Develop a visual application for lexical and syntactical analysis of a predicate term

Question

Develop a visual application for lexical and syntactical analysis of a predicate term.
If correct, it should display all lexical units.
Syntax of the term:
Constant: Natural number or string enclosed in single quotes (' ')
Variable: Identifier
Function: Identifier (term1, ..., termn) / n > 1, Allows spaces.

Answer 1

import ply.lex as lex
import ply.yacc as yacc

# Define the tokens
tokens = (
'CONSTANT',
'VARIABLE',
'FUNCTION',
)

# Regular expressions for tokens
t_CONSTANT = r"'[^']*'"
t_VARIABLE = r'[a-zA-Z_][a-zA-Z0-9_]*'
t_FUNCTION = r'[a-zA-Z_][a-zA-Z0-9_]*\s*\([^)]+\)'

# Define a parser
def p_predicate_term(p):
'''predicate_term : CONSTANT
| VARIABLE
| FUNCTION'''
p[0] = p[1]

# Error handling
def p_error(p):
print("Syntax error in input!")

# Build the lexer and parser
lexer = lex.lex()
parser = yacc.yacc()

# Input from the user
input_term = input("Enter a predicate term: ")

# Lexical analysis
lexer.input(input_term)
for token in lexer:
print(f"Token: {token.type}, Value: {token.value}")

# Syntactical analysis
parsed_term = parser.parse(input_term)
if parsed_term:
print("Syntax is correct.")
else:
print("Syntax is incorrect.")