line_buffer.py

from cStringIO import StringIO

class LineBuffer(object):
    """
    Simple line buffer implementation for line-based data streams.

    Use like this (in this example with a socket `s`):

    ------
    from line_buffer import LineBuffer
    ...
    lb = LineBuffer()
    while True:
        lb.feed(s.recv(2048))
        for line in lb:
            print(line)
        ...
    ------

    If you set `strip` to False in the constructor, CR and LF are retained,
    otherwise they are stripped.
    """

    def __init__(self, strip=True):
        self.strip = strip
        self.buffer = StringIO()

    def feed(self, data):
        self.buffer.write(data)

    def __iter__(self):
        self.buffer.seek(0)
        return self

    def next(self):
        line = self.buffer.readline()
        if line.endswith('\n'):
            return line.strip('\r\n') if self.strip else line
        else:
            self.buffer.seek(0)
            self.buffer.write(line)
            self.buffer.truncate()
            raise StopIteration