Lib/_weakrefset.py

   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 __len__(self):
  27         return sum(x() is not None for x in self.data)
  28
  29     def __contains__(self, item):
  30         return ref(item) in self.data
  31
  32     def __reduce__(self):
  33         return (self.__class__, (list(self),),
  34                 getattr(self, '__dict__', None))
  35
  36     def add(self, item):
  37         self.data.add(ref(item, self._remove))
  38
  39     def clear(self):
  40         self.data.clear()
  41
  42     def copy(self):
  43         return self.__class__(self)
  44
  45     def pop(self):
  46         while True:
  47             try:
  48                 itemref = self.data.pop()
  49             except KeyError:
  50                 raise KeyError('pop from empty WeakSet')
  51             item = itemref()
  52             if item is not None:
  53                 return item
  54
  55     def remove(self, item):
  56         self.data.remove(ref(item))
  57
  58     def discard(self, item):
  59         self.data.discard(ref(item))
  60
  61     def update(self, other):
  62         if isinstance(other, self.__class__):
  63             self.data.update(other.data)
  64         else:
  65             for element in other:
  66                 self.add(element)
  67     def __ior__(self, other):
  68         self.update(other)
  69         return self
  70
  71     # Helper functions for simple delegating methods.
  72     def _apply(self, other, method):
  73         if not isinstance(other, self.__class__):
  74             other = self.__class__(other)
  75         newdata = method(other.data)
  76         newset = self.__class__()
  77         newset.data = newdata
  78         return newset
  79
  80     def difference(self, other):
  81         return self._apply(other, self.data.difference)
  82     __sub__ = difference
  83
  84     def difference_update(self, other):
  85         if self is other:
  86             self.data.clear()
  87         else:
  88             self.data.difference_update(ref(item) for item in other)
  89     def __isub__(self, other):
  90         if self is other:
  91             self.data.clear()
  92         else:
  93             self.data.difference_update(ref(item) for item in other)
  94         return self
  95
  96     def intersection(self, other):
  97         return self._apply(other, self.data.intersection)
  98     __and__ = intersection
  99
 100     def intersection_update(self, other):
 101         self.data.intersection_update(ref(item) for item in other)
 102     def __iand__(self, other):
 103         self.data.intersection_update(ref(item) for item in other)
 104         return self
 105
 106     def issubset(self, other):
 107         return self.data.issubset(ref(item) for item in other)
 108     __lt__ = issubset
 109
 110     def __le__(self, other):
 111         return self.data <= set(ref(item) for item in other)
 112
 113     def issuperset(self, other):
 114         return self.data.issuperset(ref(item) for item in other)
 115     __gt__ = issuperset
 116
 117     def __ge__(self, other):
 118         return self.data >= set(ref(item) for item in other)
 119
 120     def __eq__(self, other):
 121         if not isinstance(other, self.__class__):
 122             return NotImplemented
 123         return self.data == set(ref(item) for item in other)
 124
 125     def symmetric_difference(self, other):
 126         return self._apply(other, self.data.symmetric_difference)
 127     __xor__ = symmetric_difference
 128
 129     def symmetric_difference_update(self, other):
 130         if self is other:
 131             self.data.clear()
 132         else:
 133             self.data.symmetric_difference_update(ref(item) for item in other)
 134     def __ixor__(self, other):
 135         if self is other:
 136             self.data.clear()
 137         else:
 138             self.data.symmetric_difference_update(ref(item) for item in other)
 139         return self
 140
 141     def union(self, other):
 142         return self._apply(other, self.data.union)
 143     __or__ = union
 144
 145     def isdisjoint(self, other):
 146         return len(self.intersection(other)) == 0