~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2006, 2007 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

# Original author: David Allouche

from bzrlib import errors, merge

from bzrlib.branch import Branch, BranchFormat, BranchReferenceFormat

from bzrlib.bzrdir import BzrDir

from bzrlib.trace import note

def switch(control_dir, to_branch):

    """Switch the branch associated with a checkout.

    :param control_dir: BzrDir of the checkout to change

    :param to_branch: branch that the checkout is to reference

    """

    _check_switch_branch_format(control_dir)

    _check_pending_merges(control_dir)

    try:

        source_repository = control_dir.open_branch().repository

    except errors.NotBranchError:

        source_repository = to_branch.repository

    _set_branch_location(control_dir, to_branch)

    tree = control_dir.open_workingtree()

    _update(tree, source_repository)

def _check_switch_branch_format(control):

    """Check that the branch format supports the switch operation.

    Note: Only lightweight checkouts are currently supported.

    This may change in the future though.

    :param control: BzrDir of the branch to check

    """

    branch_format = BranchFormat.find_format(control)

    format_string = branch_format.get_format_string()

    if not format_string.startswith("Bazaar-NG Branch Reference Format "):

        raise errors.BzrCommandError(

            'The switch command can only be used on a lightweight checkout.\n'

            'Expected branch reference, found %s at %s' % (

            format_string.strip(), control.root_transport.base))

    if not format_string == BranchReferenceFormat().get_format_string():

        raise errors.BzrCommandError(

            'Unsupported: %r' % (format_string.strip(),))        

def _check_pending_merges(control):

    """Check that there are no outstanding pending merges before switching.

    :param control: BzrDir of the branch to check

    """

    try:

        tree = control.open_workingtree()

    except errors.NotBranchError:

        # old branch is gone

        return

    # XXX: Should the tree be locked for get_parent_ids?

    existing_pending_merges = tree.get_parent_ids()[1:]

    if len(existing_pending_merges) > 0:

        raise errors.BzrCommandError('Pending merges must be '

            'committed or reverted before using switch.')

def _set_branch_location(control, to_branch):

    """Set location value of a branch reference.

    :param control: BzrDir of the checkout to change

    :param to_branch: branch that the checkout is to reference

    """

    transport = control.get_branch_transport(None)

    location = transport.put_bytes('location', to_branch.base)

def _update(tree, source_repository):

    """Update a working tree to the latest revision of its branch.

    :param tree: the working tree

    :param source_repository: repository holding the revisions

    """

    tree.lock_tree_write()

    try:

        to_branch = tree.branch

        if tree.last_revision() == to_branch.last_revision():

            note("Tree is up to date at revision %d.", to_branch.revno())

            return

        base_tree = source_repository.revision_tree(tree.last_revision())

        merge.Merge3Merger(tree, tree, base_tree, to_branch.basis_tree())

        tree.set_last_revision(to_branch.last_revision())

        note('Updated to revision %d.' % to_branch.revno())

    finally:

        tree.unlock()