Calc1, Python 3 - rextester

Calc1

#python 3.6.9

# ------------------------------------------------------------
# calclex.py
#
# tokenizer for a simple expression evaluator for
# numbers and +,-,*,/
# ------------------------------------------------------------
import ply.lex as lex
 
# List of token names.   This is always required
tokens = (
    'NUMBER',
    'PLUS',
    'MINUS',
    'TIMES',
    'DIVIDE',
    'LPAREN',
    'RPAREN',
    'RESIDUO',
    'GUIONES',
    'NUMDEC',
    'IGUAL',
    'VAR'
)
 
# Regular expression rules for simple tokens
t_PLUS    = r'\+'
t_MINUS   = r'-'
t_TIMES   = r'\*'
t_DIVIDE  = r'/'
t_LPAREN  = r'\('
t_RPAREN  = r'\)'
t_RESIDUO = r'\%'
t_GUIONES = r'===='
t_ignore  = ' \t'   # A string containing ignored characters (spaces and tabs)

def t_VAR(t):
    r'[a-zA-Z][a-zA-Z0-9]*'
    return t

def t_IGUAL(t):
    r'='
    return t

def t_NUMDEC(t) :
     r'[-+]?\d+\.\d+'
     t.value = float(t.value)    
     return t

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

# Define a rule so we can track line numbers
def t_newline(t):
     r'\n+'
     t.lexer.lineno += t.value.count('\n')
 
# Error handling rule
def t_error(t):
     print("Illegal character '%s'" % t.value[0])
     t.lexer.skip(1)
 
# Build the lexer
lexer = lex.lex()

# --- Probar el lexer construido
data1 ="Var23 = 40 + 89.23"

lexer.input(data1)

# Tokenize
while True:
     tok = lexer.token()
     if not tok: 
         break
         """
         more = input("teclee mas expresiones: ")
         if not more:
             break
         lexer.input(more)
         """
     print(tok)


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