Asynchronous child IO with pyuv

gistfile1.py

import os
import re

import pyuv


LINESEP = os.linesep.encode()
PATTERN = re.compile(r'^(?P<file_name>([A-Za-z]:)?[^:]+):'
                     '(?P<line_number>\d+):((?P<position>\d+):)?'
                     '\s+((?P<code>\w{4,4})\s+)?(?P<reason>.*)$')


class LineReaderPipe(pyuv.Pipe):

    def __init__(self, *args, **kwargs):
        super(LineReaderPipe, self).__init__(*args, **kwargs)
        self.callback = None
        self.buffer = b''

    def on_pipe_read(self, pipe, data, error):
        if error:
            pipe.close()
            return

        for line in data.splitlines(True):
            if not line[-len(LINESEP):] == LINESEP:
                self.buffer += line
                return

            line = line.strip()
            if self.buffer:
                line = self.buffer + line
                self.buffer = b''

            self.callback(line)

    def start_read(self, callback):
        self.callback = callback
        super(LineReaderPipe, self).start_read(self.on_pipe_read)


def exit_cb(proc, exit_status, term_signal):
    print (proc, exit_status, term_signal)


def process_line(line):
    match = PATTERN.match(line.decode('utf-8'))
    if match:
        print (match.group('line_number'), match.group('code'))


def main():
    loop = pyuv.Loop.default_loop()
    pipe = LineReaderPipe(loop)
    proc = pyuv.Process(loop)

    ios = [pyuv.StdIO(),
           # pyuv.StdIO(fd=1, flags=pyuv.UV_INHERIT_FD),
           pyuv.StdIO(pipe, flags=pyuv.UV_CREATE_PIPE | pyuv.UV_WRITABLE_PIPE),
           pyuv.StdIO()]

    proc.spawn('flake8', exit_cb, ('bottle.py',), stdio=ios)
    pipe.start_read(process_line)
    loop.run()


if __name__ == '__main__':
    main()