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# Copyright (C) 2004, 2005 by 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
# mbp: "you know that thing where cvs gives you conflict markers?"
# s: "i hate that."
def intersect(ra, rb):
"""Given two ranges return the range where they intersect or None.
>>> intersect((0, 10), (0, 6))
(0, 6)
>>> intersect((0, 10), (5, 15))
(5, 10)
>>> intersect((0, 10), (10, 15))
>>> intersect((0, 9), (10, 15))
>>> intersect((0, 9), (7, 15))
(7, 9)
"""
assert ra[0] <= ra[1]
assert rb[0] <= rb[1]
sa = max(ra[0], rb[0])
sb = min(ra[1], rb[1])
if sa < sb:
return sa, sb
else:
return None
def threeway(baseline, aline, bline):
if baseline == aline:
return bline
elif baseline == bline:
return aline
else:
return [aline, bline]
class Merge3(object):
"""3-way merge of texts.
Given BASE, OTHER, THIS, tries to produce a combined text
incorporating the changes from both BASE->OTHER and BASE->THIS.
All three will typically be sequences of lines."""
def __init__(self, base, a, b):
self.base = base
self.a = a
self.b = b
from difflib import SequenceMatcher
self.a_ops = SequenceMatcher(None, base, a).get_opcodes()
self.b_ops = SequenceMatcher(None, base, b).get_opcodes()
def merge_regions(self):
"""Return sequences of matching and conflicting regions.
This returns tuples, where the first value says what kind we
have:
'unchanged', start, end
Take a region of base[start:end]
'a', start, end
Non-clashing insertion from a[start:end]
Method is as follows:
The two sequences align only on regions which match the base
and both descendents. These are found by doing a two-way diff
of each one against the base, and then finding the
intersections between those regions. These "sync regions"
are by definition unchanged in both and easily dealt with.
The regions in between can be in any of three cases:
conflicted, or changed on only one side.
"""
# section a[0:ia] has been disposed of, etc
iz = ia = ib = 0
for zmatch, zend, amatch, aend, bmatch, bend in self.find_sync_regions():
matchlen = zend - zmatch
assert matchlen >= 0
assert matchlen == (aend - amatch)
assert matchlen == (bend - bmatch)
if amatch > ia: # or bmatch > ib:
# got an unmatched region; work out if either
# alternative is the same as the base
# kludge: return the whole thing as inserted into A
yield 'a', ia, amatch
ia = amatch
if matchlen > 0:
assert ia == amatch
assert ib == bmatch
assert iz == zmatch
yield 'unchanged', zmatch, zend
iz = zend
ia = aend
ib = bend
def find_sync_regions(self):
"""Return a list of sync regions, where both descendents match the base.
Generates a list of (base1, base2, a1, a2, b1, b2). There is
always a zero-length sync region at the end of all the files.
"""
from difflib import SequenceMatcher
aiter = iter(SequenceMatcher(None, self.base, self.a).get_matching_blocks())
biter = iter(SequenceMatcher(None, self.base, self.b).get_matching_blocks())
abase, amatch, alen = aiter.next()
bbase, bmatch, blen = biter.next()
while aiter and biter:
# there is an unconflicted block at i; how long does it
# extend? until whichever one ends earlier.
i = intersect((abase, abase+alen), (bbase, bbase+blen))
if i:
intbase = i[0]
intend = i[1]
intlen = intend - intbase
# found a match of base[i[0], i[1]]; this may be less than
# the region that matches in either one
assert intlen <= alen
assert intlen <= blen
assert abase <= intbase
assert bbase <= intbase
asub = amatch + (intbase - abase)
bsub = bmatch + (intbase - bbase)
aend = asub + intlen
bend = bsub + intlen
assert self.base[intbase:intend] == self.a[asub:aend], \
(self.base[intbase:intend], self.a[asub:aend])
assert self.base[intbase:intend] == self.b[bsub:bend]
yield (intbase, intend,
asub, aend,
bsub, bend)
# advance whichever one ends first in the base text
if (abase + alen) < (bbase + blen):
abase, amatch, alen = aiter.next()
else:
bbase, bmatch, blen = biter.next()
intbase = len(self.base)
abase = len(self.a)
bbase = len(self.b)
yield (intbase, intbase, abase, abase, bbase, bbase)
def find_unconflicted(self):
"""Return a list of ranges in base that are not conflicted."""
from difflib import SequenceMatcher
am = SequenceMatcher(None, self.base, self.a).get_matching_blocks()
bm = SequenceMatcher(None, self.base, self.b).get_matching_blocks()
unc = []
while am and bm:
# there is an unconflicted block at i; how long does it
# extend? until whichever one ends earlier.
a1 = am[0][0]
a2 = a1 + am[0][2]
b1 = bm[0][0]
b2 = b1 + bm[0][2]
i = intersect((a1, a2), (b1, b2))
if i:
unc.append(i)
if a2 < b2:
del am[0]
else:
del bm[0]
return unc
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