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116 lines
2.7 KiB
Python
116 lines
2.7 KiB
Python
"""Weak reference support for Python.
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This module is an implementation of PEP 205:
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http://python.sourceforge.net/peps/pep-0205.html
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"""
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import UserDict
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from _weakref import \
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getweakrefcount, \
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getweakrefs, \
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ref, \
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proxy, \
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ReferenceError, \
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CallableProxyType, \
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ProxyType, \
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ReferenceType
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ProxyTypes = (ProxyType, CallableProxyType)
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def mapping(dict=None):
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return WeakDictionary(dict)
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class WeakDictionary(UserDict.UserDict):
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# We inherit the constructor without worrying about the input
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# dictionary; since it uses our .update() method, we get the right
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# checks (if the other dictionary is a WeakDictionary, objects are
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# unwrapped on the way out, and we always wrap on the way in).
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def __getitem__(self, key):
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o = self.data.get(key)()
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if o is None:
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raise KeyError, key
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else:
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return o
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def __repr__(self):
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return "<WeakDictionary at %s>" % id(self)
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def __setitem__(self, key, value):
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def remove(o, data=self.data, key=key):
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del data[key]
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self.data[key] = ref(value, remove)
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def copy(self):
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new = WeakDictionary()
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for key, ref in self.data.items():
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o = ref()
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if o is not None:
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new[key] = o
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def get(self, key, default):
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try:
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ref = self.data[key]
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except KeyError:
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return default
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else:
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o = ref()
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if o is None:
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# This should only happen
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return default
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else:
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return o
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def items(self):
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L = []
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for key, ref in self.data.items():
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o = ref()
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if o is not None:
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L.append((key, o))
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return L
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def popitem(self):
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while 1:
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key, ref = self.data.popitem()
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o = ref()
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if o is not None:
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return key, o
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def setdefault(self, key, default):
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try:
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ref = self.data[key]
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except KeyError:
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def remove(o, data=self.data, key=key):
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del data[key]
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ref = ref(default, remove)
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self.data[key] = ref
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return default
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else:
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return ref()
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def update(self, dict):
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d = self.data
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L = []
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for key, o in dict.items():
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def remove(o, data=d, key=key):
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del data[key]
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L.append(key, ref(o, remove))
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for key, r in L:
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d[key] = r
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def values(self):
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L = []
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for ref in self.data.values():
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o = ref()
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if o is not None:
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L.append(o)
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return L
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# no longer needed
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del UserDict
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