~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2010 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

"""Merge logic for news_merge plugin."""

from __future__ import absolute_import

from bzrlib.plugins.news_merge.parser import simple_parse_lines

from bzrlib import merge, merge3

class NewsMerger(merge.ConfigurableFileMerger):

    """Merge bzr NEWS files."""

    name_prefix = "news"

    def merge_text(self, params):

        """Perform a simple 3-way merge of a bzr NEWS file.

        Each section of a bzr NEWS file is essentially an ordered set of bullet

        points, so we can simply take a set of bullet points, determine which

        bullets to add and which to remove, sort, and reserialize.

        """

        # Transform the different versions of the NEWS file into a bunch of

        # text lines where each line matches one part of the overall

        # structure, e.g. a heading or bullet.

        this_lines = list(simple_parse_lines(params.this_lines))

        other_lines = list(simple_parse_lines(params.other_lines))

        base_lines = list(simple_parse_lines(params.base_lines))

        m3 = merge3.Merge3(base_lines, this_lines, other_lines,

            allow_objects=True)

        result_chunks = []

        for group in m3.merge_groups():

            if group[0] == 'conflict':

                _, base, a, b = group

                # Are all the conflicting lines bullets?  If so, we can merge

                # this.

                for line_set in [base, a, b]:

                    for line in line_set:

                        if line[0] != 'bullet':

                            # Something else :(

                            # Maybe the default merge can cope.

                            return 'not_applicable', None

                # Calculate additions and deletions.

                new_in_a = set(a).difference(base)

                new_in_b = set(b).difference(base)

                all_new = new_in_a.union(new_in_b)

                deleted_in_a = set(base).difference(a)

                deleted_in_b = set(base).difference(b)

                # Combine into the final set of bullet points.

                final = all_new.difference(deleted_in_a).difference(

                    deleted_in_b)

                # Sort, and emit.

                final = sorted(final, key=sort_key)

                result_chunks.extend(final)

            else:

                result_chunks.extend(group[1])

        # Transform the merged elements back into real blocks of lines.

        result_lines = '\n\n'.join(chunk[1] for chunk in result_chunks)

        return 'success', result_lines

def sort_key(chunk):

    return chunk[1].replace('`', '').lower()