def fixline(line):
	# Quick check for easy case
	if '=' not in line: return line
	
	i, n = 0, len(line)
	stack = []
	while i < n:
		j = tokenprog.match(line, i)
		if j < 0:
			# A bad token; forget about the rest of this line
			print '(Syntax error:)'
			print line,
			return line
		a, b = tokenprog.regs[3] # Location of the token proper
		token = line[a:b]
		i = i+j
		if stack and token == stack[-1]:
			del stack[-1]
		elif match.has_key(token):
			stack.append(match[token])
		elif token == '=' and stack:
			line = line[:a] + '==' + line[b:]
			i, n = a + len('=='), len(line)
		elif token == '==' and not stack:
			print '(Warning: \'==\' at top level:)'
			print line,
	return line

def lex(text, textpos, filepath):
    offset = pos = 0
    end = len(text)
    escaped = False

    while 1:
        if escaped:
            offset = text.find(PREFIX, offset + 2)
            escaped = False
        else:
            offset = text.find(PREFIX, pos)
        if offset < 0 or offset == end - 1:
            break
        next = text[offset + 1]

        if next == '{':
            if offset > pos:
                yield False, text[pos:offset]
            pos = offset + 2
            level = 1
            while level:
                match = tokenprog.match(text, pos)
                if match is None:
                    raise TemplateSyntaxError('invalid syntax',  filepath,
                                              *textpos[1:])
                pos = match.end()
                tstart, tend = match.regs[3]
                token = text[tstart:tend]
                if token == '{':
                    level += 1
                elif token == '}':
                    level -= 1
            yield True, text[offset + 2:pos - 1]

        elif next in NAMESTART:
            if offset > pos:
                yield False, text[pos:offset]
                pos = offset
            pos += 1
            while pos < end:
                char = text[pos]
                if char not in NAMECHARS:
                    break
                pos += 1
            yield True, text[offset + 1:pos].strip()

        elif not escaped and next == PREFIX:
            escaped = True
            pos = offset + 1

        else:
            yield False, text[pos:offset + 1]
            pos = offset + 1

    if pos < end:
        yield False, text[pos:]

def _matchorfail(text, pos):
	match = tokenprog.match(text, pos)
	if match is None: raise ValueError(text, pos)
	return match, match.end()

def match_or_fail(text, pos):
    """match_or_fail(text, pos)"""
    match = tokenprog.match(text, pos)
    if match is None:
        raise ItplError(text, pos)
    return match, match.end()

 def matchorfail(text, pos):
     match = tokenprog.match(text, pos)  # @UndefinedVariable
     if match is None:
         raise _ItplError(text, pos)
     return match, match.end()

#! /usr/bin/env python