githelp: vendor Facebook authored extension

This commit vendors the Facebook-authored "githelp" extension. This
extension provides a "githelp" command that can be used to try to
convert a `git` command to its Mercurial equivalent. This functionality
is useful for Git users learning Mercurial.

The extension was copied from the
repository at revision 32ceeccb832c433b36e9af8196814b8e5a526775. The
following modifications were made:

* The "testedwith" value has been changed to match core's conventions.
* Support for a custom footer has been removed, as it is Facebook
  specific. The feature is useful. But the implementation wasn't
  appropriate for core.
* A test referencing "tweakdefaults" has been removed.
* Imports changed to match Mercurial's style convention.
* Double newlines in test removed.
* Pager activation changed to ui.pager().
* Initial line of githelp.py changed to add description of file.

The removal of the custom footer code was the only significant
source change. The rest were mostly cosmetic.

There are still some Facebook-isms in the extension. I'll address
these as follow-ups.

.. feature:: githelp extension

   The "githelp" extension provides the ``hg githelp`` command. This
   command attempts to convert a ``git`` command to its Mercurial
   equivalent. The extension can be useful to Git users new to
   Mercurial.

Differential Revision: https://phab.mercurial-scm.org/D1722

hgext/githelp.py

@@ -0,0 +1,1081 b''
+# 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 (
+    error,
+    extensions,
+    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 __str__(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
+
+    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: hg crecord has a better UI to record changes\n"))
+        ui.status(_("note: record and crecord will commit when complete, "
+                    "as there is no staging area in mercurial\n\n"))
+        cmd = Command('record')
+    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"))
+        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((str(cmd)), "\n")
+
+def am(ui, repo, *args, **kwargs):
+    cmdoptions=[
+    ]
+    args, opts = parseoptions(ui, cmdoptions, args)
+    cmd = Command('mimport -m')
+    ui.status(str(cmd), "\n\n")
+    ui.status(_("note: requires the MboxExtension and the MqExtension.\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((str(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)
+    try:
+        # If tweakdefaults is enabled then we have access to -p, which adds
+        # Phabricator diff ID
+        extensions.find('tweakdefaults')
+        cmd = Command('annotate -pudl')
+    except KeyError:
+        cmd = Command('annotate -udl')
+    cmd.extend([convert(v) for v in args])
+    ui.status((str(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((str(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((str(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((str(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((str(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((str(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('record')
+
+    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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(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((str(cmd)), "\n")
+        return
+
+    if opts.get('skip'):
+        cmd = Command('revert --all -r .')
+        ui.status((str(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((str(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(str(cmd), "\n\n")
+    ui.status(_("note: in hg commits can be deleted from repo but we always"
+              " have backups.\n"
+              "Please use 'hg backups --restore' or 'hg reset'" +
+              " to restore from 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'))
+
+    cmd = Command('reset')
+    if hard:
+        cmd.append('--clean')
+    cmd.append(commit)
+
+    ui.status((str(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((str(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((str(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((str(cmd)), "\n")
+
+def show(ui, repo, *args, **kwargs):
+    cmdoptions = [
+        ('', 'name-status', None, ''),
+        ('', 'pretty', '', ''),
+        ('U', 'unified', int, ''),
+    ]
+    args, opts = parseoptions(ui, cmdoptions, args)
+
+    cmd = Command('show')
+    if opts.get('name_status'):
+        if opts.get('pretty') == 'format:':
+            cmd = Command('stat')
+            cmd['--change'] = 'tip'
+        else:
+            cmd = Command('log')
+            cmd.append('--style status')
+            cmd.append('-r tip')
+    elif len(args) > 0:
+        if ispath(repo, args[0]):
+            cmd.append('.')
+        cmd.extend(args)
+        if opts.get('unified'):
+            cmd.append('--config diff.unified=%d' % (opts['unified'],))
+    elif opts.get('unified'):
+        cmd.append('--config diff.unified=%d' % (opts['unified'],))
+
+    ui.status((str(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((str(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((str(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((str(cmd)), "\n")
+
+def svnfetch(ui, repo, *args, **kwargs):
+    cmdoptions = [
+    ]
+    args, opts = parseoptions(ui, cmdoptions, args)
+
+    cmd = Command('pull')
+    cmd.append('default-push')
+
+    ui.status((str(cmd)), "\n")
+
+def svnfindrev(ui, repo, *args, **kwargs):
+    cmdoptions = [
+    ]
+    args, opts = parseoptions(ui, cmdoptions, args)
+
+    cmd = Command('log')
+    cmd['-r'] = args[0]
+
+    ui.status((str(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((str(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((str(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,
+}

tests/test-githelp.t

@@ -0,0 +1,258 b''
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > githelp =
+  > EOF
+
+  $ hg init repo
+  $ cd repo
+  $ echo foo > test_file
+  $ mkdir dir
+  $ echo foo > dir/file
+  $ echo foo > removed_file
+  $ echo foo > deleted_file
+  $ hg add -q .
+  $ hg commit -m 'bar'
+  $ hg bookmark both
+  $ touch both
+  $ touch untracked_file
+  $ hg remove removed_file
+  $ rm deleted_file
+
+githelp on a single command should succeed
+  $ hg githelp -- commit
+  hg commit
+  $ hg githelp -- git commit
+  hg commit
+
+githelp should fail nicely if we don't give it arguments
+  $ hg githelp
+  abort: missing git command - usage: hg githelp -- <git command>
+  [255]
+  $ hg githelp -- git
+  abort: missing git command - usage: hg githelp -- <git command>
+  [255]
+
+githelp on a command with options should succeed
+  $ hg githelp -- commit -pm "abc"
+  hg record -m 'abc'
+
+githelp on a command with standalone unrecognized option should succeed with warning
+  $ hg githelp -- commit -p -v
+  ignoring unknown option -v
+  hg record
+
+githelp on a command with unrecognized option packed with other options should fail with error
+  $ hg githelp -- commit -pv
+  abort: unknown option v packed with other options
+  Please try passing the option as it's own flag: -v
+  [255]
+
+githelp for git rebase --skip
+  $ hg githelp -- git rebase --skip
+  hg revert --all -r .
+  hg rebase --continue
+
+githelp for git commit --amend (hg commit --amend pulls up an editor)
+  $ hg githelp -- commit --amend
+  hg commit --amend
+
+githelp for git commit --amend --no-edit (hg amend does not pull up an editor)
+  $ hg githelp -- commit --amend --no-edit
+  hg amend
+
+githelp for git checkout -- . (checking out a directory)
+  $ hg githelp -- checkout -- .
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert .
+
+githelp for git checkout "HEAD^" (should still work to pass a rev)
+  $ hg githelp -- checkout "HEAD^"
+  hg update .^
+
+githelp checkout: args after -- should be treated as paths no matter what
+  $ hg githelp -- checkout -- HEAD
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert HEAD
+
+githelp for git checkout with rev and path
+  $ hg githelp -- checkout "HEAD^" -- file.txt
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert -r .^ file.txt
+
+githelp for git with rev and path, without separator
+  $ hg githelp -- checkout "HEAD^" file.txt
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert -r .^ file.txt
+
+githelp for checkout with a file as first argument
+  $ hg githelp -- checkout test_file
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert test_file
+
+githelp for checkout with a removed file as first argument
+  $ hg githelp -- checkout removed_file
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert removed_file
+
+githelp for checkout with a deleted file as first argument
+  $ hg githelp -- checkout deleted_file
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert deleted_file
+
+githelp for checkout with a untracked file as first argument
+  $ hg githelp -- checkout untracked_file
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert untracked_file
+
+githelp for checkout with a directory as first argument
+  $ hg githelp -- checkout dir
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert dir
+
+githelp for checkout when not in repo root
+  $ cd dir
+  $ hg githelp -- checkout file
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert file
+
+  $ cd ..
+
+githelp for checkout with an argument that is both a file and a revision
+  $ hg githelp -- checkout both
+  hg update both
+
+githelp for checkout with the -p option
+  $ hg githelp -- git checkout -p xyz
+  hg revert -i -r xyz
+
+  $ hg githelp -- git checkout -p xyz -- abc
+  note: use --no-backup to avoid creating .orig files
+  
+  hg revert -i -r xyz abc
+
+githelp for checkout with the -f option and a rev
+  $ hg githelp -- git checkout -f xyz
+  hg update -C xyz
+  $ hg githelp -- git checkout --force xyz
+  hg update -C xyz
+
+githelp for checkout with the -f option without an arg
+  $ hg githelp -- git checkout -f
+  hg revert --all
+  $ hg githelp -- git checkout --force
+  hg revert --all
+
+githelp for grep with pattern and path
+  $ hg githelp -- grep shrubbery flib/intern/
+  hg grep shrubbery flib/intern/
+
+githelp for reset, checking ~ in git becomes ~1 in mercurial
+  $ hg githelp -- reset HEAD~
+  hg reset .~1
+  $ hg githelp -- reset "HEAD^"
+  hg reset .^
+  $ hg githelp -- reset HEAD~3
+  hg reset .~3
+
+githelp for git show --name-status
+  $ hg githelp -- git show --name-status
+  hg log --style status -r tip
+
+githelp for git show --pretty=format: --name-status
+  $ hg githelp -- git show --pretty=format: --name-status
+  hg stat --change tip
+
+githelp for show with no arguments
+  $ hg githelp -- show
+  hg show
+
+githelp for show with a path
+  $ hg githelp -- show test_file
+  hg show . test_file
+
+githelp for show with not a path:
+  $ hg githelp -- show rev
+  hg show rev
+
+githelp for show with many arguments
+  $ hg githelp -- show argone argtwo
+  hg show argone argtwo
+  $ hg githelp -- show test_file argone argtwo
+  hg show . test_file argone argtwo
+
+githelp for show with --unified options
+  $ hg githelp -- show --unified=10
+  hg show --config diff.unified=10
+  $ hg githelp -- show -U100
+  hg show --config diff.unified=100
+
+githelp for show with a path and --unified
+  $ hg githelp -- show -U20 test_file
+  hg show . test_file --config diff.unified=20
+
+githelp for stash drop without name
+  $ hg githelp -- git stash drop
+  hg shelve -d <shelve name>
+
+githelp for stash drop with name
+  $ hg githelp -- git stash drop xyz
+  hg shelve -d xyz
+
+githelp for whatchanged should show deprecated message
+  $ hg githelp -- whatchanged -p
+  This command has been deprecated in the git project, thus isn't supported by this tool.
+  
+
+githelp for git branch -m renaming
+  $ hg githelp -- git branch -m old new
+  hg bookmark -m old new
+
+When the old name is omitted, git branch -m new renames the current branch.
+  $ hg githelp -- git branch -m new
+  hg bookmark -m `hg log -T"{activebookmark}" -r .` new
+
+Branch deletion in git strips commits
+  $ hg githelp -- git branch -d
+  hg strip -B
+  $ hg githelp -- git branch -d feature
+  hg strip -B feature -B
+  $ hg githelp -- git branch --delete experiment1 experiment2
+  hg strip -B experiment1 -B experiment2 -B
+
+githelp for reuse message using the shorthand
+  $ hg githelp -- git commit -C deadbeef
+  hg commit -M deadbeef
+
+githelp for reuse message using the the long version
+  $ hg githelp -- git commit --reuse-message deadbeef
+  hg commit -M deadbeef
+
+githelp for apply with no options
+  $ hg githelp -- apply
+  hg import --no-commit
+
+githelp for apply with directory strip custom
+  $ hg githelp -- apply -p 5
+  hg import --no-commit -p 5
+
+git merge-base
+  $ hg githelp -- git merge-base --is-ancestor
+  ignoring unknown option --is-ancestor
+  NOTE: ancestors() is part of the revset language.
+  Learn more about revsets with 'hg help revsets'
+  
+  hg log -T '{node}\n' -r 'ancestor(A,B)'
+
+githelp for git blame
+  $ hg githelp -- git blame
+  hg annotate -udl

tests/test-help.t

@@ -261,6 +261,7 b' Test extension help:'
        eol           automatically manage newlines in repository files
        extdiff       command to allow external programs to compare revisions
        factotum      http authentication with factotum
+       githelp       try mapping git commands to Mercurial commands
        gpg           commands to sign and verify changesets
        hgk           browse the repository in a graphical way
        highlight     syntax highlighting for hgweb (requires Pygments)