histedit: import chistedit curses UI from hg-experimental

I don't tend to like curses interfaces, but this gets enough use at
work that it seems like it's worth bringing into core. This is a
minimal import from hg-experimental revision 4c7f33bf5f00, in that
I've done the smallest amount of code movement and editing in order to
import the functionality.

.. feature::

    `hg histedit` will now present a curses UI if curses is available
    and `ui.interface` or `ui.interface.histedit` is set to `curses`.

Differential Revision: https://phab.mercurial-scm.org/D5146

hgext/histedit.py

@@ -1,1658 +1,2227 b''
 # histedit.py - interactive history editing for mercurial
 #
 # Copyright 2009 Augie Fackler <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 """interactive history editing
 
 With this extension installed, Mercurial gains one new command: histedit. Usage
 is as follows, assuming the following history::
 
  @  3[tip]   7c2fd3b9020c   2009-04-27 18:04 -0500   durin42
  |    Add delta
  |
  o  2   030b686bedc4   2009-04-27 18:04 -0500   durin42
  |    Add gamma
  |
  o  1   c561b4e977df   2009-04-27 18:04 -0500   durin42
  |    Add beta
  |
  o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42
       Add alpha
 
 If you were to run ``hg histedit c561b4e977df``, you would see the following
 file open in your editor::
 
  pick c561b4e977df Add beta
  pick 030b686bedc4 Add gamma
  pick 7c2fd3b9020c Add delta
 
  # Edit history between c561b4e977df and 7c2fd3b9020c
  #
  # Commits are listed from least to most recent
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description and date
  #  d, drop = remove commit from history
  #  m, mess = edit commit message without changing commit content
  #  b, base = checkout changeset and apply further changesets from there
  #
 
 In this file, lines beginning with ``#`` are ignored. You must specify a rule
 for each revision in your history. For example, if you had meant to add gamma
 before beta, and then wanted to add delta in the same revision as beta, you
 would reorganize the file to look like this::
 
  pick 030b686bedc4 Add gamma
  pick c561b4e977df Add beta
  fold 7c2fd3b9020c Add delta
 
  # Edit history between c561b4e977df and 7c2fd3b9020c
  #
  # Commits are listed from least to most recent
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description and date
  #  d, drop = remove commit from history
  #  m, mess = edit commit message without changing commit content
  #  b, base = checkout changeset and apply further changesets from there
  #
 
 At which point you close the editor and ``histedit`` starts working. When you
 specify a ``fold`` operation, ``histedit`` will open an editor when it folds
 those revisions together, offering you a chance to clean up the commit message::
 
  Add beta
  ***
  Add delta
 
 Edit the commit message to your liking, then close the editor. The date used
 for the commit will be the later of the two commits' dates. For this example,
 let's assume that the commit message was changed to ``Add beta and delta.``
 After histedit has run and had a chance to remove any old or temporary
 revisions it needed, the history looks like this::
 
  @  2[tip]   989b4d060121   2009-04-27 18:04 -0500   durin42
  |    Add beta and delta.
  |
  o  1   081603921c3f   2009-04-27 18:04 -0500   durin42
  |    Add gamma
  |
  o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42
       Add alpha
 
 Note that ``histedit`` does *not* remove any revisions (even its own temporary
 ones) until after it has completed all the editing operations, so it will
 probably perform several strip operations when it's done. For the above example,
 it had to run strip twice. Strip can be slow depending on a variety of factors,
 so you might need to be a little patient. You can choose to keep the original
 revisions by passing the ``--keep`` flag.
 
 The ``edit`` operation will drop you back to a command prompt,
 allowing you to edit files freely, or even use ``hg record`` to commit
 some changes as a separate commit. When you're done, any remaining
 uncommitted changes will be committed as well. When done, run ``hg
 histedit --continue`` to finish this step. If there are uncommitted
 changes, you'll be prompted for a new commit message, but the default
 commit message will be the original message for the ``edit`` ed
 revision, and the date of the original commit will be preserved.
 
 The ``message`` operation will give you a chance to revise a commit
 message without changing the contents. It's a shortcut for doing
 ``edit`` immediately followed by `hg histedit --continue``.
 
 If ``histedit`` encounters a conflict when moving a revision (while
 handling ``pick`` or ``fold``), it'll stop in a similar manner to
 ``edit`` with the difference that it won't prompt you for a commit
 message when done. If you decide at this point that you don't like how
 much work it will be to rearrange history, or that you made a mistake,
 you can use ``hg histedit --abort`` to abandon the new changes you
 have made and return to the state before you attempted to edit your
 history.
 
 If we clone the histedit-ed example repository above and add four more
 changes, such that we have the following history::
 
    @  6[tip]   038383181893   2009-04-27 18:04 -0500   stefan
    |    Add theta
    |
    o  5   140988835471   2009-04-27 18:04 -0500   stefan
    |    Add eta
    |
    o  4   122930637314   2009-04-27 18:04 -0500   stefan
    |    Add zeta
    |
    o  3   836302820282   2009-04-27 18:04 -0500   stefan
    |    Add epsilon
    |
    o  2   989b4d060121   2009-04-27 18:04 -0500   durin42
    |    Add beta and delta.
    |
    o  1   081603921c3f   2009-04-27 18:04 -0500   durin42
    |    Add gamma
    |
    o  0   d8d2fcd0e319   2009-04-27 18:04 -0500   durin42
         Add alpha
 
 If you run ``hg histedit --outgoing`` on the clone then it is the same
 as running ``hg histedit 836302820282``. If you need plan to push to a
 repository that Mercurial does not detect to be related to the source
 repo, you can add a ``--force`` option.
 
 Config
 ------
 
 Histedit rule lines are truncated to 80 characters by default. You
 can customize this behavior by setting a different length in your
 configuration file::
 
   [histedit]
   linelen = 120      # truncate rule lines at 120 characters
 
 ``hg histedit`` attempts to automatically choose an appropriate base
 revision to use. To change which base revision is used, define a
 revset in your configuration file::
 
   [histedit]
   defaultrev = only(.) & draft()
 
 By default each edited revision needs to be present in histedit commands.
 To remove revision you need to use ``drop`` operation. You can configure
 the drop to be implicit for missing commits by adding::
 
   [histedit]
   dropmissing = True
 
 By default, histedit will close the transaction after each action. For
 performance purposes, you can configure histedit to use a single transaction
 across the entire histedit. WARNING: This setting introduces a significant risk
 of losing the work you've done in a histedit if the histedit aborts
 unexpectedly::
 
   [histedit]
   singletransaction = True
 
 """
 
 from __future__ import absolute_import
 
+import fcntl
+import functools
 import os
+import struct
+import termios
 
 from mercurial.i18n import _
 from mercurial import (
     bundle2,
     cmdutil,
     context,
     copies,
     destutil,
     discovery,
     error,
     exchange,
     extensions,
     hg,
     lock,
+    logcmdutil,
     merge as mergemod,
     mergeutil,
     node,
     obsolete,
     pycompat,
     registrar,
     repair,
     scmutil,
     state as statemod,
     util,
 )
 from mercurial.utils import (
     stringutil,
 )
 
 pickle = util.pickle
 release = lock.release
 cmdtable = {}
 command = registrar.command(cmdtable)
 
 configtable = {}
 configitem = registrar.configitem(configtable)
 configitem('experimental', 'histedit.autoverb',
     default=False,
 )
 configitem('histedit', 'defaultrev',
     default=None,
 )
 configitem('histedit', 'dropmissing',
     default=False,
 )
 configitem('histedit', 'linelen',
     default=80,
 )
 configitem('histedit', 'singletransaction',
     default=False,
 )
+configitem('ui', 'interface.histedit',
+    default=None,
+)
 
 # 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'
 
 actiontable = {}
 primaryactions = set()
 secondaryactions = set()
 tertiaryactions = set()
 internalactions = set()
 
 def geteditcomment(ui, first, last):
     """ construct the editor comment
     The comment includes::
      - an intro
      - sorted primary commands
      - sorted short commands
      - sorted long commands
      - additional hints
 
     Commands are only included once.
     """
     intro = _("""Edit history between %s and %s
 
 Commits are listed from least to most recent
 
 You can reorder changesets by reordering the lines
 
 Commands:
 """)
     actions = []
     def addverb(v):
         a = actiontable[v]
         lines = a.message.split("\n")
         if len(a.verbs):
             v = ', '.join(sorted(a.verbs, key=lambda v: len(v)))
         actions.append(" %s = %s" % (v, lines[0]))
         actions.extend(['  %s' for l in lines[1:]])
 
     for v in (
          sorted(primaryactions) +
          sorted(secondaryactions) +
          sorted(tertiaryactions)
         ):
         addverb(v)
     actions.append('')
 
     hints = []
     if ui.configbool('histedit', 'dropmissing'):
         hints.append("Deleting a changeset from the list "
                      "will DISCARD it from the edited history!")
 
     lines = (intro % (first, last)).split('\n') + actions + hints
 
     return ''.join(['# %s\n' % l if l else '#\n' for l in lines])
 
 class histeditstate(object):
     def __init__(self, repo, parentctxnode=None, actions=None, keep=None,
             topmost=None, replacements=None, lock=None, wlock=None):
         self.repo = repo
         self.actions = actions
         self.keep = keep
         self.topmost = topmost
         self.parentctxnode = parentctxnode
         self.lock = lock
         self.wlock = wlock
         self.backupfile = None
         self.stateobj = statemod.cmdstate(repo, 'histedit-state')
         if replacements is None:
             self.replacements = []
         else:
             self.replacements = replacements
 
     def read(self):
         """Load histedit state from disk and set fields appropriately."""
         if not self.stateobj.exists():
             cmdutil.wrongtooltocontinue(self.repo, _('histedit'))
 
         data = self._read()
 
         self.parentctxnode = data['parentctxnode']
         actions = parserules(data['rules'], self)
         self.actions = actions
         self.keep = data['keep']
         self.topmost = data['topmost']
         self.replacements = data['replacements']
         self.backupfile = data['backupfile']
 
     def _read(self):
         fp = self.repo.vfs.read('histedit-state')
         if fp.startswith('v1\n'):
             data = self._load()
             parentctxnode, rules, keep, topmost, replacements, backupfile = data
         else:
             data = pickle.loads(fp)
             parentctxnode, rules, keep, topmost, replacements = data
             backupfile = None
         rules = "\n".join(["%s %s" % (verb, rest) for [verb, rest] in rules])
 
         return {'parentctxnode': parentctxnode, "rules": rules, "keep": keep,
                 "topmost": topmost, "replacements": replacements,
                 "backupfile": backupfile}
 
     def write(self, tr=None):
         if tr:
             tr.addfilegenerator('histedit-state', ('histedit-state',),
                                 self._write, location='plain')
         else:
             with self.repo.vfs("histedit-state", "w") as f:
                 self._write(f)
 
     def _write(self, fp):
         fp.write('v1\n')
         fp.write('%s\n' % node.hex(self.parentctxnode))
         fp.write('%s\n' % node.hex(self.topmost))
         fp.write('%s\n' % ('True' if self.keep else 'False'))
         fp.write('%d\n' % len(self.actions))
         for action in self.actions:
             fp.write('%s\n' % action.tostate())
         fp.write('%d\n' % len(self.replacements))
         for replacement in self.replacements:
             fp.write('%s%s\n' % (node.hex(replacement[0]), ''.join(node.hex(r)
                 for r in replacement[1])))
         backupfile = self.backupfile
         if not backupfile:
             backupfile = ''
         fp.write('%s\n' % backupfile)
 
     def _load(self):
         fp = self.repo.vfs('histedit-state', 'r')
         lines = [l[:-1] for l in fp.readlines()]
 
         index = 0
         lines[index] # version number
         index += 1
 
         parentctxnode = node.bin(lines[index])
         index += 1
 
         topmost = node.bin(lines[index])
         index += 1
 
         keep = lines[index] == 'True'
         index += 1
 
         # Rules
         rules = []
         rulelen = int(lines[index])
         index += 1
         for i in pycompat.xrange(rulelen):
             ruleaction = lines[index]
             index += 1
             rule = lines[index]
             index += 1
             rules.append((ruleaction, rule))
 
         # Replacements
         replacements = []
         replacementlen = int(lines[index])
         index += 1
         for i in pycompat.xrange(replacementlen):
             replacement = lines[index]
             original = node.bin(replacement[:40])
             succ = [node.bin(replacement[i:i + 40]) for i in
                     range(40, len(replacement), 40)]
             replacements.append((original, succ))
             index += 1
 
         backupfile = lines[index]
         index += 1
 
         fp.close()
 
         return parentctxnode, rules, keep, topmost, replacements, backupfile
 
     def clear(self):
         if self.inprogress():
             self.repo.vfs.unlink('histedit-state')
 
     def inprogress(self):
         return self.repo.vfs.exists('histedit-state')
 
 
 class histeditaction(object):
     def __init__(self, state, node):
         self.state = state
         self.repo = state.repo
         self.node = node
 
     @classmethod
     def fromrule(cls, state, rule):
         """Parses the given rule, returning an instance of the histeditaction.
         """
         ruleid = rule.strip().split(' ', 1)[0]
         # ruleid can be anything from rev numbers, hashes, "bookmarks" etc
         # Check for validation of rule ids and get the rulehash
         try:
             rev = node.bin(ruleid)
         except TypeError:
             try:
                 _ctx = scmutil.revsingle(state.repo, ruleid)
                 rulehash = _ctx.hex()
                 rev = node.bin(rulehash)
             except error.RepoLookupError:
                 raise error.ParseError(_("invalid changeset %s") % ruleid)
         return cls(state, rev)
 
     def verify(self, prev, expected, seen):
         """ Verifies semantic correctness of the rule"""
         repo = self.repo
         ha = node.hex(self.node)
         self.node = scmutil.resolvehexnodeidprefix(repo, ha)
         if self.node is None:
             raise error.ParseError(_('unknown changeset %s listed') % ha[:12])
         self._verifynodeconstraints(prev, expected, seen)
 
     def _verifynodeconstraints(self, prev, expected, seen):
         # by default command need a node in the edited list
         if self.node not in expected:
             raise error.ParseError(_('%s "%s" changeset was not a candidate')
                                    % (self.verb, node.short(self.node)),
                                    hint=_('only use listed changesets'))
         # and only one command per node
         if self.node in seen:
             raise error.ParseError(_('duplicated command for changeset %s') %
                                    node.short(self.node))
 
     def torule(self):
         """build a histedit rule line for an action
 
         by default lines are in the form:
         <hash> <rev> <summary>
         """
         ctx = self.repo[self.node]
         summary = _getsummary(ctx)
         line = '%s %s %d %s' % (self.verb, ctx, ctx.rev(), summary)
         # trim to 75 columns by default so it's not stupidly wide in my editor
         # (the 5 more are left for verb)
         maxlen = self.repo.ui.configint('histedit', 'linelen')
         maxlen = max(maxlen, 22) # avoid truncating hash
         return stringutil.ellipsis(line, maxlen)
 
     def tostate(self):
         """Print an action in format used by histedit state files
            (the first line is a verb, the remainder is the second)
         """
         return "%s\n%s" % (self.verb, node.hex(self.node))
 
     def run(self):
         """Runs the action. The default behavior is simply apply the action's
         rulectx onto the current parentctx."""
         self.applychange()
         self.continuedirty()
         return self.continueclean()
 
     def applychange(self):
         """Applies the changes from this action's rulectx onto the current
         parentctx, but does not commit them."""
         repo = self.repo
         rulectx = repo[self.node]
         repo.ui.pushbuffer(error=True, labeled=True)
         hg.update(repo, self.state.parentctxnode, quietempty=True)
         stats = applychanges(repo.ui, repo, rulectx, {})
         repo.dirstate.setbranch(rulectx.branch())
         if stats.unresolvedcount:
             buf = repo.ui.popbuffer()
             repo.ui.write(buf)
             raise error.InterventionRequired(
                 _('Fix up the change (%s %s)') %
                 (self.verb, node.short(self.node)),
                 hint=_('hg histedit --continue to resume'))
         else:
             repo.ui.popbuffer()
 
     def continuedirty(self):
         """Continues the action when changes have been applied to the working
         copy. The default behavior is to commit the dirty changes."""
         repo = self.repo
         rulectx = repo[self.node]
 
         editor = self.commiteditor()
         commit = commitfuncfor(repo, rulectx)
 
         commit(text=rulectx.description(), user=rulectx.user(),
                date=rulectx.date(), extra=rulectx.extra(), editor=editor)
 
     def commiteditor(self):
         """The editor to be used to edit the commit message."""
         return False
 
     def continueclean(self):
         """Continues the action when the working copy is clean. The default
         behavior is to accept the current commit as the new version of the
         rulectx."""
         ctx = self.repo['.']
         if ctx.node() == self.state.parentctxnode:
             self.repo.ui.warn(_('%s: skipping changeset (no changes)\n') %
                               node.short(self.node))
             return ctx, [(self.node, tuple())]
         if ctx.node() == self.node:
             # Nothing changed
             return ctx, []
         return ctx, [(self.node, (ctx.node(),))]
 
 def commitfuncfor(repo, src):
     """Build a commit function for the replacement of <src>
 
     This function ensure we apply the same treatment to all changesets.
 
     - Add a 'histedit_source' entry in extra.
 
     Note that fold has its own separated logic because its handling is a bit
     different and not easily factored out of the fold method.
     """
     phasemin = src.phase()
     def commitfunc(**kwargs):
         overrides = {('phases', 'new-commit'): phasemin}
         with repo.ui.configoverride(overrides, 'histedit'):
             extra = kwargs.get(r'extra', {}).copy()
             extra['histedit_source'] = src.hex()
             kwargs[r'extra'] = extra
             return repo.commit(**kwargs)
     return commitfunc
 
 def applychanges(ui, repo, ctx, opts):
     """Merge changeset from ctx (only) in the current working directory"""
     wcpar = repo.dirstate.parents()[0]
     if ctx.p1().node() == wcpar:
         # edits are "in place" we do not need to make any merge,
         # just applies changes on parent for editing
         cmdutil.revert(ui, repo, ctx, (wcpar, node.nullid), all=True)
         stats = mergemod.updateresult(0, 0, 0, 0)
     else:
         try:
             # ui.forcemerge is an internal variable, do not document
             repo.ui.setconfig('ui', 'forcemerge', opts.get('tool', ''),
                               'histedit')
             stats = mergemod.graft(repo, ctx, ctx.p1(), ['local', 'histedit'])
         finally:
             repo.ui.setconfig('ui', 'forcemerge', '', 'histedit')
     return stats
 
 def collapse(repo, firstctx, lastctx, commitopts, skipprompt=False):
     """collapse the set of revisions from first to last as new one.
 
     Expected commit options are:
         - message
         - date
         - username
     Commit message is edited in all cases.
 
     This function works in memory."""
     ctxs = list(repo.set('%d::%d', firstctx.rev(), lastctx.rev()))
     if not ctxs:
         return None
     for c in ctxs:
         if not c.mutable():
             raise error.ParseError(
                 _("cannot fold into public change %s") % node.short(c.node()))
     base = firstctx.parents()[0]
 
     # commit a new version of the old changeset, including the update
     # collect all files which might be affected
     files = set()
     for ctx in ctxs:
         files.update(ctx.files())
 
     # Recompute copies (avoid recording a -> b -> a)
     copied = copies.pathcopies(base, lastctx)
 
     # prune files which were reverted by the updates
     files = [f for f in files if not cmdutil.samefile(f, lastctx, base)]
     # commit version of these files as defined by head
     headmf = lastctx.manifest()
     def filectxfn(repo, ctx, path):
         if path in headmf:
             fctx = lastctx[path]
             flags = fctx.flags()
             mctx = context.memfilectx(repo, ctx,
                                       fctx.path(), fctx.data(),
                                       islink='l' in flags,
                                       isexec='x' in flags,
                                       copied=copied.get(path))
             return mctx
         return None
 
     if commitopts.get('message'):
         message = commitopts['message']
     else:
         message = firstctx.description()
     user = commitopts.get('user')
     date = commitopts.get('date')
     extra = commitopts.get('extra')
 
     parents = (firstctx.p1().node(), firstctx.p2().node())
     editor = None
     if not skipprompt:
         editor = cmdutil.getcommiteditor(edit=True, editform='histedit.fold')
     new = context.memctx(repo,
                          parents=parents,
                          text=message,
                          files=files,
                          filectxfn=filectxfn,
                          user=user,
                          date=date,
                          extra=extra,
                          editor=editor)
     return repo.commitctx(new)
 
 def _isdirtywc(repo):
     return repo[None].dirty(missing=True)
 
 def abortdirty():
     raise error.Abort(_('working copy has pending changes'),
         hint=_('amend, commit, or revert them and run histedit '
             '--continue, or abort with histedit --abort'))
 
 def action(verbs, message, priority=False, internal=False):
     def wrap(cls):
         assert not priority or not internal
         verb = verbs[0]
         if priority:
             primaryactions.add(verb)
         elif internal:
             internalactions.add(verb)
         elif len(verbs) > 1:
             secondaryactions.add(verb)
         else:
             tertiaryactions.add(verb)
 
         cls.verb = verb
         cls.verbs = verbs
         cls.message = message
         for verb in verbs:
             actiontable[verb] = cls
         return cls
     return wrap
 
 @action(['pick', 'p'],
         _('use commit'),
         priority=True)
 class pick(histeditaction):
     def run(self):
         rulectx = self.repo[self.node]
         if rulectx.parents()[0].node() == self.state.parentctxnode:
             self.repo.ui.debug('node %s unchanged\n' % node.short(self.node))
             return rulectx, []
 
         return super(pick, self).run()
 
 @action(['edit', 'e'],
         _('use commit, but stop for amending'),
         priority=True)
 class edit(histeditaction):
     def run(self):
         repo = self.repo
         rulectx = repo[self.node]
         hg.update(repo, self.state.parentctxnode, quietempty=True)
         applychanges(repo.ui, repo, rulectx, {})
         raise error.InterventionRequired(
             _('Editing (%s), you may commit or record as needed now.')
             % node.short(self.node),
             hint=_('hg histedit --continue to resume'))
 
     def commiteditor(self):
         return cmdutil.getcommiteditor(edit=True, editform='histedit.edit')
 
 @action(['fold', 'f'],
         _('use commit, but combine it with the one above'))
 class fold(histeditaction):
     def verify(self, prev, expected, seen):
         """ Verifies semantic correctness of the fold rule"""
         super(fold, self).verify(prev, expected, seen)
         repo = self.repo
         if not prev:
             c = repo[self.node].parents()[0]
         elif not prev.verb in ('pick', 'base'):
             return
         else:
             c = repo[prev.node]
         if not c.mutable():
             raise error.ParseError(
                 _("cannot fold into public change %s") % node.short(c.node()))
 
 
     def continuedirty(self):
         repo = self.repo
         rulectx = repo[self.node]
 
         commit = commitfuncfor(repo, rulectx)
         commit(text='fold-temp-revision %s' % node.short(self.node),
                user=rulectx.user(), date=rulectx.date(),
                extra=rulectx.extra())
 
     def continueclean(self):
         repo = self.repo
         ctx = repo['.']
         rulectx = repo[self.node]
         parentctxnode = self.state.parentctxnode
         if ctx.node() == parentctxnode:
             repo.ui.warn(_('%s: empty changeset\n') %
                               node.short(self.node))
             return ctx, [(self.node, (parentctxnode,))]
 
         parentctx = repo[parentctxnode]
         newcommits = set(c.node() for c in repo.set('(%d::. - %d)',
                                                     parentctx.rev(),
                                                     parentctx.rev()))
         if not newcommits:
             repo.ui.warn(_('%s: cannot fold - working copy is not a '
                            'descendant of previous commit %s\n') %
                            (node.short(self.node), node.short(parentctxnode)))
             return ctx, [(self.node, (ctx.node(),))]
 
         middlecommits = newcommits.copy()
         middlecommits.discard(ctx.node())
 
         return self.finishfold(repo.ui, repo, parentctx, rulectx, ctx.node(),
                                middlecommits)
 
     def skipprompt(self):
         """Returns true if the rule should skip the message editor.
 
         For example, 'fold' wants to show an editor, but 'rollup'
         doesn't want to.
         """
         return False
 
     def mergedescs(self):
         """Returns true if the rule should merge messages of multiple changes.
 
         This exists mainly so that 'rollup' rules can be a subclass of
         'fold'.
         """
         return True
 
     def firstdate(self):
         """Returns true if the rule should preserve the date of the first
         change.
 
         This exists mainly so that 'rollup' rules can be a subclass of
         'fold'.
         """
         return False
 
     def finishfold(self, ui, repo, ctx, oldctx, newnode, internalchanges):
         parent = ctx.parents()[0].node()
         hg.updaterepo(repo, parent, overwrite=False)
         ### prepare new commit data
         commitopts = {}
         commitopts['user'] = ctx.user()
         # commit message
         if not self.mergedescs():
             newmessage = ctx.description()
         else:
             newmessage = '\n***\n'.join(
                 [ctx.description()] +
                 [repo[r].description() for r in internalchanges] +
                 [oldctx.description()]) + '\n'
         commitopts['message'] = newmessage
         # date
         if self.firstdate():
             commitopts['date'] = ctx.date()
         else:
             commitopts['date'] = max(ctx.date(), oldctx.date())
         extra = ctx.extra().copy()
         # histedit_source
         # note: ctx is likely a temporary commit but that the best we can do
         #       here. This is sufficient to solve issue3681 anyway.
         extra['histedit_source'] = '%s,%s' % (ctx.hex(), oldctx.hex())
         commitopts['extra'] = extra
         phasemin = max(ctx.phase(), oldctx.phase())
         overrides = {('phases', 'new-commit'): phasemin}
         with repo.ui.configoverride(overrides, 'histedit'):
             n = collapse(repo, ctx, repo[newnode], commitopts,
                          skipprompt=self.skipprompt())
         if n is None:
             return ctx, []
         hg.updaterepo(repo, n, overwrite=False)
         replacements = [(oldctx.node(), (newnode,)),
                         (ctx.node(), (n,)),
                         (newnode, (n,)),
                        ]
         for ich in internalchanges:
             replacements.append((ich, (n,)))
         return repo[n], replacements
 
 @action(['base', 'b'],
         _('checkout changeset and apply further changesets from there'))
 class base(histeditaction):
 
     def run(self):
         if self.repo['.'].node() != self.node:
             mergemod.update(self.repo, self.node, branchmerge=False, force=True)
         return self.continueclean()
 
     def continuedirty(self):
         abortdirty()
 
     def continueclean(self):
         basectx = self.repo['.']
         return basectx, []
 
     def _verifynodeconstraints(self, prev, expected, seen):
         # base can only be use with a node not in the edited set
         if self.node in expected:
             msg = _('%s "%s" changeset was an edited list candidate')
             raise error.ParseError(
                 msg % (self.verb, node.short(self.node)),
                 hint=_('base must only use unlisted changesets'))
 
 @action(['_multifold'],
         _(
     """fold subclass used for when multiple folds happen in a row
 
     We only want to fire the editor for the folded message once when
     (say) four changes are folded down into a single change. This is
     similar to rollup, but we should preserve both messages so that
     when the last fold operation runs we can show the user all the
     commit messages in their editor.
     """),
         internal=True)
 class _multifold(fold):
     def skipprompt(self):
         return True
 
 @action(["roll", "r"],
         _("like fold, but discard this commit's description and date"))
 class rollup(fold):
     def mergedescs(self):
         return False
 
     def skipprompt(self):
         return True
 
     def firstdate(self):
         return True
 
 @action(["drop", "d"],
         _('remove commit from history'))
 class drop(histeditaction):
     def run(self):
         parentctx = self.repo[self.state.parentctxnode]
         return parentctx, [(self.node, tuple())]
 
 @action(["mess", "m"],
         _('edit commit message without changing commit content'),
         priority=True)
 class message(histeditaction):
     def commiteditor(self):
         return cmdutil.getcommiteditor(edit=True, editform='histedit.mess')
 
 def findoutgoing(ui, repo, remote=None, force=False, opts=None):
     """utility function to find the first outgoing changeset
 
     Used by initialization code"""
     if opts is None:
         opts = {}
     dest = ui.expandpath(remote or 'default-push', remote or 'default')
     dest, branches = hg.parseurl(dest, None)[:2]
     ui.status(_('comparing with %s\n') % util.hidepassword(dest))
 
     revs, checkout = hg.addbranchrevs(repo, repo, branches, None)
     other = hg.peer(repo, opts, dest)
 
     if revs:
         revs = [repo.lookup(rev) for rev in revs]
 
     outgoing = discovery.findcommonoutgoing(repo, other, revs, force=force)
     if not outgoing.missing:
         raise error.Abort(_('no outgoing ancestors'))
     roots = list(repo.revs("roots(%ln)", outgoing.missing))
     if len(roots) > 1:
         msg = _('there are ambiguous outgoing revisions')
         hint = _("see 'hg help histedit' for more detail")
         raise error.Abort(msg, hint=hint)
     return repo[roots[0]].node()
 
+# Curses Support
+try:
+    import curses
+except ImportError:
+    curses = None
+
+KEY_LIST = ['pick', 'edit', 'fold', 'drop', 'mess', 'roll']
+ACTION_LABELS = {
+    'fold': '^fold',
+    'roll': '^roll',
+}
+
+COLOR_HELP, COLOR_SELECTED, COLOR_OK, COLOR_WARN  = 1, 2, 3, 4
+
+E_QUIT, E_HISTEDIT = 1, 2
+E_PAGEDOWN, E_PAGEUP, E_LINEUP, E_LINEDOWN, E_RESIZE = 3, 4, 5, 6, 7
+MODE_INIT, MODE_PATCH, MODE_RULES, MODE_HELP = 0, 1, 2, 3
+
+KEYTABLE = {
+    'global': {
+        'h':         'next-action',
+        'KEY_RIGHT': 'next-action',
+        'l':         'prev-action',
+        'KEY_LEFT':  'prev-action',
+        'q':         'quit',
+        'c':         'histedit',
+        'C':         'histedit',
+        'v':         'showpatch',
+        '?':         'help',
+    },
+    MODE_RULES: {
+        'd':         'action-drop',
+        'e':         'action-edit',
+        'f':         'action-fold',
+        'm':         'action-mess',
+        'p':         'action-pick',
+        'r':         'action-roll',
+        ' ':         'select',
+        'j':         'down',
+        'k':         'up',
+        'KEY_DOWN':  'down',
+        'KEY_UP':    'up',
+        'J':         'move-down',
+        'K':         'move-up',
+        'KEY_NPAGE': 'move-down',
+        'KEY_PPAGE': 'move-up',
+        '0':         'goto',  # Used for 0..9
+    },
+    MODE_PATCH: {
+        ' ':         'page-down',
+        'KEY_NPAGE': 'page-down',
+        'KEY_PPAGE': 'page-up',
+        'j':         'line-down',
+        'k':         'line-up',
+        'KEY_DOWN':  'line-down',
+        'KEY_UP':    'line-up',
+        'J':         'down',
+        'K':         'up',
+    },
+    MODE_HELP: {
+    },
+}
+
+def screen_size():
+    return struct.unpack('hh', fcntl.ioctl(1, termios.TIOCGWINSZ, '    '))
+
+class histeditrule(object):
+    def __init__(self, ctx, pos, action='pick'):
+        self.ctx = ctx
+        self.action = action
+        self.origpos = pos
+        self.pos = pos
+        self.conflicts = []
+
+    def __str__(self):
+        # Some actions ('fold' and 'roll') combine a patch with a previous one.
+        # Add a marker showing which patch they apply to, and also omit the
+        # description for 'roll' (since it will get discarded). Example display:
+        #
+        #  #10 pick   316392:06a16c25c053   add option to skip tests
+        #  #11 ^roll  316393:71313c964cc5
+        #  #12 pick   316394:ab31f3973b0d   include mfbt for mozilla-config.h
+        #  #13 ^fold  316395:14ce5803f4c3   fix warnings
+        #
+        # The carets point to the changeset being folded into ("roll this
+        # changeset into the changeset above").
+        action = ACTION_LABELS.get(self.action, self.action)
+        h = self.ctx.hex()[0:12]
+        r = self.ctx.rev()
+        desc = self.ctx.description().splitlines()[0].strip()
+        if self.action == 'roll':
+            desc = ''
+        return "#{0:<2} {1:<6} {2}:{3}   {4}".format(
+                self.origpos, action, r, h, desc)
+
+    def checkconflicts(self, other):
+        if other.pos > self.pos and other.origpos <= self.origpos:
+            if set(other.ctx.files()) & set(self.ctx.files()) != set():
+                self.conflicts.append(other)
+                return self.conflicts
+
+        if other in self.conflicts:
+            self.conflicts.remove(other)
+        return self.conflicts
+
+# ============ EVENTS ===============
+def movecursor(state, oldpos, newpos):
+    '''Change the rule/changeset that the cursor is pointing to, regardless of
+    current mode (you can switch between patches from the view patch window).'''
+    state['pos'] = newpos
+
+    mode, _ = state['mode']
+    if mode == MODE_RULES:
+        # Scroll through the list by updating the view for MODE_RULES, so that
+        # even if we are not currently viewing the rules, switching back will
+        # result in the cursor's rule being visible.
+        modestate = state['modes'][MODE_RULES]
+        if newpos < modestate['line_offset']:
+            modestate['line_offset'] = newpos
+        elif newpos > modestate['line_offset'] + state['page_height'] - 1:
+            modestate['line_offset'] = newpos - state['page_height'] + 1
+
+    # Reset the patch view region to the top of the new patch.
+    state['modes'][MODE_PATCH]['line_offset'] = 0
+
+def changemode(state, mode):
+    curmode, _ = state['mode']
+    state['mode'] = (mode, curmode)
+
+def makeselection(state, pos):
+    state['selected'] = pos
+
+def swap(state, oldpos, newpos):
+    """Swap two positions and calculate necessary conflicts in
+    O(|newpos-oldpos|) time"""
+
+    rules = state['rules']
+    assert 0 <= oldpos < len(rules) and 0 <= newpos < len(rules)
+
+    rules[oldpos], rules[newpos] = rules[newpos], rules[oldpos]
+
+    # TODO: swap should not know about histeditrule's internals
+    rules[newpos].pos = newpos
+    rules[oldpos].pos = oldpos
+
+    start = min(oldpos, newpos)
+    end = max(oldpos, newpos)
+    for r in pycompat.xrange(start, end + 1):
+        rules[newpos].checkconflicts(rules[r])
+        rules[oldpos].checkconflicts(rules[r])
+
+    if state['selected']:
+        makeselection(state, newpos)
+
+def changeaction(state, pos, action):
+    """Change the action state on the given position to the new action"""
+    rules = state['rules']
+    assert 0 <= pos < len(rules)
+    rules[pos].action = action
+
+def cycleaction(state, pos, next=False):
+    """Changes the action state the next or the previous action from
+    the action list"""
+    rules = state['rules']
+    assert 0 <= pos < len(rules)
+    current = rules[pos].action
+
+    assert current in KEY_LIST
+
+    index = KEY_LIST.index(current)
+    if next:
+        index += 1
+    else:
+        index -= 1
+    changeaction(state, pos, KEY_LIST[index % len(KEY_LIST)])
+
+def changeview(state, delta, unit):
+    '''Change the region of whatever is being viewed (a patch or the list of
+    changesets). 'delta' is an amount (+/- 1) and 'unit' is 'page' or 'line'.'''
+    mode, _ = state['mode']
+    if mode != MODE_PATCH:
+        return
+    mode_state = state['modes'][mode]
+    num_lines = len(patchcontents(state))
+    page_height = state['page_height']
+    unit = page_height if unit == 'page' else 1
+    num_pages = 1 + (num_lines - 1) / page_height
+    max_offset = (num_pages - 1) * page_height
+    newline = mode_state['line_offset'] + delta * unit
+    mode_state['line_offset'] = max(0, min(max_offset, newline))
+
+def event(state, ch):
+    """Change state based on the current character input
+
+    This takes the current state and based on the current character input from
+    the user we change the state.
+    """
+    selected = state['selected']
+    oldpos = state['pos']
+    rules = state['rules']
+
+    if ch in (curses.KEY_RESIZE, "KEY_RESIZE"):
+        return E_RESIZE
+
+    lookup_ch = ch
+    if '0' <= ch <= '9':
+        lookup_ch = '0'
+
+    curmode, prevmode = state['mode']
+    action = KEYTABLE[curmode].get(lookup_ch, KEYTABLE['global'].get(lookup_ch))
+    if action is None:
+        return
+    if action in ('down', 'move-down'):
+        newpos = min(oldpos + 1, len(rules) - 1)
+        movecursor(state, oldpos, newpos)
+        if selected is not None or action == 'move-down':
+            swap(state, oldpos, newpos)
+    elif action in ('up', 'move-up'):
+        newpos = max(0, oldpos - 1)
+        movecursor(state, oldpos, newpos)
+        if selected is not None or action == 'move-up':
+            swap(state, oldpos, newpos)
+    elif action == 'next-action':
+        cycleaction(state, oldpos, next=True)
+    elif action == 'prev-action':
+        cycleaction(state, oldpos, next=False)
+    elif action == 'select':
+        selected = oldpos if selected is None else None
+        makeselection(state, selected)
+    elif action == 'goto' and int(ch) < len(rules) and len(rules) <= 10:
+        newrule = next((r for r in rules if r.origpos == int(ch)))
+        movecursor(state, oldpos, newrule.pos)
+        if selected is not None:
+            swap(state, oldpos, newrule.pos)
+    elif action.startswith('action-'):
+        changeaction(state, oldpos, action[7:])
+    elif action == 'showpatch':
+        changemode(state, MODE_PATCH if curmode != MODE_PATCH else prevmode)
+    elif action == 'help':
+        changemode(state, MODE_HELP if curmode != MODE_HELP else prevmode)
+    elif action == 'quit':
+        return E_QUIT
+    elif action == 'histedit':
+        return E_HISTEDIT
+    elif action == 'page-down':
+        return E_PAGEDOWN
+    elif action == 'page-up':
+        return E_PAGEUP
+    elif action == 'line-down':
+        return E_LINEDOWN
+    elif action == 'line-up':
+        return E_LINEUP
+
+def makecommands(rules):
+    """Returns a list of commands consumable by histedit --commands based on
+    our list of rules"""
+    commands = []
+    for rules in rules:
+        commands.append("{0} {1}\n".format(rules.action, rules.ctx))
+    return commands
+
+def addln(win, y, x, line, color=None):
+    """Add a line to the given window left padding but 100% filled with
+    whitespace characters, so that the color appears on the whole line"""
+    maxy, maxx = win.getmaxyx()
+    length = maxx - 1 - x
+    line = ("{0:<%d}" % length).format(str(line).strip())[:length]
+    if y < 0:
+        y = maxy + y
+    if x < 0:
+        x = maxx + x
+    if color:
+        win.addstr(y, x, line, color)
+    else:
+        win.addstr(y, x, line)
+
+def patchcontents(state):
+    repo = state['repo']
+    rule = state['rules'][state['pos']]
+    displayer = logcmdutil.changesetdisplayer(repo.ui, repo, {
+        'patch': True, 'verbose': True
+    }, buffered=True)
+    displayer.show(rule.ctx)
+    displayer.close()
+    return displayer.hunk[rule.ctx.rev()].splitlines()
+
+def _chisteditmain(repo, rules, stdscr):
+    # initialize color pattern
+    curses.init_pair(COLOR_HELP, curses.COLOR_WHITE, curses.COLOR_BLUE)
+    curses.init_pair(COLOR_SELECTED, curses.COLOR_BLACK, curses.COLOR_WHITE)
+    curses.init_pair(COLOR_WARN, curses.COLOR_BLACK, curses.COLOR_YELLOW)
+    curses.init_pair(COLOR_OK, curses.COLOR_BLACK, curses.COLOR_GREEN)
+
+    # don't display the cursor
+    try:
+        curses.curs_set(0)
+    except curses.error:
+        pass
+
+    def rendercommit(win, state):
+        """Renders the commit window that shows the log of the current selected
+        commit"""
+        pos = state['pos']
+        rules = state['rules']
+        rule = rules[pos]
+
+        ctx = rule.ctx
+        win.box()
+
+        maxy, maxx = win.getmaxyx()
+        length = maxx - 3
+
+        line = "changeset: {0}:{1:<12}".format(ctx.rev(), ctx)
+        win.addstr(1, 1, line[:length])
+
+        line = "user:      {0}".format(stringutil.shortuser(ctx.user()))
+        win.addstr(2, 1, line[:length])
+
+        bms = repo.nodebookmarks(ctx.node())
+        line = "bookmark:  {0}".format(' '.join(bms))
+        win.addstr(3, 1, line[:length])
+
+        line = "files:     {0}".format(','.join(ctx.files()))
+        win.addstr(4, 1, line[:length])
+
+        line = "summary:   {0}".format(ctx.description().splitlines()[0])
+        win.addstr(5, 1, line[:length])
+
+        conflicts = rule.conflicts
+        if len(conflicts) > 0:
+            conflictstr = ','.join(map(lambda r: str(r.ctx), conflicts))
+            conflictstr = "changed files overlap with {0}".format(conflictstr)
+        else:
+            conflictstr = 'no overlap'
+
+        win.addstr(6, 1, conflictstr[:length])
+        win.noutrefresh()
+
+    def helplines(mode):
+        if mode == MODE_PATCH:
+            help = """\
+?: help, k/up: line up, j/down: line down, v: stop viewing patch
+pgup: prev page, space/pgdn: next page, c: commit, q: abort
+"""
+        else:
+            help = """\
+?: help, k/up: move up, j/down: move down, space: select, v: view patch
+d: drop, e: edit, f: fold, m: mess, p: pick, r: roll
+pgup/K: move patch up, pgdn/J: move patch down, c: commit, q: abort
+"""
+        return help.splitlines()
+
+    def renderhelp(win, state):
+        maxy, maxx = win.getmaxyx()
+        mode, _ = state['mode']
+        for y, line in enumerate(helplines(mode)):
+            if y >= maxy:
+                break
+            addln(win, y, 0, line, curses.color_pair(COLOR_HELP))
+        win.noutrefresh()
+
+    def renderrules(rulesscr, state):
+        rules = state['rules']
+        pos = state['pos']
+        selected = state['selected']
+        start = state['modes'][MODE_RULES]['line_offset']
+
+        conflicts = [r.ctx for r in rules if r.conflicts]
+        if len(conflicts) > 0:
+            line = "potential conflict in %s" % ','.join(map(str, conflicts))
+            addln(rulesscr, -1, 0, line, curses.color_pair(COLOR_WARN))
+
+        for y, rule in enumerate(rules[start:]):
+            if y >= state['page_height']:
+                break
+            if len(rule.conflicts) > 0:
+                rulesscr.addstr(y, 0, " ", curses.color_pair(COLOR_WARN))
+            else:
+                rulesscr.addstr(y, 0, " ", curses.COLOR_BLACK)
+            if y + start == selected:
+                addln(rulesscr, y, 2, rule, curses.color_pair(COLOR_SELECTED))
+            elif y + start == pos:
+                addln(rulesscr, y, 2, rule, curses.A_BOLD)
+            else:
+                addln(rulesscr, y, 2, rule)
+        rulesscr.noutrefresh()
+
+    def renderstring(win, state, output):
+        maxy, maxx = win.getmaxyx()
+        length = min(maxy - 1, len(output))
+        for y in range(0, length):
+            win.addstr(y, 0, output[y])
+        win.noutrefresh()
+
+    def renderpatch(win, state):
+        start = state['modes'][MODE_PATCH]['line_offset']
+        renderstring(win, state, patchcontents(state)[start:])
+
+    def layout(mode):
+        maxy, maxx = stdscr.getmaxyx()
+        helplen = len(helplines(mode))
+        return {
+            'commit': (8, maxx),
+            'help': (helplen, maxx),
+            'main': (maxy - helplen - 8, maxx),
+        }
+
+    def drawvertwin(size, y, x):
+        win = curses.newwin(size[0], size[1], y, x)
+        y += size[0]
+        return win, y, x
+
+    state = {
+        'pos': 0,
+        'rules': rules,
+        'selected': None,
+        'mode': (MODE_INIT, MODE_INIT),
+        'page_height': None,
+        'modes': {
+            MODE_RULES: {
+                'line_offset': 0,
+            },
+            MODE_PATCH: {
+                'line_offset': 0,
+            }
+        },
+        'repo': repo,
+    }
+
+    # eventloop
+    ch = None
+    stdscr.clear()
+    stdscr.refresh()
+    while True:
+        try:
+            oldmode, _ = state['mode']
+            if oldmode == MODE_INIT:
+                changemode(state, MODE_RULES)
+            e = event(state, ch)
+
+            if e == E_QUIT:
+                return False
+            if e == E_HISTEDIT:
+                return state['rules']
+            else:
+                if e == E_RESIZE:
+                    size = screen_size()
+                    if size != stdscr.getmaxyx():
+                        curses.resizeterm(*size)
+
+                curmode, _ = state['mode']
+                sizes = layout(curmode)
+                if curmode != oldmode:
+                    state['page_height'] = sizes['main'][0]
+                    # Adjust the view to fit the current screen size.
+                    movecursor(state, state['pos'], state['pos'])
+
+                # Pack the windows against the top, each pane spread across the
+                # full width of the screen.
+                y, x = (0, 0)
+                helpwin, y, x = drawvertwin(sizes['help'], y, x)
+                mainwin, y, x = drawvertwin(sizes['main'], y, x)
+                commitwin, y, x = drawvertwin(sizes['commit'], y, x)
+
+                if e in (E_PAGEDOWN, E_PAGEUP, E_LINEDOWN, E_LINEUP):
+                    if e == E_PAGEDOWN:
+                        changeview(state, +1, 'page')
+                    elif e == E_PAGEUP:
+                        changeview(state, -1, 'page')
+                    elif e == E_LINEDOWN:
+                        changeview(state, +1, 'line')
+                    elif e == E_LINEUP:
+                        changeview(state, -1, 'line')
+
+                # start rendering
+                commitwin.erase()
+                helpwin.erase()
+                mainwin.erase()
+                if curmode == MODE_PATCH:
+                    renderpatch(mainwin, state)
+                elif curmode == MODE_HELP:
+                    renderstring(mainwin, state, __doc__.strip().splitlines())
+                else:
+                    renderrules(mainwin, state)
+                    rendercommit(commitwin, state)
+                renderhelp(helpwin, state)
+                curses.doupdate()
+                # done rendering
+                ch = stdscr.getkey()
+        except curses.error:
+            pass
+
+def _chistedit(ui, repo, *freeargs, **opts):
+    """interactively edit changeset history via a curses interface
+
+    Provides a ncurses interface to histedit. Press ? in chistedit mode
+    to see an extensive help. Requires python-curses to be installed."""
+
+    if curses is None:
+        raise error.Abort(_("Python curses library required"))
+
+    # disable color
+    ui._colormode = None
+
+    try:
+        keep = opts.get('keep')
+        revs = opts.get('rev', [])[:]
+        cmdutil.checkunfinished(repo)
+        cmdutil.bailifchanged(repo)
+
+        if os.path.exists(os.path.join(repo.path, 'histedit-state')):
+            raise error.Abort(_('history edit already in progress, try '
+                               '--continue or --abort'))
+        revs.extend(freeargs)
+        if not revs:
+            defaultrev = destutil.desthistedit(ui, repo)
+            if defaultrev is not None:
+                revs.append(defaultrev)
+        if len(revs) != 1:
+            raise error.Abort(
+                _('histedit requires exactly one ancestor revision'))
+
+        rr = list(repo.set('roots(%ld)', scmutil.revrange(repo, revs)))
+        if len(rr) != 1:
+            raise error.Abort(_('The specified revisions must have '
+                'exactly one common root'))
+        root = rr[0].node()
+
+        topmost, empty = repo.dirstate.parents()
+        revs = between(repo, root, topmost, keep)
+        if not revs:
+            raise error.Abort(_('%s is not an ancestor of working directory') %
+                             node.short(root))
+
+        ctxs = []
+        for i, r in enumerate(revs):
+            ctxs.append(histeditrule(repo[r], i))
+        rc = curses.wrapper(functools.partial(_chisteditmain, repo, ctxs))
+        curses.echo()
+        curses.endwin()
+        if rc is False:
+            ui.write(_("chistedit aborted\n"))
+            return 0
+        if type(rc) is list:
+            ui.status(_("running histedit\n"))
+            rules = makecommands(rc)
+            filename = repo.vfs.join('chistedit')
+            with open(filename, 'w+') as fp:
+                for r in rules:
+                    fp.write(r)
+            opts['commands'] = filename
+            return _texthistedit(ui, repo, *freeargs, **opts)
+    except KeyboardInterrupt:
+        pass
+    return -1
+
 @command('histedit',
     [('', 'commands', '',
       _('read history edits from the specified file'), _('FILE')),
      ('c', 'continue', False, _('continue an edit already in progress')),
      ('', 'edit-plan', False, _('edit remaining actions list')),
      ('k', 'keep', False,
       _("don't strip old nodes after edit is complete")),
      ('', 'abort', False, _('abort an edit in progress')),
      ('o', 'outgoing', False, _('changesets not found in destination')),
      ('f', 'force', False,
       _('force outgoing even for unrelated repositories')),
      ('r', 'rev', [], _('first revision to be edited'), _('REV'))] +
     cmdutil.formatteropts,
      _("[OPTIONS] ([ANCESTOR] | --outgoing [URL])"),
     helpcategory=command.CATEGORY_CHANGE_MANAGEMENT)
 def histedit(ui, repo, *freeargs, **opts):
     """interactively edit changeset history
 
     This command lets you edit a linear series of changesets (up to
     and including the working directory, which should be clean).
     You can:
 
     - `pick` to [re]order a changeset
 
     - `drop` to omit changeset
 
     - `mess` to reword the changeset commit message
 
     - `fold` to combine it with the preceding changeset (using the later date)
 
     - `roll` like fold, but discarding this commit's description and date
 
     - `edit` to edit this changeset (preserving date)
 
     - `base` to checkout changeset and apply further changesets from there
 
     There are a number of ways to select the root changeset:
 
     - Specify ANCESTOR directly
 
     - Use --outgoing -- it will be the first linear changeset not
       included in destination. (See :hg:`help config.paths.default-push`)
 
     - Otherwise, the value from the "histedit.defaultrev" config option
       is used as a revset to select the base revision when ANCESTOR is not
       specified. The first revision returned by the revset is used. By
       default, this selects the editable history that is unique to the
       ancestry of the working directory.
 
     .. container:: verbose
 
        If you use --outgoing, this command will abort if there are ambiguous
        outgoing revisions. For example, if there are multiple branches
        containing outgoing revisions.
 
        Use "min(outgoing() and ::.)" or similar revset specification
        instead of --outgoing to specify edit target revision exactly in
        such ambiguous situation. See :hg:`help revsets` for detail about
        selecting revisions.
 
     .. container:: verbose
 
        Examples:
 
          - A number of changes have been made.
            Revision 3 is no longer needed.
 
            Start history editing from revision 3::
 
              hg histedit -r 3
 
            An editor opens, containing the list of revisions,
            with specific actions specified::
 
              pick 5339bf82f0ca 3 Zworgle the foobar
              pick 8ef592ce7cc4 4 Bedazzle the zerlog
              pick 0a9639fcda9d 5 Morgify the cromulancy
 
            Additional information about the possible actions
            to take appears below the list of revisions.
 
            To remove revision 3 from the history,
            its action (at the beginning of the relevant line)
            is changed to 'drop'::
 
              drop 5339bf82f0ca 3 Zworgle the foobar
              pick 8ef592ce7cc4 4 Bedazzle the zerlog
              pick 0a9639fcda9d 5 Morgify the cromulancy
 
          - A number of changes have been made.
            Revision 2 and 4 need to be swapped.
 
            Start history editing from revision 2::
 
              hg histedit -r 2
 
            An editor opens, containing the list of revisions,
            with specific actions specified::
 
              pick 252a1af424ad 2 Blorb a morgwazzle
              pick 5339bf82f0ca 3 Zworgle the foobar
              pick 8ef592ce7cc4 4 Bedazzle the zerlog
 
            To swap revision 2 and 4, its lines are swapped
            in the editor::
 
              pick 8ef592ce7cc4 4 Bedazzle the zerlog
              pick 5339bf82f0ca 3 Zworgle the foobar
              pick 252a1af424ad 2 Blorb a morgwazzle
 
     Returns 0 on success, 1 if user intervention is required (not only
     for intentional "edit" command, but also for resolving unexpected
     conflicts).
     """
+    if ui.interface('histedit') == 'curses':
+        return _chistedit(ui, repo, *freeargs, **opts)
+    return _texthistedit(ui, repo, *freeargs, **opts)
+
+def _texthistedit(ui, repo, *freeargs, **opts):
     state = histeditstate(repo)
     try:
         state.wlock = repo.wlock()
         state.lock = repo.lock()
         _histedit(ui, repo, state, *freeargs, **opts)
     finally:
         release(state.lock, state.wlock)
 
 goalcontinue = 'continue'
 goalabort = 'abort'
 goaleditplan = 'edit-plan'
 goalnew = 'new'
 
 def _getgoal(opts):
     if opts.get('continue'):
         return goalcontinue
     if opts.get('abort'):
         return goalabort
     if opts.get('edit_plan'):
         return goaleditplan
     return goalnew
 
 def _readfile(ui, path):
     if path == '-':
         with ui.timeblockedsection('histedit'):
             return ui.fin.read()
     else:
         with open(path, 'rb') as f:
             return f.read()
 
 def _validateargs(ui, repo, state, freeargs, opts, goal, rules, revs):
     # TODO only abort if we try to histedit mq patches, not just
     # blanket if mq patches are applied somewhere
     mq = getattr(repo, 'mq', None)
     if mq and mq.applied:
         raise error.Abort(_('source has mq patches applied'))
 
     # basic argument incompatibility processing
     outg = opts.get('outgoing')
     editplan = opts.get('edit_plan')
     abort = opts.get('abort')
     force = opts.get('force')
     if force and not outg:
         raise error.Abort(_('--force only allowed with --outgoing'))
     if goal == 'continue':
         if any((outg, abort, revs, freeargs, rules, editplan)):
             raise error.Abort(_('no arguments allowed with --continue'))
     elif goal == 'abort':
         if any((outg, revs, freeargs, rules, editplan)):
             raise error.Abort(_('no arguments allowed with --abort'))
     elif goal == 'edit-plan':
         if any((outg, revs, freeargs)):
             raise error.Abort(_('only --commands argument allowed with '
                                '--edit-plan'))
     else:
         if state.inprogress():
             raise error.Abort(_('history edit already in progress, try '
                                '--continue or --abort'))
         if outg:
             if revs:
                 raise error.Abort(_('no revisions allowed with --outgoing'))
             if len(freeargs) > 1:
                 raise error.Abort(
                     _('only one repo argument allowed with --outgoing'))
         else:
             revs.extend(freeargs)
             if len(revs) == 0:
                 defaultrev = destutil.desthistedit(ui, repo)
                 if defaultrev is not None:
                     revs.append(defaultrev)
 
             if len(revs) != 1:
                 raise error.Abort(
                     _('histedit requires exactly one ancestor revision'))
 
 def _histedit(ui, repo, state, *freeargs, **opts):
     opts = pycompat.byteskwargs(opts)
     fm = ui.formatter('histedit', opts)
     fm.startitem()
     goal = _getgoal(opts)
     revs = opts.get('rev', [])
     # experimental config: ui.history-editing-backup
     nobackup = not ui.configbool('ui', 'history-editing-backup')
     rules = opts.get('commands', '')
     state.keep = opts.get('keep', False)
 
     _validateargs(ui, repo, state, freeargs, opts, goal, rules, revs)
 
     # rebuild state
     if goal == goalcontinue:
         state.read()
         state = bootstrapcontinue(ui, state, opts)
     elif goal == goaleditplan:
         _edithisteditplan(ui, repo, state, rules)
         return
     elif goal == goalabort:
         _aborthistedit(ui, repo, state, nobackup=nobackup)
         return
     else:
         # goal == goalnew
         _newhistedit(ui, repo, state, revs, freeargs, opts)
 
     _continuehistedit(ui, repo, state)
     _finishhistedit(ui, repo, state, fm)
     fm.end()
 
 def _continuehistedit(ui, repo, state):
     """This function runs after either:
     - bootstrapcontinue (if the goal is 'continue')
     - _newhistedit (if the goal is 'new')
     """
     # preprocess rules so that we can hide inner folds from the user
     # and only show one editor
     actions = state.actions[:]
     for idx, (action, nextact) in enumerate(
             zip(actions, actions[1:] + [None])):
         if action.verb == 'fold' and nextact and nextact.verb == 'fold':
             state.actions[idx].__class__ = _multifold
 
     # Force an initial state file write, so the user can run --abort/continue
     # even if there's an exception before the first transaction serialize.
     state.write()
 
     tr = None
     # Don't use singletransaction by default since it rolls the entire
     # transaction back if an unexpected exception happens (like a
     # pretxncommit hook throws, or the user aborts the commit msg editor).
     if ui.configbool("histedit", "singletransaction"):
         # Don't use a 'with' for the transaction, since actions may close
         # and reopen a transaction. For example, if the action executes an
         # external process it may choose to commit the transaction first.
         tr = repo.transaction('histedit')
     progress = ui.makeprogress(_("editing"), unit=_('changes'),
                                total=len(state.actions))
     with progress, util.acceptintervention(tr):
         while state.actions:
             state.write(tr=tr)
             actobj = state.actions[0]
             progress.increment(item=actobj.torule())
             ui.debug('histedit: processing %s %s\n' % (actobj.verb,\
                                                        actobj.torule()))
             parentctx, replacement_ = actobj.run()
             state.parentctxnode = parentctx.node()
             state.replacements.extend(replacement_)
             state.actions.pop(0)
 
     state.write()
 
 def _finishhistedit(ui, repo, state, fm):
     """This action runs when histedit is finishing its session"""
     hg.updaterepo(repo, state.parentctxnode, overwrite=False)
 
     mapping, tmpnodes, created, ntm = processreplacement(state)
     if mapping:
         for prec, succs in mapping.iteritems():
             if not succs:
                 ui.debug('histedit: %s is dropped\n' % node.short(prec))
             else:
                 ui.debug('histedit: %s is replaced by %s\n' % (
                     node.short(prec), node.short(succs[0])))
                 if len(succs) > 1:
                     m = 'histedit:                            %s'
                     for n in succs[1:]:
                         ui.debug(m % node.short(n))
 
     if not state.keep:
         if mapping:
             movetopmostbookmarks(repo, state.topmost, ntm)
             # TODO update mq state
     else:
         mapping = {}
 
     for n in tmpnodes:
         if n in repo:
             mapping[n] = ()
 
     # remove entries about unknown nodes
     nodemap = repo.unfiltered().changelog.nodemap
     mapping = {k: v for k, v in mapping.items()
                if k in nodemap and all(n in nodemap for n in v)}
     scmutil.cleanupnodes(repo, mapping, 'histedit')
     hf = fm.hexfunc
     fl = fm.formatlist
     fd = fm.formatdict
     nodechanges = fd({hf(oldn): fl([hf(n) for n in newn], name='node')
                       for oldn, newn in mapping.iteritems()},
                      key="oldnode", value="newnodes")
     fm.data(nodechanges=nodechanges)
 
     state.clear()
     if os.path.exists(repo.sjoin('undo')):
         os.unlink(repo.sjoin('undo'))
     if repo.vfs.exists('histedit-last-edit.txt'):
         repo.vfs.unlink('histedit-last-edit.txt')
 
 def _aborthistedit(ui, repo, state, nobackup=False):
     try:
         state.read()
         __, leafs, tmpnodes, __ = processreplacement(state)
         ui.debug('restore wc to old parent %s\n'
                 % node.short(state.topmost))
 
         # Recover our old commits if necessary
         if not state.topmost in repo and state.backupfile:
             backupfile = repo.vfs.join(state.backupfile)
             f = hg.openpath(ui, backupfile)
             gen = exchange.readbundle(ui, f, backupfile)
             with repo.transaction('histedit.abort') as tr:
                 bundle2.applybundle(repo, gen, tr, source='histedit',
                                     url='bundle:' + backupfile)
 
             os.remove(backupfile)
 
         # check whether we should update away
         if repo.unfiltered().revs('parents() and (%n  or %ln::)',
                                 state.parentctxnode, leafs | tmpnodes):
             hg.clean(repo, state.topmost, show_stats=True, quietempty=True)
         cleanupnode(ui, repo, tmpnodes, nobackup=nobackup)
         cleanupnode(ui, repo, leafs, nobackup=nobackup)
     except Exception:
         if state.inprogress():
             ui.warn(_('warning: encountered an exception during histedit '
                 '--abort; the repository may not have been completely '
                 'cleaned up\n'))
         raise
     finally:
             state.clear()
 
 def _edithisteditplan(ui, repo, state, rules):
     state.read()
     if not rules:
         comment = geteditcomment(ui,
                                  node.short(state.parentctxnode),
                                  node.short(state.topmost))
         rules = ruleeditor(repo, ui, state.actions, comment)
     else:
         rules = _readfile(ui, rules)
     actions = parserules(rules, state)
     ctxs = [repo[act.node] \
             for act in state.actions if act.node]
     warnverifyactions(ui, repo, actions, state, ctxs)
     state.actions = actions
     state.write()
 
 def _newhistedit(ui, repo, state, revs, freeargs, opts):
     outg = opts.get('outgoing')
     rules = opts.get('commands', '')
     force = opts.get('force')
 
     cmdutil.checkunfinished(repo)
     cmdutil.bailifchanged(repo)
 
     topmost, empty = repo.dirstate.parents()
     if outg:
         if freeargs:
             remote = freeargs[0]
         else:
             remote = None
         root = findoutgoing(ui, repo, remote, force, opts)
     else:
         rr = list(repo.set('roots(%ld)', scmutil.revrange(repo, revs)))
         if len(rr) != 1:
             raise error.Abort(_('The specified revisions must have '
                 'exactly one common root'))
         root = rr[0].node()
 
     revs = between(repo, root, topmost, state.keep)
     if not revs:
         raise error.Abort(_('%s is not an ancestor of working directory') %
                          node.short(root))
 
     ctxs = [repo[r] for r in revs]
     if not rules:
         comment = geteditcomment(ui, node.short(root), node.short(topmost))
         actions = [pick(state, r) for r in revs]
         rules = ruleeditor(repo, ui, actions, comment)
     else:
         rules = _readfile(ui, rules)
     actions = parserules(rules, state)
     warnverifyactions(ui, repo, actions, state, ctxs)
 
     parentctxnode = repo[root].parents()[0].node()
 
     state.parentctxnode = parentctxnode
     state.actions = actions
     state.topmost = topmost
     state.replacements = []
 
     ui.log("histedit", "%d actions to histedit", len(actions),
            histedit_num_actions=len(actions))
 
     # Create a backup so we can always abort completely.
     backupfile = None
     if not obsolete.isenabled(repo, obsolete.createmarkersopt):
         backupfile = repair.backupbundle(repo, [parentctxnode],
                                          [topmost], root, 'histedit')
     state.backupfile = backupfile
 
 def _getsummary(ctx):
     # a common pattern is to extract the summary but default to the empty
     # string
     summary = ctx.description() or ''
     if summary:
         summary = summary.splitlines()[0]
     return summary
 
 def bootstrapcontinue(ui, state, opts):
     repo = state.repo
 
     ms = mergemod.mergestate.read(repo)
     mergeutil.checkunresolved(ms)
 
     if state.actions:
         actobj = state.actions.pop(0)
 
         if _isdirtywc(repo):
             actobj.continuedirty()
             if _isdirtywc(repo):
                 abortdirty()
 
         parentctx, replacements = actobj.continueclean()
 
         state.parentctxnode = parentctx.node()
         state.replacements.extend(replacements)
 
     return state
 
 def between(repo, old, new, keep):
     """select and validate the set of revision to edit
 
     When keep is false, the specified set can't have children."""
     revs = repo.revs('%n::%n', old, new)
     if revs and not keep:
         if (not obsolete.isenabled(repo, obsolete.allowunstableopt) and
             repo.revs('(%ld::) - (%ld)', revs, revs)):
             raise error.Abort(_('can only histedit a changeset together '
                                 'with all its descendants'))
         if repo.revs('(%ld) and merge()', revs):
             raise error.Abort(_('cannot edit history that contains merges'))
         root = repo[revs.first()]  # list is already sorted by repo.revs()
         if not root.mutable():
             raise error.Abort(_('cannot edit public changeset: %s') % root,
                              hint=_("see 'hg help phases' for details"))
     return pycompat.maplist(repo.changelog.node, revs)
 
 def ruleeditor(repo, ui, actions, editcomment=""):
     """open an editor to edit rules
 
     rules are in the format [ [act, ctx], ...] like in state.rules
     """
     if repo.ui.configbool("experimental", "histedit.autoverb"):
         newact = util.sortdict()
         for act in actions:
             ctx = repo[act.node]
             summary = _getsummary(ctx)
             fword = summary.split(' ', 1)[0].lower()
             added = False
 
             # if it doesn't end with the special character '!' just skip this
             if fword.endswith('!'):
                 fword = fword[:-1]
                 if fword in primaryactions | secondaryactions | tertiaryactions:
                     act.verb = fword
                     # get the target summary
                     tsum = summary[len(fword) + 1:].lstrip()
                     # safe but slow: reverse iterate over the actions so we
                     # don't clash on two commits having the same summary
                     for na, l in reversed(list(newact.iteritems())):
                         actx = repo[na.node]
                         asum = _getsummary(actx)
                         if asum == tsum:
                             added = True
                             l.append(act)
                             break
 
             if not added:
                 newact[act] = []
 
         # copy over and flatten the new list
         actions = []
         for na, l in newact.iteritems():
             actions.append(na)
             actions += l
 
     rules = '\n'.join([act.torule() for act in actions])
     rules += '\n\n'
     rules += editcomment
     rules = ui.edit(rules, ui.username(), {'prefix': 'histedit'},
                     repopath=repo.path, action='histedit')
 
     # Save edit rules in .hg/histedit-last-edit.txt in case
     # the user needs to ask for help after something
     # surprising happens.
     with repo.vfs('histedit-last-edit.txt', 'wb') as f:
         f.write(rules)
 
     return rules
 
 def parserules(rules, state):
     """Read the histedit rules string and return list of action objects """
     rules = [l for l in (r.strip() for r in rules.splitlines())
                 if l and not l.startswith('#')]
     actions = []
     for r in rules:
         if ' ' not in r:
             raise error.ParseError(_('malformed line "%s"') % r)
         verb, rest = r.split(' ', 1)
 
         if verb not in actiontable:
             raise error.ParseError(_('unknown action "%s"') % verb)
 
         action = actiontable[verb].fromrule(state, rest)
         actions.append(action)
     return actions
 
 def warnverifyactions(ui, repo, actions, state, ctxs):
     try:
         verifyactions(actions, state, ctxs)
     except error.ParseError:
         if repo.vfs.exists('histedit-last-edit.txt'):
             ui.warn(_('warning: histedit rules saved '
                       'to: .hg/histedit-last-edit.txt\n'))
         raise
 
 def verifyactions(actions, state, ctxs):
     """Verify that there exists exactly one action per given changeset and
     other constraints.
 
     Will abort if there are to many or too few rules, a malformed rule,
     or a rule on a changeset outside of the user-given range.
     """
     expected = set(c.node() for c in ctxs)
     seen = set()
     prev = None
 
     if actions and actions[0].verb in ['roll', 'fold']:
         raise error.ParseError(_('first changeset cannot use verb "%s"') %
                                actions[0].verb)
 
     for action in actions:
         action.verify(prev, expected, seen)
         prev = action
         if action.node is not None:
             seen.add(action.node)
     missing = sorted(expected - seen)  # sort to stabilize output
 
     if state.repo.ui.configbool('histedit', 'dropmissing'):
         if len(actions) == 0:
             raise error.ParseError(_('no rules provided'),
                     hint=_('use strip extension to remove commits'))
 
         drops = [drop(state, n) for n in missing]
         # put the in the beginning so they execute immediately and
         # don't show in the edit-plan in the future
         actions[:0] = drops
     elif missing:
         raise error.ParseError(_('missing rules for changeset %s') %
                 node.short(missing[0]),
                 hint=_('use "drop %s" to discard, see also: '
                        "'hg help -e histedit.config'")
                        % node.short(missing[0]))
 
 def adjustreplacementsfrommarkers(repo, oldreplacements):
     """Adjust replacements from obsolescence markers
 
     Replacements structure is originally generated based on
     histedit's state and does not account for changes that are
     not recorded there. This function fixes that by adding
     data read from obsolescence markers"""
     if not obsolete.isenabled(repo, obsolete.createmarkersopt):
         return oldreplacements
 
     unfi = repo.unfiltered()
     nm = unfi.changelog.nodemap
     obsstore = repo.obsstore
     newreplacements = list(oldreplacements)
     oldsuccs = [r[1] for r in oldreplacements]
     # successors that have already been added to succstocheck once
     seensuccs = set().union(*oldsuccs) # create a set from an iterable of tuples
     succstocheck = list(seensuccs)
     while succstocheck:
         n = succstocheck.pop()
         missing = nm.get(n) is None
         markers = obsstore.successors.get(n, ())
         if missing and not markers:
             # dead end, mark it as such
             newreplacements.append((n, ()))
         for marker in markers:
             nsuccs = marker[1]
             newreplacements.append((n, nsuccs))
             for nsucc in nsuccs:
                 if nsucc not in seensuccs:
                     seensuccs.add(nsucc)
                     succstocheck.append(nsucc)
 
     return newreplacements
 
 def processreplacement(state):
     """process the list of replacements to return
 
     1) the final mapping between original and created nodes
     2) the list of temporary node created by histedit
     3) the list of new commit created by histedit"""
     replacements = adjustreplacementsfrommarkers(state.repo, state.replacements)
     allsuccs = set()
     replaced = set()
     fullmapping = {}
     # initialize basic set
     # fullmapping records all operations recorded in replacement
     for rep in replacements:
         allsuccs.update(rep[1])
         replaced.add(rep[0])
         fullmapping.setdefault(rep[0], set()).update(rep[1])
     new = allsuccs - replaced
     tmpnodes = allsuccs & replaced
     # Reduce content fullmapping into direct relation between original nodes
     # and final node created during history edition
     # Dropped changeset are replaced by an empty list
     toproceed = set(fullmapping)
     final = {}
     while toproceed:
         for x in list(toproceed):
             succs = fullmapping[x]
             for s in list(succs):
                 if s in toproceed:
                     # non final node with unknown closure
                     # We can't process this now
                     break
                 elif s in final:
                     # non final node, replace with closure
                     succs.remove(s)
                     succs.update(final[s])
             else:
                 final[x] = succs
                 toproceed.remove(x)
     # remove tmpnodes from final mapping
     for n in tmpnodes:
         del final[n]
     # we expect all changes involved in final to exist in the repo
     # turn `final` into list (topologically sorted)
     nm = state.repo.changelog.nodemap
     for prec, succs in final.items():
         final[prec] = sorted(succs, key=nm.get)
 
     # computed topmost element (necessary for bookmark)
     if new:
         newtopmost = sorted(new, key=state.repo.changelog.rev)[-1]
     elif not final:
         # Nothing rewritten at all. we won't need `newtopmost`
         # It is the same as `oldtopmost` and `processreplacement` know it
         newtopmost = None
     else:
         # every body died. The newtopmost is the parent of the root.
         r = state.repo.changelog.rev
         newtopmost = state.repo[sorted(final, key=r)[0]].p1().node()
 
     return final, tmpnodes, new, newtopmost
 
 def movetopmostbookmarks(repo, oldtopmost, newtopmost):
     """Move bookmark from oldtopmost to newly created topmost
 
     This is arguably a feature and we may only want that for the active
     bookmark. But the behavior is kept compatible with the old version for now.
     """
     if not oldtopmost or not newtopmost:
         return
     oldbmarks = repo.nodebookmarks(oldtopmost)
     if oldbmarks:
         with repo.lock(), repo.transaction('histedit') as tr:
             marks = repo._bookmarks
             changes = []
             for name in oldbmarks:
                 changes.append((name, newtopmost))
             marks.applychanges(repo, tr, changes)
 
 def cleanupnode(ui, repo, nodes, nobackup=False):
     """strip a group of nodes from the repository
 
     The set of node to strip may contains unknown nodes."""
     with repo.lock():
         # do not let filtering get in the way of the cleanse
         # we should probably get rid of obsolescence marker created during the
         # histedit, but we currently do not have such information.
         repo = repo.unfiltered()
         # Find all nodes that need to be stripped
         # (we use %lr instead of %ln to silently ignore unknown items)
         nm = repo.changelog.nodemap
         nodes = sorted(n for n in nodes if n in nm)
         roots = [c.node() for c in repo.set("roots(%ln)", nodes)]
         if roots:
             backup = not nobackup
             repair.strip(ui, repo, roots, backup=backup)
 
 def stripwrapper(orig, ui, repo, nodelist, *args, **kwargs):
     if isinstance(nodelist, str):
         nodelist = [nodelist]
     state = histeditstate(repo)
     if state.inprogress():
         state.read()
         histedit_nodes = {action.node for action
                           in state.actions if action.node}
         common_nodes = histedit_nodes & set(nodelist)
         if common_nodes:
             raise error.Abort(_("histedit in progress, can't strip %s")
                              % ', '.join(node.short(x) for x in common_nodes))
     return orig(ui, repo, nodelist, *args, **kwargs)
 
 extensions.wrapfunction(repair, 'strip', stripwrapper)
 
 def summaryhook(ui, repo):
     state = histeditstate(repo)
     if not state.inprogress():
         return
     state.read()
     if state.actions:
         # i18n: column positioning for "hg summary"
         ui.write(_('hist:   %s (histedit --continue)\n') %
                  (ui.label(_('%d remaining'), 'histedit.remaining') %
                   len(state.actions)))
 
 def extsetup(ui):
     cmdutil.summaryhooks.add('histedit', summaryhook)
     cmdutil.unfinishedstates.append(
         ['histedit-state', False, True, _('histedit in progress'),
          _("use 'hg histedit --continue' or 'hg histedit --abort'")])
     cmdutil.afterresolvedstates.append(
         ['histedit-state', _('hg histedit --continue')])

mercurial/ui.py

@@ -1,2004 +1,2008 b''
 # ui.py - user interface bits for mercurial
 #
 # Copyright 2005-2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 from __future__ import absolute_import
 
 import collections
 import contextlib
 import errno
 import getpass
 import inspect
 import os
 import re
 import signal
 import socket
 import subprocess
 import sys
 import traceback
 
 from .i18n import _
 from .node import hex
 
 from . import (
     color,
     config,
     configitems,
     encoding,
     error,
     formatter,
     progress,
     pycompat,
     rcutil,
     scmutil,
     util,
 )
 from .utils import (
     dateutil,
     procutil,
     stringutil,
 )
 
 urlreq = util.urlreq
 
 # for use with str.translate(None, _keepalnum), to keep just alphanumerics
 _keepalnum = ''.join(c for c in map(pycompat.bytechr, range(256))
                      if not c.isalnum())
 
 # The config knobs that will be altered (if unset) by ui.tweakdefaults.
 tweakrc = b"""
 [ui]
 # The rollback command is dangerous. As a rule, don't use it.
 rollback = False
 # Make `hg status` report copy information
 statuscopies = yes
 # Prefer curses UIs when available. Revert to plain-text with `text`.
 interface = curses
 
 [commands]
 # Grep working directory by default.
 grep.all-files = True
 # Make `hg status` emit cwd-relative paths by default.
 status.relative = yes
 # Refuse to perform an `hg update` that would cause a file content merge
 update.check = noconflict
 # Show conflicts information in `hg status`
 status.verbose = True
 
 [diff]
 git = 1
 showfunc = 1
 word-diff = 1
 """
 
 samplehgrcs = {
     'user':
 b"""# example user config (see 'hg help config' for more info)
 [ui]
 # name and email, e.g.
 # username = Jane Doe <[e-mail]>
 username =
 
 # We recommend enabling tweakdefaults to get slight improvements to
 # the UI over time. Make sure to set HGPLAIN in the environment when
 # writing scripts!
 # tweakdefaults = True
 
 # uncomment to disable color in command output
 # (see 'hg help color' for details)
 # color = never
 
 # uncomment to disable command output pagination
 # (see 'hg help pager' for details)
 # paginate = never
 
 [extensions]
 # uncomment these lines to enable some popular extensions
 # (see 'hg help extensions' for more info)
 #
 # churn =
 """,
 
     'cloned':
 b"""# example repository config (see 'hg help config' for more info)
 [paths]
 default = %s
 
 # path aliases to other clones of this repo in URLs or filesystem paths
 # (see 'hg help config.paths' for more info)
 #
 # default:pushurl = ssh://[e-mail]/hg/jdoes-fork
 # my-fork         = ssh://[e-mail]/hg/jdoes-fork
 # my-clone        = /home/jdoe/jdoes-clone
 
 [ui]
 # name and email (local to this repository, optional), e.g.
 # username = Jane Doe <[e-mail]>
 """,
 
     'local':
 b"""# example repository config (see 'hg help config' for more info)
 [paths]
 # path aliases to other clones of this repo in URLs or filesystem paths
 # (see 'hg help config.paths' for more info)
 #
 # default         = http://example.com/hg/example-repo
 # default:pushurl = ssh://[e-mail]/hg/jdoes-fork
 # my-fork         = ssh://[e-mail]/hg/jdoes-fork
 # my-clone        = /home/jdoe/jdoes-clone
 
 [ui]
 # name and email (local to this repository, optional), e.g.
 # username = Jane Doe <[e-mail]>
 """,
 
     'global':
 b"""# example system-wide hg config (see 'hg help config' for more info)
 
 [ui]
 # uncomment to disable color in command output
 # (see 'hg help color' for details)
 # color = never
 
 # uncomment to disable command output pagination
 # (see 'hg help pager' for details)
 # paginate = never
 
 [extensions]
 # uncomment these lines to enable some popular extensions
 # (see 'hg help extensions' for more info)
 #
 # blackbox =
 # churn =
 """,
 }
 
 def _maybestrurl(maybebytes):
     return pycompat.rapply(pycompat.strurl, maybebytes)
 
 def _maybebytesurl(maybestr):
     return pycompat.rapply(pycompat.bytesurl, maybestr)
 
 class httppasswordmgrdbproxy(object):
     """Delays loading urllib2 until it's needed."""
     def __init__(self):
         self._mgr = None
 
     def _get_mgr(self):
         if self._mgr is None:
             self._mgr = urlreq.httppasswordmgrwithdefaultrealm()
         return self._mgr
 
     def add_password(self, realm, uris, user, passwd):
         return self._get_mgr().add_password(
             _maybestrurl(realm), _maybestrurl(uris),
             _maybestrurl(user), _maybestrurl(passwd))
 
     def find_user_password(self, realm, uri):
         mgr = self._get_mgr()
         return _maybebytesurl(mgr.find_user_password(_maybestrurl(realm),
                                                      _maybestrurl(uri)))
 
 def _catchterm(*args):
     raise error.SignalInterrupt
 
 # unique object used to detect no default value has been provided when
 # retrieving configuration value.
 _unset = object()
 
 # _reqexithandlers: callbacks run at the end of a request
 _reqexithandlers = []
 
 class ui(object):
     def __init__(self, src=None):
         """Create a fresh new ui object if no src given
 
         Use uimod.ui.load() to create a ui which knows global and user configs.
         In most cases, you should use ui.copy() to create a copy of an existing
         ui object.
         """
         # _buffers: used for temporary capture of output
         self._buffers = []
         # 3-tuple describing how each buffer in the stack behaves.
         # Values are (capture stderr, capture subprocesses, apply labels).
         self._bufferstates = []
         # When a buffer is active, defines whether we are expanding labels.
         # This exists to prevent an extra list lookup.
         self._bufferapplylabels = None
         self.quiet = self.verbose = self.debugflag = self.tracebackflag = False
         self._reportuntrusted = True
         self._knownconfig = configitems.coreitems
         self._ocfg = config.config() # overlay
         self._tcfg = config.config() # trusted
         self._ucfg = config.config() # untrusted
         self._trustusers = set()
         self._trustgroups = set()
         self.callhooks = True
         # Insecure server connections requested.
         self.insecureconnections = False
         # Blocked time
         self.logblockedtimes = False
         # color mode: see mercurial/color.py for possible value
         self._colormode = None
         self._terminfoparams = {}
         self._styles = {}
         self._uninterruptible = False
 
         if src:
             self._fout = src._fout
             self._ferr = src._ferr
             self._fin = src._fin
             self._fmsg = src._fmsg
             self._fmsgout = src._fmsgout
             self._fmsgerr = src._fmsgerr
             self._finoutredirected = src._finoutredirected
             self.pageractive = src.pageractive
             self._disablepager = src._disablepager
             self._tweaked = src._tweaked
 
             self._tcfg = src._tcfg.copy()
             self._ucfg = src._ucfg.copy()
             self._ocfg = src._ocfg.copy()
             self._trustusers = src._trustusers.copy()
             self._trustgroups = src._trustgroups.copy()
             self.environ = src.environ
             self.callhooks = src.callhooks
             self.insecureconnections = src.insecureconnections
             self._colormode = src._colormode
             self._terminfoparams = src._terminfoparams.copy()
             self._styles = src._styles.copy()
 
             self.fixconfig()
 
             self.httppasswordmgrdb = src.httppasswordmgrdb
             self._blockedtimes = src._blockedtimes
         else:
             self._fout = procutil.stdout
             self._ferr = procutil.stderr
             self._fin = procutil.stdin
             self._fmsg = None
             self._fmsgout = self.fout  # configurable
             self._fmsgerr = self.ferr  # configurable
             self._finoutredirected = False
             self.pageractive = False
             self._disablepager = False
             self._tweaked = False
 
             # shared read-only environment
             self.environ = encoding.environ
 
             self.httppasswordmgrdb = httppasswordmgrdbproxy()
             self._blockedtimes = collections.defaultdict(int)
 
         allowed = self.configlist('experimental', 'exportableenviron')
         if '*' in allowed:
             self._exportableenviron = self.environ
         else:
             self._exportableenviron = {}
             for k in allowed:
                 if k in self.environ:
                     self._exportableenviron[k] = self.environ[k]
 
     @classmethod
     def load(cls):
         """Create a ui and load global and user configs"""
         u = cls()
         # we always trust global config files and environment variables
         for t, f in rcutil.rccomponents():
             if t == 'path':
                 u.readconfig(f, trust=True)
             elif t == 'items':
                 sections = set()
                 for section, name, value, source in f:
                     # do not set u._ocfg
                     # XXX clean this up once immutable config object is a thing
                     u._tcfg.set(section, name, value, source)
                     u._ucfg.set(section, name, value, source)
                     sections.add(section)
                 for section in sections:
                     u.fixconfig(section=section)
             else:
                 raise error.ProgrammingError('unknown rctype: %s' % t)
         u._maybetweakdefaults()
         return u
 
     def _maybetweakdefaults(self):
         if not self.configbool('ui', 'tweakdefaults'):
             return
         if self._tweaked or self.plain('tweakdefaults'):
             return
 
         # Note: it is SUPER IMPORTANT that you set self._tweaked to
         # True *before* any calls to setconfig(), otherwise you'll get
         # infinite recursion between setconfig and this method.
         #
         # TODO: We should extract an inner method in setconfig() to
         # avoid this weirdness.
         self._tweaked = True
         tmpcfg = config.config()
         tmpcfg.parse('<tweakdefaults>', tweakrc)
         for section in tmpcfg:
             for name, value in tmpcfg.items(section):
                 if not self.hasconfig(section, name):
                     self.setconfig(section, name, value, "<tweakdefaults>")
 
     def copy(self):
         return self.__class__(self)
 
     def resetstate(self):
         """Clear internal state that shouldn't persist across commands"""
         if self._progbar:
             self._progbar.resetstate()  # reset last-print time of progress bar
         self.httppasswordmgrdb = httppasswordmgrdbproxy()
 
     @contextlib.contextmanager
     def timeblockedsection(self, key):
         # this is open-coded below - search for timeblockedsection to find them
         starttime = util.timer()
         try:
             yield
         finally:
             self._blockedtimes[key + '_blocked'] += \
                 (util.timer() - starttime) * 1000
 
     @contextlib.contextmanager
     def uninterruptable(self):
         """Mark an operation as unsafe.
 
         Most operations on a repository are safe to interrupt, but a
         few are risky (for example repair.strip). This context manager
         lets you advise Mercurial that something risky is happening so
         that control-C etc can be blocked if desired.
         """
         enabled = self.configbool('experimental', 'nointerrupt')
         if (enabled and
             self.configbool('experimental', 'nointerrupt-interactiveonly')):
             enabled = self.interactive()
         if self._uninterruptible or not enabled:
             # if nointerrupt support is turned off, the process isn't
             # interactive, or we're already in an uninterruptable
             # block, do nothing.
             yield
             return
         def warn():
             self.warn(_("shutting down cleanly\n"))
             self.warn(
                 _("press ^C again to terminate immediately (dangerous)\n"))
             return True
         with procutil.uninterruptable(warn):
             try:
                 self._uninterruptible = True
                 yield
             finally:
                 self._uninterruptible = False
 
     def formatter(self, topic, opts):
         return formatter.formatter(self, self, topic, opts)
 
     def _trusted(self, fp, f):
         st = util.fstat(fp)
         if util.isowner(st):
             return True
 
         tusers, tgroups = self._trustusers, self._trustgroups
         if '*' in tusers or '*' in tgroups:
             return True
 
         user = util.username(st.st_uid)
         group = util.groupname(st.st_gid)
         if user in tusers or group in tgroups or user == util.username():
             return True
 
         if self._reportuntrusted:
             self.warn(_('not trusting file %s from untrusted '
                         'user %s, group %s\n') % (f, user, group))
         return False
 
     def readconfig(self, filename, root=None, trust=False,
                    sections=None, remap=None):
         try:
             fp = open(filename, r'rb')
         except IOError:
             if not sections: # ignore unless we were looking for something
                 return
             raise
 
         cfg = config.config()
         trusted = sections or trust or self._trusted(fp, filename)
 
         try:
             cfg.read(filename, fp, sections=sections, remap=remap)
             fp.close()
         except error.ConfigError as inst:
             if trusted:
                 raise
             self.warn(_("ignored: %s\n") % stringutil.forcebytestr(inst))
 
         if self.plain():
             for k in ('debug', 'fallbackencoding', 'quiet', 'slash',
                       'logtemplate', 'message-output', 'statuscopies', 'style',
                       'traceback', 'verbose'):
                 if k in cfg['ui']:
                     del cfg['ui'][k]
             for k, v in cfg.items('defaults'):
                 del cfg['defaults'][k]
             for k, v in cfg.items('commands'):
                 del cfg['commands'][k]
         # Don't remove aliases from the configuration if in the exceptionlist
         if self.plain('alias'):
             for k, v in cfg.items('alias'):
                 del cfg['alias'][k]
         if self.plain('revsetalias'):
             for k, v in cfg.items('revsetalias'):
                 del cfg['revsetalias'][k]
         if self.plain('templatealias'):
             for k, v in cfg.items('templatealias'):
                 del cfg['templatealias'][k]
 
         if trusted:
             self._tcfg.update(cfg)
             self._tcfg.update(self._ocfg)
         self._ucfg.update(cfg)
         self._ucfg.update(self._ocfg)
 
         if root is None:
             root = os.path.expanduser('~')
         self.fixconfig(root=root)
 
     def fixconfig(self, root=None, section=None):
         if section in (None, 'paths'):
             # expand vars and ~
             # translate paths relative to root (or home) into absolute paths
             root = root or encoding.getcwd()
             for c in self._tcfg, self._ucfg, self._ocfg:
                 for n, p in c.items('paths'):
                     # Ignore sub-options.
                     if ':' in n:
                         continue
                     if not p:
                         continue
                     if '%%' in p:
                         s = self.configsource('paths', n) or 'none'
                         self.warn(_("(deprecated '%%' in path %s=%s from %s)\n")
                                   % (n, p, s))
                         p = p.replace('%%', '%')
                     p = util.expandpath(p)
                     if not util.hasscheme(p) and not os.path.isabs(p):
                         p = os.path.normpath(os.path.join(root, p))
                     c.set("paths", n, p)
 
         if section in (None, 'ui'):
             # update ui options
             self._fmsgout, self._fmsgerr = _selectmsgdests(self)
             self.debugflag = self.configbool('ui', 'debug')
             self.verbose = self.debugflag or self.configbool('ui', 'verbose')
             self.quiet = not self.debugflag and self.configbool('ui', 'quiet')
             if self.verbose and self.quiet:
                 self.quiet = self.verbose = False
             self._reportuntrusted = self.debugflag or self.configbool("ui",
                 "report_untrusted")
             self.tracebackflag = self.configbool('ui', 'traceback')
             self.logblockedtimes = self.configbool('ui', 'logblockedtimes')
 
         if section in (None, 'trusted'):
             # update trust information
             self._trustusers.update(self.configlist('trusted', 'users'))
             self._trustgroups.update(self.configlist('trusted', 'groups'))
 
     def backupconfig(self, section, item):
         return (self._ocfg.backup(section, item),
                 self._tcfg.backup(section, item),
                 self._ucfg.backup(section, item),)
     def restoreconfig(self, data):
         self._ocfg.restore(data[0])
         self._tcfg.restore(data[1])
         self._ucfg.restore(data[2])
 
     def setconfig(self, section, name, value, source=''):
         for cfg in (self._ocfg, self._tcfg, self._ucfg):
             cfg.set(section, name, value, source)
         self.fixconfig(section=section)
         self._maybetweakdefaults()
 
     def _data(self, untrusted):
         return untrusted and self._ucfg or self._tcfg
 
     def configsource(self, section, name, untrusted=False):
         return self._data(untrusted).source(section, name)
 
     def config(self, section, name, default=_unset, untrusted=False):
         """return the plain string version of a config"""
         value = self._config(section, name, default=default,
                              untrusted=untrusted)
         if value is _unset:
             return None
         return value
 
     def _config(self, section, name, default=_unset, untrusted=False):
         value = itemdefault = default
         item = self._knownconfig.get(section, {}).get(name)
         alternates = [(section, name)]
 
         if item is not None:
             alternates.extend(item.alias)
             if callable(item.default):
                 itemdefault = item.default()
             else:
                 itemdefault = item.default
         else:
             msg = ("accessing unregistered config item: '%s.%s'")
             msg %= (section, name)
             self.develwarn(msg, 2, 'warn-config-unknown')
 
         if default is _unset:
             if item is None:
                 value = default
             elif item.default is configitems.dynamicdefault:
                 value = None
                 msg = "config item requires an explicit default value: '%s.%s'"
                 msg %= (section, name)
                 self.develwarn(msg, 2, 'warn-config-default')
             else:
                 value = itemdefault
         elif (item is not None
               and item.default is not configitems.dynamicdefault
               and default != itemdefault):
             msg = ("specifying a mismatched default value for a registered "
                    "config item: '%s.%s' '%s'")
             msg %= (section, name, pycompat.bytestr(default))
             self.develwarn(msg, 2, 'warn-config-default')
 
         for s, n in alternates:
             candidate = self._data(untrusted).get(s, n, None)
             if candidate is not None:
                 value = candidate
                 section = s
                 name = n
                 break
 
         if self.debugflag and not untrusted and self._reportuntrusted:
             for s, n in alternates:
                 uvalue = self._ucfg.get(s, n)
                 if uvalue is not None and uvalue != value:
                     self.debug("ignoring untrusted configuration option "
                                "%s.%s = %s\n" % (s, n, uvalue))
         return value
 
     def configsuboptions(self, section, name, default=_unset, untrusted=False):
         """Get a config option and all sub-options.
 
         Some config options have sub-options that are declared with the
         format "key:opt = value". This method is used to return the main
         option and all its declared sub-options.
 
         Returns a 2-tuple of ``(option, sub-options)``, where `sub-options``
         is a dict of defined sub-options where keys and values are strings.
         """
         main = self.config(section, name, default, untrusted=untrusted)
         data = self._data(untrusted)
         sub = {}
         prefix = '%s:' % name
         for k, v in data.items(section):
             if k.startswith(prefix):
                 sub[k[len(prefix):]] = v
 
         if self.debugflag and not untrusted and self._reportuntrusted:
             for k, v in sub.items():
                 uvalue = self._ucfg.get(section, '%s:%s' % (name, k))
                 if uvalue is not None and uvalue != v:
                     self.debug('ignoring untrusted configuration option '
                                '%s:%s.%s = %s\n' % (section, name, k, uvalue))
 
         return main, sub
 
     def configpath(self, section, name, default=_unset, untrusted=False):
         'get a path config item, expanded relative to repo root or config file'
         v = self.config(section, name, default, untrusted)
         if v is None:
             return None
         if not os.path.isabs(v) or "://" not in v:
             src = self.configsource(section, name, untrusted)
             if ':' in src:
                 base = os.path.dirname(src.rsplit(':')[0])
                 v = os.path.join(base, os.path.expanduser(v))
         return v
 
     def configbool(self, section, name, default=_unset, untrusted=False):
         """parse a configuration element as a boolean
 
         >>> u = ui(); s = b'foo'
         >>> u.setconfig(s, b'true', b'yes')
         >>> u.configbool(s, b'true')
         True
         >>> u.setconfig(s, b'false', b'no')
         >>> u.configbool(s, b'false')
         False
         >>> u.configbool(s, b'unknown')
         False
         >>> u.configbool(s, b'unknown', True)
         True
         >>> u.setconfig(s, b'invalid', b'somevalue')
         >>> u.configbool(s, b'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a boolean ('somevalue')
         """
 
         v = self._config(section, name, default, untrusted=untrusted)
         if v is None:
             return v
         if v is _unset:
             if default is _unset:
                 return False
             return default
         if isinstance(v, bool):
             return v
         b = stringutil.parsebool(v)
         if b is None:
             raise error.ConfigError(_("%s.%s is not a boolean ('%s')")
                                     % (section, name, v))
         return b
 
     def configwith(self, convert, section, name, default=_unset,
                    desc=None, untrusted=False):
         """parse a configuration element with a conversion function
 
         >>> u = ui(); s = b'foo'
         >>> u.setconfig(s, b'float1', b'42')
         >>> u.configwith(float, s, b'float1')
         42.0
         >>> u.setconfig(s, b'float2', b'-4.25')
         >>> u.configwith(float, s, b'float2')
         -4.25
         >>> u.configwith(float, s, b'unknown', 7)
         7.0
         >>> u.setconfig(s, b'invalid', b'somevalue')
         >>> u.configwith(float, s, b'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a valid float ('somevalue')
         >>> u.configwith(float, s, b'invalid', desc=b'womble')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a valid womble ('somevalue')
         """
 
         v = self.config(section, name, default, untrusted)
         if v is None:
             return v # do not attempt to convert None
         try:
             return convert(v)
         except (ValueError, error.ParseError):
             if desc is None:
                 desc = pycompat.sysbytes(convert.__name__)
             raise error.ConfigError(_("%s.%s is not a valid %s ('%s')")
                                     % (section, name, desc, v))
 
     def configint(self, section, name, default=_unset, untrusted=False):
         """parse a configuration element as an integer
 
         >>> u = ui(); s = b'foo'
         >>> u.setconfig(s, b'int1', b'42')
         >>> u.configint(s, b'int1')
         42
         >>> u.setconfig(s, b'int2', b'-42')
         >>> u.configint(s, b'int2')
         -42
         >>> u.configint(s, b'unknown', 7)
         7
         >>> u.setconfig(s, b'invalid', b'somevalue')
         >>> u.configint(s, b'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a valid integer ('somevalue')
         """
 
         return self.configwith(int, section, name, default, 'integer',
                                untrusted)
 
     def configbytes(self, section, name, default=_unset, untrusted=False):
         """parse a configuration element as a quantity in bytes
 
         Units can be specified as b (bytes), k or kb (kilobytes), m or
         mb (megabytes), g or gb (gigabytes).
 
         >>> u = ui(); s = b'foo'
         >>> u.setconfig(s, b'val1', b'42')
         >>> u.configbytes(s, b'val1')
         42
         >>> u.setconfig(s, b'val2', b'42.5 kb')
         >>> u.configbytes(s, b'val2')
         43520
         >>> u.configbytes(s, b'unknown', b'7 MB')
         7340032
         >>> u.setconfig(s, b'invalid', b'somevalue')
         >>> u.configbytes(s, b'invalid')
         Traceback (most recent call last):
             ...
         ConfigError: foo.invalid is not a byte quantity ('somevalue')
         """
 
         value = self._config(section, name, default, untrusted)
         if value is _unset:
             if default is _unset:
                 default = 0
             value = default
         if not isinstance(value, bytes):
             return value
         try:
             return util.sizetoint(value)
         except error.ParseError:
             raise error.ConfigError(_("%s.%s is not a byte quantity ('%s')")
                                     % (section, name, value))
 
     def configlist(self, section, name, default=_unset, untrusted=False):
         """parse a configuration element as a list of comma/space separated
         strings
 
         >>> u = ui(); s = b'foo'
         >>> u.setconfig(s, b'list1', b'this,is "a small" ,test')
         >>> u.configlist(s, b'list1')
         ['this', 'is', 'a small', 'test']
         >>> u.setconfig(s, b'list2', b'this, is "a small" , test ')
         >>> u.configlist(s, b'list2')
         ['this', 'is', 'a small', 'test']
         """
         # default is not always a list
         v = self.configwith(config.parselist, section, name, default,
                                'list', untrusted)
         if isinstance(v, bytes):
             return config.parselist(v)
         elif v is None:
             return []
         return v
 
     def configdate(self, section, name, default=_unset, untrusted=False):
         """parse a configuration element as a tuple of ints
 
         >>> u = ui(); s = b'foo'
         >>> u.setconfig(s, b'date', b'0 0')
         >>> u.configdate(s, b'date')
         (0, 0)
         """
         if self.config(section, name, default, untrusted):
             return self.configwith(dateutil.parsedate, section, name, default,
                                    'date', untrusted)
         if default is _unset:
             return None
         return default
 
     def hasconfig(self, section, name, untrusted=False):
         return self._data(untrusted).hasitem(section, name)
 
     def has_section(self, section, untrusted=False):
         '''tell whether section exists in config.'''
         return section in self._data(untrusted)
 
     def configitems(self, section, untrusted=False, ignoresub=False):
         items = self._data(untrusted).items(section)
         if ignoresub:
             items = [i for i in items if ':' not in i[0]]
         if self.debugflag and not untrusted and self._reportuntrusted:
             for k, v in self._ucfg.items(section):
                 if self._tcfg.get(section, k) != v:
                     self.debug("ignoring untrusted configuration option "
                                "%s.%s = %s\n" % (section, k, v))
         return items
 
     def walkconfig(self, untrusted=False):
         cfg = self._data(untrusted)
         for section in cfg.sections():
             for name, value in self.configitems(section, untrusted):
                 yield section, name, value
 
     def plain(self, feature=None):
         '''is plain mode active?
 
         Plain mode means that all configuration variables which affect
         the behavior and output of Mercurial should be
         ignored. Additionally, the output should be stable,
         reproducible and suitable for use in scripts or applications.
 
         The only way to trigger plain mode is by setting either the
         `HGPLAIN' or `HGPLAINEXCEPT' environment variables.
 
         The return value can either be
         - False if HGPLAIN is not set, or feature is in HGPLAINEXCEPT
         - False if feature is disabled by default and not included in HGPLAIN
         - True otherwise
         '''
         if ('HGPLAIN' not in encoding.environ and
                 'HGPLAINEXCEPT' not in encoding.environ):
             return False
         exceptions = encoding.environ.get('HGPLAINEXCEPT',
                 '').strip().split(',')
         # TODO: add support for HGPLAIN=+feature,-feature syntax
         if '+strictflags' not in encoding.environ.get('HGPLAIN', '').split(','):
             exceptions.append('strictflags')
         if feature and exceptions:
             return feature not in exceptions
         return True
 
     def username(self, acceptempty=False):
         """Return default username to be used in commits.
 
         Searched in this order: $HGUSER, [ui] section of hgrcs, $EMAIL
         and stop searching if one of these is set.
         If not found and acceptempty is True, returns None.
         If not found and ui.askusername is True, ask the user, else use
         ($LOGNAME or $USER or $LNAME or $USERNAME) + "@full.hostname".
         If no username could be found, raise an Abort error.
         """
         user = encoding.environ.get("HGUSER")
         if user is None:
             user = self.config("ui", "username")
             if user is not None:
                 user = os.path.expandvars(user)
         if user is None:
             user = encoding.environ.get("EMAIL")
         if user is None and acceptempty:
             return user
         if user is None and self.configbool("ui", "askusername"):
             user = self.prompt(_("enter a commit username:"), default=None)
         if user is None and not self.interactive():
             try:
                 user = '%s@%s' % (procutil.getuser(),
                                   encoding.strtolocal(socket.getfqdn()))
                 self.warn(_("no username found, using '%s' instead\n") % user)
             except KeyError:
                 pass
         if not user:
             raise error.Abort(_('no username supplied'),
                              hint=_("use 'hg config --edit' "
                                     'to set your username'))
         if "\n" in user:
             raise error.Abort(_("username %r contains a newline\n")
                               % pycompat.bytestr(user))
         return user
 
     def shortuser(self, user):
         """Return a short representation of a user name or email address."""
         if not self.verbose:
             user = stringutil.shortuser(user)
         return user
 
     def expandpath(self, loc, default=None):
         """Return repository location relative to cwd or from [paths]"""
         try:
             p = self.paths.getpath(loc)
             if p:
                 return p.rawloc
         except error.RepoError:
             pass
 
         if default:
             try:
                 p = self.paths.getpath(default)
                 if p:
                     return p.rawloc
             except error.RepoError:
                 pass
 
         return loc
 
     @util.propertycache
     def paths(self):
         return paths(self)
 
     @property
     def fout(self):
         return self._fout
 
     @fout.setter
     def fout(self, f):
         self._fout = f
         self._fmsgout, self._fmsgerr = _selectmsgdests(self)
 
     @property
     def ferr(self):
         return self._ferr
 
     @ferr.setter
     def ferr(self, f):
         self._ferr = f
         self._fmsgout, self._fmsgerr = _selectmsgdests(self)
 
     @property
     def fin(self):
         return self._fin
 
     @fin.setter
     def fin(self, f):
         self._fin = f
 
     @property
     def fmsg(self):
         """Stream dedicated for status/error messages; may be None if
         fout/ferr are used"""
         return self._fmsg
 
     @fmsg.setter
     def fmsg(self, f):
         self._fmsg = f
         self._fmsgout, self._fmsgerr = _selectmsgdests(self)
 
     def pushbuffer(self, error=False, subproc=False, labeled=False):
         """install a buffer to capture standard output of the ui object
 
         If error is True, the error output will be captured too.
 
         If subproc is True, output from subprocesses (typically hooks) will be
         captured too.
 
         If labeled is True, any labels associated with buffered
         output will be handled. By default, this has no effect
         on the output returned, but extensions and GUI tools may
         handle this argument and returned styled output. If output
         is being buffered so it can be captured and parsed or
         processed, labeled should not be set to True.
         """
         self._buffers.append([])
         self._bufferstates.append((error, subproc, labeled))
         self._bufferapplylabels = labeled
 
     def popbuffer(self):
         '''pop the last buffer and return the buffered output'''
         self._bufferstates.pop()
         if self._bufferstates:
             self._bufferapplylabels = self._bufferstates[-1][2]
         else:
             self._bufferapplylabels = None
 
         return "".join(self._buffers.pop())
 
     def _isbuffered(self, dest):
         if dest is self._fout:
             return bool(self._buffers)
         if dest is self._ferr:
             return bool(self._bufferstates and self._bufferstates[-1][0])
         return False
 
     def canwritewithoutlabels(self):
         '''check if write skips the label'''
         if self._buffers and not self._bufferapplylabels:
             return True
         return self._colormode is None
 
     def canbatchlabeledwrites(self):
         '''check if write calls with labels are batchable'''
         # Windows color printing is special, see ``write``.
         return self._colormode != 'win32'
 
     def write(self, *args, **opts):
         '''write args to output
 
         By default, this method simply writes to the buffer or stdout.
         Color mode can be set on the UI class to have the output decorated
         with color modifier before being written to stdout.
 
         The color used is controlled by an optional keyword argument, "label".
         This should be a string containing label names separated by space.
         Label names take the form of "topic.type". For example, ui.debug()
         issues a label of "ui.debug".
 
         When labeling output for a specific command, a label of
         "cmdname.type" is recommended. For example, status issues
         a label of "status.modified" for modified files.
         '''
         self._write(self._fout, *args, **opts)
 
     def write_err(self, *args, **opts):
         self._write(self._ferr, *args, **opts)
 
     def _write(self, dest, *args, **opts):
         if self._isbuffered(dest):
             if self._bufferapplylabels:
                 label = opts.get(r'label', '')
                 self._buffers[-1].extend(self.label(a, label) for a in args)
             else:
                 self._buffers[-1].extend(args)
         else:
             self._writenobuf(dest, *args, **opts)
 
     def _writenobuf(self, dest, *args, **opts):
         self._progclear()
         msg = b''.join(args)
 
         # opencode timeblockedsection because this is a critical path
         starttime = util.timer()
         try:
             if dest is self._ferr and not getattr(self._fout, 'closed', False):
                 self._fout.flush()
             if getattr(dest, 'structured', False):
                 # channel for machine-readable output with metadata, where
                 # no extra colorization is necessary.
                 dest.write(msg, **opts)
             elif self._colormode == 'win32':
                 # windows color printing is its own can of crab, defer to
                 # the color module and that is it.
                 color.win32print(self, dest.write, msg, **opts)
             else:
                 if self._colormode is not None:
                     label = opts.get(r'label', '')
                     msg = self.label(msg, label)
                 dest.write(msg)
             # stderr may be buffered under win32 when redirected to files,
             # including stdout.
             if dest is self._ferr and not getattr(self._ferr, 'closed', False):
                 dest.flush()
         except IOError as err:
             if (dest is self._ferr
                 and err.errno in (errno.EPIPE, errno.EIO, errno.EBADF)):
                 # no way to report the error, so ignore it
                 return
             raise error.StdioError(err)
         finally:
             self._blockedtimes['stdio_blocked'] += \
                 (util.timer() - starttime) * 1000
 
     def _writemsg(self, dest, *args, **opts):
         _writemsgwith(self._write, dest, *args, **opts)
 
     def _writemsgnobuf(self, dest, *args, **opts):
         _writemsgwith(self._writenobuf, dest, *args, **opts)
 
     def flush(self):
         # opencode timeblockedsection because this is a critical path
         starttime = util.timer()
         try:
             try:
                 self._fout.flush()
             except IOError as err:
                 if err.errno not in (errno.EPIPE, errno.EIO, errno.EBADF):
                     raise error.StdioError(err)
             finally:
                 try:
                     self._ferr.flush()
                 except IOError as err:
                     if err.errno not in (errno.EPIPE, errno.EIO, errno.EBADF):
                         raise error.StdioError(err)
         finally:
             self._blockedtimes['stdio_blocked'] += \
                 (util.timer() - starttime) * 1000
 
     def _isatty(self, fh):
         if self.configbool('ui', 'nontty'):
             return False
         return procutil.isatty(fh)
 
     def disablepager(self):
         self._disablepager = True
 
     def pager(self, command):
         """Start a pager for subsequent command output.
 
         Commands which produce a long stream of output should call
         this function to activate the user's preferred pagination
         mechanism (which may be no pager). Calling this function
         precludes any future use of interactive functionality, such as
         prompting the user or activating curses.
 
         Args:
           command: The full, non-aliased name of the command. That is, "log"
                    not "history, "summary" not "summ", etc.
         """
         if (self._disablepager
             or self.pageractive):
             # how pager should do is already determined
             return
 
         if not command.startswith('internal-always-') and (
             # explicit --pager=on (= 'internal-always-' prefix) should
             # take precedence over disabling factors below
             command in self.configlist('pager', 'ignore')
             or not self.configbool('ui', 'paginate')
             or not self.configbool('pager', 'attend-' + command, True)
             or encoding.environ.get('TERM') == 'dumb'
             # TODO: if we want to allow HGPLAINEXCEPT=pager,
             # formatted() will need some adjustment.
             or not self.formatted()
             or self.plain()
             or self._buffers
             # TODO: expose debugger-enabled on the UI object
             or '--debugger' in pycompat.sysargv):
             # We only want to paginate if the ui appears to be
             # interactive, the user didn't say HGPLAIN or
             # HGPLAINEXCEPT=pager, and the user didn't specify --debug.
             return
 
         pagercmd = self.config('pager', 'pager', rcutil.fallbackpager)
         if not pagercmd:
             return
 
         pagerenv = {}
         for name, value in rcutil.defaultpagerenv().items():
             if name not in encoding.environ:
                 pagerenv[name] = value
 
         self.debug('starting pager for command %s\n' %
                    stringutil.pprint(command))
         self.flush()
 
         wasformatted = self.formatted()
         if util.safehasattr(signal, "SIGPIPE"):
             signal.signal(signal.SIGPIPE, _catchterm)
         if self._runpager(pagercmd, pagerenv):
             self.pageractive = True
             # Preserve the formatted-ness of the UI. This is important
             # because we mess with stdout, which might confuse
             # auto-detection of things being formatted.
             self.setconfig('ui', 'formatted', wasformatted, 'pager')
             self.setconfig('ui', 'interactive', False, 'pager')
 
             # If pagermode differs from color.mode, reconfigure color now that
             # pageractive is set.
             cm = self._colormode
             if cm != self.config('color', 'pagermode', cm):
                 color.setup(self)
         else:
             # If the pager can't be spawned in dispatch when --pager=on is
             # given, don't try again when the command runs, to avoid a duplicate
             # warning about a missing pager command.
             self.disablepager()
 
     def _runpager(self, command, env=None):
         """Actually start the pager and set up file descriptors.
 
         This is separate in part so that extensions (like chg) can
         override how a pager is invoked.
         """
         if command == 'cat':
             # Save ourselves some work.
             return False
         # If the command doesn't contain any of these characters, we
         # assume it's a binary and exec it directly. This means for
         # simple pager command configurations, we can degrade
         # gracefully and tell the user about their broken pager.
         shell = any(c in command for c in "|&;<>()$`\\\"' \t\n*?[#~=%")
 
         if pycompat.iswindows and not shell:
             # Window's built-in `more` cannot be invoked with shell=False, but
             # its `more.com` can.  Hide this implementation detail from the
             # user so we can also get sane bad PAGER behavior.  MSYS has
             # `more.exe`, so do a cmd.exe style resolution of the executable to
             # determine which one to use.
             fullcmd = procutil.findexe(command)
             if not fullcmd:
                 self.warn(_("missing pager command '%s', skipping pager\n")
                           % command)
                 return False
 
             command = fullcmd
 
         try:
             pager = subprocess.Popen(
                 procutil.tonativestr(command), shell=shell, bufsize=-1,
                 close_fds=procutil.closefds, stdin=subprocess.PIPE,
                 stdout=procutil.stdout, stderr=procutil.stderr,
                 env=procutil.tonativeenv(procutil.shellenviron(env)))
         except OSError as e:
             if e.errno == errno.ENOENT and not shell:
                 self.warn(_("missing pager command '%s', skipping pager\n")
                           % command)
                 return False
             raise
 
         # back up original file descriptors
         stdoutfd = os.dup(procutil.stdout.fileno())
         stderrfd = os.dup(procutil.stderr.fileno())
 
         os.dup2(pager.stdin.fileno(), procutil.stdout.fileno())
         if self._isatty(procutil.stderr):
             os.dup2(pager.stdin.fileno(), procutil.stderr.fileno())
 
         @self.atexit
         def killpager():
             if util.safehasattr(signal, "SIGINT"):
                 signal.signal(signal.SIGINT, signal.SIG_IGN)
             # restore original fds, closing pager.stdin copies in the process
             os.dup2(stdoutfd, procutil.stdout.fileno())
             os.dup2(stderrfd, procutil.stderr.fileno())
             pager.stdin.close()
             pager.wait()
 
         return True
 
     @property
     def _exithandlers(self):
         return _reqexithandlers
 
     def atexit(self, func, *args, **kwargs):
         '''register a function to run after dispatching a request
 
         Handlers do not stay registered across request boundaries.'''
         self._exithandlers.append((func, args, kwargs))
         return func
 
     def interface(self, feature):
         """what interface to use for interactive console features?
 
         The interface is controlled by the value of `ui.interface` but also by
         the value of feature-specific configuration. For example:
 
         ui.interface.histedit = text
         ui.interface.chunkselector = curses
 
         Here the features are "histedit" and "chunkselector".
 
         The configuration above means that the default interfaces for commands
         is curses, the interface for histedit is text and the interface for
         selecting chunk is crecord (the best curses interface available).
 
         Consider the following example:
         ui.interface = curses
         ui.interface.histedit = text
 
         Then histedit will use the text interface and chunkselector will use
         the default curses interface (crecord at the moment).
         """
         alldefaults = frozenset(["text", "curses"])
 
         featureinterfaces = {
             "chunkselector": [
                 "text",
                 "curses",
-            ]
+            ],
+            "histedit": [
+                "text",
+                "curses",
+            ],
         }
 
         # Feature-specific interface
         if feature not in featureinterfaces.keys():
             # Programming error, not user error
             raise ValueError("Unknown feature requested %s" % feature)
 
         availableinterfaces = frozenset(featureinterfaces[feature])
         if alldefaults > availableinterfaces:
             # Programming error, not user error. We need a use case to
             # define the right thing to do here.
             raise ValueError(
                 "Feature %s does not handle all default interfaces" %
                 feature)
 
         if self.plain() or encoding.environ.get('TERM') == 'dumb':
             return "text"
 
         # Default interface for all the features
         defaultinterface = "text"
         i = self.config("ui", "interface")
         if i in alldefaults:
             defaultinterface = i
 
         choseninterface = defaultinterface
         f = self.config("ui", "interface.%s" % feature)
         if f in availableinterfaces:
             choseninterface = f
 
         if i is not None and defaultinterface != i:
             if f is not None:
                 self.warn(_("invalid value for ui.interface: %s\n") %
                           (i,))
             else:
                 self.warn(_("invalid value for ui.interface: %s (using %s)\n") %
                          (i, choseninterface))
         if f is not None and choseninterface != f:
             self.warn(_("invalid value for ui.interface.%s: %s (using %s)\n") %
                       (feature, f, choseninterface))
 
         return choseninterface
 
     def interactive(self):
         '''is interactive input allowed?
 
         An interactive session is a session where input can be reasonably read
         from `sys.stdin'. If this function returns false, any attempt to read
         from stdin should fail with an error, unless a sensible default has been
         specified.
 
         Interactiveness is triggered by the value of the `ui.interactive'
         configuration variable or - if it is unset - when `sys.stdin' points
         to a terminal device.
 
         This function refers to input only; for output, see `ui.formatted()'.
         '''
         i = self.configbool("ui", "interactive")
         if i is None:
             # some environments replace stdin without implementing isatty
             # usually those are non-interactive
             return self._isatty(self._fin)
 
         return i
 
     def termwidth(self):
         '''how wide is the terminal in columns?
         '''
         if 'COLUMNS' in encoding.environ:
             try:
                 return int(encoding.environ['COLUMNS'])
             except ValueError:
                 pass
         return scmutil.termsize(self)[0]
 
     def formatted(self):
         '''should formatted output be used?
 
         It is often desirable to format the output to suite the output medium.
         Examples of this are truncating long lines or colorizing messages.
         However, this is not often not desirable when piping output into other
         utilities, e.g. `grep'.
 
         Formatted output is triggered by the value of the `ui.formatted'
         configuration variable or - if it is unset - when `sys.stdout' points
         to a terminal device. Please note that `ui.formatted' should be
         considered an implementation detail; it is not intended for use outside
         Mercurial or its extensions.
 
         This function refers to output only; for input, see `ui.interactive()'.
         This function always returns false when in plain mode, see `ui.plain()'.
         '''
         if self.plain():
             return False
 
         i = self.configbool("ui", "formatted")
         if i is None:
             # some environments replace stdout without implementing isatty
             # usually those are non-interactive
             return self._isatty(self._fout)
 
         return i
 
     def _readline(self):
         # Replacing stdin/stdout temporarily is a hard problem on Python 3
         # because they have to be text streams with *no buffering*. Instead,
         # we use rawinput() only if call_readline() will be invoked by
         # PyOS_Readline(), so no I/O will be made at Python layer.
         usereadline = (self._isatty(self._fin) and self._isatty(self._fout)
                        and procutil.isstdin(self._fin)
                        and procutil.isstdout(self._fout))
         if usereadline:
             try:
                 # magically add command line editing support, where
                 # available
                 import readline
                 # force demandimport to really load the module
                 readline.read_history_file
                 # windows sometimes raises something other than ImportError
             except Exception:
                 usereadline = False
 
         # prompt ' ' must exist; otherwise readline may delete entire line
         # - http://bugs.python.org/issue12833
         with self.timeblockedsection('stdio'):
             if usereadline:
                 line = encoding.strtolocal(pycompat.rawinput(r' '))
                 # When stdin is in binary mode on Windows, it can cause
                 # raw_input() to emit an extra trailing carriage return
                 if pycompat.oslinesep == b'\r\n' and line.endswith(b'\r'):
                     line = line[:-1]
             else:
                 self._fout.write(b' ')
                 self._fout.flush()
                 line = self._fin.readline()
                 if not line:
                     raise EOFError
                 line = line.rstrip(pycompat.oslinesep)
 
         return line
 
     def prompt(self, msg, default="y"):
         """Prompt user with msg, read response.
         If ui is not interactive, the default is returned.
         """
         return self._prompt(msg, default=default)
 
     def _prompt(self, msg, **opts):
         default = opts[r'default']
         if not self.interactive():
             self._writemsg(self._fmsgout, msg, ' ', type='prompt', **opts)
             self._writemsg(self._fmsgout, default or '', "\n",
                            type='promptecho')
             return default
         self._writemsgnobuf(self._fmsgout, msg, type='prompt', **opts)
         self.flush()
         try:
             r = self._readline()
             if not r:
                 r = default
             if self.configbool('ui', 'promptecho'):
                 self._writemsg(self._fmsgout, r, "\n", type='promptecho')
             return r
         except EOFError:
             raise error.ResponseExpected()
 
     @staticmethod
     def extractchoices(prompt):
         """Extract prompt message and list of choices from specified prompt.
 
         This returns tuple "(message, choices)", and "choices" is the
         list of tuple "(response character, text without &)".
 
         >>> ui.extractchoices(b"awake? $$ &Yes $$ &No")
         ('awake? ', [('y', 'Yes'), ('n', 'No')])
         >>> ui.extractchoices(b"line\\nbreak? $$ &Yes $$ &No")
         ('line\\nbreak? ', [('y', 'Yes'), ('n', 'No')])
         >>> ui.extractchoices(b"want lots of $$money$$?$$Ye&s$$N&o")
         ('want lots of $$money$$?', [('s', 'Yes'), ('o', 'No')])
         """
 
         # Sadly, the prompt string may have been built with a filename
         # containing "$$" so let's try to find the first valid-looking
         # prompt to start parsing. Sadly, we also can't rely on
         # choices containing spaces, ASCII, or basically anything
         # except an ampersand followed by a character.
         m = re.match(br'(?s)(.+?)\$\$([^\$]*&[^ \$].*)', prompt)
         msg = m.group(1)
         choices = [p.strip(' ') for p in m.group(2).split('$$')]
         def choicetuple(s):
             ampidx = s.index('&')
             return s[ampidx + 1:ampidx + 2].lower(), s.replace('&', '', 1)
         return (msg, [choicetuple(s) for s in choices])
 
     def promptchoice(self, prompt, default=0):
         """Prompt user with a message, read response, and ensure it matches
         one of the provided choices. The prompt is formatted as follows:
 
            "would you like fries with that (Yn)? $$ &Yes $$ &No"
 
         The index of the choice is returned. Responses are case
         insensitive. If ui is not interactive, the default is
         returned.
         """
 
         msg, choices = self.extractchoices(prompt)
         resps = [r for r, t in choices]
         while True:
             r = self._prompt(msg, default=resps[default], choices=choices)
             if r.lower() in resps:
                 return resps.index(r.lower())
             # TODO: shouldn't it be a warning?
             self._writemsg(self._fmsgout, _("unrecognized response\n"))
 
     def getpass(self, prompt=None, default=None):
         if not self.interactive():
             return default
         try:
             self._writemsg(self._fmsgerr, prompt or _('password: '),
                            type='prompt', password=True)
             # disable getpass() only if explicitly specified. it's still valid
             # to interact with tty even if fin is not a tty.
             with self.timeblockedsection('stdio'):
                 if self.configbool('ui', 'nontty'):
                     l = self._fin.readline()
                     if not l:
                         raise EOFError
                     return l.rstrip('\n')
                 else:
                     return getpass.getpass('')
         except EOFError:
             raise error.ResponseExpected()
 
     def status(self, *msg, **opts):
         '''write status message to output (if ui.quiet is False)
 
         This adds an output label of "ui.status".
         '''
         if not self.quiet:
             self._writemsg(self._fmsgout, type='status', *msg, **opts)
 
     def warn(self, *msg, **opts):
         '''write warning message to output (stderr)
 
         This adds an output label of "ui.warning".
         '''
         self._writemsg(self._fmsgerr, type='warning', *msg, **opts)
 
     def error(self, *msg, **opts):
         '''write error message to output (stderr)
 
         This adds an output label of "ui.error".
         '''
         self._writemsg(self._fmsgerr, type='error', *msg, **opts)
 
     def note(self, *msg, **opts):
         '''write note to output (if ui.verbose is True)
 
         This adds an output label of "ui.note".
         '''
         if self.verbose:
             self._writemsg(self._fmsgout, type='note', *msg, **opts)
 
     def debug(self, *msg, **opts):
         '''write debug message to output (if ui.debugflag is True)
 
         This adds an output label of "ui.debug".
         '''
         if self.debugflag:
             self._writemsg(self._fmsgout, type='debug', *msg, **opts)
 
     def edit(self, text, user, extra=None, editform=None, pending=None,
              repopath=None, action=None):
         if action is None:
             self.develwarn('action is None but will soon be a required '
                            'parameter to ui.edit()')
         extra_defaults = {
             'prefix': 'editor',
             'suffix': '.txt',
         }
         if extra is not None:
             if extra.get('suffix') is not None:
                 self.develwarn('extra.suffix is not None but will soon be '
                                'ignored by ui.edit()')
             extra_defaults.update(extra)
         extra = extra_defaults
 
         if action == 'diff':
             suffix = '.diff'
         elif action:
             suffix = '.%s.hg.txt' % action
         else:
             suffix = extra['suffix']
 
         rdir = None
         if self.configbool('experimental', 'editortmpinhg'):
             rdir = repopath
         (fd, name) = pycompat.mkstemp(prefix='hg-' + extra['prefix'] + '-',
                                       suffix=suffix,
                                       dir=rdir)
         try:
             f = os.fdopen(fd, r'wb')
             f.write(util.tonativeeol(text))
             f.close()
 
             environ = {'HGUSER': user}
             if 'transplant_source' in extra:
                 environ.update({'HGREVISION': hex(extra['transplant_source'])})
             for label in ('intermediate-source', 'source', 'rebase_source'):
                 if label in extra:
                     environ.update({'HGREVISION': extra[label]})
                     break
             if editform:
                 environ.update({'HGEDITFORM': editform})
             if pending:
                 environ.update({'HG_PENDING': pending})
 
             editor = self.geteditor()
 
             self.system("%s \"%s\"" % (editor, name),
                         environ=environ,
                         onerr=error.Abort, errprefix=_("edit failed"),
                         blockedtag='editor')
 
             f = open(name, r'rb')
             t = util.fromnativeeol(f.read())
             f.close()
         finally:
             os.unlink(name)
 
         return t
 
     def system(self, cmd, environ=None, cwd=None, onerr=None, errprefix=None,
                blockedtag=None):
         '''execute shell command with appropriate output stream. command
         output will be redirected if fout is not stdout.
 
         if command fails and onerr is None, return status, else raise onerr
         object as exception.
         '''
         if blockedtag is None:
             # Long cmds tend to be because of an absolute path on cmd. Keep
             # the tail end instead
             cmdsuffix = cmd.translate(None, _keepalnum)[-85:]
             blockedtag = 'unknown_system_' + cmdsuffix
         out = self._fout
         if any(s[1] for s in self._bufferstates):
             out = self
         with self.timeblockedsection(blockedtag):
             rc = self._runsystem(cmd, environ=environ, cwd=cwd, out=out)
         if rc and onerr:
             errmsg = '%s %s' % (os.path.basename(cmd.split(None, 1)[0]),
                                 procutil.explainexit(rc))
             if errprefix:
                 errmsg = '%s: %s' % (errprefix, errmsg)
             raise onerr(errmsg)
         return rc
 
     def _runsystem(self, cmd, environ, cwd, out):
         """actually execute the given shell command (can be overridden by
         extensions like chg)"""
         return procutil.system(cmd, environ=environ, cwd=cwd, out=out)
 
     def traceback(self, exc=None, force=False):
         '''print exception traceback if traceback printing enabled or forced.
         only to call in exception handler. returns true if traceback
         printed.'''
         if self.tracebackflag or force:
             if exc is None:
                 exc = sys.exc_info()
             cause = getattr(exc[1], 'cause', None)
 
             if cause is not None:
                 causetb = traceback.format_tb(cause[2])
                 exctb = traceback.format_tb(exc[2])
                 exconly = traceback.format_exception_only(cause[0], cause[1])
 
                 # exclude frame where 'exc' was chained and rethrown from exctb
                 self.write_err('Traceback (most recent call last):\n',
                                ''.join(exctb[:-1]),
                                ''.join(causetb),
                                ''.join(exconly))
             else:
                 output = traceback.format_exception(exc[0], exc[1], exc[2])
                 self.write_err(encoding.strtolocal(r''.join(output)))
         return self.tracebackflag or force
 
     def geteditor(self):
         '''return editor to use'''
         if pycompat.sysplatform == 'plan9':
             # vi is the MIPS instruction simulator on Plan 9. We
             # instead default to E to plumb commit messages to
             # avoid confusion.
             editor = 'E'
         else:
             editor = 'vi'
         return (encoding.environ.get("HGEDITOR") or
                 self.config("ui", "editor", editor))
 
     @util.propertycache
     def _progbar(self):
         """setup the progbar singleton to the ui object"""
         if (self.quiet or self.debugflag
                 or self.configbool('progress', 'disable')
                 or not progress.shouldprint(self)):
             return None
         return getprogbar(self)
 
     def _progclear(self):
         """clear progress bar output if any. use it before any output"""
         if not haveprogbar(): # nothing loaded yet
             return
         if self._progbar is not None and self._progbar.printed:
             self._progbar.clear()
 
     def progress(self, topic, pos, item="", unit="", total=None):
         '''show a progress message
 
         By default a textual progress bar will be displayed if an operation
         takes too long. 'topic' is the current operation, 'item' is a
         non-numeric marker of the current position (i.e. the currently
         in-process file), 'pos' is the current numeric position (i.e.
         revision, bytes, etc.), unit is a corresponding unit label,
         and total is the highest expected pos.
 
         Multiple nested topics may be active at a time.
 
         All topics should be marked closed by setting pos to None at
         termination.
         '''
         if getattr(self._fmsgerr, 'structured', False):
             # channel for machine-readable output with metadata, just send
             # raw information
             # TODO: consider porting some useful information (e.g. estimated
             # time) from progbar. we might want to support update delay to
             # reduce the cost of transferring progress messages.
             self._fmsgerr.write(None, type=b'progress', topic=topic, pos=pos,
                                 item=item, unit=unit, total=total)
         elif self._progbar is not None:
             self._progbar.progress(topic, pos, item=item, unit=unit,
                                    total=total)
         if pos is None or not self.configbool('progress', 'debug'):
             return
 
         if unit:
             unit = ' ' + unit
         if item:
             item = ' ' + item
 
         if total:
             pct = 100.0 * pos / total
             self.debug('%s:%s %d/%d%s (%4.2f%%)\n'
                      % (topic, item, pos, total, unit, pct))
         else:
             self.debug('%s:%s %d%s\n' % (topic, item, pos, unit))
 
     def makeprogress(self, topic, unit="", total=None):
         '''exists only so low-level modules won't need to import scmutil'''
         return scmutil.progress(self, topic, unit, total)
 
     def log(self, service, *msg, **opts):
         '''hook for logging facility extensions
 
         service should be a readily-identifiable subsystem, which will
         allow filtering.
 
         *msg should be a newline-terminated format string to log, and
         then any values to %-format into that format string.
 
         **opts currently has no defined meanings.
         '''
 
     def label(self, msg, label):
         '''style msg based on supplied label
 
         If some color mode is enabled, this will add the necessary control
         characters to apply such color. In addition, 'debug' color mode adds
         markup showing which label affects a piece of text.
 
         ui.write(s, 'label') is equivalent to
         ui.write(ui.label(s, 'label')).
         '''
         if self._colormode is not None:
             return color.colorlabel(self, msg, label)
         return msg
 
     def develwarn(self, msg, stacklevel=1, config=None):
         """issue a developer warning message
 
         Use 'stacklevel' to report the offender some layers further up in the
         stack.
         """
         if not self.configbool('devel', 'all-warnings'):
             if config is None or not self.configbool('devel', config):
                 return
         msg = 'devel-warn: ' + msg
         stacklevel += 1 # get in develwarn
         if self.tracebackflag:
             util.debugstacktrace(msg, stacklevel, self._ferr, self._fout)
             self.log('develwarn', '%s at:\n%s' %
                      (msg, ''.join(util.getstackframes(stacklevel))))
         else:
             curframe = inspect.currentframe()
             calframe = inspect.getouterframes(curframe, 2)
             fname, lineno, fmsg = calframe[stacklevel][1:4]
             fname, fmsg = pycompat.sysbytes(fname), pycompat.sysbytes(fmsg)
             self.write_err('%s at: %s:%d (%s)\n'
                            % (msg, fname, lineno, fmsg))
             self.log('develwarn', '%s at: %s:%d (%s)\n',
                      msg, fname, lineno, fmsg)
             curframe = calframe = None  # avoid cycles
 
     def deprecwarn(self, msg, version, stacklevel=2):
         """issue a deprecation warning
 
         - msg: message explaining what is deprecated and how to upgrade,
         - version: last version where the API will be supported,
         """
         if not (self.configbool('devel', 'all-warnings')
                 or self.configbool('devel', 'deprec-warn')):
             return
         msg += ("\n(compatibility will be dropped after Mercurial-%s,"
                 " update your code.)") % version
         self.develwarn(msg, stacklevel=stacklevel, config='deprec-warn')
 
     def exportableenviron(self):
         """The environment variables that are safe to export, e.g. through
         hgweb.
         """
         return self._exportableenviron
 
     @contextlib.contextmanager
     def configoverride(self, overrides, source=""):
         """Context manager for temporary config overrides
         `overrides` must be a dict of the following structure:
         {(section, name) : value}"""
         backups = {}
         try:
             for (section, name), value in overrides.items():
                 backups[(section, name)] = self.backupconfig(section, name)
                 self.setconfig(section, name, value, source)
             yield
         finally:
             for __, backup in backups.items():
                 self.restoreconfig(backup)
             # just restoring ui.quiet config to the previous value is not enough
             # as it does not update ui.quiet class member
             if ('ui', 'quiet') in overrides:
                 self.fixconfig(section='ui')
 
 class paths(dict):
     """Represents a collection of paths and their configs.
 
     Data is initially derived from ui instances and the config files they have
     loaded.
     """
     def __init__(self, ui):
         dict.__init__(self)
 
         for name, loc in ui.configitems('paths', ignoresub=True):
             # No location is the same as not existing.
             if not loc:
                 continue
             loc, sub = ui.configsuboptions('paths', name)
             self[name] = path(ui, name, rawloc=loc, suboptions=sub)
 
     def getpath(self, name, default=None):
         """Return a ``path`` from a string, falling back to default.
 
         ``name`` can be a named path or locations. Locations are filesystem
         paths or URIs.
 
         Returns None if ``name`` is not a registered path, a URI, or a local
         path to a repo.
         """
         # Only fall back to default if no path was requested.
         if name is None:
             if not default:
                 default = ()
             elif not isinstance(default, (tuple, list)):
                 default = (default,)
             for k in default:
                 try:
                     return self[k]
                 except KeyError:
                     continue
             return None
 
         # Most likely empty string.
         # This may need to raise in the future.
         if not name:
             return None
 
         try:
             return self[name]
         except KeyError:
             # Try to resolve as a local path or URI.
             try:
                 # We don't pass sub-options in, so no need to pass ui instance.
                 return path(None, None, rawloc=name)
             except ValueError:
                 raise error.RepoError(_('repository %s does not exist') %
                                         name)
 
 _pathsuboptions = {}
 
 def pathsuboption(option, attr):
     """Decorator used to declare a path sub-option.
 
     Arguments are the sub-option name and the attribute it should set on
     ``path`` instances.
 
     The decorated function will receive as arguments a ``ui`` instance,
     ``path`` instance, and the string value of this option from the config.
     The function should return the value that will be set on the ``path``
     instance.
 
     This decorator can be used to perform additional verification of
     sub-options and to change the type of sub-options.
     """
     def register(func):
         _pathsuboptions[option] = (attr, func)
         return func
     return register
 
 @pathsuboption('pushurl', 'pushloc')
 def pushurlpathoption(ui, path, value):
     u = util.url(value)
     # Actually require a URL.
     if not u.scheme:
         ui.warn(_('(paths.%s:pushurl not a URL; ignoring)\n') % path.name)
         return None
 
     # Don't support the #foo syntax in the push URL to declare branch to
     # push.
     if u.fragment:
         ui.warn(_('("#fragment" in paths.%s:pushurl not supported; '
                   'ignoring)\n') % path.name)
         u.fragment = None
 
     return bytes(u)
 
 @pathsuboption('pushrev', 'pushrev')
 def pushrevpathoption(ui, path, value):
     return value
 
 class path(object):
     """Represents an individual path and its configuration."""
 
     def __init__(self, ui, name, rawloc=None, suboptions=None):
         """Construct a path from its config options.
 
         ``ui`` is the ``ui`` instance the path is coming from.
         ``name`` is the symbolic name of the path.
         ``rawloc`` is the raw location, as defined in the config.
         ``pushloc`` is the raw locations pushes should be made to.
 
         If ``name`` is not defined, we require that the location be a) a local
         filesystem path with a .hg directory or b) a URL. If not,
         ``ValueError`` is raised.
         """
         if not rawloc:
             raise ValueError('rawloc must be defined')
 
         # Locations may define branches via syntax <base>#<branch>.
         u = util.url(rawloc)
         branch = None
         if u.fragment:
             branch = u.fragment
             u.fragment = None
 
         self.url = u
         self.branch = branch
 
         self.name = name
         self.rawloc = rawloc
         self.loc = '%s' % u
 
         # When given a raw location but not a symbolic name, validate the
         # location is valid.
         if not name and not u.scheme and not self._isvalidlocalpath(self.loc):
             raise ValueError('location is not a URL or path to a local '
                              'repo: %s' % rawloc)
 
         suboptions = suboptions or {}
 
         # Now process the sub-options. If a sub-option is registered, its
         # attribute will always be present. The value will be None if there
         # was no valid sub-option.
         for suboption, (attr, func) in _pathsuboptions.iteritems():
             if suboption not in suboptions:
                 setattr(self, attr, None)
                 continue
 
             value = func(ui, self, suboptions[suboption])
             setattr(self, attr, value)
 
     def _isvalidlocalpath(self, path):
         """Returns True if the given path is a potentially valid repository.
         This is its own function so that extensions can change the definition of
         'valid' in this case (like when pulling from a git repo into a hg
         one)."""
         return os.path.isdir(os.path.join(path, '.hg'))
 
     @property
     def suboptions(self):
         """Return sub-options and their values for this path.
 
         This is intended to be used for presentation purposes.
         """
         d = {}
         for subopt, (attr, _func) in _pathsuboptions.iteritems():
             value = getattr(self, attr)
             if value is not None:
                 d[subopt] = value
         return d
 
 # we instantiate one globally shared progress bar to avoid
 # competing progress bars when multiple UI objects get created
 _progresssingleton = None
 
 def getprogbar(ui):
     global _progresssingleton
     if _progresssingleton is None:
         # passing 'ui' object to the singleton is fishy,
         # this is how the extension used to work but feel free to rework it.
         _progresssingleton = progress.progbar(ui)
     return _progresssingleton
 
 def haveprogbar():
     return _progresssingleton is not None
 
 def _selectmsgdests(ui):
     name = ui.config(b'ui', b'message-output')
     if name == b'channel':
         if ui.fmsg:
             return ui.fmsg, ui.fmsg
         else:
             # fall back to ferr if channel isn't ready so that status/error
             # messages can be printed
             return ui.ferr, ui.ferr
     if name == b'stdio':
         return ui.fout, ui.ferr
     if name == b'stderr':
         return ui.ferr, ui.ferr
     raise error.Abort(b'invalid ui.message-output destination: %s' % name)
 
 def _writemsgwith(write, dest, *args, **opts):
     """Write ui message with the given ui._write*() function
 
     The specified message type is translated to 'ui.<type>' label if the dest
     isn't a structured channel, so that the message will be colorized.
     """
     # TODO: maybe change 'type' to a mandatory option
     if r'type' in opts and not getattr(dest, 'structured', False):
         opts[r'label'] = opts.get(r'label', '') + ' ui.%s' % opts.pop(r'type')
     write(dest, *args, **opts)