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- Committer: Andrew Bennetts
- Date: 2011-03-15 07:54:39 UTC
- mfrom: (0.38.5 trunk)
- mto: This revision was merged to the branch mainline in revision 5726.
- Revision ID: andrew.bennetts@canonical.com-20110315075439-nzm293joz143cx0k
Merge bzr-changelog-merge plugin.
- files added:
- bzrlib/plugins/changelog_merge
- bzrlib/plugins/changelog_merge/tests
added
removed
bzrlib/plugins/changelog_merge/changelog_merge.py
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# Copyright (C) 2010 Canonical Ltd
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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"""Merge logic for changelog_merge plugin."""
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import difflib
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from bzrlib import merge
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from bzrlib import debug
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from bzrlib.merge3 import Merge3
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from bzrlib.trace import mutter
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def changelog_entries(lines):
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"""Return a list of changelog entries.
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:param lines: lines of a changelog file.
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:returns: list of entries. Each entry is a tuple of lines.
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"""
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entries = []
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for line in lines:
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if line[0] not in (' ', '\t', '\n'):
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# new entry
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entries.append([line])
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else:
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try:
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entry = entries[-1]
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except IndexError:
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# Cope with leading blank lines.
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entries.append([])
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entry = entries[-1]
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entry.append(line)
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return map(tuple, entries)
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def entries_to_lines(entries):
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"""Turn a list of entries into a flat iterable of lines."""
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for entry in entries:
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for line in entry:
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yield line
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class ChangeLogMerger(merge.ConfigurableFileMerger):
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"""Merge GNU-format ChangeLog files."""
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name_prefix = "changelog"
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def get_filepath(self, params, tree):
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"""Calculate the path to the file in a tree.
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This is overridden to return just the basename, rather than full path,
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so that e.g. if the config says ``changelog_merge_files = ChangeLog``,
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then all ChangeLog files in the tree will match (not just one in the
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root of the tree).
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:param params: A MergeHookParams describing the file to merge
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:param tree: a Tree, e.g. self.merger.this_tree.
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"""
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return tree.inventory[params.file_id].name
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def merge_text(self, params):
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"""Merge changelog changes.
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* new entries from other will float to the top
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* edits to older entries are preserved
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"""
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# Transform files into lists of changelog entries
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this_entries = changelog_entries(params.this_lines)
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other_entries = changelog_entries(params.other_lines)
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base_entries = changelog_entries(params.base_lines)
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try:
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result_entries = merge_entries(
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base_entries, this_entries, other_entries)
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except EntryConflict:
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return 'not_applicable' # XXX: generating a nice conflict file
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# would be better
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# Transform the merged elements back into real blocks of lines.
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return 'success', entries_to_lines(result_entries)
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class EntryConflict(Exception):
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pass
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def default_guess_edits(new_entries, deleted_entries, entry_as_str=''.join):
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"""Default implementation of guess_edits param of merge_entries.
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This algorithm does O(N^2 * logN) SequenceMatcher.ratio() calls, which is
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pretty bad, but it shouldn't be used very often.
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"""
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deleted_entries_as_strs = [
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entry_as_str(entry) for entry in deleted_entries]
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new_entries_as_strs = [
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entry_as_str(entry) for entry in new_entries]
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result_new = list(new_entries)
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result_deleted = list(deleted_entries)
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result_edits = []
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sm = difflib.SequenceMatcher()
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CUTOFF = 0.8
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while True:
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best = None
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best_score = None
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for new_entry in new_entries:
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new_entry_as_str = entry_as_str(new_entry)
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sm.set_seq1(new_entry_as_str)
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for old_entry_as_str in deleted_entries_as_strs:
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sm.set_seq2(old_entry_as_str)
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score = sm.ratio()
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if score > CUTOFF:
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if best_score is None or score > best_score:
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best = new_entry_as_str, old_entry_as_str
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best_score = score
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if best is not None:
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del_index = deleted_entries_as_strs.index(best[1])
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new_index = new_entries_as_strs.index(best[0])
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result_edits.append(
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(result_deleted[del_index], result_new[new_index]))
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del deleted_entries_as_strs[del_index], result_deleted[del_index]
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del new_entries_as_strs[new_index], result_new[new_index]
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else:
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break
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return result_new, result_deleted, result_edits
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def merge_entries(base_entries, this_entries, other_entries,
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guess_edits=default_guess_edits):
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"""Merge changelog given base, this, and other versions."""
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m3 = Merge3(base_entries, this_entries, other_entries, allow_objects=True)
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result_entries = []
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at_top = True
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for group in m3.merge_groups():
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if 'changelog_merge' in debug.debug_flags:
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mutter('merge group:\n%r', group)
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group_kind = group[0]
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if group_kind == 'conflict':
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_, base, this, other = group
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# Find additions
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new_in_other = [
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entry for entry in other if entry not in base]
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# Find deletions
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deleted_in_other = [
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entry for entry in base if entry not in other]
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if at_top and deleted_in_other:
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# Magic! Compare deletions and additions to try spot edits
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new_in_other, deleted_in_other, edits_in_other = guess_edits(
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new_in_other, deleted_in_other)
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else:
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# Changes not made at the top are always preserved as is, no
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# need to try distinguish edits from adds and deletes.
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edits_in_other = []
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if 'changelog_merge' in debug.debug_flags:
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mutter('at_top: %r', at_top)
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mutter('new_in_other: %r', new_in_other)
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mutter('deleted_in_other: %r', deleted_in_other)
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mutter('edits_in_other: %r', edits_in_other)
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# Apply deletes and edits
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updated_this = [
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entry for entry in this if entry not in deleted_in_other]
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for old_entry, new_entry in edits_in_other:
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try:
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index = updated_this.index(old_entry)
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except ValueError:
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# edited entry no longer present in this! Just give up and
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# declare a conflict.
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raise EntryConflict()
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updated_this[index] = new_entry
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if 'changelog_merge' in debug.debug_flags:
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mutter('updated_this: %r', updated_this)
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if at_top:
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# Float new entries from other to the top
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result_entries = new_in_other + result_entries
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else:
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result_entries.extend(new_in_other)
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result_entries.extend(updated_this)
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else: # unchanged, same, a, or b.
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lines = group[1]
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result_entries.extend(lines)
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at_top = False
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return result_entries
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