mirror of https://github.com/python/cpython
117 lines
2.7 KiB
Python
117 lines
2.7 KiB
Python
"""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)
|
|
|
|
|
|
def mapping(dict=None):
|
|
return WeakDictionary(dict)
|
|
|
|
|
|
class WeakDictionary(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 WeakDictionary, 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 "<WeakDictionary 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 = WeakDictionary()
|
|
for key, ref in self.data.items():
|
|
o = ref()
|
|
if o is not None:
|
|
new[key] = o
|
|
|
|
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
|
|
|
|
|
|
# no longer needed
|
|
del UserDict
|