1 # Copyright (C) 2010 W. Trevor King <wking@drexel.edu>
3 # This file is part of Hooke.
5 # Hooke is free software: you can redistribute it and/or modify it
6 # under the terms of the GNU Lesser General Public License as
7 # published by the Free Software Foundation, either version 3 of the
8 # License, or (at your option) any later version.
10 # Hooke is distributed in the hope that it will be useful, but WITHOUT
11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
12 # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
13 # Public License for more details.
15 # You should have received a copy of the GNU Lesser General Public
16 # License along with Hooke. If not, see
17 # <http://www.gnu.org/licenses/>.
19 """The `engine` module provides :class:`CommandEngine` for executing
20 :class:`hooke.command.Command`\s.
25 from .ui import CloseEngine, CommandMessage
28 class CommandEngine (object):
29 def run(self, hooke, ui_to_command_queue, command_to_ui_queue):
30 """Get a :class:`hooke.ui.QueueMessage` from the incoming
31 `ui_to_command_queue` and act accordingly.
33 If the message is a :class:`hooke.ui.CommandMessage` instance,
34 the command run may read subsequent input from
35 `ui_to_command_queue` (if it is an interactive command). The
36 command may also put assorted data into `command_to_ui_queue`.
38 When the command completes, it will put a
39 :class:`hooke.command.CommandExit` instance into
40 `command_to_ui_queue`, at which point the `CommandEngine` will
41 be ready to receive the next :class:`hooke.ui.QueueMessage`.
43 log = logging.getLogger('hooke')
45 log.debug('engine waiting for command')
46 msg = ui_to_command_queue.get()
47 if isinstance(msg, CloseEngine):
48 command_to_ui_queue.put(hooke)
50 'engine closing, placed hooke instance in return queue')
52 assert isinstance(msg, CommandMessage), type(msg)
53 log.debug('engine running %s' % msg.command.name)
54 msg.command.run(hooke, ui_to_command_queue, command_to_ui_queue,