| """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", "mapping", "proxy", "getweakrefcount", "getweakrefs", |
| "WeakKeyDictionary", "ReferenceType", "ProxyType", |
| "CallableProxyType", "ProxyTypes", "WeakValueDictionary"] |
| |
| def mapping(dict=None,weakkeys=0): |
| if weakkeys: |
| return WeakKeyDictionary(dict) |
| else: |
| return WeakValueDictionary(dict) |
| |
| |
| 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): |
| 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): |
| return self.data.get(ref(key),default) |
| |
| 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 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 |