AnalizaSin.py

from ply.lex import lex
from ply.yacc import yacc

tokens = ( 'PLUS', 'MINUS', 'TIMES', 'DIVIDE', 'LPAREN', 'RPAREN',
           'NAME', 'NUMBER' )

t_ignore = ' \t'

t_PLUS = r'\+'
t_MINUS = r'-'
t_TIMES = r'\*'
t_DIVIDE = r'/'
t_LPAREN = r'\('
t_RPAREN = r'\)'
t_NAME = r'[a-zA-Z_][a-zA-Z0-9_]*'

def t_NUMBER(t):
    r'\d+'
    t.value = int(t.value)
    return t

def t_ignore_newline(t):
    r'\n+'
    t.lexer.lineno += t.value.count('\n')

def t_error(t):
    print(f'Illegal character {t.value[0]!r}')
    t.lexer.skip(1)


# --- Parser
def p_expression(p):
    '''
    expression : term PLUS term
               | term MINUS term
    '''
    p[0] = ('binop', p[2], p[1], p[3])

def p_expression_term(p):
    '''
    expression : term
    '''
    p[0] = p[1]

def p_term(p):
    '''
    term : factor TIMES factor
         | factor DIVIDE factor
    '''
    p[0] = ('binop', p[2], p[1], p[3])

def p_term_factor(p):
    '''
    term : factor
    '''
    p[0] = p[1]

def p_factor_number(p):
    '''
    factor : NUMBER
    '''
    p[0] = ('number', p[1])

def p_factor_name(p):
    '''
    factor : NAME
    '''
    p[0] = ('name', p[1])

def p_factor_unary(p):
    '''
    factor : PLUS factor
           | MINUS factor
    '''
    p[0] = ('unary', p[1], p[2])

def p_factor_grouped(p):
    '''
    factor : LPAREN expression RPAREN
    '''
    p[0] = ('grouped', p[2])

def p_error(p):
    print(f'Syntax error at {p.value!r}')


lexer = lex()
parser = yacc()
exp = '2 * 3 + 4 * (5 - variable)'

print(f"Analizando la expresión -> {exp}")
ast = parser.parse(exp)
print(ast)
print("\n Programa Correcto")