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# -*- coding: utf-8 -*-
import collections
import collections.abc
import typing
import weakref
class WeakObjectIdDict(collections.MutableMapping):
"""
Like weakref.WeakKeyDict but internally uses object ids instead of the object reference
itself thereby avoiding the need for the object to be hashable (and therefore immutable).
"""
def __init__(self, seq=None, **kwargs):
self._refs = (
{}
) # type: collections.abc.MutableMapping[int, weakref.ReferenceType]
self._values = {} # type: collections.abc.MutableMapping[int, typing.Any]
if seq:
if isinstance(seq, collections.abc.Mapping):
for key, value in seq.items():
self[key] = value
elif isinstance(seq, collections.Iterable):
for key, value in seq:
self[key] = value
if kwargs:
for key, value in kwargs.items():
self[key] = value
def __copy__(self):
return WeakObjectIdDict(self)
def __getitem__(self, item):
try:
return self._values[id(item)]
except KeyError:
raise KeyError(str(item))
def __setitem__(self, key, value):
obj_id = id(key)
wref = weakref.ref(key, self._finalised)
self._refs[obj_id] = wref
self._values[obj_id] = value
def __delitem__(self, key):
obj_id = id(key)
del self._values[obj_id]
del self._refs[obj_id]
def __len__(self):
return len(self._values)
def __iter__(self):
for ref in self._refs.values():
yield ref()
def _finalised(self, wref):
found_id = None
for obj_id, ref in self._refs.items():
if ref == wref:
found_id = obj_id
break
# Delete both the object values and the reference itself
del self._values[found_id]
del self._refs[found_id]
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