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