hooke/engine.py

   1 # Copyright
   2
   3 """The `engine` module provides :class:`CommandEngine` for executing
   4 :class:`hooke.command.Command`\s.
   5 """
   6
   7 from .ui import CloseEngine, CommandMessage
   8
   9 class CommandEngine (object):
  10     def run(self, hooke, ui_to_command_queue, command_to_ui_queue):
  11         """Get a :class:`hooke.ui.QueueMessage` from the incoming
  12         `ui_to_command_queue` and act accordingly.
  13
  14         If the message is a :class:`hooke.ui.CommandMessage` instance,
  15         the command run may read subsequent input from
  16         `ui_to_command_queue` (if it is an interactive command).  The
  17         command may also put assorted data into `command_to_ui_queue`.
  18
  19         When the command completes, it will put a
  20         :class:`hooke.command.CommandExit` instance into
  21         `command_to_ui_queue`, at which point the `CommandEngine` will
  22         be ready to receive the next :class:`hooke.ui.QueueMessage`.
  23         """
  24         while True:
  25             msg = ui_to_command_queue.get()
  26             if isinstance(msg, CloseEngine):
  27                 break
  28             assert isinstance(msg, CommandMessage), type(msg)
  29             msg.command.run(hooke, ui_to_command_queue, command_to_ui_queue,
  30                             **msg.arguments)