83 lines
3.0 KiB
Python
83 lines
3.0 KiB
Python
"""
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Copyright 2009, Linden Research, Inc.
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See NOTICE.md for previous contributors
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Copyright 2021, Salad Dais
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All Rights Reserved.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 3 of the License, or (at your option) any later version.
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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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software Foundation,
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Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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"""
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import asyncio
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from logging import getLogger
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logger = getLogger('utilities.events')
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class Event:
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""" an object containing data which will be passed out to all subscribers """
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def __init__(self):
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self.subscribers = []
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def subscribe(self, handler, *args, one_shot=False, predicate=None, **kwargs):
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""" establish the subscribers (handlers) to this event """
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handler_tup = (handler, args, kwargs, one_shot, predicate)
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assert handler_tup not in self.subscribers
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self.subscribers.append(handler_tup)
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return self
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def _handler_key(self, handler):
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return handler[:3]
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def unsubscribe(self, handler, *args, **kwargs):
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""" remove the subscriber (handler) to this event """
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did_remove = False
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for registered in reversed(self.subscribers):
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if self._handler_key(registered) == (handler, args, kwargs):
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self.subscribers.remove(registered)
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did_remove = True
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if not did_remove:
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raise ValueError(f"Handler {handler!r} is not subscribed to this event.")
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return self
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def notify(self, args):
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for handler in self.subscribers[:]:
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handler, inner_args, kwargs, one_shot, predicate = handler
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if predicate and not predicate(args):
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continue
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if one_shot:
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self.unsubscribe(handler, *inner_args, **kwargs)
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if asyncio.iscoroutinefunction(handler):
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# Note that unsubscription may be delayed due to asyncio scheduling :)
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async def _run_handler_wrapper():
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unsubscribe = await handler(args, *inner_args, **kwargs)
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if unsubscribe:
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_ = self.unsubscribe(handler, *inner_args, **kwargs)
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asyncio.create_task(_run_handler_wrapper())
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else:
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if handler(args, *inner_args, **kwargs) and not one_shot:
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self.unsubscribe(handler, *inner_args, **kwargs)
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def __len__(self):
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return len(self.subscribers)
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def clear_subscribers(self):
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self.subscribers.clear()
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__iadd__ = subscribe
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__isub__ = unsubscribe
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__call__ = notify
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