| Raymond Hettinger | 93fa608 | 2008-02-05 00:20:01 +0000 | [diff] [blame] | 1 | # Access WeakSet through the weakref module. |
| 2 | # This code is separated-out because it is needed |
| 3 | # by abc.py to load everything else at startup. |
| 4 | |
| 5 | from _weakref import ref |
| 6 | |
| 7 | __all__ = ['WeakSet'] |
| 8 | |
| 9 | class WeakSet: |
| 10 | def __init__(self, data=None): |
| 11 | self.data = set() |
| 12 | def _remove(item, selfref=ref(self)): |
| 13 | self = selfref() |
| 14 | if self is not None: |
| 15 | self.data.discard(item) |
| 16 | self._remove = _remove |
| 17 | if data is not None: |
| 18 | self.update(data) |
| 19 | |
| 20 | def __iter__(self): |
| 21 | for itemref in self.data: |
| 22 | item = itemref() |
| 23 | if item is not None: |
| 24 | yield item |
| 25 | |
| 26 | def __contains__(self, item): |
| 27 | return ref(item) in self.data |
| 28 | |
| 29 | def __reduce__(self): |
| 30 | return (self.__class__, (list(self),), |
| 31 | getattr(self, '__dict__', None)) |
| 32 | |
| 33 | def add(self, item): |
| 34 | self.data.add(ref(item, self._remove)) |
| 35 | |
| 36 | def clear(self): |
| 37 | self.data.clear() |
| 38 | |
| 39 | def copy(self): |
| 40 | return self.__class__(self) |
| 41 | |
| 42 | def pop(self): |
| 43 | while True: |
| 44 | itemref = self.data.pop() |
| 45 | item = itemref() |
| 46 | if item is not None: |
| 47 | return item |
| 48 | |
| 49 | def remove(self, item): |
| 50 | self.data.remove(ref(item)) |
| 51 | |
| 52 | def discard(self, item): |
| 53 | self.data.discard(ref(item)) |
| 54 | |
| 55 | def update(self, other): |
| 56 | if isinstance(other, self.__class__): |
| 57 | self.data.update(other.data) |
| 58 | else: |
| 59 | for element in other: |
| 60 | self.add(element) |
| 61 | __ior__ = update |
| 62 | |
| 63 | # Helper functions for simple delegating methods. |
| 64 | def _apply(self, other, method): |
| 65 | if not isinstance(other, self.__class__): |
| 66 | other = self.__class__(other) |
| 67 | newdata = method(other.data) |
| 68 | newset = self.__class__() |
| 69 | newset.data = newdata |
| 70 | return newset |
| 71 | |
| 72 | def _apply_mutate(self, other, method): |
| 73 | if not isinstance(other, self.__class__): |
| 74 | other = self.__class__(other) |
| 75 | method(other) |
| 76 | |
| 77 | def difference(self, other): |
| 78 | return self._apply(other, self.data.difference) |
| 79 | __sub__ = difference |
| 80 | |
| 81 | def difference_update(self, other): |
| 82 | self._apply_mutate(self, self.data.difference_update) |
| 83 | __isub__ = difference_update |
| 84 | |
| 85 | def intersection(self, other): |
| 86 | return self._apply(other, self.data.intersection) |
| 87 | __and__ = intersection |
| 88 | |
| 89 | def intersection_update(self, other): |
| 90 | self._apply_mutate(self, self.data.intersection_update) |
| 91 | __iand__ = intersection_update |
| 92 | |
| 93 | def issubset(self, other): |
| 94 | return self.data.issubset(ref(item) for item in other) |
| 95 | __lt__ = issubset |
| 96 | |
| 97 | def issuperset(self, other): |
| 98 | return self.data.issuperset(ref(item) for item in other) |
| 99 | __gt__ = issuperset |
| 100 | |
| 101 | def symmetric_difference(self, other): |
| 102 | return self._apply(other, self.data.symmetric_difference) |
| 103 | __xor__ = symmetric_difference |
| 104 | |
| 105 | def symmetric_difference_update(self, other): |
| 106 | self._apply_mutate(other, self.data.symmetric_difference_update) |
| 107 | __ixor__ = symmetric_difference_update |
| 108 | |
| 109 | def union(self, other): |
| 110 | self._apply_mutate(other, self.data.union) |
| 111 | __or__ = union |