~bzr-pqm/bzr/bzr.dev : contents of bzrlib/memorytree.py at revision 3895

~bzr-pqm/bzr/bzr.dev : (revision 3895)

# Copyright (C) 2006 Canonical Ltd
#
# 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

"""MemoryTree object.

See MemoryTree for more details.
"""


from copy import deepcopy
import os

from bzrlib import (
    errors,
    mutabletree,
    osutils,
    revision as _mod_revision,
    )
from bzrlib.decorators import needs_read_lock, needs_write_lock
from bzrlib.osutils import sha_file
from bzrlib.mutabletree import needs_tree_write_lock
from bzrlib.transport.memory import MemoryTransport


class MemoryTree(mutabletree.MutableTree):
    """A MemoryTree is a specialisation of MutableTree.
    
    It maintains nearly no state outside of read_lock and write_lock
    transactions. (it keeps a reference to the branch, and its last-revision
    only).
    """

    def __init__(self, branch, revision_id):
        """Construct a MemoryTree for branch using revision_id."""
        self.branch = branch
        self.bzrdir = branch.bzrdir
        self._branch_revision_id = revision_id
        self._locks = 0
        self._lock_mode = None

    @needs_tree_write_lock
    def _add(self, files, ids, kinds):
        """See MutableTree._add."""
        for f, file_id, kind in zip(files, ids, kinds):
            if kind is None:
                kind = 'file'
            if file_id is None:
                self._inventory.add_path(f, kind=kind)
            else:
                self._inventory.add_path(f, kind=kind, file_id=file_id)

    def basis_tree(self):
        """See Tree.basis_tree()."""
        return self._basis_tree

    @staticmethod
    def create_on_branch(branch):
        """Create a MemoryTree for branch, using the last-revision of branch."""
        revision_id = _mod_revision.ensure_null(branch.last_revision())
        return MemoryTree(branch, revision_id)

    def _gather_kinds(self, files, kinds):
        """See MutableTree._gather_kinds.
        
        This implementation does not care about the file kind of
        missing files, so is a no-op.
        """

    def get_file(self, file_id, path=None):
        """See Tree.get_file."""
        if path is None:
            path = self.id2path(file_id)
        return self._file_transport.get(path)

    def get_file_sha1(self, file_id, path=None, stat_value=None):
        """See Tree.get_file_sha1()."""
        if path is None:
            path = self.id2path(file_id)
        stream = self._file_transport.get(path)
        return sha_file(stream)

    def get_root_id(self):
        return self.path2id('')

    def _comparison_data(self, entry, path):
        """See Tree._comparison_data."""
        if entry is None:
            return None, False, None
        return entry.kind, entry.executable, None

    @needs_tree_write_lock
    def rename_one(self, from_rel, to_rel):
        file_id = self.path2id(from_rel)
        to_dir, to_tail = os.path.split(to_rel)
        to_parent_id = self.path2id(to_dir)
        self._file_transport.move(from_rel, to_rel)
        self._inventory.rename(file_id, to_parent_id, to_tail)

    def path_content_summary(self, path):
        """See Tree.path_content_summary."""
        id = self.path2id(path)
        if id is None:
            return 'missing', None, None, None
        kind = self.kind(id)
        if kind == 'file':
            bytes = self._file_transport.get_bytes(path)
            size = len(bytes)
            executable = self._inventory[id].executable
            sha1 = None # no stat cache
            return (kind, size, executable, sha1)
        elif kind == 'directory':
            # memory tree does not support nested trees yet.
            return kind, None, None, None
        elif kind == 'symlink':
            raise NotImplementedError('symlink support')
        else:
            raise NotImplementedError('unknown kind')

    def _file_size(self, entry, stat_value):
        """See Tree._file_size."""
        if entry is None:
            return 0
        return entry.text_size

    @needs_read_lock
    def get_parent_ids(self):
        """See Tree.get_parent_ids.

        This implementation returns the current cached value from
            self._parent_ids.
        """
        return list(self._parent_ids)

    def has_filename(self, filename):
        """See Tree.has_filename()."""
        return self._file_transport.has(filename)

    def is_executable(self, file_id, path=None):
        return self._inventory[file_id].executable

    def kind(self, file_id):
        return self._inventory[file_id].kind

    def mkdir(self, path, file_id=None):
        """See MutableTree.mkdir()."""
        self.add(path, file_id, 'directory')
        if file_id is None:
            file_id = self.path2id(path)
        self._file_transport.mkdir(path)
        return file_id

    @needs_read_lock
    def last_revision(self):
        """See MutableTree.last_revision."""
        return self._branch_revision_id

    def lock_read(self):
        """Lock the memory tree for reading.

        This triggers population of data from the branch for its revision.
        """
        self._locks += 1
        try:
            if self._locks == 1:
                self.branch.lock_read()
                self._lock_mode = "r"
                self._populate_from_branch()
        except:
            self._locks -= 1
            raise

    def lock_tree_write(self):
        """See MutableTree.lock_tree_write()."""
        self._locks += 1
        try:
            if self._locks == 1:
                self.branch.lock_read()
                self._lock_mode = "w"
                self._populate_from_branch()
            elif self._lock_mode == "r":
                raise errors.ReadOnlyError(self)
        except:
            self._locks -= 1
            raise

    def lock_write(self):
        """See MutableTree.lock_write()."""
        self._locks += 1
        try:
            if self._locks == 1:
                self.branch.lock_write()
                self._lock_mode = "w"
                self._populate_from_branch()
            elif self._lock_mode == "r":
                raise errors.ReadOnlyError(self)
        except:
            self._locks -= 1
            raise

    def _populate_from_branch(self):
        """Populate the in-tree state from the branch."""
        self._basis_tree = self.branch.repository.revision_tree(
            self._branch_revision_id)
        if self._branch_revision_id == _mod_revision.NULL_REVISION:
            self._parent_ids = []
        else:
            self._parent_ids = [self._branch_revision_id]
        self._inventory = deepcopy(self._basis_tree._inventory)
        self._file_transport = MemoryTransport()
        # TODO copy the revision trees content, or do it lazy, or something.
        inventory_entries = self._inventory.iter_entries()
        for path, entry in inventory_entries:
            if path == '':
                continue
            if entry.kind == 'directory':
                self._file_transport.mkdir(path)
            elif entry.kind == 'file':
                self._file_transport.put_file(path,
                    self._basis_tree.get_file(entry.file_id))
            else:
                raise NotImplementedError(self._populate_from_branch)

    def put_file_bytes_non_atomic(self, file_id, bytes):
        """See MutableTree.put_file_bytes_non_atomic."""
        self._file_transport.put_bytes(self.id2path(file_id), bytes)

    def unlock(self):
        """Release a lock.

        This frees all cached state when the last lock context for the tree is
        left.
        """
        if self._locks == 1:
            self._basis_tree = None
            self._parent_ids = []
            self._inventory = None
            try:
                self.branch.unlock()
            finally:
                self._locks = 0
                self._lock_mode = None
        else:
            self._locks -= 1

    @needs_tree_write_lock
    def unversion(self, file_ids):
        """Remove the file ids in file_ids from the current versioned set.

        When a file_id is unversioned, all of its children are automatically
        unversioned.

        :param file_ids: The file ids to stop versioning.
        :raises: NoSuchId if any fileid is not currently versioned.
        """
        # XXX: This should be in mutabletree, but the inventory-save action
        # is not relevant to memory tree. Until that is done in unlock by
        # working tree, we cannot share the implementation.
        for file_id in file_ids:
            if self._inventory.has_id(file_id):
                self._inventory.remove_recursive_id(file_id)
            else:
                raise errors.NoSuchId(self, file_id)

    def set_parent_ids(self, revision_ids, allow_leftmost_as_ghost=False):
        """See MutableTree.set_parent_trees()."""
        for revision_id in revision_ids:
            _mod_revision.check_not_reserved_id(revision_id)
        if len(revision_ids) == 0:
            self._parent_ids = []
            self._basis_tree = self.branch.repository.revision_tree(
                                    _mod_revision.NULL_REVISION)
        else:
            self._parent_ids = revision_ids
            self._basis_tree = self.branch.repository.revision_tree(
                                    revision_ids[0])
            self._branch_revision_id = revision_ids[0]

    def set_parent_trees(self, parents_list, allow_leftmost_as_ghost=False):
        """See MutableTree.set_parent_trees()."""
        if len(parents_list) == 0:
            self._parent_ids = []
            self._basis_tree = self.branch.repository.revision_tree(
                                   _mod_revision.NULL_REVISION)
        else:
            if parents_list[0][1] is None and not allow_leftmost_as_ghost:
                # a ghost in the left most parent
                raise errors.GhostRevisionUnusableHere(parents_list[0][0])
            self._parent_ids = [parent_id for parent_id, tree in parents_list]
            if parents_list[0][1] is None or parents_list[0][1] == 'null:':
                self._basis_tree = self.branch.repository.revision_tree(
                                       _mod_revision.NULL_REVISION)
            else:
                self._basis_tree = parents_list[0][1]
            self._branch_revision_id = parents_list[0][0]

1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	1	# Copyright (C) 2006 Canonical Ltd
	2	#
	3	# This program is free software; you can redistribute it and/or modify
	4	# it under the terms of the GNU General Public License as published by
	5	# the Free Software Foundation; either version 2 of the License, or
	6	# (at your option) any later version.
	7	#
	8	# This program is distributed in the hope that it will be useful,
	9	# but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	11	# GNU General Public License for more details.
	12	#
	13	# You should have received a copy of the GNU General Public License
	14	# along with this program; if not, write to the Free Software
	15	# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	16
	17	"""MemoryTree object.
	18
	19	See MemoryTree for more details.
	20	"""
	21
	22
	23	from copy import deepcopy
3567.5.1 by John Arbash Meinel Implement rename_one on MemoryTree, and expose that in the Branch Builder	24	import os
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	25
2598.5.1 by Aaron Bentley Start eliminating the use of None to indicate null revision	26	from bzrlib import (
	27	errors,
	28	mutabletree,
3567.5.1 by John Arbash Meinel Implement rename_one on MemoryTree, and expose that in the Branch Builder	29	osutils,
2598.5.1 by Aaron Bentley Start eliminating the use of None to indicate null revision	30	revision as _mod_revision,
	31	)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	32	from bzrlib.decorators import needs_read_lock, needs_write_lock
	33	from bzrlib.osutils import sha_file
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	34	from bzrlib.mutabletree import needs_tree_write_lock
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	35	from bzrlib.transport.memory import MemoryTransport
	36
	37
	38	class MemoryTree(mutabletree.MutableTree):
	39	"""A MemoryTree is a specialisation of MutableTree.
	40
	41	It maintains nearly no state outside of read_lock and write_lock
	42	transactions. (it keeps a reference to the branch, and its last-revision
	43	only).
	44	"""
	45
	46	def __init__(self, branch, revision_id):
	47	"""Construct a MemoryTree for branch using revision_id."""
	48	self.branch = branch
	49	self.bzrdir = branch.bzrdir
	50	self._branch_revision_id = revision_id
	51	self._locks = 0
	52	self._lock_mode = None
	53
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	54	@needs_tree_write_lock
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	55	def _add(self, files, ids, kinds):
	56	"""See MutableTree._add."""
	57	for f, file_id, kind in zip(files, ids, kinds):
	58	if kind is None:
	59	kind = 'file'
	60	if file_id is None:
	61	self._inventory.add_path(f, kind=kind)
	62	else:
	63	self._inventory.add_path(f, kind=kind, file_id=file_id)
	64
	65	def basis_tree(self):
	66	"""See Tree.basis_tree()."""
	67	return self._basis_tree
	68
	69	@staticmethod
	70	def create_on_branch(branch):
	71	"""Create a MemoryTree for branch, using the last-revision of branch."""
2598.5.4 by Aaron Bentley Restore original Branch.last_revision behavior, fix bits that care	72	revision_id = _mod_revision.ensure_null(branch.last_revision())
2598.5.1 by Aaron Bentley Start eliminating the use of None to indicate null revision	73	return MemoryTree(branch, revision_id)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	74
	75	def _gather_kinds(self, files, kinds):
	76	"""See MutableTree._gather_kinds.
	77
	78	This implementation does not care about the file kind of
	79	missing files, so is a no-op.
	80	"""
	81
2743.3.3 by Ian Clatworthy Skip path lookup for tree.get_file() when we already know the path	82	def get_file(self, file_id, path=None):
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	83	"""See Tree.get_file."""
2743.3.3 by Ian Clatworthy Skip path lookup for tree.get_file() when we already know the path	84	if path is None:
	85	path = self.id2path(file_id)
	86	return self._file_transport.get(path)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	87
2564.2.1 by Ian Clatworthy refactor commit to support alternative population meothds	88	def get_file_sha1(self, file_id, path=None, stat_value=None):
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	89	"""See Tree.get_file_sha1()."""
	90	if path is None:
	91	path = self.id2path(file_id)
	92	stream = self._file_transport.get(path)
	93	return sha_file(stream)
	94
2946.3.5 by John Arbash Meinel MemoryTree is not tested under the tree_implementations tests.	95	def get_root_id(self):
	96	return self.path2id('')
	97
2564.2.1 by Ian Clatworthy refactor commit to support alternative population meothds	98	def _comparison_data(self, entry, path):
	99	"""See Tree._comparison_data."""
	100	if entry is None:
	101	return None, False, None
	102	return entry.kind, entry.executable, None
	103
3567.5.1 by John Arbash Meinel Implement rename_one on MemoryTree, and expose that in the Branch Builder	104	@needs_tree_write_lock
	105	def rename_one(self, from_rel, to_rel):
	106	file_id = self.path2id(from_rel)
	107	to_dir, to_tail = os.path.split(to_rel)
3514.4.44 by John Arbash Meinel Revert the path2id fix, because to_dir can be anywhere, not just	108	to_parent_id = self.path2id(to_dir)
3567.5.1 by John Arbash Meinel Implement rename_one on MemoryTree, and expose that in the Branch Builder	109	self._file_transport.move(from_rel, to_rel)
	110	self._inventory.rename(file_id, to_parent_id, to_tail)
3514.4.38 by John Arbash Meinel Use direct access to the inventory instead of path2id.	111
2776.4.2 by Robert Collins nuke _read_tree_state and snapshot from inventory, moving responsibility into the commit builder.	112	def path_content_summary(self, path):
	113	"""See Tree.path_content_summary."""
	114	id = self.path2id(path)
	115	if id is None:
	116	return 'missing', None, None, None
	117	kind = self.kind(id)
	118	if kind == 'file':
	119	bytes = self._file_transport.get_bytes(path)
	120	size = len(bytes)
	121	executable = self._inventory[id].executable
	122	sha1 = None # no stat cache
	123	return (kind, size, executable, sha1)
	124	elif kind == 'directory':
	125	# memory tree does not support nested trees yet.
	126	return kind, None, None, None
	127	elif kind == 'symlink':
	128	raise NotImplementedError('symlink support')
	129	else:
	130	raise NotImplementedError('unknown kind')
	131
2564.2.1 by Ian Clatworthy refactor commit to support alternative population meothds	132	def _file_size(self, entry, stat_value):
	133	"""See Tree._file_size."""
	134	if entry is None:
	135	return 0
	136	return entry.text_size
	137
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	138	@needs_read_lock
	139	def get_parent_ids(self):
	140	"""See Tree.get_parent_ids.
	141
	142	This implementation returns the current cached value from
	143	self._parent_ids.
	144	"""
	145	return list(self._parent_ids)
	146
	147	def has_filename(self, filename):
	148	"""See Tree.has_filename()."""
	149	return self._file_transport.has(filename)
	150
	151	def is_executable(self, file_id, path=None):
	152	return self._inventory[file_id].executable
	153
1959.4.2 by Aaron Bentley Merge bzr.dev	154	def kind(self, file_id):
	155	return self._inventory[file_id].kind
	156
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	157	def mkdir(self, path, file_id=None):
	158	"""See MutableTree.mkdir()."""
	159	self.add(path, file_id, 'directory')
	160	if file_id is None:
	161	file_id = self.path2id(path)
	162	self._file_transport.mkdir(path)
	163	return file_id
	164
1986.1.6 by Robert Collins Add MemoryTree.last_revision.	165	@needs_read_lock
	166	def last_revision(self):
	167	"""See MutableTree.last_revision."""
	168	return self._branch_revision_id
	169
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	170	def lock_read(self):
	171	"""Lock the memory tree for reading.
	172
	173	This triggers population of data from the branch for its revision.
	174	"""
	175	self._locks += 1
	176	try:
	177	if self._locks == 1:
	178	self.branch.lock_read()
	179	self._lock_mode = "r"
	180	self._populate_from_branch()
	181	except:
	182	self._locks -= 1
	183	raise
	184
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	185	def lock_tree_write(self):
	186	"""See MutableTree.lock_tree_write()."""
	187	self._locks += 1
	188	try:
	189	if self._locks == 1:
	190	self.branch.lock_read()
	191	self._lock_mode = "w"
	192	self._populate_from_branch()
	193	elif self._lock_mode == "r":
	194	raise errors.ReadOnlyError(self)
	195	except:
	196	self._locks -= 1
	197	raise
	198
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	199	def lock_write(self):
	200	"""See MutableTree.lock_write()."""
	201	self._locks += 1
	202	try:
	203	if self._locks == 1:
	204	self.branch.lock_write()
	205	self._lock_mode = "w"
	206	self._populate_from_branch()
	207	elif self._lock_mode == "r":
	208	raise errors.ReadOnlyError(self)
	209	except:
	210	self._locks -= 1
	211	raise
	212
	213	def _populate_from_branch(self):
	214	"""Populate the in-tree state from the branch."""
	215	self._basis_tree = self.branch.repository.revision_tree(
	216	self._branch_revision_id)
3668.5.4 by Jelmer Vernooij Eliminate more uses of Repository.revision_tree(None).	217	if self._branch_revision_id == _mod_revision.NULL_REVISION:
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	218	self._parent_ids = []
	219	else:
	220	self._parent_ids = [self._branch_revision_id]
	221	self._inventory = deepcopy(self._basis_tree._inventory)
	222	self._file_transport = MemoryTransport()
	223	# TODO copy the revision trees content, or do it lazy, or something.
	224	inventory_entries = self._inventory.iter_entries()
	225	for path, entry in inventory_entries:
1731.1.50 by Aaron Bentley Merge bzr.dev	226	if path == '':
1731.1.50 by Aaron Bentley Merge bzr.dev	227	continue
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	228	if entry.kind == 'directory':
	229	self._file_transport.mkdir(path)
	230	elif entry.kind == 'file':
1986.1.4 by Robert Collins Fixup deprecations from bzr.dev.	231	self._file_transport.put_file(path,
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	232	self._basis_tree.get_file(entry.file_id))
	233	else:
	234	raise NotImplementedError(self._populate_from_branch)
	235
	236	def put_file_bytes_non_atomic(self, file_id, bytes):
	237	"""See MutableTree.put_file_bytes_non_atomic."""
1986.1.4 by Robert Collins Fixup deprecations from bzr.dev.	238	self._file_transport.put_bytes(self.id2path(file_id), bytes)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	239
	240	def unlock(self):
	241	"""Release a lock.
	242
	243	This frees all cached state when the last lock context for the tree is
	244	left.
	245	"""
	246	if self._locks == 1:
	247	self._basis_tree = None
	248	self._parent_ids = []
	249	self._inventory = None
	250	try:
	251	self.branch.unlock()
	252	finally:
	253	self._locks = 0
	254	self._lock_mode = None
	255	else:
	256	self._locks -= 1
	257
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	258	@needs_tree_write_lock
1986.1.3 by Robert Collins Merge bzr.dev.	259	def unversion(self, file_ids):
	260	"""Remove the file ids in file_ids from the current versioned set.
	261
	262	When a file_id is unversioned, all of its children are automatically
	263	unversioned.
	264
	265	:param file_ids: The file ids to stop versioning.
	266	:raises: NoSuchId if any fileid is not currently versioned.
	267	"""
	268	# XXX: This should be in mutabletree, but the inventory-save action
	269	# is not relevant to memory tree. Until that is done in unlock by
	270	# working tree, we cannot share the implementation.
	271	for file_id in file_ids:
	272	if self._inventory.has_id(file_id):
	273	self._inventory.remove_recursive_id(file_id)
	274	else:
	275	raise errors.NoSuchId(self, file_id)
	276
2418.5.1 by John Arbash Meinel Make a Branch helper which can create a very basic MemoryTree with history.	277	def set_parent_ids(self, revision_ids, allow_leftmost_as_ghost=False):
	278	"""See MutableTree.set_parent_trees()."""
2598.5.2 by Aaron Bentley Got all tests passing with Branch returning 'null:' for null revision	279	for revision_id in revision_ids:
	280	_mod_revision.check_not_reserved_id(revision_id)
2418.5.1 by John Arbash Meinel Make a Branch helper which can create a very basic MemoryTree with history.	281	if len(revision_ids) == 0:
	282	self._parent_ids = []
3668.5.1 by Jelmer Vernooij Use NULL_REVISION rather than None for Repository.revision_tree().	283	self._basis_tree = self.branch.repository.revision_tree(
	284	_mod_revision.NULL_REVISION)
2418.5.1 by John Arbash Meinel Make a Branch helper which can create a very basic MemoryTree with history.	285	else:
	286	self._parent_ids = revision_ids
	287	self._basis_tree = self.branch.repository.revision_tree(
	288	revision_ids[0])
	289	self._branch_revision_id = revision_ids[0]
	290
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	291	def set_parent_trees(self, parents_list, allow_leftmost_as_ghost=False):
	292	"""See MutableTree.set_parent_trees()."""
	293	if len(parents_list) == 0:
	294	self._parent_ids = []
3668.5.1 by Jelmer Vernooij Use NULL_REVISION rather than None for Repository.revision_tree().	295	self._basis_tree = self.branch.repository.revision_tree(
	296	_mod_revision.NULL_REVISION)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	297	else:
	298	if parents_list[0][1] is None and not allow_leftmost_as_ghost:
	299	# a ghost in the left most parent
	300	raise errors.GhostRevisionUnusableHere(parents_list[0][0])
	301	self._parent_ids = [parent_id for parent_id, tree in parents_list]
2598.5.2 by Aaron Bentley Got all tests passing with Branch returning 'null:' for null revision	302	if parents_list[0][1] is None or parents_list[0][1] == 'null:':
3668.5.1 by Jelmer Vernooij Use NULL_REVISION rather than None for Repository.revision_tree().	303	self._basis_tree = self.branch.repository.revision_tree(
	304	_mod_revision.NULL_REVISION)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	305	else:
	306	self._basis_tree = parents_list[0][1]
1986.1.6 by Robert Collins Add MemoryTree.last_revision.	307	self._branch_revision_id = parents_list[0][0]