hgext/githelp.py

changegroup: capture revision delta in a data structure

The current changegroup generation code is tightly coupled to
the revlog API. This tight coupling makes it difficult to implement
alternate storage backends without requiring a large surface area
of the revlog API to be exposed. This is not desirable.

In order to support changegroup generation with non-revlog storage,
we'll need to abstract the concept of delta generation.

This commit is the first step down that road. We introduce a
data structure for representing a delta in a changegroup.

The API still leaves a lot to be desired. But at least we now
have separation between data and actions performed on it.

As part of this, we tweak behavior slightly: we no longer
concatenate the delta prefix with the metadata header. Instead,
we track and emit the prefix as a separate chunk. This shouldn't
have any meaningful impact since all the chunks just get sent to
the wire, the compressor, etc.

Because we're introducing a new object, this does add some
overhead to changegroup execution. `hg perfchangegroupchangelog`
on my clone of the Mercurial repo (~40,000 visible revisions in
the changelog) slows down a bit:

! wall 1.268600 comb 1.270000 user 1.270000 sys 0.000000 (best of 8)
! wall 1.419479 comb 1.410000 user 1.410000 sys 0.000000 (best of 8)

With for `hg bundle -t none-v2 -a /dev/null`:

before: real 6.610 secs (user 6.460+0.000 sys 0.140+0.000)
after:  real 7.210 secs (user 7.060+0.000 sys 0.140+0.000)

I plan to claw back this regression in future commits. And I may
even do away with this data structure once the refactor is complete.
For now, it makes things easier to comprehend.

Differential Revision: https://phab.mercurial-scm.org/D4075

# githelp.py - Try to map Git commands to Mercurial equivalents.
#
# Copyright 2013 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""try mapping git commands to Mercurial commands

Tries to map a given git command to a Mercurial command:

  $ hg githelp -- git checkout master
  hg update master

If an unknown command or parameter combination is detected, an error is
produced.
"""

from __future__ import absolute_import

import getopt
import re

from mercurial.i18n import _
from mercurial import (
    encoding,
    error,
    fancyopts,
    registrar,
    scmutil,
)
from mercurial.utils import (
    procutil,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'

cmdtable = {}
command = registrar.command(cmdtable)

def convert(s):
    if s.startswith("origin/"):
        return s[7:]
    if 'HEAD' in s:
        s = s.replace('HEAD', '.')
    # HEAD~ in git is .~1 in mercurial
    s = re.sub('~$', '~1', s)
    return s

@command('^githelp|git', [
    ], _('hg githelp'))
def githelp(ui, repo, *args, **kwargs):
    '''suggests the Mercurial equivalent of the given git command

    Usage: hg githelp -- <git command>
    '''

    if len(args) == 0 or (len(args) == 1 and args[0] =='git'):
        raise error.Abort(_('missing git command - '
                            'usage: hg githelp -- <git command>'))

    if args[0] == 'git':
        args = args[1:]

    cmd = args[0]
    if not cmd in gitcommands:
        raise error.Abort(_("error: unknown git command %s") % (cmd))

    ui.pager('githelp')
    args = args[1:]
    return gitcommands[cmd](ui, repo, *args, **kwargs)

def parseoptions(ui, cmdoptions, args):
    cmdoptions = list(cmdoptions)
    opts = {}
    args = list(args)
    while True:
        try:
            args = fancyopts.fancyopts(list(args), cmdoptions, opts, True)
            break
        except getopt.GetoptError as ex:
            flag = None
            if "requires argument" in ex.msg:
                raise
            if ('--' + ex.opt) in ex.msg:
                flag = '--' + ex.opt
            elif ('-' + ex.opt) in ex.msg:
                flag = '-' + ex.opt
            else:
                raise error.Abort(_("unknown option %s") % ex.opt)
            try:
                args.remove(flag)
            except Exception:
                msg = _("unknown option '%s' packed with other options")
                hint = _("please try passing the option as its own flag: -%s")
                raise error.Abort(msg % ex.opt, hint=hint % ex.opt)

            ui.warn(_("ignoring unknown option %s\n") % flag)

    args = list([convert(x) for x in args])
    opts = dict([(k, convert(v)) if isinstance(v, str) else (k, v)
                                 for k, v in opts.iteritems()])

    return args, opts

class Command(object):
    def __init__(self, name):
        self.name = name
        self.args = []
        self.opts = {}

    def __bytes__(self):
        cmd = "hg " + self.name
        if self.opts:
            for k, values in sorted(self.opts.iteritems()):
                for v in values:
                    if v:
                        cmd += " %s %s" % (k, v)
                    else:
                        cmd += " %s" % (k,)
        if self.args:
            cmd += " "
            cmd += " ".join(self.args)
        return cmd

    __str__ = encoding.strmethod(__bytes__)

    def append(self, value):
        self.args.append(value)

    def extend(self, values):
        self.args.extend(values)

    def __setitem__(self, key, value):
        values = self.opts.setdefault(key, [])
        values.append(value)

    def __and__(self, other):
        return AndCommand(self, other)

class AndCommand(object):
    def __init__(self, left, right):
        self.left = left
        self.right = right

    def __str__(self):
        return "%s && %s" % (self.left, self.right)

    def __and__(self, other):
        return AndCommand(self, other)

def add(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('A', 'all', None, ''),
        ('p', 'patch', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if (opts.get('patch')):
        ui.status(_("note: Mercurial will commit when complete, "
                    "as there is no staging area in Mercurial\n\n"))
        cmd = Command('commit --interactive')
    else:
        cmd = Command("add")

        if not opts.get('all'):
            cmd.extend(args)
        else:
            ui.status(_("note: use hg addremove to remove files that have "
                        "been deleted\n\n"))

    ui.status((bytes(cmd)), "\n")

def am(ui, repo, *args, **kwargs):
    cmdoptions=[
    ]
    args, opts = parseoptions(ui, cmdoptions, args)
    cmd = Command('import')
    ui.status(bytes(cmd), "\n")

def apply(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('p', 'p', int, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('import --no-commit')
    if (opts.get('p')):
        cmd['-p'] = opts.get('p')
    cmd.extend(args)

    ui.status((bytes(cmd)), "\n")

def bisect(ui, repo, *args, **kwargs):
    ui.status(_("see 'hg help bisect' for how to use bisect\n\n"))

def blame(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)
    cmd = Command('annotate -udl')
    cmd.extend([convert(v) for v in args])
    ui.status((bytes(cmd)), "\n")

def branch(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'set-upstream', None, ''),
        ('', 'set-upstream-to', '', ''),
        ('d', 'delete', None, ''),
        ('D', 'delete', None, ''),
        ('m', 'move', None, ''),
        ('M', 'move', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command("bookmark")

    if opts.get('set_upstream') or opts.get('set_upstream_to'):
        ui.status(_("Mercurial has no concept of upstream branches\n"))
        return
    elif opts.get('delete'):
        cmd = Command("strip")
        for branch in args:
            cmd['-B'] = branch
        else:
            cmd['-B'] = None
    elif opts.get('move'):
        if len(args) > 0:
            if len(args) > 1:
                old = args.pop(0)
            else:
                # shell command to output the active bookmark for the active
                # revision
                old = '`hg log -T"{activebookmark}" -r .`'
        else:
            raise error.Abort(_('missing newbranch argument'))
        new = args[0]
        cmd['-m'] = old
        cmd.append(new)
    else:
        if len(args) > 1:
            cmd['-r'] = args[1]
            cmd.append(args[0])
        elif len(args) == 1:
            cmd.append(args[0])
    ui.status((bytes(cmd)), "\n")

def ispath(repo, string):
    """
    The first argument to git checkout can either be a revision or a path. Let's
    generally assume it's a revision, unless it's obviously a path. There are
    too many ways to spell revisions in git for us to reasonably catch all of
    them, so let's be conservative.
    """
    if scmutil.isrevsymbol(repo, string):
        # if it's definitely a revision let's not even check if a file of the
        # same name exists.
        return False

    cwd = repo.getcwd()
    if cwd == '':
        repopath = string
    else:
        repopath = cwd + '/' + string

    exists = repo.wvfs.exists(repopath)
    if exists:
        return True

    manifest = repo['.'].manifest()

    didexist = (repopath in manifest) or manifest.hasdir(repopath)

    return didexist

def checkout(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('b', 'branch', '', ''),
        ('B', 'branch', '', ''),
        ('f', 'force', None, ''),
        ('p', 'patch', None, ''),
    ]
    paths = []
    if '--' in args:
        sepindex = args.index('--')
        paths.extend(args[sepindex + 1:])
        args = args[:sepindex]

    args, opts = parseoptions(ui, cmdoptions, args)

    rev = None
    if args and ispath(repo, args[0]):
        paths = args + paths
    elif args:
        rev = args[0]
        paths = args[1:] + paths

    cmd = Command('update')

    if opts.get('force'):
        if paths or rev:
            cmd['-C'] = None

    if opts.get('patch'):
        cmd = Command('revert')
        cmd['-i'] = None

    if opts.get('branch'):
        if len(args) == 0:
            cmd = Command('bookmark')
            cmd.append(opts.get('branch'))
        else:
            cmd.append(args[0])
            bookcmd = Command('bookmark')
            bookcmd.append(opts.get('branch'))
            cmd = cmd & bookcmd
    # if there is any path argument supplied, use revert instead of update
    elif len(paths) > 0:
        ui.status(_("note: use --no-backup to avoid creating .orig files\n\n"))
        cmd = Command('revert')
        if opts.get('patch'):
            cmd['-i'] = None
        if rev:
            cmd['-r'] = rev
        cmd.extend(paths)
    elif rev:
        if opts.get('patch'):
            cmd['-r'] = rev
        else:
            cmd.append(rev)
    elif opts.get('force'):
        cmd = Command('revert')
        cmd['--all'] = None
    else:
        raise error.Abort(_("a commit must be specified"))

    ui.status((bytes(cmd)), "\n")

def cherrypick(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'continue', None, ''),
        ('', 'abort', None, ''),
        ('e', 'edit', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('graft')

    if opts.get('edit'):
        cmd['--edit'] = None
    if opts.get('continue'):
        cmd['--continue'] = None
    elif opts.get('abort'):
        ui.status(_("note: hg graft does not have --abort\n\n"))
        return
    else:
        cmd.extend(args)

    ui.status((bytes(cmd)), "\n")

def clean(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('d', 'd', None, ''),
        ('f', 'force', None, ''),
        ('x', 'x', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('purge')
    if opts.get('x'):
        cmd['--all'] = None
    cmd.extend(args)

    ui.status((bytes(cmd)), "\n")

def clone(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'bare', None, ''),
        ('n', 'no-checkout', None, ''),
        ('b', 'branch', '', ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if len(args) == 0:
        raise error.Abort(_("a repository to clone must be specified"))

    cmd = Command('clone')
    cmd.append(args[0])
    if len(args) > 1:
        cmd.append(args[1])

    if opts.get('bare'):
        cmd['-U'] = None
        ui.status(_("note: Mercurial does not have bare clones. "
                    "-U will clone the repo without checking out a commit\n\n"))
    elif opts.get('no_checkout'):
        cmd['-U'] = None

    if opts.get('branch'):
        cocmd = Command("update")
        cocmd.append(opts.get('branch'))
        cmd = cmd & cocmd

    ui.status((bytes(cmd)), "\n")

def commit(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('a', 'all', None, ''),
        ('m', 'message', '', ''),
        ('p', 'patch', None, ''),
        ('C', 'reuse-message', '', ''),
        ('F', 'file', '', ''),
        ('', 'author', '', ''),
        ('', 'date', '', ''),
        ('', 'amend', None, ''),
        ('', 'no-edit', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('commit')
    if opts.get('patch'):
        cmd = Command('commit --interactive')

    if opts.get('amend'):
        if opts.get('no_edit'):
            cmd = Command('amend')
        else:
            cmd['--amend'] = None

    if opts.get('reuse_message'):
        cmd['-M'] = opts.get('reuse_message')

    if opts.get('message'):
        cmd['-m'] = "'%s'" % (opts.get('message'),)

    if opts.get('all'):
        ui.status(_("note: Mercurial doesn't have a staging area, "
                    "so there is no --all. -A will add and remove files "
                    "for you though.\n\n"))

    if opts.get('file'):
        cmd['-l'] = opts.get('file')

    if opts.get('author'):
        cmd['-u'] = opts.get('author')

    if opts.get('date'):
        cmd['-d'] = opts.get('date')

    cmd.extend(args)

    ui.status((bytes(cmd)), "\n")

def deprecated(ui, repo, *args, **kwargs):
    ui.warn(_('this command has been deprecated in the git project, '
              'thus isn\'t supported by this tool\n\n'))

def diff(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('a', 'all', None, ''),
        ('', 'cached', None, ''),
        ('R', 'reverse', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('diff')

    if opts.get('cached'):
        ui.status(_('note: Mercurial has no concept of a staging area, '
                    'so --cached does nothing\n\n'))

    if opts.get('reverse'):
        cmd['--reverse'] = None

    for a in list(args):
        args.remove(a)
        try:
            repo.revs(a)
            cmd['-r'] = a
        except Exception:
            cmd.append(a)

    ui.status((bytes(cmd)), "\n")

def difftool(ui, repo, *args, **kwargs):
    ui.status(_('Mercurial does not enable external difftool by default. You '
        'need to enable the extdiff extension in your .hgrc file by adding\n'
        'extdiff =\n'
        'to the [extensions] section and then running\n\n'
        'hg extdiff -p <program>\n\n'
        'See \'hg help extdiff\' and \'hg help -e extdiff\' for more '
        'information.\n'))

def fetch(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'all', None, ''),
        ('f', 'force', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('pull')

    if len(args) > 0:
        cmd.append(args[0])
        if len(args) > 1:
            ui.status(_("note: Mercurial doesn't have refspecs. "
                        "-r can be used to specify which commits you want to "
                        "pull. -B can be used to specify which bookmark you "
                        "want to pull.\n\n"))
            for v in args[1:]:
                if v in repo._bookmarks:
                    cmd['-B'] = v
                else:
                    cmd['-r'] = v

    ui.status((bytes(cmd)), "\n")

def grep(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('grep')

    # For basic usage, git grep and hg grep are the same. They both have the
    # pattern first, followed by paths.
    cmd.extend(args)

    ui.status((bytes(cmd)), "\n")

def init(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('init')

    if len(args) > 0:
        cmd.append(args[0])

    ui.status((bytes(cmd)), "\n")

def log(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'follow', None, ''),
        ('', 'decorate', None, ''),
        ('n', 'number', '', ''),
        ('1', '1', None, ''),
        ('', 'pretty', '', ''),
        ('', 'format', '', ''),
        ('', 'oneline', None, ''),
        ('', 'stat', None, ''),
        ('', 'graph', None, ''),
        ('p', 'patch', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)
    ui.status(_('note: -v prints the entire commit message like Git does. To '
                'print just the first line, drop the -v.\n\n'))
    ui.status(_("note: see hg help revset for information on how to filter "
                "log output\n\n"))

    cmd = Command('log')
    cmd['-v'] = None

    if opts.get('number'):
        cmd['-l'] = opts.get('number')
    if opts.get('1'):
        cmd['-l'] = '1'
    if opts.get('stat'):
        cmd['--stat'] = None
    if opts.get('graph'):
        cmd['-G'] = None
    if opts.get('patch'):
        cmd['-p'] = None

    if opts.get('pretty') or opts.get('format') or opts.get('oneline'):
        format = opts.get('format', '')
        if 'format:' in format:
            ui.status(_("note: --format format:??? equates to Mercurial's "
                        "--template. See hg help templates for more info.\n\n"))
            cmd['--template'] = '???'
        else:
            ui.status(_("note: --pretty/format/oneline equate to Mercurial's "
                        "--style or --template. See hg help templates for "
                        "more info.\n\n"))
            cmd['--style'] = '???'

    if len(args) > 0:
        if '..' in args[0]:
            since, until = args[0].split('..')
            cmd['-r'] = "'%s::%s'" % (since, until)
            del args[0]
        cmd.extend(args)

    ui.status((bytes(cmd)), "\n")

def lsfiles(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('c', 'cached', None, ''),
        ('d', 'deleted', None, ''),
        ('m', 'modified', None, ''),
        ('o', 'others', None, ''),
        ('i', 'ignored', None, ''),
        ('s', 'stage', None, ''),
        ('z', '_zero', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if (opts.get('modified') or opts.get('deleted')
        or opts.get('others') or opts.get('ignored')):
        cmd = Command('status')
        if opts.get('deleted'):
            cmd['-d'] = None
        if opts.get('modified'):
            cmd['-m'] = None
        if opts.get('others'):
            cmd['-o'] = None
        if opts.get('ignored'):
            cmd['-i'] = None
    else:
        cmd = Command('files')
    if opts.get('stage'):
        ui.status(_("note: Mercurial doesn't have a staging area, ignoring "
                  "--stage\n"))
    if opts.get('_zero'):
        cmd['-0'] = None
    cmd.append('.')
    for include in args:
        cmd['-I'] = procutil.shellquote(include)

    ui.status((bytes(cmd)), "\n")

def merge(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('merge')

    if len(args) > 0:
        cmd.append(args[len(args) - 1])

    ui.status((bytes(cmd)), "\n")

def mergebase(ui, repo, *args, **kwargs):
    cmdoptions = []
    args, opts = parseoptions(ui, cmdoptions, args)

    if len(args) != 2:
        args = ['A', 'B']

    cmd = Command("log -T '{node}\\n' -r 'ancestor(%s,%s)'"
                  % (args[0], args[1]))

    ui.status(_('note: ancestors() is part of the revset language\n'),
              _("(learn more about revsets with 'hg help revsets')\n\n"))
    ui.status((bytes(cmd)), "\n")

def mergetool(ui, repo, *args, **kwargs):
    cmdoptions = []
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command("resolve")

    if len(args) == 0:
        cmd['--all'] = None
    cmd.extend(args)
    ui.status((bytes(cmd)), "\n")

def mv(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('f', 'force', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('mv')
    cmd.extend(args)

    if opts.get('force'):
        cmd['-f'] = None

    ui.status((bytes(cmd)), "\n")

def pull(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'all', None, ''),
        ('f', 'force', None, ''),
        ('r', 'rebase', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('pull')
    cmd['--rebase'] = None

    if len(args) > 0:
        cmd.append(args[0])
        if len(args) > 1:
            ui.status(_("note: Mercurial doesn't have refspecs. "
                        "-r can be used to specify which commits you want to "
                        "pull. -B can be used to specify which bookmark you "
                        "want to pull.\n\n"))
            for v in args[1:]:
                if v in repo._bookmarks:
                    cmd['-B'] = v
                else:
                    cmd['-r'] = v

    ui.status((bytes(cmd)), "\n")

def push(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'all', None, ''),
        ('f', 'force', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('push')

    if len(args) > 0:
        cmd.append(args[0])
        if len(args) > 1:
            ui.status(_("note: Mercurial doesn't have refspecs. "
                        "-r can be used to specify which commits you want "
                        "to push. -B can be used to specify which bookmark "
                        "you want to push.\n\n"))
            for v in args[1:]:
                if v in repo._bookmarks:
                    cmd['-B'] = v
                else:
                    cmd['-r'] = v

    if opts.get('force'):
        cmd['-f'] = None

    ui.status((bytes(cmd)), "\n")

def rebase(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'all', None, ''),
        ('i', 'interactive', None, ''),
        ('', 'onto', '', ''),
        ('', 'abort', None, ''),
        ('', 'continue', None, ''),
        ('', 'skip', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if opts.get('interactive'):
        ui.status(_("note: hg histedit does not perform a rebase. "
                    "It just edits history.\n\n"))
        cmd = Command('histedit')
        if len(args) > 0:
            ui.status(_("also note: 'hg histedit' will automatically detect"
                      " your stack, so no second argument is necessary\n\n"))
        ui.status((bytes(cmd)), "\n")
        return

    if opts.get('skip'):
        cmd = Command('revert --all -r .')
        ui.status((bytes(cmd)), "\n")

    cmd = Command('rebase')

    if opts.get('continue') or opts.get('skip'):
        cmd['--continue'] = None
    if opts.get('abort'):
        cmd['--abort'] = None

    if opts.get('onto'):
        ui.status(_("note: if you're trying to lift a commit off one branch, "
                    "try hg rebase -d <destination commit> -s <commit to be "
                    "lifted>\n\n"))
        cmd['-d'] = convert(opts.get('onto'))
        if len(args) < 2:
            raise error.Abort(_("expected format: git rebase --onto X Y Z"))
        cmd['-s'] = "'::%s - ::%s'" % (convert(args[1]), convert(args[0]))
    else:
        if len(args) == 1:
            cmd['-d'] = convert(args[0])
        elif len(args) == 2:
            cmd['-d'] = convert(args[0])
            cmd['-b'] = convert(args[1])

    ui.status((bytes(cmd)), "\n")

def reflog(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'all', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('journal')
    if opts.get('all'):
        cmd['--all'] = None
    if len(args) > 0:
        cmd.append(args[0])

    ui.status(bytes(cmd), "\n\n")
    ui.status(_("note: in hg commits can be deleted from repo but we always"
              " have backups\n"))

def reset(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'soft', None, ''),
        ('', 'hard', None, ''),
        ('', 'mixed', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    commit = convert(args[0] if len(args) > 0 else '.')
    hard = opts.get('hard')

    if opts.get('mixed'):
        ui.status(_('note: --mixed has no meaning since Mercurial has no '
                    'staging area\n\n'))
    if opts.get('soft'):
        ui.status(_('note: --soft has no meaning since Mercurial has no '
                    'staging area\n\n'))

    cmd = Command('update')
    if hard:
        cmd.append('--clean')

    cmd.append(commit)

    ui.status((bytes(cmd)), "\n")

def revert(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if len(args) > 1:
        ui.status(_("note: hg backout doesn't support multiple commits at "
                    "once\n\n"))

    cmd = Command('backout')
    if args:
        cmd.append(args[0])

    ui.status((bytes(cmd)), "\n")

def revparse(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'show-cdup', None, ''),
        ('', 'show-toplevel', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if opts.get('show_cdup') or opts.get('show_toplevel'):
        cmd = Command('root')
        if opts.get('show_cdup'):
            ui.status(_("note: hg root prints the root of the repository\n\n"))
        ui.status((bytes(cmd)), "\n")
    else:
        ui.status(_("note: see hg help revset for how to refer to commits\n"))

def rm(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('f', 'force', None, ''),
        ('n', 'dry-run', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('rm')
    cmd.extend(args)

    if opts.get('force'):
        cmd['-f'] = None
    if opts.get('dry_run'):
        cmd['-n'] = None

    ui.status((bytes(cmd)), "\n")

def show(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'name-status', None, ''),
        ('', 'pretty', '', ''),
        ('U', 'unified', int, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if opts.get('name_status'):
        if opts.get('pretty') == 'format:':
            cmd = Command('status')
            cmd['--change'] = '.'
        else:
            cmd = Command('log')
            cmd.append('--style status')
            cmd.append('-r .')
    elif len(args) > 0:
        if ispath(repo, args[0]):
            cmd = Command('cat')
        else:
            cmd = Command('export')
        cmd.extend(args)
        if opts.get('unified'):
            cmd.append('--config diff.unified=%d' % (opts['unified'],))
    elif opts.get('unified'):
        cmd = Command('export')
        cmd.append('--config diff.unified=%d' % (opts['unified'],))
    else:
        cmd = Command('export')

    ui.status((bytes(cmd)), "\n")

def stash(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('shelve')
    action = args[0] if len(args) > 0 else None

    if action == 'list':
        cmd['-l'] = None
    elif action == 'drop':
        cmd['-d'] = None
        if len(args) > 1:
            cmd.append(args[1])
        else:
            cmd.append('<shelve name>')
    elif action == 'pop' or action == 'apply':
        cmd = Command('unshelve')
        if len(args) > 1:
            cmd.append(args[1])
        if action == 'apply':
            cmd['--keep'] = None
    elif (action == 'branch' or action == 'show' or action == 'clear'
        or action == 'create'):
        ui.status(_("note: Mercurial doesn't have equivalents to the "
                    "git stash branch, show, clear, or create actions\n\n"))
        return
    else:
        if len(args) > 0:
            if args[0] != 'save':
                cmd['--name'] = args[0]
            elif len(args) > 1:
                cmd['--name'] = args[1]

    ui.status((bytes(cmd)), "\n")

def status(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('', 'ignored', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('status')
    cmd.extend(args)

    if opts.get('ignored'):
        cmd['-i'] = None

    ui.status((bytes(cmd)), "\n")

def svn(ui, repo, *args, **kwargs):
    if not args:
        raise error.Abort(_('missing svn command'))
    svncmd = args[0]
    if svncmd not in gitsvncommands:
        raise error.Abort(_('unknown git svn command "%s"') % (svncmd))

    args = args[1:]
    return gitsvncommands[svncmd](ui, repo, *args, **kwargs)

def svndcommit(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('push')

    ui.status((bytes(cmd)), "\n")

def svnfetch(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    cmd = Command('pull')
    cmd.append('default-push')

    ui.status((bytes(cmd)), "\n")

def svnfindrev(ui, repo, *args, **kwargs):
    cmdoptions = [
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if not args:
        raise error.Abort(_('missing find-rev argument'))

    cmd = Command('log')
    cmd['-r'] = args[0]

    ui.status((bytes(cmd)), "\n")

def svnrebase(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('l', 'local', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    pullcmd = Command('pull')
    pullcmd.append('default-push')
    rebasecmd = Command('rebase')
    rebasecmd.append('tip')

    cmd = pullcmd & rebasecmd

    ui.status((bytes(cmd)), "\n")

def tag(ui, repo, *args, **kwargs):
    cmdoptions = [
        ('f', 'force', None, ''),
        ('l', 'list', None, ''),
        ('d', 'delete', None, ''),
    ]
    args, opts = parseoptions(ui, cmdoptions, args)

    if opts.get('list'):
        cmd = Command('tags')
    else:
        cmd = Command('tag')

        if not args:
            raise error.Abort(_('missing tag argument'))

        cmd.append(args[0])
        if len(args) > 1:
            cmd['-r'] = args[1]

        if opts.get('delete'):
            cmd['--remove'] = None

        if opts.get('force'):
            cmd['-f'] = None

    ui.status((bytes(cmd)), "\n")

gitcommands = {
    'add': add,
    'am': am,
    'apply': apply,
    'bisect': bisect,
    'blame': blame,
    'branch': branch,
    'checkout': checkout,
    'cherry-pick': cherrypick,
    'clean': clean,
    'clone': clone,
    'commit': commit,
    'diff': diff,
    'difftool': difftool,
    'fetch': fetch,
    'grep': grep,
    'init': init,
    'log': log,
    'ls-files': lsfiles,
    'merge': merge,
    'merge-base': mergebase,
    'mergetool': mergetool,
    'mv': mv,
    'pull': pull,
    'push': push,
    'rebase': rebase,
    'reflog': reflog,
    'reset': reset,
    'revert': revert,
    'rev-parse': revparse,
    'rm': rm,
    'show': show,
    'stash': stash,
    'status': status,
    'svn': svn,
    'tag': tag,
    'whatchanged': deprecated,
}

gitsvncommands = {
    'dcommit': svndcommit,
    'fetch': svnfetch,
    'find-rev': svnfindrev,
    'rebase': svnrebase,
}