~bzr-pqm/bzr/bzr.dev : contents of bzrlib/memorytree.py at revision 5777.5.5

~bzr-pqm/bzr/bzr.dev : (revision 5777.5.5)

# 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""MemoryTree object.

See MemoryTree for more details.
"""


import os

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


class MemoryTree(mutabletree.MutableInventoryTree):
    """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

    def is_control_filename(self, filename):
        # Memory tree doesn't have any control filenames
        return False

    @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._set_basis()
        if self._branch_revision_id == _mod_revision.NULL_REVISION:
            self._parent_ids = []
        else:
            self._parent_ids = [self._branch_revision_id]
        self._inventory = self._basis_tree._inventory._get_mutable_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._branch_revision_id = _mod_revision.NULL_REVISION
        else:
            self._parent_ids = revision_ids
            self._branch_revision_id = revision_ids[0]
        self._allow_leftmost_as_ghost = allow_leftmost_as_ghost
        self._set_basis()
    
    def _set_basis(self):
        try:
            self._basis_tree = self.branch.repository.revision_tree(
                self._branch_revision_id)
        except errors.NoSuchRevision:
            if self._allow_leftmost_as_ghost:
                self._basis_tree = self.branch.repository.revision_tree(
                    _mod_revision.NULL_REVISION)
            else:
                raise

    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
4183.7.1 by Sabin Iacob update FSF mailing address	15	# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	16
	17	"""MemoryTree object.
	18
	19	See MemoryTree for more details.
	20	"""
	21
	22
3567.5.1 by John Arbash Meinel Implement rename_one on MemoryTree, and expose that in the Branch Builder	23	import os
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	24
2598.5.1 by Aaron Bentley Start eliminating the use of None to indicate null revision	25	from bzrlib import (
	26	errors,
	27	mutabletree,
	28	revision as _mod_revision,
	29	)
5121.2.4 by Jelmer Vernooij Remove more unused imports.	30	from bzrlib.decorators import needs_read_lock
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	31	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.	32	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	33	from bzrlib.transport.memory import MemoryTransport
	34
	35
5777.4.1 by Jelmer Vernooij Split inventory-specific code out of MutableTree into MutableInventoryTree.	36	class MemoryTree(mutabletree.MutableInventoryTree):
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	37	"""A MemoryTree is a specialisation of MutableTree.
3943.8.1 by Marius Kruger remove all trailing whitespace from bzr source	38
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	39	It maintains nearly no state outside of read_lock and write_lock
	40	transactions. (it keeps a reference to the branch, and its last-revision
	41	only).
	42	"""
	43
	44	def __init__(self, branch, revision_id):
	45	"""Construct a MemoryTree for branch using revision_id."""
	46	self.branch = branch
	47	self.bzrdir = branch.bzrdir
	48	self._branch_revision_id = revision_id
	49	self._locks = 0
	50	self._lock_mode = None
	51
5699.2.1 by Jelmer Vernooij Move is_control_filename() from Tree to MutableTree.	52	def is_control_filename(self, filename):
	53	# Memory tree doesn't have any control filenames
	54	return False
	55
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	56	@needs_tree_write_lock
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	57	def _add(self, files, ids, kinds):
	58	"""See MutableTree._add."""
	59	for f, file_id, kind in zip(files, ids, kinds):
	60	if kind is None:
	61	kind = 'file'
	62	if file_id is None:
	63	self._inventory.add_path(f, kind=kind)
	64	else:
	65	self._inventory.add_path(f, kind=kind, file_id=file_id)
	66
	67	def basis_tree(self):
	68	"""See Tree.basis_tree()."""
	69	return self._basis_tree
	70
	71	@staticmethod
	72	def create_on_branch(branch):
	73	"""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	74	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	75	return MemoryTree(branch, revision_id)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	76
	77	def _gather_kinds(self, files, kinds):
	78	"""See MutableTree._gather_kinds.
3943.8.1 by Marius Kruger remove all trailing whitespace from bzr source	79
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	80	This implementation does not care about the file kind of
	81	missing files, so is a no-op.
	82	"""
	83
2743.3.3 by Ian Clatworthy Skip path lookup for tree.get_file() when we already know the path	84	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	85	"""See Tree.get_file."""
2743.3.3 by Ian Clatworthy Skip path lookup for tree.get_file() when we already know the path	86	if path is None:
	87	path = self.id2path(file_id)
	88	return self._file_transport.get(path)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	89
2564.2.1 by Ian Clatworthy refactor commit to support alternative population meothds	90	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	91	"""See Tree.get_file_sha1()."""
	92	if path is None:
	93	path = self.id2path(file_id)
	94	stream = self._file_transport.get(path)
	95	return sha_file(stream)
	96
2946.3.5 by John Arbash Meinel MemoryTree is not tested under the tree_implementations tests.	97	def get_root_id(self):
	98	return self.path2id('')
	99
2564.2.1 by Ian Clatworthy refactor commit to support alternative population meothds	100	def _comparison_data(self, entry, path):
	101	"""See Tree._comparison_data."""
	102	if entry is None:
	103	return None, False, None
	104	return entry.kind, entry.executable, None
	105
3567.5.1 by John Arbash Meinel Implement rename_one on MemoryTree, and expose that in the Branch Builder	106	@needs_tree_write_lock
	107	def rename_one(self, from_rel, to_rel):
	108	file_id = self.path2id(from_rel)
	109	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	110	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	111	self._file_transport.move(from_rel, to_rel)
	112	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.	113
2776.4.2 by Robert Collins nuke _read_tree_state and snapshot from inventory, moving responsibility into the commit builder.	114	def path_content_summary(self, path):
	115	"""See Tree.path_content_summary."""
	116	id = self.path2id(path)
	117	if id is None:
	118	return 'missing', None, None, None
	119	kind = self.kind(id)
	120	if kind == 'file':
	121	bytes = self._file_transport.get_bytes(path)
	122	size = len(bytes)
	123	executable = self._inventory[id].executable
	124	sha1 = None # no stat cache
	125	return (kind, size, executable, sha1)
	126	elif kind == 'directory':
	127	# memory tree does not support nested trees yet.
	128	return kind, None, None, None
	129	elif kind == 'symlink':
	130	raise NotImplementedError('symlink support')
	131	else:
	132	raise NotImplementedError('unknown kind')
	133
2564.2.1 by Ian Clatworthy refactor commit to support alternative population meothds	134	def _file_size(self, entry, stat_value):
	135	"""See Tree._file_size."""
	136	if entry is None:
	137	return 0
	138	return entry.text_size
	139
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	140	@needs_read_lock
	141	def get_parent_ids(self):
	142	"""See Tree.get_parent_ids.
	143
	144	This implementation returns the current cached value from
	145	self._parent_ids.
	146	"""
	147	return list(self._parent_ids)
	148
	149	def has_filename(self, filename):
	150	"""See Tree.has_filename()."""
	151	return self._file_transport.has(filename)
	152
	153	def is_executable(self, file_id, path=None):
	154	return self._inventory[file_id].executable
	155
1959.4.2 by Aaron Bentley Merge bzr.dev	156	def kind(self, file_id):
	157	return self._inventory[file_id].kind
	158
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	159	def mkdir(self, path, file_id=None):
	160	"""See MutableTree.mkdir()."""
	161	self.add(path, file_id, 'directory')
	162	if file_id is None:
	163	file_id = self.path2id(path)
	164	self._file_transport.mkdir(path)
	165	return file_id
	166
1986.1.6 by Robert Collins Add MemoryTree.last_revision.	167	@needs_read_lock
	168	def last_revision(self):
	169	"""See MutableTree.last_revision."""
	170	return self._branch_revision_id
	171
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	172	def lock_read(self):
	173	"""Lock the memory tree for reading.
	174
	175	This triggers population of data from the branch for its revision.
	176	"""
	177	self._locks += 1
	178	try:
	179	if self._locks == 1:
	180	self.branch.lock_read()
	181	self._lock_mode = "r"
	182	self._populate_from_branch()
	183	except:
	184	self._locks -= 1
	185	raise
	186
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	187	def lock_tree_write(self):
	188	"""See MutableTree.lock_tree_write()."""
	189	self._locks += 1
	190	try:
	191	if self._locks == 1:
	192	self.branch.lock_read()
	193	self._lock_mode = "w"
	194	self._populate_from_branch()
	195	elif self._lock_mode == "r":
	196	raise errors.ReadOnlyError(self)
	197	except:
	198	self._locks -= 1
	199	raise
	200
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	201	def lock_write(self):
	202	"""See MutableTree.lock_write()."""
	203	self._locks += 1
	204	try:
	205	if self._locks == 1:
	206	self.branch.lock_write()
	207	self._lock_mode = "w"
	208	self._populate_from_branch()
	209	elif self._lock_mode == "r":
	210	raise errors.ReadOnlyError(self)
	211	except:
	212	self._locks -= 1
	213	raise
	214
	215	def _populate_from_branch(self):
	216	"""Populate the in-tree state from the branch."""
4190.1.4 by Robert Collins Cache ghosts when we can get them from a RemoteRepository in get_parent_map.	217	self._set_basis()
3668.5.4 by Jelmer Vernooij Eliminate more uses of Repository.revision_tree(None).	218	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	219	self._parent_ids = []
	220	else:
	221	self._parent_ids = [self._branch_revision_id]
4244.2.1 by Vincent Ladeuil inv._get_mutable_inventory() - prepare for CHKInventory	222	self._inventory = self._basis_tree._inventory._get_mutable_inventory()
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	223	self._file_transport = MemoryTransport()
	224	# TODO copy the revision trees content, or do it lazy, or something.
	225	inventory_entries = self._inventory.iter_entries()
	226	for path, entry in inventory_entries:
1731.1.50 by Aaron Bentley Merge bzr.dev	227	if path == '':
1731.1.50 by Aaron Bentley Merge bzr.dev	228	continue
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	229	if entry.kind == 'directory':
	230	self._file_transport.mkdir(path)
	231	elif entry.kind == 'file':
1986.1.4 by Robert Collins Fixup deprecations from bzr.dev.	232	self._file_transport.put_file(path,
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	233	self._basis_tree.get_file(entry.file_id))
	234	else:
	235	raise NotImplementedError(self._populate_from_branch)
	236
	237	def put_file_bytes_non_atomic(self, file_id, bytes):
	238	"""See MutableTree.put_file_bytes_non_atomic."""
1986.1.4 by Robert Collins Fixup deprecations from bzr.dev.	239	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	240
	241	def unlock(self):
	242	"""Release a lock.
	243
	244	This frees all cached state when the last lock context for the tree is
	245	left.
	246	"""
	247	if self._locks == 1:
	248	self._basis_tree = None
	249	self._parent_ids = []
	250	self._inventory = None
	251	try:
	252	self.branch.unlock()
	253	finally:
	254	self._locks = 0
	255	self._lock_mode = None
	256	else:
	257	self._locks -= 1
	258
1986.1.8 by Robert Collins Update to bzr.dev, which involves adding lock_tree_write to MutableTree and MemoryTree.	259	@needs_tree_write_lock
1986.1.3 by Robert Collins Merge bzr.dev.	260	def unversion(self, file_ids):
	261	"""Remove the file ids in file_ids from the current versioned set.
	262
	263	When a file_id is unversioned, all of its children are automatically
	264	unversioned.
	265
	266	:param file_ids: The file ids to stop versioning.
	267	:raises: NoSuchId if any fileid is not currently versioned.
	268	"""
	269	# XXX: This should be in mutabletree, but the inventory-save action
	270	# is not relevant to memory tree. Until that is done in unlock by
	271	# working tree, we cannot share the implementation.
	272	for file_id in file_ids:
	273	if self._inventory.has_id(file_id):
	274	self._inventory.remove_recursive_id(file_id)
	275	else:
	276	raise errors.NoSuchId(self, file_id)
	277
2418.5.1 by John Arbash Meinel Make a Branch helper which can create a very basic MemoryTree with history.	278	def set_parent_ids(self, revision_ids, allow_leftmost_as_ghost=False):
	279	"""See MutableTree.set_parent_trees()."""
2598.5.2 by Aaron Bentley Got all tests passing with Branch returning 'null:' for null revision	280	for revision_id in revision_ids:
	281	_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.	282	if len(revision_ids) == 0:
	283	self._parent_ids = []
4190.1.4 by Robert Collins Cache ghosts when we can get them from a RemoteRepository in get_parent_map.	284	self._branch_revision_id = _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._branch_revision_id = revision_ids[0]
4190.1.4 by Robert Collins Cache ghosts when we can get them from a RemoteRepository in get_parent_map.	288	self._allow_leftmost_as_ghost = allow_leftmost_as_ghost
	289	self._set_basis()
	290
	291	def _set_basis(self):
	292	try:
	293	self._basis_tree = self.branch.repository.revision_tree(
	294	self._branch_revision_id)
	295	except errors.NoSuchRevision:
	296	if self._allow_leftmost_as_ghost:
	297	self._basis_tree = self.branch.repository.revision_tree(
	298	_mod_revision.NULL_REVISION)
	299	else:
	300	raise
2418.5.1 by John Arbash Meinel Make a Branch helper which can create a very basic MemoryTree with history.	301
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	302	def set_parent_trees(self, parents_list, allow_leftmost_as_ghost=False):
	303	"""See MutableTree.set_parent_trees()."""
	304	if len(parents_list) == 0:
	305	self._parent_ids = []
3668.5.1 by Jelmer Vernooij Use NULL_REVISION rather than None for Repository.revision_tree().	306	self._basis_tree = self.branch.repository.revision_tree(
	307	_mod_revision.NULL_REVISION)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	308	else:
	309	if parents_list[0][1] is None and not allow_leftmost_as_ghost:
	310	# a ghost in the left most parent
	311	raise errors.GhostRevisionUnusableHere(parents_list[0][0])
	312	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	313	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().	314	self._basis_tree = self.branch.repository.revision_tree(
	315	_mod_revision.NULL_REVISION)
1986.1.2 by Robert Collins Various changes to allow non-workingtree specific tests to run entirely	316	else:
	317	self._basis_tree = parents_list[0][1]
1986.1.6 by Robert Collins Add MemoryTree.last_revision.	318	self._branch_revision_id = parents_list[0][0]