plugins/rb/Coroutine.py

   1 # -*- Mode: python; coding: utf-8; tab-width: 8; indent-tabs-mode: t; -*-
   2 #
   3 # Copyright (C) 2006 - Ed Catmur <ed@catmur.co.uk>
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation; either version 2, or (at your option)
   8 # any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program; if not, write to the Free Software
  17 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA.
  18
  19 class Coroutine:
  20         """A simple message-passing coroutine implementation.
  21         Not thread- or signal-safe.
  22         Usage:
  23                 def my_iter (plexer, args):
  24                         some_async_task (..., callback=plexer.send (tokens))
  25                         yield None
  26                         tokens, (data, ) = plexer.receive ()
  27                         ...
  28                 Coroutine (my_iter, args).begin ()
  29         """
  30         def __init__ (self, iter, *args):
  31                 self._continuation = iter (self, *args)
  32                 self._executing = False
  33         def _resume (self):
  34                 if not self._executing:
  35                         self._executing = True
  36                         try:
  37                                 try:
  38                                         self._continuation.next ()
  39                                         while self._data:
  40                                                 self._continuation.next ()
  41                                 except StopIteration:
  42                                         pass
  43                         finally:
  44                                 self._executing = False
  45         def clear (self):
  46                 self._data = []
  47         def begin (self):
  48                 self.clear ()
  49                 self._resume ()
  50         def send (self, *tokens):
  51                 def callback (*args):
  52                         self._data.append ((tokens, args))
  53                         self._resume ()
  54                 return callback
  55         def receive (self):
  56                 return self._data.pop (0)
  57