| 4710c53d |
1 | # Access WeakSet through the weakref module.\r |
| 2 | # This code is separated-out because it is needed\r |
| 3 | # by abc.py to load everything else at startup.\r |
| 4 | \r |
| 5 | from _weakref import ref\r |
| 6 | \r |
| 7 | __all__ = ['WeakSet']\r |
| 8 | \r |
| 9 | \r |
| 10 | class _IterationGuard(object):\r |
| 11 | # This context manager registers itself in the current iterators of the\r |
| 12 | # weak container, such as to delay all removals until the context manager\r |
| 13 | # exits.\r |
| 14 | # This technique should be relatively thread-safe (since sets are).\r |
| 15 | \r |
| 16 | def __init__(self, weakcontainer):\r |
| 17 | # Don't create cycles\r |
| 18 | self.weakcontainer = ref(weakcontainer)\r |
| 19 | \r |
| 20 | def __enter__(self):\r |
| 21 | w = self.weakcontainer()\r |
| 22 | if w is not None:\r |
| 23 | w._iterating.add(self)\r |
| 24 | return self\r |
| 25 | \r |
| 26 | def __exit__(self, e, t, b):\r |
| 27 | w = self.weakcontainer()\r |
| 28 | if w is not None:\r |
| 29 | s = w._iterating\r |
| 30 | s.remove(self)\r |
| 31 | if not s:\r |
| 32 | w._commit_removals()\r |
| 33 | \r |
| 34 | \r |
| 35 | class WeakSet(object):\r |
| 36 | def __init__(self, data=None):\r |
| 37 | self.data = set()\r |
| 38 | def _remove(item, selfref=ref(self)):\r |
| 39 | self = selfref()\r |
| 40 | if self is not None:\r |
| 41 | if self._iterating:\r |
| 42 | self._pending_removals.append(item)\r |
| 43 | else:\r |
| 44 | self.data.discard(item)\r |
| 45 | self._remove = _remove\r |
| 46 | # A list of keys to be removed\r |
| 47 | self._pending_removals = []\r |
| 48 | self._iterating = set()\r |
| 49 | if data is not None:\r |
| 50 | self.update(data)\r |
| 51 | \r |
| 52 | def _commit_removals(self):\r |
| 53 | l = self._pending_removals\r |
| 54 | discard = self.data.discard\r |
| 55 | while l:\r |
| 56 | discard(l.pop())\r |
| 57 | \r |
| 58 | def __iter__(self):\r |
| 59 | with _IterationGuard(self):\r |
| 60 | for itemref in self.data:\r |
| 61 | item = itemref()\r |
| 62 | if item is not None:\r |
| 63 | yield item\r |
| 64 | \r |
| 65 | def __len__(self):\r |
| 66 | return sum(x() is not None for x in self.data)\r |
| 67 | \r |
| 68 | def __contains__(self, item):\r |
| 69 | try:\r |
| 70 | wr = ref(item)\r |
| 71 | except TypeError:\r |
| 72 | return False\r |
| 73 | return wr in self.data\r |
| 74 | \r |
| 75 | def __reduce__(self):\r |
| 76 | return (self.__class__, (list(self),),\r |
| 77 | getattr(self, '__dict__', None))\r |
| 78 | \r |
| 79 | __hash__ = None\r |
| 80 | \r |
| 81 | def add(self, item):\r |
| 82 | if self._pending_removals:\r |
| 83 | self._commit_removals()\r |
| 84 | self.data.add(ref(item, self._remove))\r |
| 85 | \r |
| 86 | def clear(self):\r |
| 87 | if self._pending_removals:\r |
| 88 | self._commit_removals()\r |
| 89 | self.data.clear()\r |
| 90 | \r |
| 91 | def copy(self):\r |
| 92 | return self.__class__(self)\r |
| 93 | \r |
| 94 | def pop(self):\r |
| 95 | if self._pending_removals:\r |
| 96 | self._commit_removals()\r |
| 97 | while True:\r |
| 98 | try:\r |
| 99 | itemref = self.data.pop()\r |
| 100 | except KeyError:\r |
| 101 | raise KeyError('pop from empty WeakSet')\r |
| 102 | item = itemref()\r |
| 103 | if item is not None:\r |
| 104 | return item\r |
| 105 | \r |
| 106 | def remove(self, item):\r |
| 107 | if self._pending_removals:\r |
| 108 | self._commit_removals()\r |
| 109 | self.data.remove(ref(item))\r |
| 110 | \r |
| 111 | def discard(self, item):\r |
| 112 | if self._pending_removals:\r |
| 113 | self._commit_removals()\r |
| 114 | self.data.discard(ref(item))\r |
| 115 | \r |
| 116 | def update(self, other):\r |
| 117 | if self._pending_removals:\r |
| 118 | self._commit_removals()\r |
| 119 | if isinstance(other, self.__class__):\r |
| 120 | self.data.update(other.data)\r |
| 121 | else:\r |
| 122 | for element in other:\r |
| 123 | self.add(element)\r |
| 124 | \r |
| 125 | def __ior__(self, other):\r |
| 126 | self.update(other)\r |
| 127 | return self\r |
| 128 | \r |
| 129 | # Helper functions for simple delegating methods.\r |
| 130 | def _apply(self, other, method):\r |
| 131 | if not isinstance(other, self.__class__):\r |
| 132 | other = self.__class__(other)\r |
| 133 | newdata = method(other.data)\r |
| 134 | newset = self.__class__()\r |
| 135 | newset.data = newdata\r |
| 136 | return newset\r |
| 137 | \r |
| 138 | def difference(self, other):\r |
| 139 | return self._apply(other, self.data.difference)\r |
| 140 | __sub__ = difference\r |
| 141 | \r |
| 142 | def difference_update(self, other):\r |
| 143 | if self._pending_removals:\r |
| 144 | self._commit_removals()\r |
| 145 | if self is other:\r |
| 146 | self.data.clear()\r |
| 147 | else:\r |
| 148 | self.data.difference_update(ref(item) for item in other)\r |
| 149 | def __isub__(self, other):\r |
| 150 | if self._pending_removals:\r |
| 151 | self._commit_removals()\r |
| 152 | if self is other:\r |
| 153 | self.data.clear()\r |
| 154 | else:\r |
| 155 | self.data.difference_update(ref(item) for item in other)\r |
| 156 | return self\r |
| 157 | \r |
| 158 | def intersection(self, other):\r |
| 159 | return self._apply(other, self.data.intersection)\r |
| 160 | __and__ = intersection\r |
| 161 | \r |
| 162 | def intersection_update(self, other):\r |
| 163 | if self._pending_removals:\r |
| 164 | self._commit_removals()\r |
| 165 | self.data.intersection_update(ref(item) for item in other)\r |
| 166 | def __iand__(self, other):\r |
| 167 | if self._pending_removals:\r |
| 168 | self._commit_removals()\r |
| 169 | self.data.intersection_update(ref(item) for item in other)\r |
| 170 | return self\r |
| 171 | \r |
| 172 | def issubset(self, other):\r |
| 173 | return self.data.issubset(ref(item) for item in other)\r |
| 174 | __lt__ = issubset\r |
| 175 | \r |
| 176 | def __le__(self, other):\r |
| 177 | return self.data <= set(ref(item) for item in other)\r |
| 178 | \r |
| 179 | def issuperset(self, other):\r |
| 180 | return self.data.issuperset(ref(item) for item in other)\r |
| 181 | __gt__ = issuperset\r |
| 182 | \r |
| 183 | def __ge__(self, other):\r |
| 184 | return self.data >= set(ref(item) for item in other)\r |
| 185 | \r |
| 186 | def __eq__(self, other):\r |
| 187 | if not isinstance(other, self.__class__):\r |
| 188 | return NotImplemented\r |
| 189 | return self.data == set(ref(item) for item in other)\r |
| 190 | \r |
| 191 | def symmetric_difference(self, other):\r |
| 192 | return self._apply(other, self.data.symmetric_difference)\r |
| 193 | __xor__ = symmetric_difference\r |
| 194 | \r |
| 195 | def symmetric_difference_update(self, other):\r |
| 196 | if self._pending_removals:\r |
| 197 | self._commit_removals()\r |
| 198 | if self is other:\r |
| 199 | self.data.clear()\r |
| 200 | else:\r |
| 201 | self.data.symmetric_difference_update(ref(item) for item in other)\r |
| 202 | def __ixor__(self, other):\r |
| 203 | if self._pending_removals:\r |
| 204 | self._commit_removals()\r |
| 205 | if self is other:\r |
| 206 | self.data.clear()\r |
| 207 | else:\r |
| 208 | self.data.symmetric_difference_update(ref(item) for item in other)\r |
| 209 | return self\r |
| 210 | \r |
| 211 | def union(self, other):\r |
| 212 | return self._apply(other, self.data.union)\r |
| 213 | __or__ = union\r |
| 214 | \r |
| 215 | def isdisjoint(self, other):\r |
| 216 | return len(self.intersection(other)) == 0\r |
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