~bzr-pqm/bzr/bzr.dev

# Copyright (C) 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Tag strategies.

These are contained within a branch and normally constructed

when the branch is opened.  Clients should typically do

  Branch.tags.add('name', 'value')

"""

# NOTE: I was going to call this tags.py, but vim seems to think all files

# called tags* are ctags files... mbp 20070220.

from warnings import warn

from bzrlib.lazy_import import lazy_import

lazy_import(globals(), """

from bzrlib.util import bencode

""")

from bzrlib import (

    errors,

    trace,

    )

class _Tags(object):

    def __init__(self, branch):

        self.branch = branch

    def has_tag(self, tag_name):

        return self.get_tag_dict().has_key(tag_name)

class DisabledTags(_Tags):

    """Tag storage that refuses to store anything.

    This is used by older formats that can't store tags.

    """

    def _not_supported(self, *a, **k):

        raise errors.TagsNotSupported(self.branch)

    set_tag = _not_supported

    get_tag_dict = _not_supported

    _set_tag_dict = _not_supported

    lookup_tag = _not_supported

    delete_tag = _not_supported

    def merge_to(self, to_tags, overwrite=False):

        # we never have anything to copy

        pass

    def get_reverse_tag_dict(self):

        # There aren't any tags, so the reverse mapping is empty.

        return {}

class BasicTags(_Tags):

    """Tag storage in an unversioned branch control file.

    """

    def set_tag(self, tag_name, tag_target):

        """Add a tag definition to the branch.

        Behaviour if the tag is already present is not defined (yet).

        """

        # all done with a write lock held, so this looks atomic

        self.branch.lock_write()

        try:

            master = self.branch.get_master_branch()

            if master is not None:

                master.tags.set_tag(tag_name, tag_target)

            td = self.get_tag_dict()

            td[tag_name] = tag_target

            self._set_tag_dict(td)

        finally:

            self.branch.unlock()

    def lookup_tag(self, tag_name):

        """Return the referent string of a tag"""

        td = self.get_tag_dict()

        try:

            return td[tag_name]

        except KeyError:

            raise errors.NoSuchTag(tag_name)

    def get_tag_dict(self):

        self.branch.lock_read()

        try:

            try:

                tag_content = self.branch._get_tags_bytes()

            except errors.NoSuchFile, e:

                # ugly, but only abentley should see this :)

                trace.warning('No branch/tags file in %s.  '

                     'This branch was probably created by bzr 0.15pre.  '

                     'Create an empty file to silence this message.'

                     % (self.branch, ))

                return {}

            return self._deserialize_tag_dict(tag_content)

        finally:

            self.branch.unlock()

    def get_reverse_tag_dict(self):

        """Returns a dict with revisions as keys

           and a list of tags for that revision as value"""

        d = self.get_tag_dict()

        rev = {}

        for key in d:

            try:

                rev[d[key]].append(key)

            except KeyError:

                rev[d[key]] = [key]

        return rev

    def delete_tag(self, tag_name):

        """Delete a tag definition.

        """

        self.branch.lock_write()

        try:

            d = self.get_tag_dict()

            try:

                del d[tag_name]

            except KeyError:

                raise errors.NoSuchTag(tag_name)

            master = self.branch.get_master_branch()

            if master is not None:

                try:

                    master.tags.delete_tag(tag_name)

                except errors.NoSuchTag:

                    pass

            self._set_tag_dict(d)

        finally:

            self.branch.unlock()

    def _set_tag_dict(self, new_dict):

        """Replace all tag definitions

        WARNING: Calling this on an unlocked branch will lock it, and will

        replace the tags without warning on conflicts.

        :param new_dict: Dictionary from tag name to target.

        """

        return self.branch._set_tags_bytes(self._serialize_tag_dict(new_dict))

    def _serialize_tag_dict(self, tag_dict):

        td = dict((k.encode('utf-8'), v)

                  for k,v in tag_dict.items())

        return bencode.bencode(td)

    def _deserialize_tag_dict(self, tag_content):

        """Convert the tag file into a dictionary of tags"""

        # was a special case to make initialization easy, an empty definition

        # is an empty dictionary

        if tag_content == '':

            return {}

        try:

            r = {}

            for k, v in bencode.bdecode(tag_content).items():

                r[k.decode('utf-8')] = v

            return r

        except ValueError, e:

            raise ValueError("failed to deserialize tag dictionary %r: %s"

                % (tag_content, e))

    def merge_to(self, to_tags, overwrite=False):

        """Copy tags between repositories if necessary and possible.

        This method has common command-line behaviour about handling

        error cases.

        All new definitions are copied across, except that tags that already

        exist keep their existing definitions.

        :param to_tags: Branch to receive these tags

        :param overwrite: Overwrite conflicting tags in the target branch

        :returns: A list of tags that conflicted, each of which is

            (tagname, source_target, dest_target), or None if no copying was

            done.

        """

        if self.branch == to_tags.branch:

            return

        if not self.branch.supports_tags():

            # obviously nothing to copy

            return

        source_dict = self.get_tag_dict()

        if not source_dict:

            # no tags in the source, and we don't want to clobber anything

            # that's in the destination

            return

        to_tags.branch.lock_write()

        try:

            dest_dict = to_tags.get_tag_dict()

            result, conflicts = self._reconcile_tags(source_dict, dest_dict,

                                                     overwrite)

            if result != dest_dict:

                to_tags._set_tag_dict(result)

        finally:

            to_tags.branch.unlock()

        return conflicts

    def _reconcile_tags(self, source_dict, dest_dict, overwrite):

        """Do a two-way merge of two tag dictionaries.

        only in source => source value

        only in destination => destination value

        same definitions => that

        different definitions => if overwrite is False, keep destination

            value and give a warning, otherwise use the source value

        :returns: (result_dict,

            [(conflicting_tag, source_target, dest_target)])

        """

        conflicts = []

        result = dict(dest_dict) # copy

        for name, target in source_dict.items():

            if name not in result or overwrite:

                result[name] = target

            elif result[name] == target:

                pass

            else:

                conflicts.append((name, target, result[name]))

        return result, conflicts

def _merge_tags_if_possible(from_branch, to_branch):

    from_branch.tags.merge_to(to_branch.tags)