cybertools/util/multikey.py
helmutm 4004ebd1cb renamed util.index to multikey
git-svn-id: svn://svn.cy55.de/Zope3/src/cybertools/trunk@2513 fd906abe-77d9-0310-91a1-e0d9ade77398
2008-04-10 13:28:03 +00:00

78 lines
2.3 KiB
Python

#
# Copyright (c) 2006 Helmut Merz helmutm@cy55.de
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# 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
#
"""
Dictionaries with multiple keys.
$Id$
"""
_not_found = object()
class MultiKeyDict(object):
def __init__(self, keylen=None):
self.keylen = keylen
self.mapping = {}
def __setitem__(self, key, value):
assert type(key) is tuple
assert len(key) > 0
if self.keylen is None:
self.keylen = len(key)
assert len(key) == self.keylen
mapping = self.mapping
for n, k in enumerate(key):
if n == self.keylen - 1:
mapping[k] = value
else:
mapping = mapping.setdefault(k, {})
def __getitem__(self, key):
r = self.get(key, _not_found)
if r is _not_found:
raise KeyError(key)
return r
def get(self, key, default=None):
assert type(key) is tuple
assert len(key) == self.keylen
mapping = self.mapping
for k in key:
entry = mapping.get(k, _not_found)
if entry == _not_found:
entry = self._fallback(mapping, k)
if entry == _not_found:
return default
mapping = entry
return entry
def _fallback(self, mapping, key):
return mapping.get(None, _not_found)
def items(self):
result = []
self._step(result, (), self.mapping)
return tuple(result)
def _step(self, result, entry, value):
if len(entry) < self.keylen:
for k, v in value.items():
self._step(result, entry+(k,), v)
else:
result.append((entry, value))