class StreamFilter(Filter):

    '''Wraps a reader in a way that's usable to a filter stream that does not

    require lines to be strings. Reports EOF as '' instead of StopIteration.'''

    def __init__(self, reader):

        Filter.__init__(self, None, reader)

    def readline(self):

        try: return self.reader.next()

        except StopIteration: return '' # EOF