1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
- # Access WeakSet through the weakref module.
- # This code is separated-out because it is needed
- # by abc.py to load everything else at startup.
- from _weakref import ref
- __all__ = ['WeakSet']
- class _IterationGuard:
- # This context manager registers itself in the current iterators of the
- # weak container, such as to delay all removals until the context manager
- # exits.
- # This technique should be relatively thread-safe (since sets are).
- def __init__(self, weakcontainer):
- # Don't create cycles
- self.weakcontainer = ref(weakcontainer)
- def __enter__(self):
- w = self.weakcontainer()
- if w is not None:
- w._iterating.add(self)
- return self
- def __exit__(self, e, t, b):
- w = self.weakcontainer()
- if w is not None:
- s = w._iterating
- s.remove(self)
- if not s:
- w._commit_removals()
- class WeakSet:
- def __init__(self, data=None):
- self.data = set()
- def _remove(item, selfref=ref(self)):
- self = selfref()
- if self is not None:
- if self._iterating:
- self._pending_removals.append(item)
- else:
- self.data.discard(item)
- self._remove = _remove
- # A list of keys to be removed
- self._pending_removals = []
- self._iterating = set()
- if data is not None:
- self.update(data)
- def _commit_removals(self):
- l = self._pending_removals
- discard = self.data.discard
- while l:
- discard(l.pop())
- def __iter__(self):
- with _IterationGuard(self):
- for itemref in self.data:
- item = itemref()
- if item is not None:
- # Caveat: the iterator will keep a strong reference to
- # `item` until it is resumed or closed.
- yield item
- def __len__(self):
- return len(self.data) - len(self._pending_removals)
- def __contains__(self, item):
- try:
- wr = ref(item)
- except TypeError:
- return False
- return wr in self.data
- def __reduce__(self):
- return (self.__class__, (list(self),),
- getattr(self, '__dict__', None))
- def add(self, item):
- if self._pending_removals:
- self._commit_removals()
- self.data.add(ref(item, self._remove))
- def clear(self):
- if self._pending_removals:
- self._commit_removals()
- self.data.clear()
- def copy(self):
- return self.__class__(self)
- def pop(self):
- if self._pending_removals:
- self._commit_removals()
- while True:
- try:
- itemref = self.data.pop()
- except KeyError:
- raise KeyError('pop from empty WeakSet') from None
- item = itemref()
- if item is not None:
- return item
- def remove(self, item):
- if self._pending_removals:
- self._commit_removals()
- self.data.remove(ref(item))
- def discard(self, item):
- if self._pending_removals:
- self._commit_removals()
- self.data.discard(ref(item))
- def update(self, other):
- if self._pending_removals:
- self._commit_removals()
- for element in other:
- self.add(element)
- def __ior__(self, other):
- self.update(other)
- return self
- def difference(self, other):
- newset = self.copy()
- newset.difference_update(other)
- return newset
- __sub__ = difference
- def difference_update(self, other):
- self.__isub__(other)
- def __isub__(self, other):
- if self._pending_removals:
- self._commit_removals()
- if self is other:
- self.data.clear()
- else:
- self.data.difference_update(ref(item) for item in other)
- return self
- def intersection(self, other):
- return self.__class__(item for item in other if item in self)
- __and__ = intersection
- def intersection_update(self, other):
- self.__iand__(other)
- def __iand__(self, other):
- if self._pending_removals:
- self._commit_removals()
- self.data.intersection_update(ref(item) for item in other)
- return self
- def issubset(self, other):
- return self.data.issubset(ref(item) for item in other)
- __le__ = issubset
- def __lt__(self, other):
- return self.data < set(map(ref, other))
- def issuperset(self, other):
- return self.data.issuperset(ref(item) for item in other)
- __ge__ = issuperset
- def __gt__(self, other):
- return self.data > set(map(ref, other))
- def __eq__(self, other):
- if not isinstance(other, self.__class__):
- return NotImplemented
- return self.data == set(map(ref, other))
- def symmetric_difference(self, other):
- newset = self.copy()
- newset.symmetric_difference_update(other)
- return newset
- __xor__ = symmetric_difference
- def symmetric_difference_update(self, other):
- self.__ixor__(other)
- def __ixor__(self, other):
- if self._pending_removals:
- self._commit_removals()
- if self is other:
- self.data.clear()
- else:
- self.data.symmetric_difference_update(ref(item, self._remove) for item in other)
- return self
- def union(self, other):
- return self.__class__(e for s in (self, other) for e in s)
- __or__ = union
- def isdisjoint(self, other):
- return len(self.intersection(other)) == 0
|