mercurial/simplemerge.py
author Pierre-Yves David <pierre-yves.david@octobus.net>
Wed, 16 Oct 2019 17:49:30 +0200
changeset 43254 181d28ba05da
parent 43077 687b865b95ad
child 43486 3b581ad59459
permissions -rw-r--r--
copies: avoid instancing more changectx to access parent revisions We just need to know the revision numbers of the parents, creating full context is needlessly expensive. This provide a small, but noticeable performance boost. revision: large amount; added files: large amount; rename small amount; c3b14617fbd7 9ba6ab77fd29 before: ! wall 2.885636 comb 2.900000 user 2.870000 sys 0.030000 (median of 10) after: ! wall 2.702270 comb 2.710000 user 2.690000 sys 0.020000 (median of 10) revision: large amount; added files: small amount; rename small amount; c3b14617fbd7 f650a9b140d2 before: ! wall 4.298271 comb 4.290000 user 4.240000 sys 0.050000 (median of 10) after: ! wall 3.976610 comb 3.970000 user 3.920000 sys 0.050000 (median of 10) revision: large amount; added files: large amount; rename large amount; 08ea3258278e d9fa043f30c0 before: ! wall 0.773397 comb 0.770000 user 0.770000 sys 0.000000 (median of 11) after: ! wall 0.701634 comb 0.700000 user 0.700000 sys 0.000000 (median of 13) revision: small amount; added files: large amount; rename large amount; df6f7a526b60 a83dc6a2d56f before: ! wall 0.013585 comb 0.010000 user 0.010000 sys 0.000000 (median of 217) after: ! wall 0.013550 comb 0.010000 user 0.010000 sys 0.000000 (median of 218) revision: small amount; added files: large amount; rename small amount; 4aa4e1f8e19a 169138063d63 before: ! wall 0.003202 comb 0.000000 user 0.000000 sys 0.000000 (median of 929) after: ! wall 0.002993 comb 0.010000 user 0.010000 sys 0.000000 (median of 992) revision: small amount; added files: small amount; rename small amount; 4bc173b045a6 964879152e2e before: ! wall 0.000077 comb 0.000000 user 0.000000 sys 0.000000 (median of 12060) after: ! wall 0.000072 comb 0.000000 user 0.000000 sys 0.000000 (median of 12804) revision: medium amount; added files: large amount; rename medium amount; c95f1ced15f2 2c68e87c3efe before: ! wall 0.510614 comb 0.500000 user 0.500000 sys 0.000000 (median of 18) after: ! wall 0.473681 comb 0.470000 user 0.470000 sys 0.000000 (median of 20) revision: medium amount; added files: medium amount; rename small amount; d343da0c55a8 d7746d32bf9d before: ! wall 0.126552 comb 0.130000 user 0.130000 sys 0.000000 (median of 77) after: ! wall 0.115240 comb 0.110000 user 0.110000 sys 0.000000 (median of 85) Differential Revision: https://phab.mercurial-scm.org/D7122

# 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_lines(
        self,
        name_a=None,
        name_b=None,
        name_base=None,
        start_marker=b'<<<<<<<',
        mid_marker=b'=======',
        end_marker=b'>>>>>>>',
        base_marker=None,
        localorother=None,
        minimize=False,
    ):
        """Return merge in cvs-like form.
        """
        self.conflicts = False
        newline = b'\n'
        if len(self.a) > 0:
            if self.a[0].endswith(b'\r\n'):
                newline = b'\r\n'
            elif self.a[0].endswith(b'\r'):
                newline = b'\r'
        if name_a and start_marker:
            start_marker = start_marker + b' ' + name_a
        if name_b and end_marker:
            end_marker = end_marker + b' ' + name_b
        if name_base and base_marker:
            base_marker = base_marker + b' ' + name_base
        merge_regions = self.merge_regions()
        if minimize:
            merge_regions = self.minimize(merge_regions)
        for t in merge_regions:
            what = t[0]
            if what == b'unchanged':
                for i in range(t[1], t[2]):
                    yield self.base[i]
            elif what == b'a' or what == b'same':
                for i in range(t[1], t[2]):
                    yield self.a[i]
            elif what == b'b':
                for i in range(t[1], t[2]):
                    yield self.b[i]
            elif what == b'conflict':
                if localorother == b'local':
                    for i in range(t[3], t[4]):
                        yield self.a[i]
                elif localorother == b'other':
                    for i in range(t[5], t[6]):
                        yield self.b[i]
                else:
                    self.conflicts = True
                    if start_marker is not None:
                        yield start_marker + newline
                    for i in range(t[3], t[4]):
                        yield self.a[i]
                    if base_marker is not None:
                        yield base_marker + newline
                        for i in range(t[1], t[2]):
                            yield self.base[i]
                    if mid_marker is not None:
                        yield mid_marker + newline
                    for i in range(t[5], t[6]):
                        yield self.b[i]
                    if end_marker is not None:
                        yield end_marker + newline
            else:
                raise ValueError(what)

    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 minimize(self, merge_regions):
        """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.
        """
        for region in merge_regions:
            if region[0] != b"conflict":
                yield region
                continue
            issue, z1, z2, a1, a2, b1, b2 = region
            alen = a2 - a1
            blen = b2 - b1

            # find matches at the front
            ii = 0
            while (
                ii < alen and ii < blen and self.a[a1 + ii] == self.b[b1 + ii]
            ):
                ii += 1
            startmatches = ii

            # find matches at the end
            ii = 0
            while (
                ii < alen
                and ii < blen
                and self.a[a2 - ii - 1] == self.b[b2 - ii - 1]
            ):
                ii += 1
            endmatches = ii

            if startmatches > 0:
                yield b'same', a1, a1 + startmatches

            yield (
                b'conflict',
                z1,
                z2,
                a1 + startmatches,
                a2 - endmatches,
                b1 + startmatches,
                b2 - endmatches,
            )

            if endmatches > 0:
                yield b'same', a2 - endmatches, a2

    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 find_unconflicted(self):
        """Return a list of ranges in base that are not conflicted."""
        am = mdiff.get_matching_blocks(self.basetext, self.atext)
        bm = mdiff.get_matching_blocks(self.basetext, self.btext)

        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


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(b'quiet'):
            ui.warn(_(b'warning: %s\n') % msg)
        if not opts.get(b'text'):
            raise error.Abort(msg)
    return text


def _picklabels(defaults, overrides):
    if len(overrides) > 3:
        raise error.Abort(_(b"can only specify three labels."))
    result = defaults[:]
    for i, override in enumerate(overrides):
        result[i] = override
    return result


def simplemerge(ui, localctx, basectx, otherctx, **opts):
    """Performs the simplemerge algorithm.

    The merged result is written into `localctx`.
    """
    opts = pycompat.byteskwargs(opts)

    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)

    mode = opts.get(b'mode', b'merge')
    name_a, name_b, name_base = None, None, None
    if mode != b'union':
        name_a, name_b, name_base = _picklabels(
            [localctx.path(), otherctx.path(), None], opts.get(b'label', [])
        )

    try:
        localtext = readctx(localctx)
        basetext = readctx(basectx)
        othertext = readctx(otherctx)
    except error.Abort:
        return 1

    m3 = Merge3Text(basetext, localtext, othertext)
    extrakwargs = {
        b"localorother": opts.get(b"localorother", None),
        b'minimize': True,
    }
    if mode == b'union':
        extrakwargs[b'start_marker'] = None
        extrakwargs[b'mid_marker'] = None
        extrakwargs[b'end_marker'] = None
    elif name_base is not None:
        extrakwargs[b'base_marker'] = b'|||||||'
        extrakwargs[b'name_base'] = name_base
        extrakwargs[b'minimize'] = False

    mergedtext = b""
    for line in m3.merge_lines(
        name_a=name_a, name_b=name_b, **pycompat.strkwargs(extrakwargs)
    ):
        if opts.get(b'print'):
            ui.fout.write(line)
        else:
            mergedtext += line

    if not opts.get(b'print'):
        localctx.write(mergedtext, localctx.flags())

    if m3.conflicts and not mode == b'union':
        return 1