keep (key, value)s in a map.
if key or value was garbage collected, remove the corresponding records.
Python, 114 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 | #!/usr/bin/env python
#
# Copyright 2010- Hui Zhang
# E-mail: hui.zh012@gmail.com
#
# Distributed under the terms of the GPL (GNU Public License)
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
from functools import partial
from weakref import ref
### weak ref key holder
def _ref(value, ondel):
try:
vref = ref(value, ondel)
except:
vref = lambda:value
return vref
class weakmap(object):
def __init__(self):
self.__map = {}
self.__valmemo = {}
self.__backref = {}
def set(self, key, value):
ikey, ival = id(key), id(value)
self.__map[ikey] = (ival,
_ref(key, partial(self.forget_key, ikey))
)
if ival not in self.__valmemo:
self.__valmemo[ival] = _ref(value, partial(self.forget_value, ival))
self.__backref.setdefault(ival, set()).add(ikey)
def get(self, key, **kwargs):
ikey = id(key)
if ikey in self.__map:
return self.__valmemo[self.__map[ikey][0]]()
if 'default' in kwargs:
return kwargs['default']
raise KeyError(str(key))
def pop(self, key):
ikey = id(key)
if ikey in self.__map:
value = self.__valmemo[self.__map[ikey][0]]()
self.forget_key(ikey)
return value
else:
raise KeyError(str(key))
def forget_key(self, keyid, obj=None):
if keyid in self.__map:
ival = self.__map.pop(keyid)[0]
self.__backref[ival].remove(keyid)
if not self.__backref[ival]:
self.__backref.pop(ival)
self.__valmemo.pop(ival)
def forget_value(self, valueid, obj=None):
for ikey in self.__backref.get(valueid, ()):
if ikey in self.__map:
self.__map.pop(ikey)
for d in [self.__backref, self.__valmemo]:
if valueid in d:
d.pop(valueid)
def __iter__(self):
for k, v in self.__map.iteritems():
k = v[1]()
v = self.__valmemo[v[0]]()
yield (k, v)
class weakkeymap(object):
def __init__(self):
self.__map = {}
def set(self, key, value):
ikey = id(key)
self.__map[ikey] = (value,
_ref(key, partial(self.forget_key, ikey))
)
def get(self, key, **kwargs):
ikey = id(key)
if ikey in self.__map:
return self.__map[ikey][0]
if 'default' in kwargs:
return kwargs['default']
raise KeyError(str(key))
def pop(self, key):
ikey = id(key)
if ikey in self.__map:
return self.__map.pop(ikey)[0]
else:
raise KeyError(str(key))
def forget_key(self, keyid, obj=None):
if keyid in self.__map:
self.__map.pop(keyid)
def __iter__(self):
for k, v in self.__map.iteritems():
k = v[1]()
yield (k, v[0])
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