342 lines
12 KiB
Python
342 lines
12 KiB
Python
# Copyright (C) 2009-2010 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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Provides a tiny framework with simple, yet powerful and extensible
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architecture to implement commands in a straight and flexible,
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declarative way.
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"""
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from types import FunctionType
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from inspect import getargspec, getdoc
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from gajim.command_system.dispatcher import Host, Container
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from gajim.command_system.dispatcher import get_command, list_commands
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from gajim.command_system.mapping import parse_arguments, adapt_arguments
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from gajim.command_system.errors import DefinitionError, CommandError, NoCommandError
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class CommandHost(metaclass=Host):
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"""
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Command host is a hub between numerous command processors and
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command containers. Aimed to participate in a dispatching process in
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order to provide clean and transparent architecture.
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The AUTOMATIC class variable, which must be defined by a command
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host, specifies whether the command host should be automatically
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dispatched and enabled by the dispatcher or not.
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"""
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__metaclass__ = Host
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class CommandContainer(metaclass=Container):
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"""
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Command container is an entity which holds defined commands,
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allowing them to be dispatched and processed correctly. Each
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command container may be bound to a one or more command hosts.
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The AUTOMATIC class variable, which must be defined by a command
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processor, specifies whether the command processor should be
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automatically dispatched and enabled by the dispatcher or not.
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Bounding is controlled by the HOSTS class variable, which must be
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defined by the command container. This variable should contain a
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sequence of hosts to bound to, as a tuple or list.
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"""
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__metaclass__ = Container
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class CommandProcessor:
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"""
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Command processor is an immediate command emitter. It does not
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participate in the dispatching process directly, but must define a
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host to bound to.
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Bounding is controlled by the COMMAND_HOST variable, which must be
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defined in the body of the command processor. This variable should
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be set to a specific command host.
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"""
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# This defines a command prefix (or an initializer), which should
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# precede a text in order for it to be processed as a command.
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COMMAND_PREFIX = '/'
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def process_as_command(self, text):
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"""
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Try to process text as a command. Returns True if it has been
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processed as a command and False otherwise.
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"""
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# pylint: disable=assignment-from-no-return
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prefix = text.startswith(self.COMMAND_PREFIX)
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length = len(text) > len(self.COMMAND_PREFIX)
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if not (prefix and length):
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return False
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body = text[len(self.COMMAND_PREFIX):]
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body = body.strip()
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parts = body.split(None, 1)
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name, arguments = parts if len(parts) > 1 else (parts[0], None)
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flag = self.looks_like_command(text, body, name, arguments)
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if flag is not None:
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return flag
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self.execute_command(name, arguments)
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return True
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def execute_command(self, name, arguments):
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command = self.get_command(name)
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args, opts = parse_arguments(arguments) if arguments else ([], [])
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args, kwargs = adapt_arguments(command, arguments, args, opts)
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if self.command_preprocessor(command, name, arguments, args, kwargs):
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return
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value = command(self, *args, **kwargs)
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self.command_postprocessor(command, name, arguments, args, kwargs, value)
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def command_preprocessor(self, command, name, arguments, args, kwargs):
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"""
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Redefine this method in the subclass to execute custom code
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before command gets executed.
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If returns True then command execution will be interrupted and
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command will not be executed.
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"""
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pass
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def command_postprocessor(self, command, name, arguments, args, kwargs, value):
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"""
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Redefine this method in the subclass to execute custom code
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after command gets executed.
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"""
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pass
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def looks_like_command(self, text, body, name, arguments):
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"""
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This hook is being called before any processing, but after it
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was determined that text looks like a command.
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If returns value other then None - then further processing will
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be interrupted and that value will be used to return from
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process_as_command.
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"""
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pass
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def get_command(self, name):
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command = get_command(self.COMMAND_HOST, name)
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if not command:
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raise NoCommandError("Command does not exist", name=name)
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return command
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def list_commands(self):
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commands = list_commands(self.COMMAND_HOST)
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commands = dict(commands)
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return sorted(set(commands.values()), key=lambda k: k.__repr__())
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class Command:
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def __init__(self, handler, *names, **properties):
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self.handler = handler
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self.names = names
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# Automatically set all the properties passed to a constructor
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# by the command decorator.
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for key, value in properties.items():
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setattr(self, key, value)
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def __call__(self, *args, **kwargs):
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try:
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return self.handler(*args, **kwargs)
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# This allows to use a shortcut way of raising an exception
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# inside a handler. That is to raise a CommandError without
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# command or name attributes set. They will be set to a
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# corresponding values right here in case if they was not set by
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# the one who raised an exception.
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except CommandError as error:
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if not error.command and not error.name:
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raise CommandError(error.message, self)
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raise
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# This one is a little bit too wide, but as Python does not have
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# anything more constrained - there is no other choice. Take a
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# look here if command complains about invalid arguments while
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# they are ok.
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except TypeError:
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raise CommandError("Command received invalid arguments", self)
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def __repr__(self):
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return "<Command %s>" % ', '.join(self.names)
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def __cmp__(self, other):
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if self.first_name > other.first_name:
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return 1
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if self.first_name < other.first_name:
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return -1
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return 0
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@property
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def first_name(self):
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return self.names[0]
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@property
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def native_name(self):
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return self.handler.__name__
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def extract_documentation(self):
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"""
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Extract handler's documentation which is a doc-string and
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transform it to a usable format.
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"""
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return getdoc(self.handler)
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def extract_description(self):
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"""
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Extract handler's description (which is a first line of the
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documentation). Try to keep them simple yet meaningful.
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"""
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documentation = self.extract_documentation()
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return documentation.split('\n', 1)[0] if documentation else None
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def extract_specification(self):
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"""
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Extract handler's arguments specification, as it was defined
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preserving their order.
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"""
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names, var_args, var_kwargs, defaults = getargspec(self.handler)
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# Behavior of this code need to be checked. Might yield
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# incorrect results on some rare occasions.
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spec_args = names[:-len(defaults) if defaults else len(names)]
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spec_kwargs = list(zip(names[-len(defaults):], defaults)) if defaults else {}
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# Removing self from arguments specification. Command handler
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# should receive the processors as a first argument, which
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# should be self by the canonical means.
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if spec_args.pop(0) != 'self':
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raise DefinitionError("First argument must be self", self)
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return spec_args, spec_kwargs, var_args, var_kwargs
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def command(*names, **properties):
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"""
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A decorator for defining commands in a declarative way. Provides
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facilities for setting command's names and properties.
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Names should contain a set of names (aliases) by which the command
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can be reached. If no names are given - the native name (the one
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extracted from the command handler) will be used.
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If native=True is given (default) and names is non-empty - then the
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native name of the command will be prepended in addition to the
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given names.
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If usage=True is given (default) - then command help will be
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appended with autogenerated usage info, based of the command handler
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arguments introspection.
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If source=True is given - then the first argument of the command
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will receive the source arguments, as a raw, unprocessed string. The
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further mapping of arguments and options will not be affected.
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If raw=True is given - then command considered to be raw and should
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define positional arguments only. If it defines only one positional
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argument - this argument will receive all the raw and unprocessed
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arguments. If the command defines more then one positional argument
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- then all the arguments except the last one will be processed
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normally; the last argument will get what is left after the
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processing as raw and unprocessed string.
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If empty=True is given - this will allow to call a raw command
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without arguments.
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If extra=True is given - then all the extra arguments passed to a
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command will be collected into a sequence and given to the last
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positional argument.
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If overlap=True is given - then all the extra arguments will be
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mapped as if they were values for the keyword arguments.
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If expand=True is given (default) - then short, one-letter options
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will be expanded to a verbose ones, based of the comparison of the
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first letter. If more then one option with the same first letter is
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given - then only first one will be used in the expansion.
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"""
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names = list(names)
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native = properties.get('native', True)
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usage = properties.get('usage', True)
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source = properties.get('source', False)
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raw = properties.get('raw', False)
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empty = properties.get('empty', False)
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extra = properties.get('extra', False)
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overlap = properties.get('overlap', False)
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expand = properties.get('expand', True)
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if empty and not raw:
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raise DefinitionError("Empty option can be used only with raw commands")
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if extra and overlap:
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raise DefinitionError("Extra and overlap options can not be used together")
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properties = {
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'usage': usage,
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'source': source,
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'raw': raw,
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'extra': extra,
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'overlap': overlap,
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'empty': empty,
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'expand': expand
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}
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def decorator(handler):
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"""
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Decorator which receives handler as a first argument and then
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wraps it in the command which then returns back.
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"""
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command = Command(handler, *names, **properties)
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# Extract and inject a native name if either no other names are
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# specified or native property is enabled, while making
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# sure it is going to be the first one in the list.
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if not names or native:
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names.insert(0, command.native_name)
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command.names = tuple(names)
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return command
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# Workaround if we are getting called without parameters. Keep in
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# mind that in that case - first item in the names will be the
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# handler.
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if names and isinstance(names[0], FunctionType):
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return decorator(names.pop(0))
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return decorator
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def doc(text):
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"""
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This decorator is used to bind a documentation (a help) to a
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command.
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"""
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def decorator(target):
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if isinstance(target, Command):
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target.handler.__doc__ = text
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else:
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target.__doc__ = text
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return target
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return decorator
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