90 lines
2.9 KiB
Python
90 lines
2.9 KiB
Python
# Copyright (C) 2009 Alexander Cherniuk <ts33kr@gmail.com>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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"""
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The backbone of the command system. Provides automatic dispatching which does
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not require explicit registering commands or containers and remains active even
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after everything is done, so new commands can be added during the runtime.
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"""
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from types import NoneType
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class Dispatcher(type):
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containers = {}
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commands = {}
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@classmethod
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def register_host(klass, host):
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klass.containers[host] = []
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@classmethod
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def register_container(klass, container):
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for host in container.HOSTS:
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klass.containers[host].append(container)
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@classmethod
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def register_commands(klass, container):
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klass.commands[container] = {}
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for command in klass.traverse_commands(container):
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for name in command.names:
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klass.commands[container][name] = command
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@classmethod
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def get_command(klass, host, name):
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for container in klass.containers[host]:
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command = klass.commands[container].get(name)
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if command:
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return command
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@classmethod
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def list_commands(klass, host):
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for container in klass.containers[host]:
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commands = klass.commands[container]
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for name, command in commands.iteritems():
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yield name, command
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@classmethod
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def traverse_commands(klass, container):
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for name in dir(container):
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attribute = getattr(container, name)
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if klass.is_command(attribute):
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yield attribute
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@staticmethod
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def is_root(ns):
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meta = ns.get('__metaclass__', NoneType)
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return issubclass(meta, Dispatcher)
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@staticmethod
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def is_command(attribute):
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name = attribute.__class__.__name__
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return name == 'Command'
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class HostDispatcher(Dispatcher):
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def __init__(klass, name, bases, ns):
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if not Dispatcher.is_root(ns):
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HostDispatcher.register_host(klass)
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super(HostDispatcher, klass).__init__(name, bases, ns)
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class ContainerDispatcher(Dispatcher):
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def __init__(klass, name, bases, ns):
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if not Dispatcher.is_root(ns):
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ContainerDispatcher.register_container(klass)
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ContainerDispatcher.register_commands(klass)
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super(ContainerDispatcher, klass).__init__(name, bases, ns)
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