cdecl.py challenge

[Simon Burton]

To the curious C/python programmer,

Am hacking a cdecl.py today (fish book under-arm).
Any one up for a race/collab?
(This is something for the cookbook, i reckon.)
Here is my (barely doing anything) code so far:

#!/usr/bin/env python

import sys
from string import *

type_list = "void char signed unsigned short int long float double struct union enum".split()
qual_list = "const volatile".split()
def classify(s):
  if s in type_list: return "TYPE"
  if s in qual_list: return "QUAL"
  else: return "ID"

def next_tok(s):
  i=0
  while i < len(s):
    if s[i].isalnum():
      j=i+1
      while j<len(s):
        if s[j].isalnum():
          j=j+1
          continue
        else:
          break
      tok = s[i:j]
      s = s[j:]
      return tok, classify(tok), s
    if s[i] in '*()[];,':
      tok = s[i]
      s=s[i+1:]
      return tok, "PUNCT", s
    i=i+1
  return "", "", ""

def cdecl(s):
  tok, tp, s = next_tok(s)
  while tok:
    print tok, tp
    tok, tp, s = next_tok(s)
     
sys.stdout.write(">>> ")
if not sys.argv[1:]:
  s = sys.stdin.readline()
else:
  s = join(sys.argv[1:])
cdecl( s )