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# Copyright (C) 2005 by Canonical Ltd
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# Authors: Robert Collins <robert.collins@canonical.com>
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""This module provides an IdentityMap."""
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import bzrlib.errors as errors
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class IdentityMap(object):
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"""An in memory map from object id to instance.
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An IdentityMap maps from keys to single instances of objects in memory.
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We have explicit calls on the map for the root of each inheritance tree
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that is store in the map. Look for find_CLASS and add_CLASS methods.
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def add_revision_history(self, revision_history):
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"""Add a revision_history object to the map.
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There can only be one!
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if self._revision_history is not None:
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raise errors.BzrError("A revision history (%s) is already "
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"identity map" % self._revision_history)
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self._revision_history = revision_history
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def add_weave(self, id, weave):
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"""Add weave to the map with a given id."""
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if self._weave_key(id) in self._map:
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raise errors.BzrError('weave %s already in the identity map' % id)
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self._map[self._weave_key(id)] = weave
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self._reverse_map[weave] = self._weave_key(id)
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def find_revision_history(self):
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return self._revision_history
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def find_weave(self, id):
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"""Return the weave for 'id', or None if it is not present."""
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return self._map.get(self._weave_key(id), None)
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super(IdentityMap, self).__init__()
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self._reverse_map = {}
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self._revision_history = None
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def remove_object(self, an_object):
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"""Remove object from map."""
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if isinstance(an_object, list):
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if self._revision_history is an_object:
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self._revision_history = None
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raise KeyError('%r not in identity map' % an_object)
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self._map.pop(self._reverse_map[an_object])
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self._reverse_map.pop(an_object)
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def _weave_key(self, id):
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"""Return the key for a weaves id."""
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class NullIdentityMap(object):
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"""A pretend in memory map from object id to instance.
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A NullIdentityMap is an Identity map that does not store anything in it.
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def add_weave(self, id, weave):
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"""See IdentityMap.add_weave."""
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def add_revision_history(self, revision_history):
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"""See IdentityMap.add_revision_history."""
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def find_weave(self, id):
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"""See IdentityMap.find_weave."""
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def find_revision_history(self):
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"""See IdentityMap.find_revision_history."""
added
removed
bzrlib/identitymap.py
