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# Copyright (C) 2005, 2006 Canonical Ltd
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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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# 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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# 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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# Author: Martin Pool <mbp@canonical.com>
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# Aaron Bentley <aaron.bentley@utoronto.ca>
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from difflib import SequenceMatcher
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class TextMerge(object):
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"""Base class for text-mergers
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Subclasses must implement _merge_struct.
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Many methods produce or consume structured merge information.
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This is an iterable of tuples of lists of lines.
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Each tuple may have a length of 1 - 3, depending on whether the region it
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represents is conflicted.
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Unconflicted region tuples have length 1.
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Conflicted region tuples have length 2 or 3. Index 1 is text_a, e.g. THIS.
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Index 1 is text_b, e.g. OTHER. Index 2 is optional. If present, it
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# TODO: Show some version information (e.g. author, date) on conflicted
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A_MARKER = '<<<<<<< \n'
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B_MARKER = '>>>>>>> \n'
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SPLIT_MARKER = '=======\n'
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def __init__(self, a_marker=A_MARKER, b_marker=B_MARKER,
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split_marker=SPLIT_MARKER):
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self.a_marker = a_marker
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self.b_marker = b_marker
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self.split_marker = split_marker
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def _merge_struct(self):
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"""Return structured merge info. Must be implemented by subclasses.
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See TextMerge docstring for details on the format.
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raise NotImplementedError('_merge_struct is abstract')
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def struct_to_lines(self, struct_iter):
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"""Convert merge result tuples to lines"""
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for lines in struct_iter:
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yield self.split_marker
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def iter_useful(self, struct_iter):
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"""Iterate through input tuples, skipping empty ones."""
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for group in struct_iter:
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elif len(group) > 1 and len(group[1]) > 0:
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def merge_lines(self, reprocess=False):
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"""Produce an iterable of lines, suitable for writing to a file
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Returns a tuple of (line iterable, conflict indicator)
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If reprocess is True, a two-way merge will be performed on the
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intermediate structure, to reduce conflict regions.
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for group in self.merge_struct(reprocess):
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return self.struct_to_lines(struct), conflicts
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def merge_struct(self, reprocess=False):
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"""Produce structured merge info"""
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struct_iter = self.iter_useful(self._merge_struct())
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return self.reprocess_struct(struct_iter)
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def reprocess_struct(struct_iter):
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""" Perform a two-way merge on structural merge info.
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This reduces the size of conflict regions, but breaks the connection
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between the BASE text and the conflict region.
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This process may split a single conflict region into several smaller
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ones, but will not introduce new conflicts.
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for group in struct_iter:
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for newgroup in Merge2(group[0], group[1]).merge_struct():
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class Merge2(TextMerge):
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In a two way merge, common regions are shown as unconflicting, and uncommon
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regions produce conflicts.
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def __init__(self, lines_a, lines_b, a_marker=TextMerge.A_MARKER,
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b_marker=TextMerge.B_MARKER,
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split_marker=TextMerge.SPLIT_MARKER):
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TextMerge.__init__(self, a_marker, b_marker, split_marker)
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self.lines_a = lines_a
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self.lines_b = lines_b
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def _merge_struct(self):
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"""Return structured merge info.
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See TextMerge docstring.
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sm = SequenceMatcher(None, self.lines_a, self.lines_b)
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for ai, bi, l in sm.get_matching_blocks():
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yield(self.lines_a[pos_a:ai], self.lines_b[pos_b:bi])
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yield(self.lines_a[ai:ai+l],)
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# final non-matching lines
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yield(self.lines_a[pos_a:-1], self.lines_b[pos_b:-1])
added
removed
bzrlib/textmerge.py
