine-op (mach)
(declare (type machine mach))
(unop (machine-stack mach)
(machine-sp mach)
#',word-op))))
(defun-machine-binop "add")
(defun-machine-binop "sub")
(defun-machine-binop "mul")
(defun-machine-binop "div")
(defun-machine-binop "mod")
(defun-machine-binop "lt")
(defun-machine-binop "gt")
(defun-machine-binop "le")
(defun-machine-binop "ge")
(defun-machine-binop "eq")
(defun-machine-binop "ne")
(defun-machine-binop "and")
(defun-machine-binop "or")
(defun-machine-unop "neg")
(defun machine-not (mach)
(declare (type machine mach))
(unop (machine-stack mach)
(machine-sp mach)
#'word-cmp))
(defun machine-prtc (mach)
(declare (type machine mach))
(prtc (machine-stack mach)
(machine-sp mach)
(machine-output mach)))
(defun machine-prti (mach)
(declare (type machine mach))
(prti (machine-stack mach)
(machine-sp mach)
(machine-output mach)))
(defun machine-prts (mach)
(declare (type machine mach))
(prts (machine-stack mach)
(machine-sp mach)
(machine-strings mach)
(machine-output mach)))
(defun machine-fetch (mach)
(declare (type machine mach))
(fetch (machine-stack mach)
(machine-sp mach)
(machine-code mach)
(machine-ip mach)
(machine-data mach)))
(defun machine-store (mach)
(declare (type machine mach))
(store (machine-stack mach)
(machine-sp mach)
(machine-code mach)
(machine-ip mach)
(machine-data mach)))
(defun machine-push (mach)
(declare (type machine mach))
(pushi (machine-stack mach)
(machine-sp mach)
(machine-code mach)
(machine-ip mach)))
(defun machine-jmp (mach)
(declare (type machine mach))
(jri (machine-code mach)
(machine-ip mach)))
(defun machine-jz (mach)
(declare (type machine mach))
(jriz (machine-stack mach)
(machine-sp mach)
(machine-code mach)
(machine-ip mach)))
(defun get-opcode (mach)
(declare (type machine mach))
(let ((code (machine-code mach))
(ip (machine-ip mach)))
(let ((j (elt ip 0)))
(unless (< j executable-memory-size)
(warn "address past end of executable memory")
(uiop:quit 1))
(let ((opcode (elt code j)))
(setf (elt ip 0) (1+ j))
opcode))))
(defun run-instruction (mach opcode)
(declare (type machine mach))
(declare (type fixnum opcode))
(let ((op-mod-4 (logand opcode #x3))
(op-div-4 (ash opcode -2)))
(trivia:match op-div-4
(0 (trivia:match op-mod-4
(1 (machine-add mach))
(2 (machine-sub mach))
(3 (machine-mul mach))))
(1 (trivia:match op-mod-4
(0 (machine-div mach))
(1 (machine-mod mach))
(2 (machine-lt mach))
(3 (machine-gt mach))))
(2 (trivia:match op-mod-4
(0 (machine-le mach))
(1 (machine-ge mach))
(2 (machine-eq mach))
(3 (machine-ne mach))))
(3 (trivia:match op-mod-4
(0 (machine-and mach))
(1 (machine-or mach))
(2 (machine-neg mach))
(3 (machine-not mach))))
(4 (trivia:match op-mod-4
(0 (machine-prtc mach))
(1 (machine-prti mach))
(2 (machine-prts mach))
(3 (machine-fetch mach))))
(5 (trivia:match op-mod-4
(0 (machine-store mach))
(1 (machine-push mach))
(2 (machine-jmp mach))
(3 (machine-jz mach)))))))
(defun run-vm (mach)
(declare (type machine mach))
(let ((opcode-for-halt (the fixnum (opcode-from-name "halt")))
(opcode-for-add (the fixnum (opcode-from-name "add")))
(opcode-for-jz (the fixnum (opcode-from-name "jz"))))
(loop for opcode = (the fixnum (get-opcode mach))
until (= opcode opcode-for-halt)
do (progn (when (or (< opcode opcode-for-add)
(< opcode-for-jz opcode))
(warn "unsupported opcode")
(uiop:quit 1))
(run-instruction mach opcode)))))
(defun usage-error ()
(princ "Usage: vm [INPUTFILE [OUTPUTFILE]]" *standard-output*)
(terpri *standard-output*)
(princ "If either INPUTFILE or OUTPUTFILE is \"-\", the respective"
*standard-output*)
(princ " standard I/O is used." *standard-output*)
(terpri *standard-output*)
(uiop:quit 1))
(defun get-filenames (argv)
(trivia:match argv
((list) '("-" "-"))
((list inpf-filename) `(,inpf-filename "-"))
((list inpf-filename outf-filename) `(,inpf-filename
,outf-filename))
(_ (usage-error))))
(defun main (&rest argv)
(let* ((filenames (get-filenames argv))
(inpf-filename (car filenames))
(inpf (open-inpf inpf-filename))
(outf-filename (cadr filenames))
(outf (open-outf outf-filename))
(sizes (read-datasize-and-strings-count inpf))
(datasize (car sizes))
(strings-count (cadr sizes))
(strings (read-string-literals inpf strings-count))
(instructions (read-instructions inpf))
;; We shall remain noncommittal about how strings are stored
;; on the hypothetical machine.
(strings (coerce strings 'simple-vector))
(mach (make-machine :strings strings
:output outf)))
(unless (<= datasize data-memory-size)
(warn "the VM's data memory size is exceeded")
(uiop:quit 1))
(load-executable-memory (machine-code mach) instructions)
(run-vm mach)
(unless (string= inpf-filename "-")
(close inpf))
(unless (string= outf-filename "-")
(close outf))
(uiop:quit 0)))
;;; vim: set ft=lisp lisp: |
http://rosettacode.org/wiki/Compiler/code_generator | Compiler/code generator | A code generator translates the output of the syntax analyzer and/or semantic analyzer
into lower level code, either assembly, object, or virtual.
Task[edit]
Take the output of the Syntax analyzer task - which is a flattened Abstract Syntax Tree (AST) - and convert it to virtual machine code, that can be run by the
Virtual machine interpreter. The output is in text format, and represents virtual assembly code.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
while.ast can be input into the code generator.
The following table shows the input to lex, lex output, the AST produced by the parser, and the generated virtual assembly code.
Run as: lex < while.t | parse | gen
Input to lex
Output from lex, input to parse
Output from parse
Output from gen, input to VM
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
Input format
As shown in the table, above, the output from the syntax analyzer is a flattened AST.
In the AST, Identifier, Integer, and String, are terminal nodes, e.g, they do not have child nodes.
Loading this data into an internal parse tree should be as simple as:
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";"
return None
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Output format - refer to the table above
The first line is the header: Size of data, and number of constant strings.
size of data is the number of 32-bit unique variables used. In this example, one variable, count
number of constant strings is just that - how many there are
After that, the constant strings
Finally, the assembly code
Registers
sp: the stack pointer - points to the next top of stack. The stack is a 32-bit integer array.
pc: the program counter - points to the current instruction to be performed. The code is an array of bytes.
Data
32-bit integers and strings
Instructions
Each instruction is one byte. The following instructions also have a 32-bit integer operand:
fetch [index]
where index is an index into the data array.
store [index]
where index is an index into the data array.
push n
where value is a 32-bit integer that will be pushed onto the stack.
jmp (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
jz (n) addr
where (n) is a 32-bit integer specifying the distance between the current location and the
desired location. addr is an unsigned value of the actual code address.
The following instructions do not have an operand. They perform their operation directly
against the stack:
For the following instructions, the operation is performed against the top two entries in
the stack:
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
For the following instructions, the operation is performed against the top entry in the
stack:
neg
not
prtc
Print the word at stack top as a character.
prti
Print the word at stack top as an integer.
prts
Stack top points to an index into the string pool. Print that entry.
halt
Unconditional stop.
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Virtual Machine Interpreter task
AST Interpreter task
| #ALGOL_W | ALGOL W | begin % code generator %
% parse tree nodes %
record node( integer type
; reference(node) left, right
; integer iValue % nString/nIndentifier number or nInteger value %
);
integer nIdentifier, nString, nInteger, nSequence, nIf, nPrtc, nPrts
, nPrti, nWhile, nAssign, nNegate, nNot, nMultiply
, nDivide, nMod, nAdd, nSubtract, nLess, nLessEqual
, nGreater, nGreaterEqual, nEqual, nNotEqual, nAnd, nOr
;
string(14) array ndName ( 1 :: 25 );
integer array nOp ( 1 :: 25 );
integer MAX_NODE_TYPE;
% string literals and identifiers - uses a linked list - a hash table might be better... %
string(1) array text ( 0 :: 4095 );
integer textNext, TEXT_MAX;
record textElement ( integer start, length; reference(textElement) next );
reference(textElement) idList, stList;
% op codes %
integer oFetch, oStore, oPush
, oAdd, oSub, oMul, oDiv, oMod, oLt, oGt, oLe, oGe, oEq, oNe
, oAnd, oOr, oNeg, oNot, oJmp, oJz, oPrtc, oPrts, oPrti, oHalt
;
string(6) array opName ( 1 :: 24 );
% code - although this is intended to be byte code, as we are going to output %
% an assembler source, we use integers for convenience %
% labelLocations are: - ( referencing location + 1 ) if they have been referenced but not defined yet, %
% zero if they are unreferenced and undefined, %
% ( referencing location + 1 ) if they are defined %
integer array byteCode ( 0 :: 4095 );
integer array labelLocation( 1 :: 4096 );
integer nextLocation, MAX_LOCATION, nextLabelNumber, MAX_LABEL_NUMBER;
% returns a new node with left and right branches %
reference(node) procedure opNode ( integer value opType; reference(node) value opLeft, opRight ) ; begin
node( opType, opLeft, opRight, 0 )
end opNode ;
% returns a new operand node %
reference(node) procedure operandNode ( integer value opType, opValue ) ; begin
node( opType, null, null, opValue )
end operandNode ;
% reports an error and stops %
procedure genError( string(80) value message ); begin
integer errorPos;
write( s_w := 0, "**** Code generation error: " );
errorPos := 0;
while errorPos < 80 and message( errorPos // 1 ) not = "." do begin
writeon( s_w := 0, message( errorPos // 1 ) );
errorPos := errorPos + 1
end while_not_at_end_of_message ;
writeon( s_w := 0, "." );
assert( false )
end genError ;
% reads a node from standard input %
reference(node) procedure readNode ; begin
reference(node) resultNode;
% parses a string from line and stores it in a string in the text array %
% - if it is not already present in the specified textElement list. %
% returns the position of the string in the text array %
integer procedure readString ( reference(textElement) value result txList; string(1) value terminator ) ; begin
string(256) str;
integer sLen, sPos, ePos;
logical found;
reference(textElement) txPos, txLastPos;
% get the text of the string %
str := " ";
sLen := 0;
str( sLen // 1 ) := line( lPos // 1 );
sLen := sLen + 1;
lPos := lPos + 1;
while lPos <= 255 and line( lPos // 1 ) not = terminator do begin
str( sLen // 1 ) := line( lPos // 1 );
sLen := sLen + 1;
lPos := lPos + 1
end while_more_string ;
if lPos > 255 then genError( "Unterminated String in node file." );
% attempt to find the text in the list of strings/identifiers %
txLastPos := txPos := txList;
found := false;
ePos := 0;
while not found and txPos not = null do begin
ePos := ePos + 1;
found := ( length(txPos) = sLen );
sPos := 0;
while found and sPos < sLen do begin
found := str( sPos // 1 ) = text( start(txPos) + sPos );
sPos := sPos + 1
end while_not_found ;
txLastPos := txPos;
if not found then txPos := next(txPos)
end while_string_not_found ;
if not found then begin
% the string/identifier is not in the list - add it %
ePos := ePos + 1;
if txList = null then txList := textElement( textNext, sLen, null )
else next(txLastPos) := textElement( textNext, sLen, null );
if textNext + sLen > TEXT_MAX then genError( "Text space exhausted." )
else begin
for cPos := 0 until sLen - 1 do begin
text( textNext ) := str( cPos // 1 );
textNext := textNext + 1
end for_cPos
end
end if_not_found ;
ePos
end readString ;
% gets an integer from the line - no checks for valid digits %
integer procedure readInteger ; begin
integer n;
n := 0;
while line( lPos // 1 ) not = " " do begin
n := ( n * 10 ) + ( decode( line( lPos // 1 ) ) - decode( "0" ) );
lPos := lPos + 1
end while_not_end_of_integer ;
n
end readInteger ;
string(256) line;
string(16) name;
integer lPos, tPos, ndType;
tPos := lPos := 0;
readcard( line );
% get the node type name %
while line( lPos // 1 ) = " " do lPos := lPos + 1;
name := "";
while lPos < 256 and line( lPos // 1 ) not = " " do begin
name( tPos // 1 ) := line( lPos // 1 );
lPos := lPos + 1;
tPos := tPos + 1
end while_more_name ;
% determine the node type %
ndType := 1;
resultNode := null;
if name not = ";" then begin
% not a null node %
while ndType <= MAX_NODE_TYPE and name not = ndName( ndType ) do ndType := ndType + 1;
if ndType > MAX_NODE_TYPE then genError( "Malformed node." );
% handle the additional parameter for identifier/string/integer, or sub-nodes for operator nodes %
if ndType = nInteger or ndType = nIdentifier or ndType = nString then begin
while line( lPos // 1 ) = " " do lPos := lPos + 1;
if ndType = nInteger then resultNode := operandNode( ndType, readInteger )
else if ndType = nIdentifier then resultNode := operandNode( ndType, readString( idList, " " ) )
else % ndType = nString % resultNode := operandNode( ndType, readString( stList, """" ) )
end
else begin
% operator node %
reference(node) leftNode;
leftNode := readNode;
resultNode := opNode( ndType, leftNode, readNode )
end
end if_non_null_node ;
resultNode
end readNode ;
% returns the next free label number %
integer procedure newLabel ; begin
nextLabelNumber := nextLabelNumber + 1;
if nextLabelNumber > MAX_LABEL_NUMBER then genError( "Program too complex" );
nextLabelNumber
end newLabel ;
% defines the specified label to be at the next location %
procedure defineLabel ( integer value labelNumber ) ; begin
if labelLocation( labelNumber ) > 0 then genError( "Label already defined" )
else begin
% this is the first definition of the label, define it and if it has already been referenced, fill in the reference %
integer currValue;
currValue := labelLocation( labelNumber );
labelLocation( labelNumber ) := nextLocation + 1; % we store pc + 1 to ensure the label location is positive %
if currValue < 0 then % already referenced % byteCode( - ( currValue + 1 ) ) := labelLocation( labelNumber )
end
end defineLabel ;
% stores a byte in the code %
procedure genByte ( integer value byteValue ) ; begin
if nextLocation > MAX_LOCATION then genError( "Program too large" );
byteCode( nextLocation ) := byteValue;
nextLocation := nextLocation + 1
end genByte ;
% stores an integer in the code %
procedure genInteger ( integer value integerValue ) ; begin
% we are storing the bytes of the code in separate integers for convenience %
genByte( integerValue ); genByte( 0 ); genByte( 0 ); genByte( 0 )
end genInteger ;
% generates an operation acting on an address %
procedure genDataOp ( integer value opCode, address ) ; begin
genByte( opCode );
genInteger( address )
end genDataOp ;
% generates a nullary operation %
procedure genOp0 ( integer value opCode ) ; begin
genByte( opCode )
end genOp0 ;
% generates a unary/binary operation %
procedure genOp ( reference(node) value n ) ; begin
gen( left(n) );
gen( right(n) ); % right will be null for a unary op so no code will be generated %
genByte( nOp( type(n) ) )
end genOp ;
% generates a jump operation %
procedure genJump ( integer value opCode, labelNumber ) ; begin
genByte( opCode );
% if the label is not defined yet - set it's location to the negative of the referencing location %
% so it can be resolved later %
if labelLocation( labelNumber ) = 0 then labelLocation( labelNumber ) := - ( nextLocation + 1 );
genInteger( labelLocation( labelNumber ) )
end genJump ;
% generates code for the node n %
procedure gen ( reference(node) value n ) ; begin
if n = null then % empty node % begin end
else if type(n) = nIdentifier then genDataOp( oFetch, iValue(n) )
else if type(n) = nString then genDataOp( oPush, iValue(n) - 1 )
else if type(n) = nInteger then genDataOp( oPush, iValue(n) )
else if type(n) = nSequence then begin
gen( left(n) );
gen( right(n) )
end
else if type(n) = nIf then % if-else % begin
integer elseLabel;
elseLabel := newLabel;
gen( left(n) );
genJump( oJz, elseLabel );
gen( left( right(n) ) );
if right(right(n)) = null then % no "else" part % defineLabel( elseLabel )
else begin
% have an "else" part %
integer endIfLabel;
endIfLabel := newLabel;
genJump( oJmp, endIfLabel );
defineLabel( elseLabel );
gen( right(right(n)) );
defineLabel( endIfLabel )
end
end
else if type(n) = nWhile then % while-loop % begin
integer loopLabel, exitLabel;
loopLabel := newLabel;
exitLabel := newLabel;
defineLabel( loopLabel );
gen( left(n) );
genJump( oJz, exitLabel );
gen( right(n) );
genJump( oJmp, loopLabel );
defineLabel( exitLabel )
end
else if type(n) = nAssign then % assignment % begin
gen( right( n ) );
genDataOp( oStore, iValue(left(n)) )
end
else genOp( n )
end gen ;
% outputs the generated code to standard output %
procedure emitCode ; begin
% counts the number of elements in a text element list %
integer procedure countElements ( reference(textElement) value txHead ) ; begin
integer count;
reference(textElement) txPos;
count := 0;
txPos := txHead;
while txPos not = null do begin
count := count + 1;
txPos := next(txPos)
end while_txPos_not_null ;
count
end countElements ;
integer pc, op;
reference(textElement) txPos;
% code header %
write( i_w := 1, s_w := 0
, "Datasize: ", countElements( idList )
, " Strings: ", countElements( stList )
);
% output the string literals %
txPos := stList;
while txPos not = null do begin
integer cPos;
write( """" );
cPos := 1; % start from 1 to skip over the leading " %
while cPos < length(txPos) do begin
writeon( s_w := 0, text( start(txPos) + cPos ) );
cPos := cPos + 1
end while_not_end_of_string ;
writeon( s_w := 0, """" );
txPos := next(txPos)
end while_not_at_end_of_literals ;
% code body %
pc := 0;
while pc < nextLocation do begin
op := byteCode( pc );
write( i_w := 4, s_w := 0, pc, " ", opName( op ) );
pc := pc + 1;
if op = oFetch or op = oStore then begin
% data load/store - add the address in square brackets %
writeon( i_w := 1, s_w := 0, "[", byteCode( pc ) - 1, "]" );
pc := pc + 4
end
else if op = oPush then begin
% push constant - add the constant %
writeon( i_w := 1, s_w := 0, byteCode( pc ) );
pc := pc + 4
end
else if op = oJmp or op = oJz then begin
% jump - show the relative address in brackets and the absolute address %
writeon( i_w := 1, s_w := 0, "(", ( byteCode( pc ) - 1 ) - pc, ") ", byteCode( pc ) - 1 );
pc := pc + 4
end
end while_pc_lt_nextLocation
end emitCode ;
oFetch := 1; opName( oFetch ) := "fetch"; oStore := 2; opName( oStore ) := "store"; oPush := 3; opName( oPush ) := "push";
oAdd := 4; opName( oAdd ) := "add"; oSub := 5; opName( oSub ) := "sub"; oMul := 6; opName( oMul ) := "mul";
oDiv := 7; opName( oDiv ) := "div"; oMod := 8; opName( oMod ) := "mod"; oLt := 9; opName( oLt ) := "lt";
oGt := 10; opName( oGt ) := "gt"; oLe := 11; opName( oLe ) := "le"; oGe := 12; opName( oGe ) := "ge";
oEq := 13; opName( oEq ) := "eq"; oNe := 14; opName( oNe ) := "ne"; oAnd := 15; opName( oAnd ) := "and";
oOr := 16; opName( oOr ) := "or"; oNeg := 17; opName( oNeg ) := "neg"; oNot := 18; opName( oNot ) := "not";
oJmp := 19; opName( oJmp ) := "jmp"; oJz := 20; opName( oJz ) := "jz"; oPrtc := 21; opName( oPrtc ) := "prtc";
oPrts := 22; opName( oPrts ) := "prts"; oPrti := 23; opName( oPrti ) := "prti"; oHalt := 24; opName( oHalt ) := "halt";
nIdentifier := 1; ndName( nIdentifier ) := "Identifier"; nString := 2; ndName( nString ) := "String";
nInteger := 3; ndName( nInteger ) := "Integer"; nSequence := 4; ndName( nSequence ) := "Sequence";
nIf := 5; ndName( nIf ) := "If"; nPrtc := 6; ndName( nPrtc ) := "Prtc";
nPrts := 7; ndName( nPrts ) := "Prts"; nPrti := 8; ndName( nPrti ) := "Prti";
nWhile := 9; ndName( nWhile ) := "While"; nAssign := 10; ndName( nAssign ) := "Assign";
nNegate := 11; ndName( nNegate ) := "Negate"; nNot := 12; ndName( nNot ) := "Not";
nMultiply := 13; ndName( nMultiply ) := "Multiply"; nDivide := 14; ndName( nDivide ) := "Divide";
nMod := 15; ndName( nMod ) := "Mod"; nAdd := 16; ndName( nAdd ) := "Add";
nSubtract := 17; ndName( nSubtract ) := "Subtract"; nLess := 18; ndName( nLess ) := "Less";
nLessEqual := 19; ndName( nLessEqual ) := "LessEqual"; nGreater := 20; ndName( nGreater ) := "Greater";
nGreaterEqual := 21; ndName( nGreaterEqual ) := "GreaterEqual"; nEqual := 22; ndName( nEqual ) := "Equal";
nNotEqual := 23; ndName( nNotEqual ) := "NotEqual"; nAnd := 24; ndName( nAnd ) := "And";
nOr := 25; ndName( nOr ) := "Or";
MAX_NODE_TYPE := 25; TEXT_MAX := 4095; textNext := 0;
stList := idList := null;
for nPos := 1 until MAX_NODE_TYPE do nOp( nPos ) := -1;
nOp( nPrtc ) := oPrtc; nOp( nPrts ) := oPrts; nOp( nPrti ) := oPrti; nOp( nNegate ) := oNeg; nOp( nNot ) := oNot;
nOp( nMultiply ) := oMul; nOp( nDivide ) := oDiv; nOp( nMod ) := oMod; nOp( nAdd ) := oAdd; nOp( nSubtract ) := oSub;
nOp( nLess ) := oLt; nOp( nLessEqual ) := oLe; nOp( nGreater ) := oGt; nOp( nGreaterEqual ) := oGe; nOp( nEqual ) := oEq;
nOp( nNotEqual ) := oNe; nOp( nAnd ) := oAnd; nOp( nOr ) := oOr;
nextLocation := 0; MAX_LOCATION := 4095;
for pc := 0 until MAX_LOCATION do byteCode( pc ) := 0;
nextLabelNumber := 0; MAX_LABEL_NUMBER := 4096;
for lPos := 1 until MAX_LABEL_NUMBER do labelLocation( lPos ) := 0;
% parse the output from the syntax analyser and generate code from the parse tree %
gen( readNode );
genOp0( oHalt );
emitCode
end. |
http://rosettacode.org/wiki/Compare_sorting_algorithms%27_performance | Compare sorting algorithms' performance |
Sorting Algorithm
This is a sorting algorithm. It may be applied to a set of data in order to sort it.
For comparing various sorts, see compare sorts.
For other sorting algorithms, see sorting algorithms, or:
O(n logn) sorts
Heap sort |
Merge sort |
Patience sort |
Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort
Measure a relative performance of sorting algorithms implementations.
Plot execution time vs. input sequence length dependencies for various implementation of sorting algorithm and different input sequence types (example figures).
Consider three type of input sequences:
ones: sequence of all 1's. Example: {1, 1, 1, 1, 1}
range: ascending sequence, i.e. already sorted. Example: {1, 2, 3, 10, 15}
shuffled range: sequence with elements randomly distributed. Example: {5, 3, 9, 6, 8}
Consider at least two different sorting functions (different algorithms or/and different implementation of the same algorithm).
For example, consider Bubble Sort, Insertion sort, Quicksort or/and implementations of Quicksort with different pivot selection mechanisms. Where possible, use existing implementations.
Preliminary subtask:
Bubble Sort, Insertion sort, Quicksort, Radix sort, Shell sort
Query Performance
Write float arrays to a text file
Plot x, y arrays
Polynomial Fitting
General steps:
Define sorting routines to be considered.
Define appropriate sequence generators and write timings.
Plot timings.
What conclusions about relative performance of the sorting routines could be made based on the plots?
| #BBC_BASIC | BBC BASIC | HIMEM = PAGE + 2000000
INSTALL @lib$+"SORTLIB"
INSTALL @lib$+"TIMERLIB"
Sort% = FN_sortinit(0,0)
Timer% = FN_ontimer(1000, PROCtimer, 1)
PRINT "Array size:", 1000, 10000, 100000
@% = &2020A
FOR patt% = 1 TO 4
CASE patt% OF
WHEN 1: PRINT '"Data set to all ones:"
WHEN 2: PRINT '"Data ascending sequence:"
WHEN 3: PRINT '"Data randomly shuffled:"
WHEN 4: PRINT '"Data descending sequence:"
ENDCASE
FOR type% = 1 TO 6
CASE type% OF
WHEN 1: PRINT "Internal (lib)";
WHEN 2: PRINT "Quicksort ";
WHEN 3: PRINT "Radix sort ";
WHEN 4: PRINT "Shellsort ";
WHEN 5: PRINT "Bubblesort ";
WHEN 6: PRINT "Insertion sort";
ENDCASE
FOR power% = 3 TO 5
PROCsorttest(patt%, type%, 10^power%)
NEXT
PRINT
NEXT type%
NEXT patt%
END
DEF PROCsorttest(patt%, type%, size%)
LOCAL a%(), C%, I%
DIM a%(size%-1)
CASE patt% OF
WHEN 1: a%() = 1 : a%() = 1
WHEN 2: FOR I% = 0 TO size%-1 : a%(I%) = I% : NEXT
WHEN 3: FOR I% = 0 TO size%-1 : a%(I%) = I% : NEXT
C% = RND(-123456) : REM Seed
FOR I% = size% TO 2 STEP -1 : SWAP a%(I%-1),a%(RND(I%)-1) : NEXT
WHEN 4: FOR I% = 0 TO size%-1 : a%(I%) = size%-1-I% : NEXT
ENDCASE
Start% = TIME
ON ERROR LOCAL PRINT , " >100.00" ; : ENDPROC
CASE type% OF
WHEN 1: C% = size% : CALL Sort%, a%(0)
WHEN 2: PROCquicksort(a%(), 0, size%)
WHEN 3: PROCradixsort(a%(), size%, 10)
WHEN 4: PROCshellsort(a%(), size%)
WHEN 5: PROCbubblesort(a%(), size%)
WHEN 6: PROCinsertionsort(a%(), size%)
ENDCASE
PRINT , (TIME - Start%)/100;
FOR I% = 0 TO size%-2
IF a%(I%) > a%(I%+1) ERROR 100, "Sort failed!"
NEXT
ENDPROC
DEF PROCtimer
Start% += 0
IF (TIME - Start%) > 10000 ERROR 111, ""
ENDPROC
DEF PROCbubblesort(a%(), n%)
LOCAL i%, l%
REPEAT
l% = 0
FOR i% = 1 TO n%-1
IF a%(i%-1) > a%(i%) THEN
SWAP a%(i%-1),a%(i%)
l% = i%
ENDIF
NEXT
n% = l%
UNTIL l% = 0
ENDPROC
DEF PROCinsertionsort(a%(), n%)
LOCAL i%, j%, t%
FOR i% = 1 TO n%-1
t% = a%(i%)
j% = i%
WHILE j%>0 AND t%<a%(ABS(j%-1))
a%(j%) = a%(j%-1)
j% -= 1
ENDWHILE
a%(j%) = t%
NEXT
ENDPROC
DEF PROCquicksort(a%(), s%, n%)
LOCAL l%, p%, r%, t%
IF n% < 2 THEN ENDPROC
t% = s% + n% - 1
l% = s%
r% = t%
p% = a%((l% + r%) DIV 2)
REPEAT
WHILE a%(l%) < p% l% += 1 : ENDWHILE
WHILE a%(r%) > p% r% -= 1 : ENDWHILE
IF l% <= r% THEN
SWAP a%(l%), a%(r%)
l% += 1
r% -= 1
ENDIF
UNTIL l% > r%
IF s% < r% PROCquicksort(a%(), s%, r% - s% + 1)
IF l% < t% PROCquicksort(a%(), l%, t% - l% + 1 )
ENDPROC
DEF PROCshellsort(a%(), n%)
LOCAL h%, i%, j%, k%
h% = n%
WHILE h%
IF h% = 2 h% = 1 ELSE h% DIV= 2.2
FOR i% = h% TO n% - 1
k% = a%(i%)
j% = i%
WHILE j% >= h% AND k% < a%(ABS(j% - h%))
a%(j%) = a%(j% - h%)
j% -= h%
ENDWHILE
a%(j%) = k%
NEXT
ENDWHILE
ENDPROC
DEF PROCradixsort(a%(), n%, r%)
LOCAL d%, e%, i%, l%, m%, b%(), bucket%()
DIM b%(DIM(a%(),1)), bucket%(r%-1)
FOR i% = 0 TO n%-1
IF a%(i%) < l% l% = a%(i%)
IF a%(i%) > m% m% = a%(i%)
NEXT
a%() -= l%
m% -= l%
e% = 1
WHILE m% DIV e%
bucket%() = 0
FOR i% = 0 TO n%-1
bucket%(a%(i%) DIV e% MOD r%) += 1
NEXT
FOR i% = 1 TO r%-1
bucket%(i%) += bucket%(i% - 1)
NEXT
FOR i% = n%-1 TO 0 STEP -1
d% = a%(i%) DIV e% MOD r%
bucket%(d%) -= 1
b%(bucket%(d%)) = a%(i%)
NEXT
a%() = b%()
e% *= r%
ENDWHILE
a%() += l%
ENDPROC |
http://rosettacode.org/wiki/Compare_sorting_algorithms%27_performance | Compare sorting algorithms' performance |
Sorting Algorithm
This is a sorting algorithm. It may be applied to a set of data in order to sort it.
For comparing various sorts, see compare sorts.
For other sorting algorithms, see sorting algorithms, or:
O(n logn) sorts
Heap sort |
Merge sort |
Patience sort |
Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort
Measure a relative performance of sorting algorithms implementations.
Plot execution time vs. input sequence length dependencies for various implementation of sorting algorithm and different input sequence types (example figures).
Consider three type of input sequences:
ones: sequence of all 1's. Example: {1, 1, 1, 1, 1}
range: ascending sequence, i.e. already sorted. Example: {1, 2, 3, 10, 15}
shuffled range: sequence with elements randomly distributed. Example: {5, 3, 9, 6, 8}
Consider at least two different sorting functions (different algorithms or/and different implementation of the same algorithm).
For example, consider Bubble Sort, Insertion sort, Quicksort or/and implementations of Quicksort with different pivot selection mechanisms. Where possible, use existing implementations.
Preliminary subtask:
Bubble Sort, Insertion sort, Quicksort, Radix sort, Shell sort
Query Performance
Write float arrays to a text file
Plot x, y arrays
Polynomial Fitting
General steps:
Define sorting routines to be considered.
Define appropriate sequence generators and write timings.
Plot timings.
What conclusions about relative performance of the sorting routines could be made based on the plots?
| #C | C | #ifndef _CSEQUENCE_H
#define _CSEQUENCE_H
#include <stdlib.h>
void setfillconst(double c);
void fillwithconst(double *v, int n);
void fillwithrrange(double *v, int n);
void shuffledrange(double *v, int n);
#endif |
http://rosettacode.org/wiki/Compiler/AST_interpreter | Compiler/AST interpreter | An AST interpreter interprets an Abstract Syntax Tree (AST)
produced by a Syntax Analyzer.
Task[edit]
Take the AST output from the Syntax analyzer task, and interpret it as appropriate.
Refer to the Syntax analyzer task for details of the AST.
Loading the AST from the syntax analyzer is as simple as (pseudo code)
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
The interpreter algorithm is relatively simple
interp(x)
if x == NULL return NULL
elif x.node_type == Integer return x.value converted to an integer
elif x.node_type == Ident return the current value of variable x.value
elif x.node_type == String return x.value
elif x.node_type == Assign
globals[x.left.value] = interp(x.right)
return NULL
elif x.node_type is a binary operator return interp(x.left) operator interp(x.right)
elif x.node_type is a unary operator, return return operator interp(x.left)
elif x.node_type == If
if (interp(x.left)) then interp(x.right.left)
else interp(x.right.right)
return NULL
elif x.node_type == While
while (interp(x.left)) do interp(x.right)
return NULL
elif x.node_type == Prtc
print interp(x.left) as a character, no newline
return NULL
elif x.node_type == Prti
print interp(x.left) as an integer, no newline
return NULL
elif x.node_type == Prts
print interp(x.left) as a string, respecting newlines ("\n")
return NULL
elif x.node_type == Sequence
interp(x.left)
interp(x.right)
return NULL
else
error("unknown node type")
Notes:
Because of the simple nature of our tiny language, Semantic analysis is not needed.
Your interpreter should use C like division semantics, for both division and modulus. For division of positive operands, only the non-fractional portion of the result should be returned. In other words, the result should be truncated towards 0.
This means, for instance, that 3 / 2 should result in 1.
For division when one of the operands is negative, the result should be truncated towards 0.
This means, for instance, that 3 / -2 should result in -1.
Test program
prime.t
lex <prime.t | parse | interp
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
101 is prime
Total primes found: 26
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Syntax Analyzer task
Code Generator task
Virtual Machine Interpreter task
| #Nim | Nim | import os, strutils, streams, tables
import ast_parser
type
ValueKind = enum valNil, valInt, valString
# Representation of a value.
Value = object
case kind: ValueKind
of valNil: nil
of valInt: intVal: int
of valString: stringVal: string
# Range of binary operators.
BinaryOperator = range[nMultiply..nOr]
# Table of variables.
var variables: Table[string, Value]
type RunTimeError = object of CatchableError
#---------------------------------------------------------------------------------------------------
template newInt(val: typed): Value =
## Create an integer value.
Value(kind: valInt, intVal: val)
#---------------------------------------------------------------------------------------------------
proc interp(node: Node): Value =
## Interpret code starting at "node".
if node.isNil:
return Value(kind: valNil)
case node.kind
of nInteger:
result = Value(kind: valInt, intVal: node.intVal)
of nIdentifier:
if node.name notin variables:
raise newException(RunTimeError, "Variable {node.name} is not initialized.")
result = variables[node.name]
of nString:
result = Value(kind: valString, stringVal: node.stringVal)
of nAssign:
variables[node.left.name] = interp(node.right)
of nNegate:
result = newInt(-interp(node.left).intVal)
of nNot:
result = newInt(not interp(node.left).intVal)
of BinaryOperator.low..BinaryOperator.high:
let left = interp(node.left)
let right = interp(node.right)
case BinaryOperator(node.kind)
of nMultiply:
result = newInt(left.intVal * right.intVal)
of nDivide:
result = newInt(left.intVal div right.intVal)
of nMod:
result = newInt(left.intVal mod right.intVal)
of nAdd:
result = newInt(left.intVal + right.intVal)
of nSubtract:
result = newInt(left.intVal - right.intVal)
of nLess:
result = newInt(ord(left.intVal < right.intVal))
of nLessEqual:
result = newInt(ord(left.intVal <= right.intVal))
of nGreater:
result = newInt(ord(left.intVal > right.intVal))
of nGreaterEqual:
result = newInt(ord(left.intVal >= right.intVal))
of nEqual:
result = newInt(ord(left.intVal == right.intVal))
of nNotEqual:
result = newInt(ord(left.intVal != right.intVal))
of nAnd:
result = newInt(left.intVal and right.intVal)
of nOr:
result = newInt(left.intVal or right.intVal)
of nIf:
if interp(node.left).intVal != 0:
discard interp(node.right.left)
else:
discard interp(node.right.right)
of nWhile:
while interp(node.left).intVal != 0:
discard interp(node.right)
of nPrtc:
stdout.write(chr(interp(node.left).intVal))
of nPrti:
stdout.write(interp(node.left).intVal)
of nPrts:
stdout.write(interp(node.left).stringVal)
of nSequence:
discard interp(node.left)
discard interp(node.right)
#---------------------------------------------------------------------------------------------------
import re
proc loadAst(stream: Stream): Node =
## Load a linear AST and build a binary tree.
let line = stream.readLine().strip()
if line.startsWith(';'):
return nil
var fields = line.split(' ', 1)
let kind = parseEnum[NodeKind](fields[0])
if kind in {nIdentifier, nString, nInteger}:
if fields.len < 2:
raise newException(ValueError, "Missing value field for " & fields[0])
else:
fields[1] = fields[1].strip()
case kind
of nIdentifier:
return Node(kind: nIdentifier, name: fields[1])
of nString:
str = fields[1].replacef(re"([^\\])(\\n)", "$1\n").replace(r"\\", r"\").replace("\"", "")
return Node(kind: nString, stringVal: str)
of nInteger:
return Node(kind: nInteger, intVal: parseInt(fields[1]))
else:
if fields.len > 1:
raise newException(ValueError, "Extra field for " & fields[0])
let left = stream.loadAst()
let right = stream.loadAst()
result = newNode(kind, left, right)
#———————————————————————————————————————————————————————————————————————————————————————————————————
var stream: Stream
var toClose = false
if paramCount() < 1:
stream = newFileStream(stdin)
else:
stream = newFileStream(paramStr(1))
toClose = true
let ast = loadAst(stream)
if toClose: stream.close()
discard ast.interp() |
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #BQN | BQN | Compare ← >·(⍒⊑¨)⊸⊏≠⊸⋈¨
•Show Compare ⟨"hello", "person"⟩
•Show Compare ⟨"abcd", "123456789", "abcdef", "1234567"⟩ |
http://rosettacode.org/wiki/Compare_length_of_two_strings | Compare length of two strings |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Given two strings of different length, determine which string is longer or shorter. Print both strings and their length, one on each line. Print the longer one first.
Measure the length of your string in terms of bytes or characters, as appropriate for your language. If your language doesn't have an operator for measuring the length of a string, note it.
Extra credit
Given more than two strings:
list = ["abcd","123456789","abcdef","1234567"]
Show the strings in descending length order.
Other tasks related to string operations:
Metrics
Array length
String length
Copy a string
Empty string (assignment)
Counting
Word frequency
Letter frequency
Jewels and stones
I before E except after C
Bioinformatics/base count
Count occurrences of a substring
Count how many vowels and consonants occur in a string
Remove/replace
XXXX redacted
Conjugate a Latin verb
Remove vowels from a string
String interpolation (included)
Strip block comments
Strip comments from a string
Strip a set of characters from a string
Strip whitespace from a string -- top and tail
Strip control codes and extended characters from a string
Anagrams/Derangements/shuffling
Word wheel
ABC problem
Sattolo cycle
Knuth shuffle
Ordered words
Superpermutation minimisation
Textonyms (using a phone text pad)
Anagrams
Anagrams/Deranged anagrams
Permutations/Derangements
Find/Search/Determine
ABC words
Odd words
Word ladder
Semordnilap
Word search
Wordiff (game)
String matching
Tea cup rim text
Alternade words
Changeable words
State name puzzle
String comparison
Unique characters
Unique characters in each string
Extract file extension
Levenshtein distance
Palindrome detection
Common list elements
Longest common suffix
Longest common prefix
Compare a list of strings
Longest common substring
Find common directory path
Words from neighbour ones
Change e letters to i in words
Non-continuous subsequences
Longest common subsequence
Longest palindromic substrings
Longest increasing subsequence
Words containing "the" substring
Sum of the digits of n is substring of n
Determine if a string is numeric
Determine if a string is collapsible
Determine if a string is squeezable
Determine if a string has all unique characters
Determine if a string has all the same characters
Longest substrings without repeating characters
Find words which contains all the vowels
Find words which contains most consonants
Find words which contains more than 3 vowels
Find words which first and last three letters are equals
Find words which odd letters are consonants and even letters are vowels or vice_versa
Formatting
Substring
Rep-string
Word wrap
String case
Align columns
Literals/String
Repeat a string
Brace expansion
Brace expansion using ranges
Reverse a string
Phrase reversals
Comma quibbling
Special characters
String concatenation
Substring/Top and tail
Commatizing numbers
Reverse words in a string
Suffixation of decimal numbers
Long literals, with continuations
Numerical and alphabetical suffixes
Abbreviations, easy
Abbreviations, simple
Abbreviations, automatic
Song lyrics/poems/Mad Libs/phrases
Mad Libs
Magic 8-ball
99 Bottles of Beer
The Name Game (a song)
The Old lady swallowed a fly
The Twelve Days of Christmas
Tokenize
Text between
Tokenize a string
Word break problem
Tokenize a string with escaping
Split a character string based on change of character
Sequences
Show ASCII table
De Bruijn sequences
Self-referential sequences
Generate lower case ASCII alphabet
| #C | C | #include <stdio.h>
#include <stdlib.h>
#include <string.h>
int cmp(const int* a, const int* b)
{
return *b - *a; // reverse sort!
}
void compareAndReportStringsLength(const char* strings[], const int n)
{
if (n > 0)
{
char* has_length = "has length";
char* predicate_max = "and is the longest string";
char* predicate_min = "and is the shortest string";
char* predicate_ave = "and is neither the longest nor the shortest string";
int* si = malloc(2 * n * sizeof(int));
if (si != NULL)
{
for (int i = 0; i < n; i++)
{
si[2 * i] = strlen(strings[i]);
si[2 * i + 1] = i;
}
qsort(si, n, 2 * sizeof(int), cmp);
int max = si[0];
int min = si[2 * (n - 1)];
for (int i = 0; i < n; i++)
{
int length = si[2 * i];
char* string = strings[si[2 * i + 1]];
char* predicate;
if (length == max)
predicate = predicate_max;
else if (length == min)
predicate = predicate_min;
else
predicate = predicate_ave;
printf("\"%s\" %s %d %s\n",
string, has_length, length, predicate);
}
free(si);
}
else
{
fputs("unable allocate memory buffer", stderr);
}
}
}
int main(int argc, char* argv[])
{
char* list[] = { "abcd", "123456789", "abcdef", "1234567" };
compareAndReportStringsLength(list, 4);
return EXIT_SUCCESS;
} |
http://rosettacode.org/wiki/Compiler/syntax_analyzer | Compiler/syntax analyzer | A Syntax analyzer transforms a token stream (from the Lexical analyzer)
into a Syntax tree, based on a grammar.
Task[edit]
Take the output from the Lexical analyzer task,
and convert it to an Abstract Syntax Tree (AST),
based on the grammar below. The output should be in a flattened format.
The program should read input from a file and/or stdin, and write output to a file and/or
stdout. If the language being used has a parser module/library/class, it would be great
if two versions of the solution are provided: One without the parser module, and one
with.
Grammar
The simple programming language to be analyzed is more or less a (very tiny) subset of
C. The formal grammar in
Extended Backus-Naur Form (EBNF):
stmt_list = {stmt} ;
stmt = ';'
| Identifier '=' expr ';'
| 'while' paren_expr stmt
| 'if' paren_expr stmt ['else' stmt]
| 'print' '(' prt_list ')' ';'
| 'putc' paren_expr ';'
| '{' stmt_list '}'
;
paren_expr = '(' expr ')' ;
prt_list = (string | expr) {',' (String | expr)} ;
expr = and_expr {'||' and_expr} ;
and_expr = equality_expr {'&&' equality_expr} ;
equality_expr = relational_expr [('==' | '!=') relational_expr] ;
relational_expr = addition_expr [('<' | '<=' | '>' | '>=') addition_expr] ;
addition_expr = multiplication_expr {('+' | '-') multiplication_expr} ;
multiplication_expr = primary {('*' | '/' | '%') primary } ;
primary = Identifier
| Integer
| '(' expr ')'
| ('+' | '-' | '!') primary
;
The resulting AST should be formulated as a Binary Tree.
Example - given the simple program (below), stored in a file called while.t, create the list of tokens, using one of the Lexical analyzer solutions
lex < while.t > while.lex
Run one of the Syntax analyzer solutions
parse < while.lex > while.ast
The following table shows the input to lex, lex output, and the AST produced by the parser
Input to lex
Output from lex, input to parse
Output from parse
count = 1;
while (count < 10) {
print("count is: ", count, "\n");
count = count + 1;
}
1 1 Identifier count
1 7 Op_assign
1 9 Integer 1
1 10 Semicolon
2 1 Keyword_while
2 7 LeftParen
2 8 Identifier count
2 14 Op_less
2 16 Integer 10
2 18 RightParen
2 20 LeftBrace
3 5 Keyword_print
3 10 LeftParen
3 11 String "count is: "
3 23 Comma
3 25 Identifier count
3 30 Comma
3 32 String "\n"
3 36 RightParen
3 37 Semicolon
4 5 Identifier count
4 11 Op_assign
4 13 Identifier count
4 19 Op_add
4 21 Integer 1
4 22 Semicolon
5 1 RightBrace
6 1 End_of_input
Sequence
Sequence
;
Assign
Identifier count
Integer 1
While
Less
Identifier count
Integer 10
Sequence
Sequence
;
Sequence
Sequence
Sequence
;
Prts
String "count is: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
Specifications
List of node type names
Identifier String Integer Sequence If Prtc Prts Prti While Assign Negate Not Multiply Divide Mod
Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
In the text below, Null/Empty nodes are represented by ";".
Non-terminal (internal) nodes
For Operators, the following nodes should be created:
Multiply Divide Mod Add Subtract Less LessEqual Greater GreaterEqual Equal NotEqual And Or
For each of the above nodes, the left and right sub-nodes are the operands of the
respective operation.
In pseudo S-Expression format:
(Operator expression expression)
Negate, Not
For these node types, the left node is the operand, and the right node is null.
(Operator expression ;)
Sequence - sub-nodes are either statements or Sequences.
If - left node is the expression, the right node is If node, with it's left node being the
if-true statement part, and the right node being the if-false (else) statement part.
(If expression (If statement else-statement))
If there is not an else, the tree becomes:
(If expression (If statement ;))
Prtc
(Prtc (expression) ;)
Prts
(Prts (String "the string") ;)
Prti
(Prti (Integer 12345) ;)
While - left node is the expression, the right node is the statement.
(While expression statement)
Assign - left node is the left-hand side of the assignment, the right node is the
right-hand side of the assignment.
(Assign Identifier expression)
Terminal (leaf) nodes:
Identifier: (Identifier ident_name)
Integer: (Integer 12345)
String: (String "Hello World!")
";": Empty node
Some simple examples
Sequences denote a list node; they are used to represent a list. semicolon's represent a null node, e.g., the end of this path.
This simple program:
a=11;
Produces the following AST, encoded as a binary tree:
Under each non-leaf node are two '|' lines. The first represents the left sub-node, the second represents the right sub-node:
(1) Sequence
(2) |-- ;
(3) |-- Assign
(4) |-- Identifier: a
(5) |-- Integer: 11
In flattened form:
(1) Sequence
(2) ;
(3) Assign
(4) Identifier a
(5) Integer 11
This program:
a=11;
b=22;
c=33;
Produces the following AST:
( 1) Sequence
( 2) |-- Sequence
( 3) | |-- Sequence
( 4) | | |-- ;
( 5) | | |-- Assign
( 6) | | |-- Identifier: a
( 7) | | |-- Integer: 11
( 8) | |-- Assign
( 9) | |-- Identifier: b
(10) | |-- Integer: 22
(11) |-- Assign
(12) |-- Identifier: c
(13) |-- Integer: 33
In flattened form:
( 1) Sequence
( 2) Sequence
( 3) Sequence
( 4) ;
( 5) Assign
( 6) Identifier a
( 7) Integer 11
( 8) Assign
( 9) Identifier b
(10) Integer 22
(11) Assign
(12) Identifier c
(13) Integer 33
Pseudo-code for the parser.
Uses Precedence Climbing for expression parsing, and
Recursive Descent for statement parsing. The AST is also built:
def expr(p)
if tok is "("
x = paren_expr()
elif tok in ["-", "+", "!"]
gettok()
y = expr(precedence of operator)
if operator was "+"
x = y
else
x = make_node(operator, y)
elif tok is an Identifier
x = make_leaf(Identifier, variable name)
gettok()
elif tok is an Integer constant
x = make_leaf(Integer, integer value)
gettok()
else
error()
while tok is a binary operator and precedence of tok >= p
save_tok = tok
gettok()
q = precedence of save_tok
if save_tok is not right associative
q += 1
x = make_node(Operator save_tok represents, x, expr(q))
return x
def paren_expr()
expect("(")
x = expr(0)
expect(")")
return x
def stmt()
t = NULL
if accept("if")
e = paren_expr()
s = stmt()
t = make_node(If, e, make_node(If, s, accept("else") ? stmt() : NULL))
elif accept("putc")
t = make_node(Prtc, paren_expr())
expect(";")
elif accept("print")
expect("(")
repeat
if tok is a string
e = make_node(Prts, make_leaf(String, the string))
gettok()
else
e = make_node(Prti, expr(0))
t = make_node(Sequence, t, e)
until not accept(",")
expect(")")
expect(";")
elif tok is ";"
gettok()
elif tok is an Identifier
v = make_leaf(Identifier, variable name)
gettok()
expect("=")
t = make_node(Assign, v, expr(0))
expect(";")
elif accept("while")
e = paren_expr()
t = make_node(While, e, stmt()
elif accept("{")
while tok not equal "}" and tok not equal end-of-file
t = make_node(Sequence, t, stmt())
expect("}")
elif tok is end-of-file
pass
else
error()
return t
def parse()
t = NULL
gettok()
repeat
t = make_node(Sequence, t, stmt())
until tok is end-of-file
return t
Once the AST is built, it should be output in a flattened format. This can be as simple as the following
def prt_ast(t)
if t == NULL
print(";\n")
else
print(t.node_type)
if t.node_type in [Identifier, Integer, String] # leaf node
print the value of the Ident, Integer or String, "\n"
else
print("\n")
prt_ast(t.left)
prt_ast(t.right)
If the AST is correctly built, loading it into a subsequent program should be as simple as
def load_ast()
line = readline()
# Each line has at least one token
line_list = tokenize the line, respecting double quotes
text = line_list[0] # first token is always the node type
if text == ";" # a terminal node
return NULL
node_type = text # could convert to internal form if desired
# A line with two tokens is a leaf node
# Leaf nodes are: Identifier, Integer, String
# The 2nd token is the value
if len(line_list) > 1
return make_leaf(node_type, line_list[1])
left = load_ast()
right = load_ast()
return make_node(node_type, left, right)
Finally, the AST can also be tested by running it against one of the AST Interpreter solutions.
Test program, assuming this is in a file called prime.t
lex <prime.t | parse
Input to lex
Output from lex, input to parse
Output from parse
/*
Simple prime number generator
*/
count = 1;
n = 1;
limit = 100;
while (n < limit) {
k=3;
p=1;
n=n+2;
while ((k*k<=n) && (p)) {
p=n/k*k!=n;
k=k+2;
}
if (p) {
print(n, " is prime\n");
count = count + 1;
}
}
print("Total primes found: ", count, "\n");
4 1 Identifier count
4 7 Op_assign
4 9 Integer 1
4 10 Semicolon
5 1 Identifier n
5 3 Op_assign
5 5 Integer 1
5 6 Semicolon
6 1 Identifier limit
6 7 Op_assign
6 9 Integer 100
6 12 Semicolon
7 1 Keyword_while
7 7 LeftParen
7 8 Identifier n
7 10 Op_less
7 12 Identifier limit
7 17 RightParen
7 19 LeftBrace
8 5 Identifier k
8 6 Op_assign
8 7 Integer 3
8 8 Semicolon
9 5 Identifier p
9 6 Op_assign
9 7 Integer 1
9 8 Semicolon
10 5 Identifier n
10 6 Op_assign
10 7 Identifier n
10 8 Op_add
10 9 Integer 2
10 10 Semicolon
11 5 Keyword_while
11 11 LeftParen
11 12 LeftParen
11 13 Identifier k
11 14 Op_multiply
11 15 Identifier k
11 16 Op_lessequal
11 18 Identifier n
11 19 RightParen
11 21 Op_and
11 24 LeftParen
11 25 Identifier p
11 26 RightParen
11 27 RightParen
11 29 LeftBrace
12 9 Identifier p
12 10 Op_assign
12 11 Identifier n
12 12 Op_divide
12 13 Identifier k
12 14 Op_multiply
12 15 Identifier k
12 16 Op_notequal
12 18 Identifier n
12 19 Semicolon
13 9 Identifier k
13 10 Op_assign
13 11 Identifier k
13 12 Op_add
13 13 Integer 2
13 14 Semicolon
14 5 RightBrace
15 5 Keyword_if
15 8 LeftParen
15 9 Identifier p
15 10 RightParen
15 12 LeftBrace
16 9 Keyword_print
16 14 LeftParen
16 15 Identifier n
16 16 Comma
16 18 String " is prime\n"
16 31 RightParen
16 32 Semicolon
17 9 Identifier count
17 15 Op_assign
17 17 Identifier count
17 23 Op_add
17 25 Integer 1
17 26 Semicolon
18 5 RightBrace
19 1 RightBrace
20 1 Keyword_print
20 6 LeftParen
20 7 String "Total primes found: "
20 29 Comma
20 31 Identifier count
20 36 Comma
20 38 String "\n"
20 42 RightParen
20 43 Semicolon
21 1 End_of_input
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier count
Integer 1
Assign
Identifier n
Integer 1
Assign
Identifier limit
Integer 100
While
Less
Identifier n
Identifier limit
Sequence
Sequence
Sequence
Sequence
Sequence
;
Assign
Identifier k
Integer 3
Assign
Identifier p
Integer 1
Assign
Identifier n
Add
Identifier n
Integer 2
While
And
LessEqual
Multiply
Identifier k
Identifier k
Identifier n
Identifier p
Sequence
Sequence
;
Assign
Identifier p
NotEqual
Multiply
Divide
Identifier n
Identifier k
Identifier k
Identifier n
Assign
Identifier k
Add
Identifier k
Integer 2
If
Identifier p
If
Sequence
Sequence
;
Sequence
Sequence
;
Prti
Identifier n
;
Prts
String " is prime\n"
;
Assign
Identifier count
Add
Identifier count
Integer 1
;
Sequence
Sequence
Sequence
;
Prts
String "Total primes found: "
;
Prti
Identifier count
;
Prts
String "\n"
;
Additional examples
Your solution should pass all the test cases above and the additional tests found Here.
Reference
The C and Python versions can be considered reference implementations.
Related Tasks
Lexical Analyzer task
Code Generator task
Virtual Machine Interpreter task
AST Interpreter task
| #Go | Go | package main
import (
"bufio"
"fmt"
"log"
"os"
"strconv"
"strings"
)
type TokenType int
const (
tkEOI TokenType = iota
tkMul
tkDiv
tkMod
tkAdd
tkSub
tkNegate
tkNot
tkLss
tkLeq
tkGtr
tkGeq
tkEql
tkNeq
tkAssign
tkAnd
tkOr
tkIf
tkElse
tkWhile
tkPrint
tkPutc
tkLparen
tkRparen
tkLbrace
tkRbrace
tkSemi
tkComma
tkIdent
tkInteger
tkString
)
type NodeType int
const (
ndIdent NodeType = iota
ndString
ndInteger
ndSequence
ndIf
ndPrtc
ndPrts
ndPrti
ndWhile
ndAssign
ndNegate
ndNot
ndMul
ndDiv
ndMod
ndAdd
ndSub
ndLss
ndLeq
ndGtr
ndGeq
ndEql
ndNeq
ndAnd
ndOr
)
type tokS struct {
tok TokenType
errLn int
errCol int
text string // ident or string literal or integer value
}
type Tree struct {
nodeType NodeType
left *Tree
right *Tree
value string
}
// dependency: Ordered by tok, must remain in same order as TokenType consts
type atr struct {
text string
enumText string
tok TokenType
rightAssociative bool
isBinary bool
isUnary bool
precedence int
nodeType NodeType
}
var atrs = []atr{
{"EOI", "End_of_input", tkEOI, false, false, false, -1, -1},
{"*", "Op_multiply", tkMul, false, true, false, 13, ndMul},
{"/", "Op_divide", tkDiv, false, true, false, 13, ndDiv},
{"%", "Op_mod", tkMod, false, true, false, 13, ndMod},
{"+", "Op_add", tkAdd, false, true, false, 12, ndAdd},
{"-", "Op_subtract", tkSub, false, true, false, 12, ndSub},
{"-", "Op_negate", tkNegate, false, false, true, 14, ndNegate},
{"!", "Op_not", tkNot, false, false, true, 14, ndNot},
{"<", "Op_less", tkLss, false, true, false, 10, ndLss},
{"<=", "Op_lessequal", tkLeq, false, true, false, 10, ndLeq},
{">", "Op_greater", tkGtr, false, true, false, 10, ndGtr},
{">=", "Op_greaterequal", tkGeq, false, true, false, 10, ndGeq},
{"==", "Op_equal", tkEql, false, true, false, 9, ndEql},
{"!=", "Op_notequal", tkNeq, false, true, false, 9, ndNeq},
{"=", "Op_assign", tkAssign, false, false, false, -1, ndAssign},
{"&&", "Op_and", tkAnd, false, true, false, 5, ndAnd},
{"||", "Op_or", tkOr, false, true, false, 4, ndOr},
{"if", "Keyword_if", tkIf, false, false, false, -1, ndIf},
{"else", "Keyword_else", tkElse, false, false, false, -1, -1},
{"while", "Keyword_while", tkWhile, false, false, false, -1, ndWhile},
{"print", "Keyword_print", tkPrint, false, false, false, -1, -1},
{"putc", "Keyword_putc", tkPutc, false, false, false, -1, -1},
{"(", "LeftParen", tkLparen, false, false, false, -1, -1},
{")", "RightParen", tkRparen, false, false, false, -1, -1},
{"{", "LeftBrace", tkLbrace, false, false, false, -1, -1},
{"}", "RightBrace", tkRbrace, false, false, false, -1, -1},
{";", "Semicolon", tkSemi, false, false, false, -1, -1},
{",", "Comma", tkComma, false, false, false, -1, -1},
{"Ident", "Identifier", tkIdent, false, false, false, -1, ndIdent},
{"Integer literal", "Integer", tkInteger, false, false, false, -1, ndInteger},
{"String literal", "String", tkString, false, false, false, -1, ndString},
}
var displayNodes = []string{
"Identifier", "String", "Integer", "Sequence", "If", "Prtc", "Prts", "Prti",
"While", "Assign", "Negate", "Not", "Multiply", "Divide", "Mod", "Add",
"Subtract", "Less", "LessEqual", "Greater", "GreaterEqual", "Equal",
"NotEqual", "And", "Or",
}
var (
err error
token tokS
scanner *bufio.Scanner
)
func reportError(errLine, errCol int, msg string) {
log.Fatalf("(%d, %d) error : %s\n", errLine, errCol, msg)
}
func check(err error) {
if err != nil {
log.Fatal(err)
}
}
func getEum(name string) TokenType { // return internal version of name#
for _, atr := range atrs {
if atr.enumText == name {
return atr.tok
}
}
reportError(0, 0, fmt.Sprintf("Unknown token %s\n", name))
return tkEOI
}
func getTok() tokS {
tok := tokS{}
if scanner.Scan() {
line := strings.TrimRight(scanner.Text(), " \t")
fields := strings.Fields(line)
// [ ]*{lineno}[ ]+{colno}[ ]+token[ ]+optional
tok.errLn, err = strconv.Atoi(fields[0])
check(err)
tok.errCol, err = strconv.Atoi(fields[1])
check(err)
tok.tok = getEum(fields[2])
le := len(fields)
if le == 4 {
tok.text = fields[3]
} else if le > 4 {
idx := strings.Index(line, `"`)
tok.text = line[idx:]
}
}
check(scanner.Err())
return tok
}
func makeNode(nodeType NodeType, left *Tree, right *Tree) *Tree {
return &Tree{nodeType, left, right, ""}
}
func makeLeaf(nodeType NodeType, value string) *Tree {
return &Tree{nodeType, nil, nil, value}
}
func expect(msg string, s TokenType) {
if token.tok == s {
token = getTok()
return
}
reportError(token.errLn, token.errCol,
fmt.Sprintf("%s: Expecting '%s', found '%s'\n", msg, atrs[s].text, atrs[token.tok].text))
}
func expr(p int) *Tree {
var x, node *Tree
switch token.tok {
case tkLparen:
x = parenExpr()
case tkSub, tkAdd:
op := token.tok
token = getTok()
node = expr(atrs[tkNegate].precedence)
if op == tkSub {
x = makeNode(ndNegate, node, nil)
} else {
x = node
}
case tkNot:
token = getTok()
x = makeNode(ndNot, expr(atrs[tkNot].precedence), nil)
case tkIdent:
x = makeLeaf(ndIdent, token.text)
token = getTok()
case tkInteger:
x = makeLeaf(ndInteger, token.text)
token = getTok()
default:
reportError(token.errLn, token.errCol,
fmt.Sprintf("Expecting a primary, found: %s\n", atrs[token.tok].text))
}
for atrs[token.tok].isBinary && atrs[token.tok].precedence >= p {
op := token.tok
token = getTok()
q := atrs[op].precedence
if !atrs[op].rightAssociative {
q++
}
node = expr(q)
x = makeNode(atrs[op].nodeType, x, node)
}
return x
}
func parenExpr() *Tree {
expect("parenExpr", tkLparen)
t := expr(0)
expect("parenExpr", tkRparen)
return t
}
func stmt() *Tree {
var t, v, e, s, s2 *Tree
switch token.tok {
case tkIf:
token = getTok()
e = parenExpr()
s = stmt()
s2 = nil
if token.tok == tkElse {
token = getTok()
s2 = stmt()
}
t = makeNode(ndIf, e, makeNode(ndIf, s, s2))
case tkPutc:
token = getTok()
e = parenExpr()
t = makeNode(ndPrtc, e, nil)
expect("Putc", tkSemi)
case tkPrint: // print '(' expr {',' expr} ')'
token = getTok()
for expect("Print", tkLparen); ; expect("Print", tkComma) {
if token.tok == tkString {
e = makeNode(ndPrts, makeLeaf(ndString, token.text), nil)
token = getTok()
} else {
e = makeNode(ndPrti, expr(0), nil)
}
t = makeNode(ndSequence, t, e)
if token.tok != tkComma {
break
}
}
expect("Print", tkRparen)
expect("Print", tkSemi)
case tkSemi:
token = getTok()
case tkIdent:
v = makeLeaf(ndIdent, token.text)
token = getTok()
expect("assign", tkAssign)
e = expr(0)
t = makeNode(ndAssign, v, e)
expect("assign", tkSemi)
case tkWhile:
token = getTok()
e = parenExpr()
s = stmt()
t = makeNode(ndWhile, e, s)
case tkLbrace: // {stmt}
for expect("Lbrace", tkLbrace); token.tok != tkRbrace && token.tok != tkEOI; {
t = makeNode(ndSequence, t, stmt())
}
expect("Lbrace", tkRbrace)
case tkEOI:
// do nothing
default:
reportError(token.errLn, token.errCol,
fmt.Sprintf("expecting start of statement, found '%s'\n", atrs[token.tok].text))
}
return t
}
func parse() *Tree {
var t *Tree
token = getTok()
for {
t = makeNode(ndSequence, t, stmt())
if t == nil || token.tok == tkEOI {
break
}
}
return t
}
func prtAst(t *Tree) {
if t == nil {
fmt.Print(";\n")
} else {
fmt.Printf("%-14s ", displayNodes[t.nodeType])
if t.nodeType == ndIdent || t.nodeType == ndInteger || t.nodeType == ndString {
fmt.Printf("%s\n", t.value)
} else {
fmt.Println()
prtAst(t.left)
prtAst(t.right)
}
}
}
func main() {
source, err := os.Open("source.txt")
check(err)
defer source.Close()
scanner = bufio.NewScanner(source)
prtAst(parse())
} |
http://rosettacode.org/wiki/Conway%27s_Game_of_Life | Conway's Game of Life | The Game of Life is a cellular automaton devised by the British mathematician John Horton Conway in 1970. It is the best-known example of a cellular automaton.
Conway's game of life is described here:
A cell C is represented by a 1 when alive, or 0 when dead, in an m-by-m (or m×m) square array of cells.
We calculate N - the sum of live cells in C's eight-location neighbourhood, then cell C is alive or dead in the next generation based on the following table:
C N new C
1 0,1 -> 0 # Lonely
1 4,5,6,7,8 -> 0 # Overcrowded
1 2,3 -> 1 # Lives
0 3 -> 1 # It takes three to give birth!
0 0,1,2,4,5,6,7,8 -> 0 # Barren
Assume cells beyond the boundary are always dead.
The "game" is actually a zero-player game, meaning that its evolution is determined by its initial state, needing no input from human players. One interacts with the Game of Life by creating an initial configuration and observing how it evolves.
Task
Although you should test your implementation on more complex examples such as the glider in a larger universe, show the action of the blinker (three adjoining cells in a row all alive), over three generations, in a 3 by 3 grid.
References
Its creator John Conway, explains the game of life. Video from numberphile on youtube.
John Conway Inventing Game of Life - Numberphile video.
Related task
Langton's ant - another well known cellular automaton.
| #BQN | BQN | Life←{
r←¯1(⌽⎉1)¯1⌽(2+≢𝕩)↑𝕩
s←∨´ (1∾<r) ∧ 3‿4 = <+´⥊ ¯1‿0‿1 (⌽⎉1)⌜ ¯1‿0‿1 ⌽⌜ <r
1(↓⎉1) ¯1(↓⎉1) 1↓ ¯1↓s
}
blinker←>⟨0‿0‿0,1‿1‿1,0‿0‿0⟩
(<".#") ⊏¨˜ Life⍟(↕3) blinker |
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