hgext/githelp.py

xdiff: add a preprocessing step that trims files

xdiff has a `xdl_trim_ends` step that removes common lines, unmatchable
lines. That is in theory good, but happens too late - after splitting,
hashing, and adjusting the hash values so they are unique. Those splitting,
hashing and adjusting hash values steps could have noticeable overhead.

Diffing two large files with minor (one-line-ish) changes are not uncommon.
In that case, the raw performance of those preparation steps seriously
matter. Even allocating an O(N) array and storing line offsets to it is
expensive.  Therefore my previous attempts [1] [2] cannot be good enough
since they do not remove the O(N) array assignment.

This patch adds a preprocessing step - `xdl_trim_files` that runs before
other preprocessing steps. It counts common prefix and suffix and lines in
them (needed for displaying line number), without doing anything else.

Testing with a crafted large (169MB) file, with minor change:

```
  open('a','w').write(''.join('%s\n' % (i % 100000) for i in xrange(30000000) if i != 6000000))
  open('b','w').write(''.join('%s\n' % (i % 100000) for i in xrange(30000000) if i != 6003000))
```

Running xdiff by a simple binary [3], this patch improves the xdiff perf by
more than 10x for the above case:

```
  # xdiff before this patch
  2.41s user 1.13s system 98% cpu 3.592 total
  # xdiff after this patch
  0.14s user 0.16s system 98% cpu 0.309 total
  # gnu diffutils
  0.12s user 0.15s system 98% cpu 0.272 total
  # (best of 20 runs)
```

It's still slightly slower than GNU diffutils. But it's pretty close now.

Testing with real repo data:

For the whole repo, this patch makes xdiff 25% faster:

```
  # hg perfbdiff --count 100 --alldata -c d334afc585e2 --blocks [--xdiff]
  # xdiff, after
  ! wall 0.058861 comb 0.050000 user 0.050000 sys 0.000000 (best of 100)
  # xdiff, before
  ! wall 0.077816 comb 0.080000 user 0.080000 sys 0.000000 (best of 91)
  # bdiff
  ! wall 0.117473 comb 0.120000 user 0.120000 sys 0.000000 (best of 67)
```

For files that are long (ex. commands.py), the speedup is more than 3x, very
significant:

```
  # hg perfbdiff --count 3000 --blocks commands.py.i 1 [--xdiff]
  # xdiff, after
  ! wall 0.690583 comb 0.690000 user 0.690000 sys 0.000000 (best of 12)
  # xdiff, before
  ! wall 2.240361 comb 2.210000 user 2.210000 sys 0.000000 (best of 4)
  # bdiff
  ! wall 2.469852 comb 2.440000 user 2.440000 sys 0.000000 (best of 4)
```

[1]: https://phab.mercurial-scm.org/D2631
[2]: https://phab.mercurial-scm.org/D2634
[3]:

```
// Code to run xdiff from command line. No proper error handling.
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "mercurial/thirdparty/xdiff/xdiff.h"
#define ensure(x) if (!(x)) exit(255);
mmfile_t readfile(const char *path) {
  struct stat st; int fd = open(path, O_RDONLY);
  fstat(fd, &st); mmfile_t file = { malloc(st.st_size), st.st_size };
  ensure(read(fd, file.ptr, st.st_size) == st.st_size); close(fd);
  return file;
}
int main(int argc, char const *argv[]) {
  mmfile_t a = readfile(argv[1]), b = readfile(argv[2]);
  xpparam_t xpp = {0}; xdemitconf_t xecfg = {0}; xdemitcb_t ecb = {0};
  xdl_diff(&a, &b, &xpp, &xecfg, &ecb);
  return 0;
}
```

Differential Revision: https://phab.mercurial-scm.org/D2686

# 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,
    util,
)

# 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:
                raise error.Abort(
                    "unknown option {0} packed with other options\n"
                    "Please try passing the option as it's own flag: -{0}" \
                    .format(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 .`'
        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 string in repo:
        # 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'] = util.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):
    svncmd = args[0]
    if not svncmd in gitsvncommands:
        ui.warn(_("error: unknown git svn command %s\n") % (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)

    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')
        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,
}