# example.py
#
# Example of a tokenizer

import re
from collections import namedtuple

NAME = r'(?P<NAME>[a-zA-Z_][a-zA-Z_0-9]*)'
NUM  = r'(?P<NUM>\d+)'
PLUS = r'(?P<PLUS>\+)'
TIMES = r'(?P<TIMES>\*)'
EQ    = r'(?P<EQ>=)'
WS    = r'(?P<WS>\s+)'

master_pat = re.compile('|'.join([NAME, NUM, PLUS, TIMES, EQ, WS]))

Token = namedtuple('Token', ['type','value'])

def generate_tokens(pat, text):
    scanner = pat.scanner(text)
    for m in iter(scanner.match, None):
        yield Token(m.lastgroup, m.group())

for tok in generate_tokens(master_pat, 'foo = 42'):
    print(tok)