Блочный алгоритм удаления комментариев из файла

comments.py

from StringIO import StringIO
import re
import itertools

s = 'text1 text2 /* asdasd */ text3 /* /*asdasd */ text4'

BLOCK = 6  # even number!

OPEN = 1
CLOSE = 2
another = {OPEN: CLOSE, CLOSE: OPEN}

def blocked(f, position=False):
    while True:
        block = f.read(BLOCK)
        if not block:
            break
        if position:
            yield (block, f.pos - BLOCK)
        else:
            yield block

def finder(block):
    block, pos = block
    comments = [(m.start() + pos, OPEN) for m in re.finditer('/\*', block)] + \
            [(m.end() + pos, CLOSE) for m in re.finditer('\*/', block)]
    return comments

def reducer(datafile):
    def do_reduce(data, item, waiting=[OPEN]):
        if waiting[0] == item[1]:
            waiting[0] = another[waiting[0]]
            new_data = datafile.read(item[0] - datafile.pos)

            if item[1] == OPEN:
                data.append(new_data)
                return data
            else:
                return data
        else:
            return data
    return do_reduce

datafile = StringIO(s)


comments = itertools.chain([[]], *map(finder, blocked(datafile, position=True)))
datafile.seek(0)
result = ''.join(reduce(reducer(datafile), comments)) + datafile.read()
print result