~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 bzrlib.plugins.news_merge.parser import simple_parse

from bzrlib import merge3

magic_marker = '|NEWS-MERGE-MAGIC-MARKER|'

def news_merger(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.

    def munge(lines):

        return list(blocks_to_fakelines(simple_parse(''.join(lines))))

    this_lines = munge(params.this_lines)

    other_lines = munge(params.other_lines)

    base_lines = munge(params.base_lines)

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

    result_lines = []

    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 not line.startswith('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_lines.extend(final)

        else:

            result_lines.extend(group[1])

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

    return 'success', list(fakelines_to_blocks(result_lines))

def blocks_to_fakelines(blocks):

    for kind, text in blocks:

        yield '%s%s%s' % (kind, magic_marker, text)

def fakelines_to_blocks(fakelines):

    fakelines = list(fakelines)

    # Strip out the magic_marker, and reinstate the \n\n between blocks

    for fakeline in fakelines[:-1]:

        yield fakeline.split(magic_marker, 1)[1] + '\n\n'

    # The final block doesn't have a trailing \n\n.

    for fakeline in fakelines[-1:]:

        yield fakeline.split(magic_marker, 1)[1]

def sort_key(s):

    return s.replace('`', '').lower()