weakref.py revision 312a5dc539b583abcbbf006942a4ceead9b9172b
141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake"""Weak reference support for Python. 241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred DrakeThis module is an implementation of PEP 205: 441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drakehttp://python.sourceforge.net/peps/pep-0205.html 641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake""" 741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drakeimport UserDict 941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 1041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drakefrom _weakref import \ 1141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake getweakrefcount, \ 1241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake getweakrefs, \ 1341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ref, \ 1441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake proxy, \ 1541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ReferenceError, \ 1641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake CallableProxyType, \ 1741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ProxyType, \ 1841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ReferenceType 1941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 2041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred DrakeProxyTypes = (ProxyType, CallableProxyType) 2141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 2241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 2341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drakedef mapping(dict=None): 2441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return WeakDictionary(dict) 2541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 2641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 2741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drakeclass WeakDictionary(UserDict.UserDict): 2841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 2941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake # We inherit the constructor without worrying about the input 3041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake # dictionary; since it uses our .update() method, we get the right 3141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake # checks (if the other dictionary is a WeakDictionary, objects are 3241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake # unwrapped on the way out, and we always wrap on the way in). 3341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 3441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def __getitem__(self, key): 3541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake o = self.data.get(key)() 3641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake if o is None: 3741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake raise KeyError, key 3841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake else: 3941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return o 4041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 4141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def __repr__(self): 4241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return "<WeakDictionary at %s>" % id(self) 4341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 4441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def __setitem__(self, key, value): 4541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def remove(o, data=self.data, key=key): 4641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake del data[key] 4741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake self.data[key] = ref(value, remove) 4841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 4941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def copy(self): 5041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake new = WeakDictionary() 5141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake for key, ref in self.data.items(): 5241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake o = ref() 5341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake if o is not None: 5441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake new[key] = o 5541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 5641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def get(self, key, default): 5741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake try: 5841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ref = self.data[key] 5941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake except KeyError: 6041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return default 6141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake else: 6241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake o = ref() 6341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake if o is None: 6441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake # This should only happen 6541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return default 6641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake else: 6741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return o 6841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 6941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def items(self): 70312a5dc539b583abcbbf006942a4ceead9b9172bFred Drake L = [] 71312a5dc539b583abcbbf006942a4ceead9b9172bFred Drake for key, ref in self.data.items(): 7241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake key, ref = L[i] 7341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake o = ref() 7441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake if o is not None: 75312a5dc539b583abcbbf006942a4ceead9b9172bFred Drake L.append((key, o)) 7641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return L 7741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 7841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def popitem(self): 7941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake while 1: 8041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake key, ref = self.data.popitem() 8141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake o = ref() 8241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake if o is not None: 8341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return key, o 8441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 8541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def setdefault(self, key, default): 8641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake try: 8741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ref = self.data[key] 8841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake except KeyError: 8941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def remove(o, data=self.data, key=key): 9041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake del data[key] 9141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake ref = ref(default, remove) 9241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake self.data[key] = ref 9341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return default 9441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake else: 9541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return ref() 9641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 9741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def update(self, dict): 9841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake d = self.data 9941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake L = [] 10041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake for key, o in dict.items(): 10141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def remove(o, data=d, key=key): 10241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake del data[key] 10341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake L.append(key, ref(o, remove)) 10441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake for key, r in L: 10541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake d[key] = r 10641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 10741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake def values(self): 10841deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake L = [] 10941deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake for ref in self.data.values(): 11041deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake o = ref() 11141deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake if o is not None: 11241deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake L.append(o) 11341deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake return L 11441deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 11541deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake 11641deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drake# no longer needed 11741deb1efc2f969b58e49af669cc20d15ccdb04c6Fred Drakedel UserDict 118