import Test
import sys
from Plex import *

letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_"

wax = Any("(")
wane = Any(")")
letter = Any(letters)
space = Any(" \t\n")

def open_paren(s, t):
  s.counter = s.counter + 1

def close_paren(s, t):
  s.counter = s.counter - 1

def got_a_letter(s, t):
  if s.counter == 0:
    return 'letter'
  else:
    return None

lex = Lexicon([
  (wax, open_paren),
  (wane, close_paren),
  (letter, got_a_letter),
  (space, IGNORE)
], 
debug = Test.debug,
timings = sys.stderr
)

class MyScanner(Scanner):
  counter = 0
  trace = 0

Test.run(lex, "test4", scanner_class = MyScanner, trace = 0)