# I/O

class WrapStream:

    '''Forwards close() to the underlying stream'''

    def __init__(self, stream): self.stream = stream

    def close(self): self.stream.close()

class StreamIter(WrapStream):

    Unlike stream.__iter__(), doesn't wait for EOF to start returning lines.

    Offers curr() method.

    '''

    def __init__(self, stream):

    def __iter__(self): return self

    def curr(self):

        if self.line == None: self.line = self.stream.readline()

        if self.line == '': raise StopIteration

        return self.line

    def next(self):

        line = self.curr()

        self.line = None

        return line

    for line in StreamIter(from_): to.write(line)

    def __init__(self, stream, timeout):

    '''Wraps a stream, filtering each string read or written'''

    def __init__(self, filter_, stream):

    '''Wraps a stream, running a trace function on each string read or written

    '''

    def __init__(self, trace, stream):

        def filter_(str_):

            trace(str_)

            return str_

        FilterStream.__init__(self, filter_, stream)

    '''Wraps a unidirectional stream, making the current line number available.

    def __init__(self, stream):

        self.line_num = 1

        def trace(str_): self.line_num += str_.count('\n')

class CaptureStream(TracedStream):

    '''Wraps a stream, capturing matching text.

        self.recording = False

        def trace(str_):

            if not self.recording:

                start_idx = str_.find(start_str)

                if start_idx >= 0:

                    self.recording = True

                    self.matches.append('')

            if self.recording:

                end_idx = str_.find(end_str)

                if end_idx >= 0:

                    self.recording = False

                    end_idx += len(end_str)

                else: end_idx = len(str_)

                self.matches[-1] += str_[start_idx:end_idx]

        TracedStream.__init__(self, trace, stream)