Create app.py

app.py

@@ -0,0 +1,312 @@
+import copy
+import streamlit as st
+
+stateMap = {}
+diction = {}
+start_symbol = "" 
+rules = []
+statesDict={}
+stateCount = 0
+separatedRulesList = []
+
+def grammarAugmentation(rules, nonterm_userdef, start_symbol):
+    newRules = []
+    newChar = start_symbol + "'"
+    while (newChar in nonterm_userdef):
+        newChar += "'"
+    newRules.append([newChar, ['.', start_symbol]])
+    for rule in rules:
+        k = rule.split("->")
+        lhs = k[0].strip()
+        rhs = k[1].strip()
+        multirhs = rhs.split('|')
+        for rhs1 in multirhs:
+            rhs1 = rhs1.strip().split()
+            rhs1.insert(0, '.')
+            newRules.append([lhs, rhs1])
+    return newRules
+
+def findClosure(input_state, dotSymbol):
+    global separatedRulesList
+
+    closureSet = []
+
+    if isinstance(input_state, int):
+        for rule in separatedRulesList:
+            if rule[0] == dotSymbol:
+                closureSet.append(rule)
+    else:
+        closureSet = input_state
+
+    prevLen = -1
+    while prevLen != len(closureSet):
+        prevLen = len(closureSet)
+
+        tempClosureSet = []
+        for rule in closureSet:
+            indexOfDot = rule[1].index('.')
+            if rule[1][-1] != '.':
+                dotPointsHere = rule[1][indexOfDot + 1]
+                for in_rule in separatedRulesList:
+                    if dotPointsHere == in_rule[0] and in_rule not in tempClosureSet:
+                        tempClosureSet.append(in_rule)
+
+        for rule in tempClosureSet:
+            if rule not in closureSet:
+                closureSet.append(rule)
+    return closureSet
+
+def compute_GOTO(state):
+    global statesDict, stateCount
+    generateStatesFor = []
+    for rule in statesDict[state]:
+        if rule[1][-1] != '.':
+            indexOfDot = rule[1].index('.')
+            dotPointsHere = rule[1][indexOfDot + 1]
+            if dotPointsHere not in generateStatesFor:
+                generateStatesFor.append(dotPointsHere)
+    if len(generateStatesFor) != 0:
+        for symbol in generateStatesFor:
+            GOTO(state, symbol)
+    return
+
+def GOTO(state, charNextToDot):
+    global statesDict, stateCount, stateMap
+    newState = []
+    for rule in statesDict[state]:
+        indexOfDot = rule[1].index('.')
+        if rule[1][-1] != '.':
+            if rule[1][indexOfDot + 1] == charNextToDot:
+                shiftedRule = copy.deepcopy(rule)
+                shiftedRule[1][indexOfDot] = shiftedRule[1][indexOfDot + 1]
+                shiftedRule[1][indexOfDot + 1] = '.'
+                newState.append(shiftedRule)
+
+    addClosureRules = []
+    for rule in newState:
+        indexDot = rule[1].index('.')
+        if rule[1][-1] != '.':
+            closureRes = findClosure(newState, rule[1][indexDot + 1])
+            for rule in closureRes:
+                if rule not in addClosureRules and rule not in newState:
+                    addClosureRules.append(rule)
+
+    for rule in addClosureRules:
+        newState.append(rule)
+
+    stateExists = -1
+    for state_num in statesDict:
+        if statesDict[state_num] == newState:
+            stateExists = state_num
+            break
+
+    if stateExists == -1:
+        stateCount += 1
+        statesDict[stateCount] = newState
+        stateMap[(state, charNextToDot)] = stateCount
+    else:
+        stateMap[(state, charNextToDot)] = stateExists
+    return
+
+def generateStates(I0):
+    global statesDict, stateCount
+
+    statesDict[0] = I0
+    stateCount = 0
+    prev_len = -1
+    called_GOTO_on = []
+    while (len(statesDict) != prev_len):
+        prev_len = len(statesDict)
+        keys = list(statesDict.keys())
+        for key in keys:
+            if key not in called_GOTO_on:
+                called_GOTO_on.append(key)
+                compute_GOTO(key)
+    return
+
+def first(rule):
+    global diction, term_userdef
+    if len(rule) != 0 and (rule is not None):
+        if rule[0] in term_userdef:
+            return rule[0]
+        elif rule[0] == '#':
+            return '#'
+    if len(rule) != 0:
+        if rule[0] in list(diction.keys()):
+            fres = []
+            rhs_rules = diction[rule[0]]
+            for itr in rhs_rules:
+                indivRes = first(itr)
+                if type(indivRes) is list:
+                    for i in indivRes:
+                        fres.append(i)
+                else:
+                    fres.append(indivRes)
+
+            if '#' not in fres:
+                return fres
+            else:
+                newList = []
+                fres.remove('#')
+                if len(rule) > 1:
+                    ansNew = first(rule[1:])
+                    if ansNew != None:
+                        if type(ansNew) is list:
+                            newList = fres + ansNew
+                        else:
+                            newList = fres + [ansNew]
+                    else:
+                        newList = fres
+                    return newList
+                fres.append('#')
+                return fres
+
+def follow(nt):
+    global start_symbol, diction
+    solset = set()
+    if nt == start_symbol:
+        solset.add('$')
+    for curNT in diction:
+        rhs = diction[curNT]
+        for subrule in rhs:
+            if nt in subrule:
+                while nt in subrule:
+                    index_nt = subrule.index(nt)
+                    subrule = subrule[index_nt + 1:]
+                    if len(subrule) != 0:
+                        res = first(subrule)
+                        if '#' in res:
+                            newList = []
+                            res.remove('#')
+                            ansNew = follow(curNT)
+                            if ansNew != None:
+                                if type(ansNew) is list:
+                                    newList = res + ansNew
+                                else:
+                                    newList = res + [ansNew]
+                            else:
+                                newList = res
+                            res = newList
+                    else:
+                        if nt != curNT:
+                            res = follow(curNT)
+
+                    if res is not None:
+                        if type(res) is list:
+                            for g in res:
+                                solset.add(g)
+                        else:
+                            solset.add(res)
+    return list(solset)
+
+def createParseTable(statesDict, stateMap, T, NT):
+    global separatedRulesList, diction
+
+    parse_table = {i: {} for i in range(len(statesDict))}
+
+    for (state, symbol) in stateMap:
+        if symbol in T:
+            parse_table[state][symbol] = f'S{stateMap[(state, symbol)]}'
+        elif symbol in NT:
+            parse_table[state][symbol] = str(stateMap[(state, symbol)])
+
+    for state in statesDict:
+        for item in statesDict[state]:
+            if item[1][-1] == '.':  
+                prod = f"{item[0]} -> {' '.join(item[1][:-1])}"
+           
+                if prod == f"{separatedRulesList[0][0]} -> {separatedRulesList[0][1][1]}":
+                    parse_table[state]['$'] = 'ACC'
+                else:
+                    rule_index = next(
+                        (i for i, rule in enumerate(separatedRulesList) if rule == item),
+                        None  
+                    )
+
+                    if rule_index is None:
+                        print(f"Warning: Rule for item {item} not found in separatedRulesList.")
+                        continue  
+
+                    for symbol in T + ['$']:
+                        if symbol not in parse_table[state]:
+                            parse_table[state][symbol] = f'R{rule_index}'
+
+    return parse_table
+
+
+def main():
+    st.title("SLR(1) Parser Generator")
+
+    st.header("Grammar Input")
+    rules = st.text_area("Enter the grammar rules (one per line):", 
+                         "E -> E + T | T\nT -> T * F | F\nF -> ( E ) | id")
+    rules = rules.split('\n')
+    
+    nonterm_userdef = st.text_input("Enter the non-terminal symbols (separated by space):", "E T F")
+    nonterm_userdef = nonterm_userdef.split()
+    
+    term_userdef = st.text_input("Enter the terminal symbols (separated by space):", "id + * ( )")
+    term_userdef = term_userdef.split()
+    
+    start_symbol = st.text_input("Enter the start symbol:", "E")
+
+    if st.button("Generate SLR(1) Parser"):
+        st.subheader("Original Grammar Input:")
+        for rule in rules:
+            st.write(rule)
+
+        st.subheader("Grammar after Augmentation:")
+        global separatedRulesList
+        separatedRulesList = grammarAugmentation(rules, nonterm_userdef, start_symbol)
+        for rule in separatedRulesList:
+            st.write(f"{rule[0]} -> {' '.join(rule[1])}")
+
+        start_symbol = separatedRulesList[0][0]
+        st.subheader("Calculated Closure: I0")
+        I0 = findClosure(0, start_symbol)
+
+        st.write("I0:")
+        for rule in I0:
+            st.write(f"{rule[0]} -> {' '.join(rule[1])}")
+
+        generateStates(I0)
+
+        st.subheader("Generated States:")
+        for state, rules in statesDict.items():
+            st.write(f"I{state}:")
+            for rule in rules:
+                st.write(f"  {rule[0]} -> {' '.join(rule[1])}")
+            st.write("")
+
+        st.subheader("SLR(1) Parsing Table")
+        table = createParseTable(statesDict, stateMap, term_userdef, nonterm_userdef)
+  
+        cols = ['State'] + term_userdef + ['$'] + nonterm_userdef
+        table_data = []
+        for state in range(len(statesDict)):
+            row = [f'I{state}']
+            for symbol in term_userdef + ['$'] + nonterm_userdef:
+                row.append(table[state].get(symbol, ''))
+            table_data.append(row)
+        
+        st.table([cols] + table_data)
+
+        compact_table = "State`" + '`'.join(term_userdef + ['$'] + nonterm_userdef) + '`'
+        for state in range(len(statesDict)):
+            compact_table += f"I{state}"
+            for symbol in term_userdef + ['$'] + nonterm_userdef:
+                compact_table += table[state].get(symbol, '')
+        st.subheader("Follow Sets")
+        follow_sets = {}
+        for nt in nonterm_userdef:
+            follow_set = follow(nt)
+            follow_sets[nt] = follow_set
+            st.write(f"Follow({nt}): {{ {' , '.join(follow_set)} }}")
+        compact_follow = "Non-Terminal`Follow Set\n"
+        for nt, follow_set in follow_sets.items():
+            compact_follow += f"{nt}`{{ {' , '.join(follow_set)} }}\n"
+        
+        st.text_area("Compact Follow Sets Representation:", value=compact_follow, height=300)
+
+if __name__ == "__main__":
+    main()