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# cython: infer_types=True
# cython: language_level=3
# cython: auto_pickle=False
#
# Tree visitor and transform framework
#
from __future__ import absolute_import, print_function
import sys
import inspect
from . import TypeSlots
from . import Builtin
from . import Nodes
from . import ExprNodes
from . import Errors
from . import DebugFlags
from . import Future
import cython
cython.declare(_PRINTABLE=tuple)
if sys.version_info[0] >= 3:
_PRINTABLE = (bytes, str, int, float)
else:
_PRINTABLE = (str, unicode, long, int, float)
class TreeVisitor(object):
"""
Base class for writing visitors for a Cython tree, contains utilities for
recursing such trees using visitors. Each node is
expected to have a child_attrs iterable containing the names of attributes
containing child nodes or lists of child nodes. Lists are not considered
part of the tree structure (i.e. contained nodes are considered direct
children of the parent node).
visit_children visits each of the children of a given node (see the visit_children
documentation). When recursing the tree using visit_children, an attribute
access_path is maintained which gives information about the current location
in the tree as a stack of tuples: (parent_node, attrname, index), representing
the node, attribute and optional list index that was taken in each step in the path to
the current node.
Example:
>>> class SampleNode(object):
... child_attrs = ["head", "body"]
... def __init__(self, value, head=None, body=None):
... self.value = value
... self.head = head
... self.body = body
... def __repr__(self): return "SampleNode(%s)" % self.value
...
>>> tree = SampleNode(0, SampleNode(1), [SampleNode(2), SampleNode(3)])
>>> class MyVisitor(TreeVisitor):
... def visit_SampleNode(self, node):
... print("in %s %s" % (node.value, self.access_path))
... self.visitchildren(node)
... print("out %s" % node.value)
...
>>> MyVisitor().visit(tree)
in 0 []
in 1 [(SampleNode(0), 'head', None)]
out 1
in 2 [(SampleNode(0), 'body', 0)]
out 2
in 3 [(SampleNode(0), 'body', 1)]
out 3
out 0
"""
def __init__(self):
super(TreeVisitor, self).__init__()
self.dispatch_table = {}
self.access_path = []
def dump_node(self, node):
ignored = list(node.child_attrs or []) + [
u'child_attrs', u'pos', u'gil_message', u'cpp_message', u'subexprs']
values = []
pos = getattr(node, 'pos', None)
if pos:
source = pos[0]
if source:
import os.path
source = os.path.basename(source.get_description())
values.append(u'%s:%s:%s' % (source, pos[1], pos[2]))
attribute_names = dir(node)
for attr in attribute_names:
if attr in ignored:
continue
if attr.startswith('_') or attr.endswith('_'):
continue
try:
value = getattr(node, attr)
except AttributeError:
continue
if value is None or value == 0:
continue
elif isinstance(value, list):
value = u'[...]/%d' % len(value)
elif not isinstance(value, _PRINTABLE):
continue
else:
value = repr(value)
values.append(u'%s = %s' % (attr, value))
return u'%s(%s)' % (node.__class__.__name__, u',\n '.join(values))
def _find_node_path(self, stacktrace):
import os.path
last_traceback = stacktrace
nodes = []
while hasattr(stacktrace, 'tb_frame'):
frame = stacktrace.tb_frame
node = frame.f_locals.get(u'self')
if isinstance(node, Nodes.Node):
code = frame.f_code
method_name = code.co_name
pos = (os.path.basename(code.co_filename),
frame.f_lineno)
nodes.append((node, method_name, pos))
last_traceback = stacktrace
stacktrace = stacktrace.tb_next
return (last_traceback, nodes)
def _raise_compiler_error(self, child, e):
trace = ['']
for parent, attribute, index in self.access_path:
node = getattr(parent, attribute)
if index is None:
index = ''
else:
node = node[index]
index = u'[%d]' % index
trace.append(u'%s.%s%s = %s' % (
parent.__class__.__name__, attribute, index,
self.dump_node(node)))
stacktrace, called_nodes = self._find_node_path(sys.exc_info()[2])
last_node = child
for node, method_name, pos in called_nodes:
last_node = node
trace.append(u"File '%s', line %d, in %s: %s" % (
pos[0], pos[1], method_name, self.dump_node(node)))
raise Errors.CompilerCrash(
getattr(last_node, 'pos', None), self.__class__.__name__,
u'\n'.join(trace), e, stacktrace)
@cython.final
def find_handler(self, obj):
# to resolve, try entire hierarchy
cls = type(obj)
pattern = "visit_%s"
mro = inspect.getmro(cls)
for mro_cls in mro:
handler_method = getattr(self, pattern % mro_cls.__name__, None)
if handler_method is not None:
return handler_method
print(type(self), cls)
if self.access_path:
print(self.access_path)
print(self.access_path[-1][0].pos)
print(self.access_path[-1][0].__dict__)
raise RuntimeError("Visitor %r does not accept object: %s" % (self, obj))
def visit(self, obj):
return self._visit(obj)
@cython.final
def _visit(self, obj):
try:
try:
handler_method = self.dispatch_table[type(obj)]
except KeyError:
handler_method = self.find_handler(obj)
self.dispatch_table[type(obj)] = handler_method
return handler_method(obj)
except Errors.CompileError:
raise
except Errors.AbortError:
raise
except Exception as e:
if DebugFlags.debug_no_exception_intercept:
raise
self._raise_compiler_error(obj, e)
@cython.final
def _visitchild(self, child, parent, attrname, idx):
self.access_path.append((parent, attrname, idx))
result = self._visit(child)
self.access_path.pop()
return result
def visitchildren(self, parent, attrs=None):
return self._visitchildren(parent, attrs)
@cython.final
@cython.locals(idx=cython.Py_ssize_t)
def _visitchildren(self, parent, attrs):
"""
Visits the children of the given parent. If parent is None, returns
immediately (returning None).
The return value is a dictionary giving the results for each
child (mapping the attribute name to either the return value
or a list of return values (in the case of multiple children
in an attribute)).
"""
if parent is None: return None
result = {}
for attr in parent.child_attrs:
if attrs is not None and attr not in attrs: continue
child = getattr(parent, attr)
if child is not None:
if type(child) is list:
childretval = [self._visitchild(x, parent, attr, idx) for idx, x in enumerate(child)]
else:
childretval = self._visitchild(child, parent, attr, None)
assert not isinstance(childretval, list), 'Cannot insert list here: %s in %r' % (attr, parent)
result[attr] = childretval
return result
class VisitorTransform(TreeVisitor):
"""
A tree transform is a base class for visitors that wants to do stream
processing of the structure (rather than attributes etc.) of a tree.
It implements __call__ to simply visit the argument node.
It requires the visitor methods to return the nodes which should take
the place of the visited node in the result tree (which can be the same
or one or more replacement). Specifically, if the return value from
a visitor method is:
- [] or None; the visited node will be removed (set to None if an attribute and
removed if in a list)
- A single node; the visited node will be replaced by the returned node.
- A list of nodes; the visited nodes will be replaced by all the nodes in the
list. This will only work if the node was already a member of a list; if it
was not, an exception will be raised. (Typically you want to ensure that you
are within a StatListNode or similar before doing this.)
"""
def visitchildren(self, parent, attrs=None, exclude=None):
# generic def entry point for calls from Python subclasses
if exclude is not None:
attrs = self._select_attrs(parent.child_attrs if attrs is None else attrs, exclude)
return self._process_children(parent, attrs)
@cython.final
def _select_attrs(self, attrs, exclude):
return [name for name in attrs if name not in exclude]
@cython.final
def _process_children(self, parent, attrs=None):
# fast cdef entry point for calls from Cython subclasses
result = self._visitchildren(parent, attrs)
for attr, newnode in result.items():
if type(newnode) is list:
newnode = self._flatten_list(newnode)
setattr(parent, attr, newnode)
return result
@cython.final
def _flatten_list(self, orig_list):
# Flatten the list one level and remove any None
newlist = []
for x in orig_list:
if x is not None:
if type(x) is list:
newlist.extend(x)
else:
newlist.append(x)
return newlist
def recurse_to_children(self, node):
self._process_children(node)
return node
def __call__(self, root):
return self._visit(root)
class CythonTransform(VisitorTransform):
"""
Certain common conventions and utilities for Cython transforms.
- Sets up the context of the pipeline in self.context
- Tracks directives in effect in self.current_directives
"""
def __init__(self, context):
super(CythonTransform, self).__init__()
self.context = context
def __call__(self, node):
from . import ModuleNode
if isinstance(node, ModuleNode.ModuleNode):
self.current_directives = node.directives
return super(CythonTransform, self).__call__(node)
def visit_CompilerDirectivesNode(self, node):
old = self.current_directives
self.current_directives = node.directives
self._process_children(node)
self.current_directives = old
return node
def visit_Node(self, node):
self._process_children(node)
return node
class ScopeTrackingTransform(CythonTransform):
# Keeps track of type of scopes
#scope_type: can be either of 'module', 'function', 'cclass', 'pyclass', 'struct'
#scope_node: the node that owns the current scope
def visit_ModuleNode(self, node):
self.scope_type = 'module'
self.scope_node = node
self._process_children(node)
return node
def visit_scope(self, node, scope_type):
prev = self.scope_type, self.scope_node
self.scope_type = scope_type
self.scope_node = node
self._process_children(node)
self.scope_type, self.scope_node = prev
return node
def visit_CClassDefNode(self, node):
return self.visit_scope(node, 'cclass')
def visit_PyClassDefNode(self, node):
return self.visit_scope(node, 'pyclass')
def visit_FuncDefNode(self, node):
return self.visit_scope(node, 'function')
def visit_CStructOrUnionDefNode(self, node):
return self.visit_scope(node, 'struct')
class EnvTransform(CythonTransform):
"""
This transformation keeps a stack of the environments.
"""
def __call__(self, root):
self.env_stack = []
self.enter_scope(root, root.scope)
return super(EnvTransform, self).__call__(root)
def current_env(self):
return self.env_stack[-1][1]
def current_scope_node(self):
return self.env_stack[-1][0]
def global_scope(self):
return self.current_env().global_scope()
def enter_scope(self, node, scope):
self.env_stack.append((node, scope))
def exit_scope(self):
self.env_stack.pop()
def visit_FuncDefNode(self, node):
self.enter_scope(node, node.local_scope)
self._process_children(node)
self.exit_scope()
return node
def visit_GeneratorBodyDefNode(self, node):
self._process_children(node)
return node
def visit_ClassDefNode(self, node):
self.enter_scope(node, node.scope)
self._process_children(node)
self.exit_scope()
return node
def visit_CStructOrUnionDefNode(self, node):
self.enter_scope(node, node.scope)
self._process_children(node)
self.exit_scope()
return node
def visit_ScopedExprNode(self, node):
if node.expr_scope:
self.enter_scope(node, node.expr_scope)
self._process_children(node)
self.exit_scope()
else:
self._process_children(node)
return node
def visit_CArgDeclNode(self, node):
# default arguments are evaluated in the outer scope
if node.default:
attrs = [attr for attr in node.child_attrs if attr != 'default']
self._process_children(node, attrs)
self.enter_scope(node, self.current_env().outer_scope)
self.visitchildren(node, ('default',))
self.exit_scope()
else:
self._process_children(node)
return node
class NodeRefCleanupMixin(object):
"""
Clean up references to nodes that were replaced.
NOTE: this implementation assumes that the replacement is
done first, before hitting any further references during
normal tree traversal. This needs to be arranged by calling
"self.visitchildren()" at a proper place in the transform
and by ordering the "child_attrs" of nodes appropriately.
"""
def __init__(self, *args):
super(NodeRefCleanupMixin, self).__init__(*args)
self._replacements = {}
def visit_CloneNode(self, node):
arg = node.arg
if arg not in self._replacements:
self.visitchildren(arg)
node.arg = self._replacements.get(arg, arg)
return node
def visit_ResultRefNode(self, node):
expr = node.expression
if expr is None or expr not in self._replacements:
self.visitchildren(node)
expr = node.expression
if expr is not None:
node.expression = self._replacements.get(expr, expr)
return node
def replace(self, node, replacement):
self._replacements[node] = replacement
return replacement
find_special_method_for_binary_operator = {
'<': '__lt__',
'<=': '__le__',
'==': '__eq__',
'!=': '__ne__',
'>=': '__ge__',
'>': '__gt__',
'+': '__add__',
'&': '__and__',
'/': '__div__',
'//': '__floordiv__',
'<<': '__lshift__',
'%': '__mod__',
'*': '__mul__',
'|': '__or__',
'**': '__pow__',
'>>': '__rshift__',
'-': '__sub__',
'^': '__xor__',
'in': '__contains__',
}.get
find_special_method_for_unary_operator = {
'not': '__not__',
'~': '__inv__',
'-': '__neg__',
'+': '__pos__',
}.get
class MethodDispatcherTransform(EnvTransform):
"""
Base class for transformations that want to intercept on specific
builtin functions or methods of builtin types, including special
methods triggered by Python operators. Must run after declaration
analysis when entries were assigned.
Naming pattern for handler methods is as follows:
* builtin functions: _handle_(general|simple|any)_function_NAME
* builtin methods: _handle_(general|simple|any)_method_TYPENAME_METHODNAME
"""
# only visit call nodes and Python operations
def visit_GeneralCallNode(self, node):
self._process_children(node)
function = node.function
if not function.type.is_pyobject:
return node
arg_tuple = node.positional_args
if not isinstance(arg_tuple, ExprNodes.TupleNode):
return node
keyword_args = node.keyword_args
if keyword_args and not isinstance(keyword_args, ExprNodes.DictNode):
# can't handle **kwargs
return node
args = arg_tuple.args
return self._dispatch_to_handler(node, function, args, keyword_args)
def visit_SimpleCallNode(self, node):
self._process_children(node)
function = node.function
if function.type.is_pyobject:
arg_tuple = node.arg_tuple
if not isinstance(arg_tuple, ExprNodes.TupleNode):
return node
args = arg_tuple.args
else:
args = node.args
return self._dispatch_to_handler(node, function, args, None)
def visit_PrimaryCmpNode(self, node):
if node.cascade:
# not currently handled below
self._process_children(node)
return node
return self._visit_binop_node(node)
def visit_BinopNode(self, node):
return self._visit_binop_node(node)
def _visit_binop_node(self, node):
self._process_children(node)
# FIXME: could special case 'not_in'
special_method_name = find_special_method_for_binary_operator(node.operator)
if special_method_name:
operand1, operand2 = node.operand1, node.operand2
if special_method_name == '__contains__':
operand1, operand2 = operand2, operand1
elif special_method_name == '__div__':
if Future.division in self.current_env().global_scope().context.future_directives:
special_method_name = '__truediv__'
obj_type = operand1.type
if obj_type.is_builtin_type:
type_name = obj_type.name
else:
type_name = "object" # safety measure
node = self._dispatch_to_method_handler(
special_method_name, None, False, type_name,
node, None, [operand1, operand2], None)
return node
def visit_UnopNode(self, node):
self._process_children(node)
special_method_name = find_special_method_for_unary_operator(node.operator)
if special_method_name:
operand = node.operand
obj_type = operand.type
if obj_type.is_builtin_type:
type_name = obj_type.name
else:
type_name = "object" # safety measure
node = self._dispatch_to_method_handler(
special_method_name, None, False, type_name,
node, None, [operand], None)
return node
### dispatch to specific handlers
def _find_handler(self, match_name, has_kwargs):
call_type = has_kwargs and 'general' or 'simple'
handler = getattr(self, '_handle_%s_%s' % (call_type, match_name), None)
if handler is None:
handler = getattr(self, '_handle_any_%s' % match_name, None)
return handler
def _delegate_to_assigned_value(self, node, function, arg_list, kwargs):
assignment = function.cf_state[0]
value = assignment.rhs
if value.is_name:
if not value.entry or len(value.entry.cf_assignments) > 1:
# the variable might have been reassigned => play safe
return node
elif value.is_attribute and value.obj.is_name:
if not value.obj.entry or len(value.obj.entry.cf_assignments) > 1:
# the underlying variable might have been reassigned => play safe
return node
else:
return node
return self._dispatch_to_handler(
node, value, arg_list, kwargs)
def _dispatch_to_handler(self, node, function, arg_list, kwargs):
if function.is_name:
# we only consider functions that are either builtin
# Python functions or builtins that were already replaced
# into a C function call (defined in the builtin scope)
if not function.entry:
return node
entry = function.entry
is_builtin = (
entry.is_builtin or
entry is self.current_env().builtin_scope().lookup_here(function.name))
if not is_builtin:
if function.cf_state and function.cf_state.is_single:
# we know the value of the variable
# => see if it's usable instead
return self._delegate_to_assigned_value(
node, function, arg_list, kwargs)
if arg_list and entry.is_cmethod and entry.scope and entry.scope.parent_type.is_builtin_type:
if entry.scope.parent_type is arg_list[0].type:
# Optimised (unbound) method of a builtin type => try to "de-optimise".
return self._dispatch_to_method_handler(
entry.name, self_arg=None, is_unbound_method=True,
type_name=entry.scope.parent_type.name,
node=node, function=function, arg_list=arg_list, kwargs=kwargs)
return node
function_handler = self._find_handler(
"function_%s" % function.name, kwargs)
if function_handler is None:
return self._handle_function(node, function.name, function, arg_list, kwargs)
if kwargs:
return function_handler(node, function, arg_list, kwargs)
else:
return function_handler(node, function, arg_list)
elif function.is_attribute:
attr_name = function.attribute
if function.type.is_pyobject:
self_arg = function.obj
elif node.self and function.entry:
entry = function.entry.as_variable
if not entry or not entry.is_builtin:
return node
# C implementation of a Python builtin method - see if we find further matches
self_arg = node.self
arg_list = arg_list[1:] # drop CloneNode of self argument
else:
return node
obj_type = self_arg.type
is_unbound_method = False
if obj_type.is_builtin_type:
if obj_type is Builtin.type_type and self_arg.is_name and arg_list and arg_list[0].type.is_pyobject:
# calling an unbound method like 'list.append(L,x)'
# (ignoring 'type.mro()' here ...)
type_name = self_arg.name
self_arg = None
is_unbound_method = True
else:
type_name = obj_type.name
else:
type_name = "object" # safety measure
return self._dispatch_to_method_handler(
attr_name, self_arg, is_unbound_method, type_name,
node, function, arg_list, kwargs)
else:
return node
def _dispatch_to_method_handler(self, attr_name, self_arg,
is_unbound_method, type_name,
node, function, arg_list, kwargs):
method_handler = self._find_handler(
"method_%s_%s" % (type_name, attr_name), kwargs)
if method_handler is None:
if (attr_name in TypeSlots.method_name_to_slot
or attr_name == '__new__'):
method_handler = self._find_handler(
"slot%s" % attr_name, kwargs)
if method_handler is None:
return self._handle_method(
node, type_name, attr_name, function,
arg_list, is_unbound_method, kwargs)
if self_arg is not None:
arg_list = [self_arg] + list(arg_list)
if kwargs:
result = method_handler(
node, function, arg_list, is_unbound_method, kwargs)
else:
result = method_handler(
node, function, arg_list, is_unbound_method)
return result
def _handle_function(self, node, function_name, function, arg_list, kwargs):
"""Fallback handler"""
return node
def _handle_method(self, node, type_name, attr_name, function,
arg_list, is_unbound_method, kwargs):
"""Fallback handler"""
return node
class RecursiveNodeReplacer(VisitorTransform):
"""
Recursively replace all occurrences of a node in a subtree by
another node.
"""
def __init__(self, orig_node, new_node):
super(RecursiveNodeReplacer, self).__init__()
self.orig_node, self.new_node = orig_node, new_node
def visit_CloneNode(self, node):
if node is self.orig_node:
return self.new_node
if node.arg is self.orig_node:
node.arg = self.new_node
return node
def visit_Node(self, node):
self._process_children(node)
if node is self.orig_node:
return self.new_node
else:
return node
def recursively_replace_node(tree, old_node, new_node):
replace_in = RecursiveNodeReplacer(old_node, new_node)
replace_in(tree)
class NodeFinder(TreeVisitor):
"""
Find out if a node appears in a subtree.
"""
def __init__(self, node):
super(NodeFinder, self).__init__()
self.node = node
self.found = False
def visit_Node(self, node):
if self.found:
pass # short-circuit
elif node is self.node:
self.found = True
else:
self._visitchildren(node, None)
def tree_contains(tree, node):
finder = NodeFinder(node)
finder.visit(tree)
return finder.found
# Utils
def replace_node(ptr, value):
"""Replaces a node. ptr is of the form used on the access path stack
(parent, attrname, listidx|None)
"""
parent, attrname, listidx = ptr
if listidx is None:
setattr(parent, attrname, value)
else:
getattr(parent, attrname)[listidx] = value
class PrintTree(TreeVisitor):
"""Prints a representation of the tree to standard output.
Subclass and override repr_of to provide more information
about nodes. """
def __init__(self, start=None, end=None):
TreeVisitor.__init__(self)
self._indent = ""
if start is not None or end is not None:
self._line_range = (start or 0, end or 2**30)
else:
self._line_range = None
def indent(self):
self._indent += " "
def unindent(self):
self._indent = self._indent[:-2]
def __call__(self, tree, phase=None):
print("Parse tree dump at phase '%s'" % phase)
self.visit(tree)
return tree
# Don't do anything about process_list, the defaults gives
# nice-looking name[idx] nodes which will visually appear
# under the parent-node, not displaying the list itself in
# the hierarchy.
def visit_Node(self, node):
self._print_node(node)
self.indent()
self.visitchildren(node)
self.unindent()
return node
def visit_CloneNode(self, node):
self._print_node(node)
self.indent()
line = node.pos[1]
if self._line_range is None or self._line_range[0] <= line <= self._line_range[1]:
print("%s- %s: %s" % (self._indent, 'arg', self.repr_of(node.arg)))
self.indent()
self.visitchildren(node.arg)
self.unindent()
self.unindent()
return node
def _print_node(self, node):
line = node.pos[1]
if self._line_range is None or self._line_range[0] <= line <= self._line_range[1]:
if len(self.access_path) == 0:
name = "(root)"
else:
parent, attr, idx = self.access_path[-1]
if idx is not None:
name = "%s[%d]" % (attr, idx)
else:
name = attr
print("%s- %s: %s" % (self._indent, name, self.repr_of(node)))
def repr_of(self, node):
if node is None:
return "(none)"
else:
result = node.__class__.__name__
if isinstance(node, ExprNodes.NameNode):
result += "(type=%s, name=\"%s\")" % (repr(node.type), node.name)
elif isinstance(node, Nodes.DefNode):
result += "(name=\"%s\")" % node.name
elif isinstance(node, ExprNodes.ExprNode):
t = node.type
result += "(type=%s)" % repr(t)
elif node.pos:
pos = node.pos
path = pos[0].get_description()
if '/' in path:
path = path.split('/')[-1]
if '\\' in path:
path = path.split('\\')[-1]
result += "(pos=(%s:%s:%s))" % (path, pos[1], pos[2])
return result
if __name__ == "__main__":
import doctest
doctest.testmod()
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