~bzr-pqm/bzr/bzr.dev : contents of bzrlib/identitymap.py at revision 1788

~bzr-pqm/bzr/bzr.dev : (revision 1788)

# Copyright (C) 2005 by Canonical Ltd
#   Authors: Robert Collins <robert.collins@canonical.com>
#
# 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

"""This module provides an IdentityMap."""


import bzrlib.errors as errors


class IdentityMap(object):
    """An in memory map from object id to instance.
    
    An IdentityMap maps from keys to single instances of objects in memory.
    We have explicit calls on the map for the root of each inheritance tree
    that is store in the map. Look for find_CLASS and add_CLASS methods.
    """

    def add_revision_history(self, revision_history):
        """Add a revision_history object to the map.

        There can only be one!
        """
        if self._revision_history is not None:
            raise errors.BzrError("A revision history (%s) is already "
                                  "identity map" % self._revision_history)
        self._revision_history = revision_history

    def add_weave(self, id, weave):
        """Add weave to the map with a given id."""
        if self._weave_key(id) in self._map:
            raise errors.BzrError('weave %s already in the identity map' % id)
        self._map[self._weave_key(id)] = weave
        self._reverse_map[weave] = self._weave_key(id)

    def find_revision_history(self):
        return self._revision_history

    def find_weave(self, id):
        """Return the weave for 'id', or None if it is not present."""
        return self._map.get(self._weave_key(id), None)

    def __init__(self):
        super(IdentityMap, self).__init__()
        self._map = {}
        self._reverse_map = {}
        self._revision_history = None

    def remove_object(self, an_object):
        """Remove object from map."""
        if isinstance(an_object, list):
            if self._revision_history is an_object:
                self._revision_history = None
            else:
                raise KeyError('%r not in identity map' % an_object)
        else:
            self._map.pop(self._reverse_map[an_object])
            self._reverse_map.pop(an_object)

    def _weave_key(self, id):
        """Return the key for a weaves id."""
        return "weave-" + id

        
class NullIdentityMap(object):
    """A pretend in memory map from object id to instance.
    
    A NullIdentityMap is an Identity map that does not store anything in it.
    """

    def add_weave(self, id, weave):
        """See IdentityMap.add_weave."""

    def add_revision_history(self, revision_history):
        """See IdentityMap.add_revision_history."""

    def find_weave(self, id):
        """See IdentityMap.find_weave."""
        return None

    def find_revision_history(self):
        """See IdentityMap.find_revision_history."""

1417.1.6 by Robert Collins introduce transactions for grouping actions done to and with branches	1	# Copyright (C) 2005 by Canonical Ltd
	2	# Authors: Robert Collins <robert.collins@canonical.com>
	3	#
	4	# This program is free software; you can redistribute it and/or modify
	5	# it under the terms of the GNU General Public License as published by
	6	# the Free Software Foundation; either version 2 of the License, or
	7	# (at your option) any later version.
	8	#
	9	# This program is distributed in the hope that it will be useful,
	10	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	# GNU General Public License for more details.
	13	#
	14	# You should have received a copy of the GNU General Public License
	15	# along with this program; if not, write to the Free Software
	16	# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	17
	18	"""This module provides an IdentityMap."""
	19
	20
	21	import bzrlib.errors as errors
	22
	23
	24	class IdentityMap(object):
	25	"""An in memory map from object id to instance.
	26
	27	An IdentityMap maps from keys to single instances of objects in memory.
	28	We have explicit calls on the map for the root of each inheritance tree
	29	that is store in the map. Look for find_CLASS and add_CLASS methods.
	30	"""
	31
1417.1.12 by Robert Collins cache revision history during read transactions	32	def add_revision_history(self, revision_history):
	33	"""Add a revision_history object to the map.
	34
	35	There can only be one!
	36	"""
	37	if self._revision_history is not None:
	38	raise errors.BzrError("A revision history (%s) is already "
	39	"identity map" % self._revision_history)
	40	self._revision_history = revision_history
	41
1417.1.6 by Robert Collins introduce transactions for grouping actions done to and with branches	42	def add_weave(self, id, weave):
	43	"""Add weave to the map with a given id."""
	44	if self._weave_key(id) in self._map:
	45	raise errors.BzrError('weave %s already in the identity map' % id)
	46	self._map[self._weave_key(id)] = weave
1417.1.10 by Robert Collins add a cache bound to Transactions, and a precious facility, so that we keep inventory.weave in memory, but can discard weaves for other such files.	47	self._reverse_map[weave] = self._weave_key(id)
1417.1.6 by Robert Collins introduce transactions for grouping actions done to and with branches	48
1417.1.12 by Robert Collins cache revision history during read transactions	49	def find_revision_history(self):
	50	return self._revision_history
	51
1417.1.6 by Robert Collins introduce transactions for grouping actions done to and with branches	52	def find_weave(self, id):
	53	"""Return the weave for 'id', or None if it is not present."""
	54	return self._map.get(self._weave_key(id), None)
	55
	56	def __init__(self):
	57	super(IdentityMap, self).__init__()
	58	self._map = {}
1417.1.10 by Robert Collins add a cache bound to Transactions, and a precious facility, so that we keep inventory.weave in memory, but can discard weaves for other such files.	59	self._reverse_map = {}
1417.1.12 by Robert Collins cache revision history during read transactions	60	self._revision_history = None
1417.1.10 by Robert Collins add a cache bound to Transactions, and a precious facility, so that we keep inventory.weave in memory, but can discard weaves for other such files.	61
	62	def remove_object(self, an_object):
1417.1.12 by Robert Collins cache revision history during read transactions	63	"""Remove object from map."""
	64	if isinstance(an_object, list):
	65	if self._revision_history is an_object:
	66	self._revision_history = None
	67	else:
	68	raise KeyError('%r not in identity map' % an_object)
	69	else:
1417.1.10 by Robert Collins add a cache bound to Transactions, and a precious facility, so that we keep inventory.weave in memory, but can discard weaves for other such files.	70	self._map.pop(self._reverse_map[an_object])
	71	self._reverse_map.pop(an_object)
1417.1.6 by Robert Collins introduce transactions for grouping actions done to and with branches	72
	73	def _weave_key(self, id):
	74	"""Return the key for a weaves id."""
	75	return "weave-" + id
	76
	77
	78	class NullIdentityMap(object):
	79	"""A pretend in memory map from object id to instance.
	80
	81	A NullIdentityMap is an Identity map that does not store anything in it.
	82	"""
	83
	84	def add_weave(self, id, weave):
	85	"""See IdentityMap.add_weave."""
	86
1417.1.12 by Robert Collins cache revision history during read transactions	87	def add_revision_history(self, revision_history):
	88	"""See IdentityMap.add_revision_history."""
	89
1417.1.6 by Robert Collins introduce transactions for grouping actions done to and with branches	90	def find_weave(self, id):
	91	"""See IdentityMap.find_weave."""
	92	return None
	93
1417.1.12 by Robert Collins cache revision history during read transactions	94	def find_revision_history(self):
	95	"""See IdentityMap.find_revision_history."""