contrib/simplemerge

rebase: add boolean config item rebase.store-source

This allows to use rebase without recording a rebase_source extra
field. This is useful for example to build a mirror converted from
another SCM (such as svn) by converting only new revisions, and
then incrementally add them to the destination by pulling from the
newly converted (unrelated) repo and rebasing the new revisions
onto the last old already stored changeset. Without this patch the
rebased changesets would always receive some rebase_source that
would depend on the particular history of the conversion process,
instead of only depending on the original source revisions.

This is used to implement a hg mirror repo of SvarDOS (a partially
nonfree but completely redistributable DOS distribution) in the
scripts at https://hg.pushbx.org/ecm/svardos.scr/

In particular, cre.sh creates an svn mirror, upd.sh recreates an
entire hg repo from the svn mirror (which takes too long to do in a
regular job), and akt.sh uses hg convert with the config item
convert.svn.startrev to incrementally convert only the two most
recent revisions already found in the mirror destination plus any
possible new revisions. If any are found, the temporary repo's
changesets are pulled into the destination (as changesets from an
unrelated repository). Then the changesets corresponding to the new
revisions are rebased onto the prior final changeset. (Finally, the
two remaining duplicates of the prior head and its parent are
stripped from the destination repository.)

Without this patch, the particular rebase_source extra field would
depend on the order and times at which akt.sh was used, instead of
only depending on the source repository. In other words, whatever
sequence of upd.sh and akt.sh is used at whatever times, it is
desired that the final output repositories always match each other
exactly.

#!/usr/bin/env python3

import getopt
import sys

import hgdemandimport

hgdemandimport.enable()

from mercurial.i18n import _
from mercurial import (
    context,
    error,
    fancyopts,
    simplemerge,
    ui as uimod,
    util,
)
from mercurial.utils import procutil, stringutil

options = [
    (b'L', b'label', [], _(b'labels to use on conflict markers')),
    (b'a', b'text', None, _(b'treat all files as text')),
    (b'p', b'print', None, _(b'print results instead of overwriting LOCAL')),
    (b'', b'no-minimal', None, _(b'no effect (DEPRECATED)')),
    (b'h', b'help', None, _(b'display help and exit')),
    (b'q', b'quiet', None, _(b'suppress output')),
]

usage = _(
    b'''simplemerge [OPTS] LOCAL BASE OTHER

    Simple three-way file merge utility with a minimal feature set.

    Apply to LOCAL the changes necessary to go from BASE to OTHER.

    By default, LOCAL is overwritten with the results of this operation.
'''
)


class ParseError(Exception):
    """Exception raised on errors in parsing the command line."""


def showhelp():
    procutil.stdout.write(usage)
    procutil.stdout.write(b'\noptions:\n')

    out_opts = []
    for shortopt, longopt, default, desc in options:
        out_opts.append(
            (
                b'%2s%s'
                % (
                    shortopt and b'-%s' % shortopt,
                    longopt and b' --%s' % longopt,
                ),
                b'%s' % desc,
            )
        )
    opts_len = max([len(opt[0]) for opt in out_opts])
    for first, second in out_opts:
        procutil.stdout.write(b' %-*s  %s\n' % (opts_len, first, second))


def _verifytext(input, ui, quiet=False, allow_binary=False):
    """verifies that text is non-binary (unless opts[text] is passed,
    then we just warn)"""
    if stringutil.binary(input.text()):
        msg = _(b"%s looks like a binary file.") % input.fctx.path()
        if not quiet:
            ui.warn(_(b'warning: %s\n') % msg)
        if not allow_binary:
            sys.exit(1)


try:
    for fp in (sys.stdin, procutil.stdout, sys.stderr):
        procutil.setbinary(fp)

    opts = {}
    try:
        bargv = [a.encode('utf8') for a in sys.argv[1:]]
        args = fancyopts.fancyopts(bargv, options, opts)
    except getopt.GetoptError as e:
        raise ParseError(e)
    if opts[b'help']:
        showhelp()
        sys.exit(0)
    if len(args) != 3:
        raise ParseError(_(b'wrong number of arguments').decode('utf8'))
    mode = b'merge'
    if len(opts[b'label']) > 2:
        mode = b'merge3'
    local, base, other = args
    overrides = opts[b'label']
    if len(overrides) > 3:
        raise error.InputError(b'can only specify three labels.')
    labels = [local, other, base]
    labels[: len(overrides)] = overrides
    local_input = simplemerge.MergeInput(
        context.arbitraryfilectx(local), labels[0]
    )
    other_input = simplemerge.MergeInput(
        context.arbitraryfilectx(other), labels[1]
    )
    base_input = simplemerge.MergeInput(
        context.arbitraryfilectx(base), labels[2]
    )

    quiet = opts.get(b'quiet')
    allow_binary = opts.get(b'text')
    ui = uimod.ui.load()
    _verifytext(local_input, ui, quiet=quiet, allow_binary=allow_binary)
    _verifytext(base_input, ui, quiet=quiet, allow_binary=allow_binary)
    _verifytext(other_input, ui, quiet=quiet, allow_binary=allow_binary)

    merged_text, conflicts = simplemerge.simplemerge(
        local_input,
        base_input,
        other_input,
        mode,
        allow_binary=allow_binary,
    )
    if opts.get(b'print'):
        ui.fout.write(merged_text)
    else:
        util.writefile(local, merged_text)
    sys.exit(1 if conflicts else 0)
except ParseError as e:
    e = stringutil.forcebytestr(e)
    procutil.stdout.write(b"%s: %s\n" % (sys.argv[0].encode('utf8'), e))
    showhelp()
    sys.exit(1)
except error.Abort as e:
    procutil.stderr.write(b"abort: %s\n" % e)
    sys.exit(255)
except KeyboardInterrupt:
    sys.exit(255)