# By Eyal Lotem and Yair Chuchem, 2007
import weakref
class WeakKeyValueDict(object):
"""
A dict in which items are removed whenever either key or value are
garbage-collected.
"""
def __init__(self, *args, **kw):
init_dict = dict(*args, **kw)
self._d = weakref.WeakKeyDictionary(
(key, self._create_value(key, value))
for key, value in init_dict.iteritems())
def _create_value(self, key, value):
key_weakref = weakref.ref(key)
def value_collected(wr):
del self[key_weakref()]
return weakref.ref(value, value_collected)
def __getitem__(self, key):
return self._d[key]()
def __setitem__(self, key, value):
self._d[key] = self._create_value(key, value)
def __delitem__(self, key):
del self._d[key]
def __len__(self):
return len(self._d)
def __cmp__(self, other):
try:
other_iteritems = other.iteritems
except AttributeError:
return NotImplemented
return cmp(sorted(self.iteritems()),
sorted(other_iteritems()))
def __hash__(self):
raise TypeError("%s objects not hashable" % (self.__class__.__name__,))
def __contains__(self, key):
return key in self._d
def __iter__(self):
return self.iterkeys()
def iterkeys(self):
return self._d.iterkeys()
def keys(self):
return list(self.iterkeys())
def itervalues(self):
for value in self._d.itervalues():
yield value()
def values(self):
return list(self.itervalues())
def iteritems(self):
for key in self._d:
yield self._d[key]()
def items(self):
return list(self.iteritems())
def update(self, other):
for key, value in other.iteritems():
self[key] = value
def __repr__(self):
return repr(self._d)
def clear(self):
self._d.clear()
def copy(self):
return WeakKeyValueDict(self)
def get(self, key, default=None):
if key in self:
return self[key]
return default
def has_key(self, key):
return key in self
def pop(self, key, *args):
if args:
return self._pop_with_default(key, *args)
return self._pop(key)
def _pop(self, key):
return self._d.pop(key)()
def _pop_with_default(self, key, default):
if key in self:
return self._d.pop(key)
return default
def popitem(self):
key, value = self._d.popitem()
return key, value()
def setdefault(self, key, default):
if key in self:
return self[key]
self[key] = default
return default
