Digital Assignment -1
COURSE NAME: Compiler Design Lab
COURSE CODE: BCSE307P
FACULTY NAME: Sabyasachi Kamila
NAME OF THE STUDENT: A.Dileesha
REGISTRATION NUMBER: 22BCI0131
Question
Write a program in any language to create a Symbol Table to Insert, Delete, Display all <token,
lexeme> pairs from a given Input code Snippet.
Input code snippet also can be of any language.
Sample Input:
float f1;
int x, i=0;
while(i<5)
if((i+2) == 3)
break;
else
print("Value of i =%d", i);
Sample Output:
Make a Symbol Table entry where following details should be present
Token, lexeme
id, f1
id, x
id, I
key, float
key, int
... .so on, all token, lexeme pairs
You should also be able to insert/delete/display any<token, lexeme> pairs
Code:
import re
class Symbol:
def __init__(self, token, lexeme):
self.token = token
self.lexeme = lexeme
def __str__(self):
return f"{self.token}, {self.lexeme}"
class SymbolTable:
def __init__(self):
self.symbols = []
self.keywords = {"int", "float", "char", "while", "if", "break", "else",
"print","double","cout","continue","for","do","while","in","and","goto","not","is","or","string","vect
or","tuple","arrayList","println","input","void","def","new","class","struct","cout","cin","map"}
def add_symbol(self, token, lexeme):
self.symbols.append(Symbol(token, lexeme))
print(f"Inserted: ({token}, {lexeme})")
def delete_symbol(self, lexeme):
initial_length = len(self.symbols)
self.symbols = [s for s in self.symbols if s.lexeme != lexeme]
if len(self.symbols) < initial_length:
print(f"Deleted symbol with lexeme: {lexeme}")
else:
print(f"Symbol with lexeme '{lexeme}' not found.")
def display_symbol_table(self):
print("\nToken, lexeme")
for symbol in self.symbols:
print(symbol)
def parse_code(self, code):
identifiers = set()
key = set()
lit = set()
literals = re.findall(r'"[^"]*"', code)
code = re.sub(r'"[^"]*"', '', code)
symbols = re.findall(r'\b\w+\b', code)
for literal in literals:
lit.add(literal)
for symbol in symbols:
if symbol.isdigit():
lit.add(symbol)
elif symbol.isalnum():
if symbol not in self.keywords:
identifiers.add(symbol)
else:
key.add(symbol)
for keyword in key:
symbol_table.add_symbol("key", keyword)
for identifier in identifiers:
symbol_table.add_symbol("id", identifier)
for literal in lit:
symbol_table.add_symbol("lit", literal)
code_lines = []
print("Enter code:")
while True:
line = input()
if line.strip() == "":
break
code_lines.append(line)
code_snippet = "\n".join(code_lines)
symbol_table = SymbolTable()
symbol_table.parse_code(code_snippet)
symbol_table.display_symbol_table()
while True:
action = input("\nDo you want to add or delete a symbol? (Enter 'add', 'delete', 'display', or 'quit'):
").strip().lower()
if action == 'add':
new_code_snippet = input("Enter new line of code: ")
symbol_table.parse_code(new_code_snippet)
elif action == 'delete':
lexeme = input("Enter the lexeme of the symbol to delete: ").strip()
symbol_table.delete_symbol(lexeme)
elif action == 'display':
symbol_table.display_symbol_table()
elif action == 'quit':
break
else:
print("Invalid action. Please enter 'add', 'delete', or 'quit'.")
symbol_table.display_symbol_table()
Output:
