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
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
|
# 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(object):
# 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(object):
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:
yield item
def __len__(self):
return sum(x() is not None for x in self.data)
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))
__hash__ = 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')
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()
if isinstance(other, self.__class__):
self.data.update(other.data)
else:
for element in other:
self.add(element)
def __ior__(self, other):
self.update(other)
return self
# Helper functions for simple delegating methods.
def _apply(self, other, method):
if not isinstance(other, self.__class__):
other = self.__class__(other)
newdata = method(other.data)
newset = self.__class__()
newset.data = newdata
return newset
def difference(self, other):
return self._apply(other, self.data.difference)
__sub__ = difference
def difference_update(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)
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._apply(other, self.data.intersection)
__and__ = intersection
def intersection_update(self, other):
if self._pending_removals:
self._commit_removals()
self.data.intersection_update(ref(item) for item in 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)
__lt__ = issubset
def __le__(self, other):
return self.data <= set(ref(item) for item in other)
def issuperset(self, other):
return self.data.issuperset(ref(item) for item in other)
__gt__ = issuperset
def __ge__(self, other):
return self.data >= set(ref(item) for item in other)
def __eq__(self, other):
if not isinstance(other, self.__class__):
return NotImplemented
return self.data == set(ref(item) for item in other)
def symmetric_difference(self, other):
return self._apply(other, self.data.symmetric_difference)
__xor__ = symmetric_difference
def symmetric_difference_update(self, other):
if self._pending_removals:
self._commit_removals()
if self is other:
self.data.clear()
else:
self.data.symmetric_difference_update(ref(item) for item in 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) for item in other)
return self
def union(self, other):
return self._apply(other, self.data.union)
__or__ = union
def isdisjoint(self, other):
return len(self.intersection(other)) == 0
|
