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# -*- coding: utf-8 -*-
#
# This file is part of Linux Show Player
#
# Copyright 2012-2016 Francesco Ceruti <ceppofrancy@gmail.com>
#
# Linux Show Player is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Linux Show Player 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 Linux Show Player. If not, see <http://www.gnu.org/licenses/>.
class ClassBasedRegistry:
"""Allow to register/un-register and filter items using a reference class.
The filter "check" whenever the filter-class is a subclass of
the one used to register the item or exactly the the same.
.. highlight::
reg = ClassBasedRegistry()
reg.add_item('Object-Item', object)
reg.add_item('List-Item', list)
list(reg.filter(object)) # ['Object-Item', 'List-Item']
list(reg.filter(list)) # ['List-Item']
"""
def __init__(self):
self._registry = {}
def add_item(self, item, ref_class=object):
"""Register a item for ref_class."""
if ref_class not in self._registry:
self._registry[ref_class] = [item]
elif item not in self._registry[ref_class]:
self._registry[ref_class].append(item)
def remove_item(self, item):
"""Remove all the occurrences of the given item."""
for ref_class in self._registry:
try:
self._registry[ref_class].remove(item)
except ValueError:
pass
def filter(self, ref_class=object):
"""Return an iterator over items registered with ref_class
or subclasses.
The items are sorted by ref_class name.
"""
for class_ in sorted(self._registry.keys(), key=str):
if issubclass(ref_class, class_):
yield from self._registry[class_]
def clear_class(self, ref_class=object):
"""Remove all the items for ref_class."""
self._registry[ref_class].clear()
def ref_classes(self):
"""Return a view-like object of all the registered references."""
return self._registry.keys()
def clear(self):
self._registry.clear()
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