Mercurial > hg
view mercurial/simplemerge.py @ 48564:c2537aec3bb6
simplemerge: change _minimize() to minimize a single conflict
`_minimize()` is weird in that it changes `a_lines` and `b_lines` but
leaves `base_lines` unchanged, which means they'll be
inconsistent. That was fine because the caller never used
`base_lines`. With the recent refactorings of this code, we can now
make this function cleaner by having it minimize a single conflict and
not care about `base_lines`.
This also makes the code simpler and makes the code for each
`render_*()` function more similar.
Differential Revision: https://phab.mercurial-scm.org/D11981
author | Martin von Zweigbergk <martinvonz@google.com> |
---|---|
date | Tue, 11 Jan 2022 22:13:56 -0800 |
parents | ad0c6bf6f02e |
children | 7ed4c4753891 |
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# Copyright (C) 2004, 2005 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, see <http://www.gnu.org/licenses/>. # mbp: "you know that thing where cvs gives you conflict markers?" # s: "i hate that." from __future__ import absolute_import from .i18n import _ from . import ( error, mdiff, pycompat, ) from .utils import stringutil class CantReprocessAndShowBase(Exception): pass 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 compare_range(a, astart, aend, b, bstart, bend): """Compare a[astart:aend] == b[bstart:bend], without slicing.""" if (aend - astart) != (bend - bstart): return False for ia, ib in zip( pycompat.xrange(astart, aend), pycompat.xrange(bstart, bend) ): if a[ia] != b[ib]: return False else: return True class Merge3Text(object): """3-way merge of texts. Given strings BASE, OTHER, THIS, tries to produce a combined text incorporating the changes from both BASE->OTHER and BASE->THIS.""" def __init__(self, basetext, atext, btext, base=None, a=None, b=None): self.basetext = basetext self.atext = atext self.btext = btext if base is None: base = mdiff.splitnewlines(basetext) if a is None: a = mdiff.splitnewlines(atext) if b is None: b = mdiff.splitnewlines(btext) self.base = base self.a = a self.b = b def merge_groups(self): """Yield sequence of line groups. Each one is a tuple: 'unchanged', lines Lines unchanged from base 'a', lines Lines taken from a 'same', lines Lines taken from a (and equal to b) 'b', lines Lines taken from b 'conflict', (base_lines, a_lines, b_lines) Lines from base were changed to either a or b and conflict. """ for t in self.merge_regions(): what = t[0] if what == b'unchanged': yield what, self.base[t[1] : t[2]] elif what == b'a' or what == b'same': yield what, self.a[t[1] : t[2]] elif what == b'b': yield what, self.b[t[1] : t[2]] elif what == b'conflict': yield ( what, ( self.base[t[1] : t[2]], self.a[t[3] : t[4]], self.b[t[5] : t[6]], ), ) else: raise ValueError(what) 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] 'same', astart, aend b and a are different from base but give the same result 'a', start, end Non-clashing insertion from a[start:end] 'conflict', zstart, zend, astart, aend, bstart, bend Conflict between a and b, with z as common ancestor Method is as follows: The two sequences align only on regions which match the base and both descendants. 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 region in self.find_sync_regions(): zmatch, zend, amatch, aend, bmatch, bend = region # print 'match base [%d:%d]' % (zmatch, zend) matchlen = zend - zmatch assert matchlen >= 0 assert matchlen == (aend - amatch) assert matchlen == (bend - bmatch) len_a = amatch - ia len_b = bmatch - ib len_base = zmatch - iz assert len_a >= 0 assert len_b >= 0 assert len_base >= 0 # print 'unmatched a=%d, b=%d' % (len_a, len_b) if len_a or len_b: # try to avoid actually slicing the lists equal_a = compare_range( self.a, ia, amatch, self.base, iz, zmatch ) equal_b = compare_range( self.b, ib, bmatch, self.base, iz, zmatch ) same = compare_range(self.a, ia, amatch, self.b, ib, bmatch) if same: yield b'same', ia, amatch elif equal_a and not equal_b: yield b'b', ib, bmatch elif equal_b and not equal_a: yield b'a', ia, amatch elif not equal_a and not equal_b: yield b'conflict', iz, zmatch, ia, amatch, ib, bmatch else: raise AssertionError(b"can't handle a=b=base but unmatched") ia = amatch ib = bmatch iz = zmatch # if the same part of the base was deleted on both sides # that's OK, we can just skip it. if matchlen > 0: assert ia == amatch assert ib == bmatch assert iz == zmatch yield b'unchanged', zmatch, zend iz = zend ia = aend ib = bend def find_sync_regions(self): """Return a list of sync regions, where both descendants 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. """ ia = ib = 0 amatches = mdiff.get_matching_blocks(self.basetext, self.atext) bmatches = mdiff.get_matching_blocks(self.basetext, self.btext) len_a = len(amatches) len_b = len(bmatches) sl = [] while ia < len_a and ib < len_b: abase, amatch, alen = amatches[ia] bbase, bmatch, blen = bmatches[ib] # 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] sl.append((intbase, intend, asub, aend, bsub, bend)) # advance whichever one ends first in the base text if (abase + alen) < (bbase + blen): ia += 1 else: ib += 1 intbase = len(self.base) abase = len(self.a) bbase = len(self.b) sl.append((intbase, intbase, abase, abase, bbase, bbase)) return sl def _verifytext(text, path, ui, opts): """verifies that text is non-binary (unless opts[text] is passed, then we just warn)""" if stringutil.binary(text): msg = _(b"%s looks like a binary file.") % path if not opts.get('quiet'): ui.warn(_(b'warning: %s\n') % msg) if not opts.get('text'): raise error.Abort(msg) return text def _picklabels(overrides): if len(overrides) > 3: raise error.Abort(_(b"can only specify three labels.")) result = [None, None, None] for i, override in enumerate(overrides): result[i] = override return result def _detect_newline(m3): if len(m3.a) > 0: if m3.a[0].endswith(b'\r\n'): return b'\r\n' elif m3.a[0].endswith(b'\r'): return b'\r' return b'\n' def _minimize(a_lines, b_lines): """Trim conflict regions of lines where A and B sides match. Lines where both A and B have made the same changes at the beginning or the end of each merge region are eliminated from the conflict region and are instead considered the same. """ alen = len(a_lines) blen = len(b_lines) # find matches at the front ii = 0 while ii < alen and ii < blen and a_lines[ii] == b_lines[ii]: ii += 1 startmatches = ii # find matches at the end ii = 0 while ii < alen and ii < blen and a_lines[-ii - 1] == b_lines[-ii - 1]: ii += 1 endmatches = ii lines_before = a_lines[:startmatches] new_a_lines = a_lines[startmatches : alen - endmatches] new_b_lines = b_lines[startmatches : blen - endmatches] lines_after = a_lines[alen - endmatches :] return lines_before, new_a_lines, new_b_lines, lines_after def render_minimized( m3, name_a=None, name_b=None, start_marker=b'<<<<<<<', mid_marker=b'=======', end_marker=b'>>>>>>>', ): """Return merge in cvs-like form.""" newline = _detect_newline(m3) conflicts = False if name_a: start_marker = start_marker + b' ' + name_a if name_b: end_marker = end_marker + b' ' + name_b merge_groups = m3.merge_groups() lines = [] for what, group_lines in merge_groups: if what == b'conflict': conflicts = True base_lines, a_lines, b_lines = group_lines minimized = _minimize(a_lines, b_lines) lines_before, a_lines, b_lines, lines_after = minimized lines.extend(lines_before) lines.append(start_marker + newline) lines.extend(a_lines) lines.append(mid_marker + newline) lines.extend(b_lines) lines.append(end_marker + newline) lines.extend(lines_after) else: lines.extend(group_lines) return lines, conflicts def render_merge3(m3, name_a, name_b, name_base): """Render conflicts as 3-way conflict markers.""" newline = _detect_newline(m3) conflicts = False lines = [] for what, group_lines in m3.merge_groups(): if what == b'conflict': base_lines, a_lines, b_lines = group_lines conflicts = True lines.append(b'<<<<<<< ' + name_a + newline) lines.extend(a_lines) lines.append(b'||||||| ' + name_base + newline) lines.extend(base_lines) lines.append(b'=======' + newline) lines.extend(b_lines) lines.append(b'>>>>>>> ' + name_b + newline) else: lines.extend(group_lines) return lines, conflicts def render_mergediff(m3, name_a, name_b, name_base): """Render conflicts as conflict markers with one snapshot and one diff.""" newline = _detect_newline(m3) lines = [] conflicts = False for what, group_lines in m3.merge_groups(): if what == b'conflict': base_lines, a_lines, b_lines = group_lines base_text = b''.join(base_lines) b_blocks = list( mdiff.allblocks( base_text, b''.join(b_lines), lines1=base_lines, lines2=b_lines, ) ) a_blocks = list( mdiff.allblocks( base_text, b''.join(a_lines), lines1=base_lines, lines2=b_lines, ) ) def matching_lines(blocks): return sum( block[1] - block[0] for block, kind in blocks if kind == b'=' ) def diff_lines(blocks, lines1, lines2): for block, kind in blocks: if kind == b'=': for line in lines1[block[0] : block[1]]: yield b' ' + line else: for line in lines1[block[0] : block[1]]: yield b'-' + line for line in lines2[block[2] : block[3]]: yield b'+' + line lines.append(b"<<<<<<<" + newline) if matching_lines(a_blocks) < matching_lines(b_blocks): lines.append(b"======= " + name_a + newline) lines.extend(a_lines) lines.append(b"------- " + name_base + newline) lines.append(b"+++++++ " + name_b + newline) lines.extend(diff_lines(b_blocks, base_lines, b_lines)) else: lines.append(b"------- " + name_base + newline) lines.append(b"+++++++ " + name_a + newline) lines.extend(diff_lines(a_blocks, base_lines, a_lines)) lines.append(b"======= " + name_b + newline) lines.extend(b_lines) lines.append(b">>>>>>>" + newline) conflicts = True else: lines.extend(group_lines) return lines, conflicts def _resolve(m3, sides): lines = [] for what, group_lines in m3.merge_groups(): if what == b'conflict': for side in sides: lines.extend(group_lines[side]) else: lines.extend(group_lines) return lines def simplemerge(ui, localctx, basectx, otherctx, **opts): """Performs the simplemerge algorithm. The merged result is written into `localctx`. """ def readctx(ctx): # Merges were always run in the working copy before, which means # they used decoded data, if the user defined any repository # filters. # # Maintain that behavior today for BC, though perhaps in the future # it'd be worth considering whether merging encoded data (what the # repository usually sees) might be more useful. return _verifytext(ctx.decodeddata(), ctx.path(), ui, opts) try: localtext = readctx(localctx) basetext = readctx(basectx) othertext = readctx(otherctx) except error.Abort: return 1 m3 = Merge3Text(basetext, localtext, othertext) conflicts = False mode = opts.get('mode', b'merge') if mode == b'union': lines = _resolve(m3, (1, 2)) elif mode == b'local': lines = _resolve(m3, (1,)) elif mode == b'other': lines = _resolve(m3, (2,)) else: name_a, name_b, name_base = _picklabels(opts.get('label', [])) if mode == b'mergediff': lines, conflicts = render_mergediff(m3, name_a, name_b, name_base) elif mode == b'merge3': lines, conflicts = render_merge3(m3, name_a, name_b, name_base) else: lines, conflicts = render_minimized(m3, name_a, name_b) mergedtext = b''.join(lines) if opts.get('print'): ui.fout.write(mergedtext) else: # localctx.flags() already has the merged flags (done in # mergestate.resolve()) localctx.write(mergedtext, localctx.flags()) if conflicts: return 1