mirror of
https://github.com/status-im/spiff-arena.git
synced 2025-01-15 12:44:52 +00:00
7c219fd731
git-subtree-dir: SpiffWorkflow git-subtree-split: 63db3e45947ec66b8d0efc2c74064004f8ff482c
245 lines
8.7 KiB
Python
245 lines
8.7 KiB
Python
# -*- coding: utf-8 -*-
|
|
|
|
from builtins import object
|
|
#
|
|
# DO NOT EDIT THIS FILE.
|
|
# THIS CODE IS TAKE FROM Exscript.util:
|
|
# https://github.com/knipknap/exscript/tree/master/src/Exscript/util
|
|
#
|
|
|
|
# Copyright (C) 2007-2010 Samuel Abels.
|
|
#
|
|
# This program is free software; you can redistribute it and/or modify
|
|
# it under the terms of the GNU General Public License version 2, as
|
|
# published by the Free Software Foundation.
|
|
#
|
|
# This program is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU General Public License
|
|
# along with this program; if not, write to the Free Software
|
|
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
"""
|
|
A simple signal/event mechanism.
|
|
"""
|
|
from threading import Lock
|
|
from . import weakmethod
|
|
|
|
|
|
class Event(object):
|
|
|
|
"""
|
|
A simple signal/event mechanism, to be used like this::
|
|
|
|
def mycallback(arg, **kwargs):
|
|
print arg, kwargs['foo']
|
|
|
|
myevent = Event()
|
|
myevent.connect(mycallback)
|
|
myevent.emit('test', foo = 'bar')
|
|
# Or just: myevent('test', foo = 'bar')
|
|
"""
|
|
|
|
def __init__(self):
|
|
"""
|
|
Constructor.
|
|
"""
|
|
# To save memory, we do NOT init the subscriber attributes with
|
|
# lists. Unfortunately this makes a lot of the code in this class
|
|
# more messy than it should be, but events are used so widely in
|
|
# Exscript that this change makes a huge difference to the memory
|
|
# footprint.
|
|
self.lock = None
|
|
self.weak_subscribers = None
|
|
self.hard_subscribers = None
|
|
|
|
def __call__(self, *args, **kwargs):
|
|
"""
|
|
Like emit().
|
|
"""
|
|
return self.emit(*args, **kwargs)
|
|
|
|
def connect(self, callback, *args, **kwargs):
|
|
"""
|
|
Connects the event with the given callback.
|
|
When the signal is emitted, the callback is invoked.
|
|
|
|
.. note::
|
|
|
|
The signal handler is stored with a hard reference, so you
|
|
need to make sure to call :class:`disconnect()` if you want the
|
|
handler
|
|
to be garbage collected.
|
|
|
|
:type callback: object
|
|
:param callback: The callback function.
|
|
:type args: tuple
|
|
:param args: Optional arguments passed to the callback.
|
|
:type kwargs: dict
|
|
:param kwargs: Optional keyword arguments passed to the callback.
|
|
"""
|
|
if self.is_connected(callback):
|
|
raise AttributeError('callback is already connected')
|
|
if self.hard_subscribers is None:
|
|
self.hard_subscribers = []
|
|
self.hard_subscribers.append((callback, args, kwargs))
|
|
|
|
def listen(self, callback, *args, **kwargs):
|
|
"""
|
|
Like :class:`connect()`, but uses a weak reference instead of a
|
|
normal reference.
|
|
The signal is automatically disconnected as soon as the handler
|
|
is garbage collected.
|
|
|
|
.. note::
|
|
|
|
Storing signal handlers as weak references means that if
|
|
your handler is a local function, it may be garbage collected. To
|
|
prevent this, use :class:`connect()` instead.
|
|
|
|
:type callback: object
|
|
:param callback: The callback function.
|
|
:type args: tuple
|
|
:param args: Optional arguments passed to the callback.
|
|
:type kwargs: dict
|
|
:param kwargs: Optional keyword arguments passed to the callback.
|
|
:rtype: :class:`Exscript.util.weakmethod.WeakMethod`
|
|
:returns: The newly created weak reference to the callback.
|
|
"""
|
|
if self.lock is None:
|
|
self.lock = Lock()
|
|
with self.lock:
|
|
if self.is_connected(callback):
|
|
raise AttributeError('callback is already connected')
|
|
if self.weak_subscribers is None:
|
|
self.weak_subscribers = []
|
|
ref = weakmethod.ref(callback, self._try_disconnect)
|
|
self.weak_subscribers.append((ref, args, kwargs))
|
|
return ref
|
|
|
|
def n_subscribers(self):
|
|
"""
|
|
Returns the number of connected subscribers.
|
|
|
|
:rtype: int
|
|
:returns: The number of subscribers.
|
|
"""
|
|
hard = self.hard_subscribers and len(self.hard_subscribers) or 0
|
|
weak = self.weak_subscribers and len(self.weak_subscribers) or 0
|
|
return hard + weak
|
|
|
|
def _hard_callbacks(self):
|
|
return [s[0] for s in self.hard_subscribers]
|
|
|
|
def _weakly_connected_index(self, callback):
|
|
if self.weak_subscribers is None:
|
|
return None
|
|
weak = [s[0].get_function() for s in self.weak_subscribers]
|
|
try:
|
|
return weak.index(callback)
|
|
except ValueError:
|
|
return None
|
|
|
|
def is_connected(self, callback):
|
|
"""
|
|
Returns True if the event is connected to the given function.
|
|
|
|
:type callback: object
|
|
:param callback: The callback function.
|
|
:rtype: bool
|
|
:returns: Whether the signal is connected to the given function.
|
|
"""
|
|
index = self._weakly_connected_index(callback)
|
|
if index is not None:
|
|
return True
|
|
if self.hard_subscribers is None:
|
|
return False
|
|
return callback in self._hard_callbacks()
|
|
|
|
def emit(self, *args, **kwargs):
|
|
"""
|
|
Emits the signal, passing the given arguments to the callbacks.
|
|
If one of the callbacks returns a value other than None, no further
|
|
callbacks are invoked and the return value of the callback is
|
|
returned to the caller of emit().
|
|
|
|
:type args: tuple
|
|
:param args: Optional arguments passed to the callbacks.
|
|
:type kwargs: dict
|
|
:param kwargs: Optional keyword arguments passed to the callbacks.
|
|
:rtype: object
|
|
:returns: Returns None if all callbacks returned None. Returns
|
|
the return value of the last invoked callback otherwise.
|
|
"""
|
|
if self.hard_subscribers is not None:
|
|
for callback, user_args, user_kwargs in self.hard_subscribers:
|
|
kwargs.update(user_kwargs)
|
|
result = callback(*args + user_args, **kwargs)
|
|
if result is not None:
|
|
return result
|
|
|
|
if self.weak_subscribers is not None:
|
|
for callback, user_args, user_kwargs in self.weak_subscribers:
|
|
kwargs.update(user_kwargs)
|
|
|
|
# Even though WeakMethod notifies us when the underlying
|
|
# function is destroyed, and we remove the item from the
|
|
# the list of subscribers, there is no guarantee that
|
|
# this notification has already happened because the garbage
|
|
# collector may run while this loop is executed.
|
|
# Disabling the garbage collector temporarily also does
|
|
# not work, because other threads may be trying to do
|
|
# the same, causing yet another race condition.
|
|
# So the only solution is to skip such functions.
|
|
cb_func = callback.get_function()
|
|
if cb_func is None:
|
|
continue
|
|
result = cb_func(*args + user_args, **kwargs)
|
|
if result is not None:
|
|
return result
|
|
|
|
def _try_disconnect(self, ref):
|
|
"""
|
|
Called by the weak reference when its target dies.
|
|
In other words, we can assert that self.weak_subscribers is not
|
|
None at this time.
|
|
"""
|
|
with self.lock:
|
|
weak = [s[0] for s in self.weak_subscribers]
|
|
try:
|
|
index = weak.index(ref)
|
|
except ValueError:
|
|
# subscriber was already removed by a call to disconnect()
|
|
pass
|
|
else:
|
|
self.weak_subscribers.pop(index)
|
|
|
|
def disconnect(self, callback):
|
|
"""
|
|
Disconnects the signal from the given function.
|
|
|
|
:type callback: object
|
|
:param callback: The callback function.
|
|
"""
|
|
if self.weak_subscribers is not None:
|
|
with self.lock:
|
|
index = self._weakly_connected_index(callback)
|
|
if index is not None:
|
|
self.weak_subscribers.pop(index)[0]
|
|
if self.hard_subscribers is not None:
|
|
try:
|
|
index = self._hard_callbacks().index(callback)
|
|
except ValueError:
|
|
pass
|
|
else:
|
|
self.hard_subscribers.pop(index)
|
|
|
|
def disconnect_all(self):
|
|
"""
|
|
Disconnects all connected functions from all signals.
|
|
"""
|
|
self.hard_subscribers = None
|
|
self.weak_subscribers = None
|