lex_state_try.py

# lex_state_try.py
#
# Declaration of a state for which no rules are defined

import sys
if ".." not in sys.path: sys.path.insert(0,"..")

import ply.lex as lex

tokens = [ 
    "PLUS",
    "MINUS",
    "NUMBER",
    ]

states = (('comment', 'exclusive'),)

t_PLUS = r'\+'
t_MINUS = r'-'
t_NUMBER = r'\d+'

t_ignore = " \t"

# Comments
def t_comment(t):
    r'/\*'
    t.lexer.begin('comment')
    print("Entering comment state")

def t_comment_body_part(t):
    r'(.|\n)*\*/'
    print("comment body %s" % t)
    t.lexer.begin('INITIAL')

def t_error(t):
    pass

t_comment_error = t_error
t_comment_ignore = t_ignore

lex.lex()

data = "3 + 4 /* This is a comment */ + 10"

lex.runmain(data=data)