histedit: constant-ify the constraints list

Used a class as a namespace, and then wired up a classmethod to return
all known constraints. I'm mostly happy with this, even though it's
kind of weird for hg.

hgext/histedit.py

@@ -1,1312 +1,1317 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
  #  d, drop = remove commit from history
  #  m, mess = edit commit message without changing commit content
  #
 
 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
  #  d, drop = remove commit from history
  #  m, mess = edit commit message without changing commit content
  #
 
 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. 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. You'll be prompted for a
 new commit message, but the default commit message will be the
 original message for the ``edit`` ed revision.
 
 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.
 
 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
 """
 
 try:
     import cPickle as pickle
     pickle.dump # import now
 except ImportError:
     import pickle
 import errno
 import os
 import sys
 
 from mercurial import bundle2
 from mercurial import cmdutil
 from mercurial import discovery
 from mercurial import error
 from mercurial import copies
 from mercurial import context
 from mercurial import exchange
 from mercurial import extensions
 from mercurial import hg
 from mercurial import node
 from mercurial import repair
 from mercurial import scmutil
 from mercurial import util
 from mercurial import obsolete
 from mercurial import merge as mergemod
 from mercurial.lock import release
 from mercurial.i18n import _
 
 cmdtable = {}
 command = cmdutil.command(cmdtable)
 
+class _constraints(object):
+    # aborts if there are multiple rules for one node
+    noduplicates = 'noduplicates'
+    # abort if the node does belong to edited stack
+    forceother = 'forceother'
+    # abort if the node doesn't belong to edited stack
+    noother = 'noother'
+
+    @classmethod
+    def known(cls):
+        return set([v for k, v in cls.__dict__.items() if k[0] != '_'])
+
 # Note for extension authors: ONLY specify testedwith = 'internal' 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 = 'internal'
 
 # i18n: command names and abbreviations must remain untranslated
 editcomment = _("""# Edit history between %s and %s
 #
 # 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
 #  d, drop = remove commit from history
 #  m, mess = edit commit message without changing commit content
 #
 """)
 
 class histeditstate(object):
     def __init__(self, repo, parentctxnode=None, rules=None, keep=None,
             topmost=None, replacements=None, lock=None, wlock=None):
         self.repo = repo
         self.rules = rules
         self.keep = keep
         self.topmost = topmost
         self.parentctxnode = parentctxnode
         self.lock = lock
         self.wlock = wlock
         self.backupfile = None
         if replacements is None:
             self.replacements = []
         else:
             self.replacements = replacements
 
     def read(self):
         """Load histedit state from disk and set fields appropriately."""
         try:
             fp = self.repo.vfs('histedit-state', 'r')
         except IOError as err:
             if err.errno != errno.ENOENT:
                 raise
             raise error.Abort(_('no histedit in progress'))
 
         try:
             data = pickle.load(fp)
             parentctxnode, rules, keep, topmost, replacements = data
             backupfile = None
         except pickle.UnpicklingError:
             data = self._load()
             parentctxnode, rules, keep, topmost, replacements, backupfile = data
 
         self.parentctxnode = parentctxnode
         self.rules = rules
         self.keep = keep
         self.topmost = topmost
         self.replacements = replacements
         self.backupfile = backupfile
 
     def write(self):
         fp = self.repo.vfs('histedit-state', 'w')
         fp.write('v1\n')
         fp.write('%s\n' % node.hex(self.parentctxnode))
         fp.write('%s\n' % node.hex(self.topmost))
         fp.write('%s\n' % self.keep)
         fp.write('%d\n' % len(self.rules))
         for rule in self.rules:
             fp.write('%s\n' % rule[0]) # action
             fp.write('%s\n' % rule[1]) # remainder
         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)
         fp.close()
 
     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 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 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.
         """
         repo = state.repo
         rulehash = rule.strip().split(' ', 1)[0]
         try:
             node = repo[rulehash].node()
         except error.RepoError:
             raise error.Abort(_('unknown changeset %s listed') % rulehash[:12])
         return cls(state, node)
 
     def constraints(self):
         """Return a set of constrains that this action should be verified for
-
-           Available constraints:
-               noduplicates - aborts if there are multiple rules for one node
-               noother - abort if the node doesn't belong to edited stack
-               forceother - abort if the node does belong to edited stack
         """
-
-        return set(['noduplicates', 'noother'])
+        return set([_constraints.noduplicates, _constraints.noother])
 
     def nodetoverify(self):
         """Returns a node associated with the action that will be used for
         verification purposes.
 
         If the action doesn't correspond to node it should return None
         """
         return 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]
         hg.update(repo, self.state.parentctxnode)
         stats = applychanges(repo.ui, repo, rulectx, {})
         if stats and stats[3] > 0:
             raise error.InterventionRequired(_('Fix up the change and run '
                                             'hg histedit --continue'))
 
     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: empty changeset\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):
         phasebackup = repo.ui.backupconfig('phases', 'new-commit')
         try:
             repo.ui.setconfig('phases', 'new-commit', phasemin,
                               'histedit')
             extra = kwargs.get('extra', {}).copy()
             extra['histedit_source'] = src.hex()
             kwargs['extra'] = extra
             return repo.commit(**kwargs)
         finally:
             repo.ui.restoreconfig(phasebackup)
     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 edition
         cmdutil.revert(ui, repo, ctx, (wcpar, node.nullid), all=True)
         stats = None
     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, first, last, 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', first, last))
     if not ctxs:
         return None
     for c in ctxs:
         if not c.mutable():
             raise error.Abort(
                 _("cannot fold into public change %s") % node.short(c.node()))
     base = first.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, last)
 
     # prune files which were reverted by the updates
     def samefile(f):
         if f in last.manifest():
             a = last.filectx(f)
             if f in base.manifest():
                 b = base.filectx(f)
                 return (a.data() == b.data()
                         and a.flags() == b.flags())
             else:
                 return False
         else:
             return f not in base.manifest()
     files = [f for f in files if not samefile(f)]
     # commit version of these files as defined by head
     headmf = last.manifest()
     def filectxfn(repo, ctx, path):
         if path in headmf:
             fctx = last[path]
             flags = fctx.flags()
             mctx = context.memfilectx(repo,
                                       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 = first.description()
     user = commitopts.get('user')
     date = commitopts.get('date')
     extra = commitopts.get('extra')
 
     parents = (first.p1().node(), first.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'))
 
 
 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()
 
 class edit(histeditaction):
     def run(self):
         repo = self.repo
         rulectx = repo[self.node]
         hg.update(repo, self.state.parentctxnode)
         applychanges(repo.ui, repo, rulectx, {})
         raise error.InterventionRequired(
             _('Make changes as needed, you may commit or record as needed '
               'now.\nWhen you are finished, run hg histedit --continue to '
               'resume.'))
 
     def commiteditor(self):
         return cmdutil.getcommiteditor(edit=True, editform='histedit.edit')
 
 class fold(histeditaction):
     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,
                                                  parentctx))
         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 finishfold(self, ui, repo, ctx, oldctx, newnode, internalchanges):
         parent = ctx.parents()[0].node()
         hg.update(repo, parent)
         ### 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
         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
         phasebackup = repo.ui.backupconfig('phases', 'new-commit')
         try:
             phasemin = max(ctx.phase(), oldctx.phase())
             repo.ui.setconfig('phases', 'new-commit', phasemin, 'histedit')
             n = collapse(repo, ctx, repo[newnode], commitopts,
                          skipprompt=self.skipprompt())
         finally:
             repo.ui.restoreconfig(phasebackup)
         if n is None:
             return ctx, []
         hg.update(repo, n)
         replacements = [(oldctx.node(), (newnode,)),
                         (ctx.node(), (n,)),
                         (newnode, (n,)),
                        ]
         for ich in internalchanges:
             replacements.append((ich, (n,)))
         return repo[n], replacements
 
 class base(histeditaction):
     def constraints(self):
-        return set(['forceother'])
+        return set([_constraints.forceother])
 
     def run(self):
         if self.repo['.'].node() != self.node:
             mergemod.update(self.repo, self.node, False, True, False)
             #                                     branchmerge, force, partial)
         return self.continueclean()
 
     def continuedirty(self):
         abortdirty()
 
     def continueclean(self):
         basectx = self.repo['.']
         return basectx, []
 
 class _multifold(fold):
     """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.
     """
     def skipprompt(self):
         return True
 
 class rollup(fold):
     def mergedescs(self):
         return False
 
     def skipprompt(self):
         return True
 
 class drop(histeditaction):
     def run(self):
         parentctx = self.repo[self.state.parentctxnode]
         return parentctx, [(self.node, tuple())]
 
 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, revs = hg.parseurl(dest, None)[:2]
     ui.status(_('comparing with %s\n') % util.hidepassword(dest))
 
     revs, checkout = hg.addbranchrevs(repo, repo, revs, 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 1 < len(roots):
         msg = _('there are ambiguous outgoing revisions')
         hint = _('see "hg help histedit" for more detail')
         raise error.Abort(msg, hint=hint)
     return repo.lookup(roots[0])
 
 actiontable = {'p': pick,
                'pick': pick,
                'e': edit,
                'edit': edit,
                'f': fold,
                'fold': fold,
                '_multifold': _multifold,
                'r': rollup,
                'roll': rollup,
                'd': drop,
                'drop': drop,
                'm': message,
                'mess': message,
                }
 
 @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'))],
      _("ANCESTOR | --outgoing [URL]"))
 def histedit(ui, repo, *freeargs, **opts):
     """interactively edit changeset history
 
     This command edits changesets between ANCESTOR and the parent of
     the working directory.
 
     With --outgoing, this edits changesets not found in the
     destination repository. If URL of the destination is omitted, the
     'default-push' (or 'default') path will be used.
 
     For safety, this command is also aborted if there are ambiguous
     outgoing revisions which may confuse users: 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.
 
     Returns 0 on success, 1 if user intervention is required (not only
     for intentional "edit" command, but also for resolving unexpected
     conflicts).
     """
     state = histeditstate(repo)
     try:
         state.wlock = repo.wlock()
         state.lock = repo.lock()
         _histedit(ui, repo, state, *freeargs, **opts)
     finally:
         release(state.lock, state.wlock)
 
 def _histedit(ui, repo, state, *freeargs, **opts):
     # TODO only abort if we try and 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')
     cont = opts.get('continue')
     editplan = opts.get('edit_plan')
     abort = opts.get('abort')
     force = opts.get('force')
     rules = opts.get('commands', '')
     revs = opts.get('rev', [])
     goal = 'new' # This invocation goal, in new, continue, abort
     if force and not outg:
         raise error.Abort(_('--force only allowed with --outgoing'))
     if cont:
         if any((outg, abort, revs, freeargs, rules, editplan)):
             raise error.Abort(_('no arguments allowed with --continue'))
         goal = 'continue'
     elif abort:
         if any((outg, revs, freeargs, rules, editplan)):
             raise error.Abort(_('no arguments allowed with --abort'))
         goal = 'abort'
     elif editplan:
         if any((outg, revs, freeargs)):
             raise error.Abort(_('only --commands argument allowed with '
                                '--edit-plan'))
         goal = 'edit-plan'
     else:
         if os.path.exists(os.path.join(repo.path, 'histedit-state')):
             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:
                 # experimental config: histedit.defaultrev
                 histeditdefault = ui.config('histedit', 'defaultrev')
                 if histeditdefault:
                     revs.append(histeditdefault)
             if len(revs) != 1:
                 raise error.Abort(
                     _('histedit requires exactly one ancestor revision'))
 
 
     replacements = []
     state.keep = opts.get('keep', False)
     supportsmarkers = obsolete.isenabled(repo, obsolete.createmarkersopt)
 
     # rebuild state
     if goal == 'continue':
         state.read()
         state = bootstrapcontinue(ui, state, opts)
     elif goal == 'edit-plan':
         state.read()
         if not rules:
             comment = editcomment % (node.short(state.parentctxnode),
                                      node.short(state.topmost))
             rules = ruleeditor(repo, ui, state.rules, comment)
         else:
             if rules == '-':
                 f = sys.stdin
             else:
                 f = open(rules)
             rules = f.read()
             f.close()
         rules = [l for l in (r.strip() for r in rules.splitlines())
                  if l and not l.startswith('#')]
         rules = verifyrules(rules, state, [repo[c] for [_a, c] in state.rules])
         state.rules = rules
         state.write()
         return
     elif goal == 'abort':
         try:
             state.read()
             tmpnodes, leafs = newnodestoabort(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.join(state.backupfile)
                 f = hg.openpath(ui, backupfile)
                 gen = exchange.readbundle(ui, f, backupfile)
                 tr = repo.transaction('histedit.abort')
                 try:
                     if not isinstance(gen, bundle2.unbundle20):
                         gen.apply(repo, 'histedit', 'bundle:' + backupfile)
                     if isinstance(gen, bundle2.unbundle20):
                         bundle2.applybundle(repo, gen, tr,
                                             source='histedit',
                                             url='bundle:' + backupfile)
                     tr.close()
                 finally:
                     tr.release()
 
                 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)
             cleanupnode(ui, repo, 'created', tmpnodes)
             cleanupnode(ui, repo, 'temp', leafs)
         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()
         return
     else:
         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 = editcomment % (node.short(root), node.short(topmost))
             rules = ruleeditor(repo, ui, [['pick', c] for c in ctxs], comment)
         else:
             if rules == '-':
                 f = sys.stdin
             else:
                 f = open(rules)
             rules = f.read()
             f.close()
         rules = [l for l in (r.strip() for r in rules.splitlines())
                  if l and not l.startswith('#')]
         rules = verifyrules(rules, state, ctxs)
 
         parentctxnode = repo[root].parents()[0].node()
 
         state.parentctxnode = parentctxnode
         state.rules = rules
         state.topmost = topmost
         state.replacements = replacements
 
         # Create a backup so we can always abort completely.
         backupfile = None
         if not obsolete.isenabled(repo, obsolete.createmarkersopt):
             backupfile = repair._bundle(repo, [parentctxnode], [topmost], root,
                                         'histedit')
         state.backupfile = backupfile
 
     # preprocess rules so that we can hide inner folds from the user
     # and only show one editor
     rules = state.rules[:]
     for idx, ((action, ha), (nextact, unused)) in enumerate(
             zip(rules, rules[1:] + [(None, None)])):
         if action == 'fold' and nextact == 'fold':
             state.rules[idx] = '_multifold', ha
 
     while state.rules:
         state.write()
         action, ha = state.rules.pop(0)
         ui.debug('histedit: processing %s %s\n' % (action, ha[:12]))
         actobj = actiontable[action].fromrule(state, ha)
         parentctx, replacement_ = actobj.run()
         state.parentctxnode = parentctx.node()
         state.replacements.extend(replacement_)
     state.write()
 
     hg.update(repo, state.parentctxnode)
 
     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 supportsmarkers:
         # Only create markers if the temp nodes weren't already removed.
         obsolete.createmarkers(repo, ((repo[t],()) for t in sorted(tmpnodes)
                                        if t in repo))
     else:
         cleanupnode(ui, repo, 'temp', tmpnodes)
 
     if not state.keep:
         if mapping:
             movebookmarks(ui, repo, mapping, state.topmost, ntm)
             # TODO update mq state
         if supportsmarkers:
             markers = []
             # sort by revision number because it sound "right"
             for prec in sorted(mapping, key=repo.changelog.rev):
                 succs = mapping[prec]
                 markers.append((repo[prec],
                                 tuple(repo[s] for s in succs)))
             if markers:
                 obsolete.createmarkers(repo, markers)
         else:
             cleanupnode(ui, repo, 'replaced', mapping)
 
     state.clear()
     if os.path.exists(repo.sjoin('undo')):
         os.unlink(repo.sjoin('undo'))
 
 def bootstrapcontinue(ui, state, opts):
     repo = state.repo
     if state.rules:
         action, currentnode = state.rules.pop(0)
 
         actobj = actiontable[action].fromrule(state, currentnode)
 
         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."""
     ctxs = list(repo.set('%n::%n', old, new))
     if ctxs and not keep:
         if (not obsolete.isenabled(repo, obsolete.allowunstableopt) and
             repo.revs('(%ld::) - (%ld)', ctxs, ctxs)):
             raise error.Abort(_('cannot edit history that would orphan nodes'))
         if repo.revs('(%ld) and merge()', ctxs):
             raise error.Abort(_('cannot edit history that contains merges'))
         root = ctxs[0] # list is already sorted by repo.set
         if not root.mutable():
             raise error.Abort(_('cannot edit public changeset: %s') % root,
                              hint=_('see "hg help phases" for details'))
     return [c.node() for c in ctxs]
 
 def makedesc(repo, action, rev):
     """build a initial action line for a ctx
 
     line are in the form:
 
       <action> <hash> <rev> <summary>
     """
     ctx = repo[rev]
     summary = ''
     if ctx.description():
         summary = ctx.description().splitlines()[0]
     line = '%s %s %d %s' % (action, ctx, ctx.rev(), summary)
     # trim to 80 columns so it's not stupidly wide in my editor
     maxlen = repo.ui.configint('histedit', 'linelen', default=80)
     maxlen = max(maxlen, 22) # avoid truncating hash
     return util.ellipsis(line, maxlen)
 
 def ruleeditor(repo, ui, rules, editcomment=""):
     """open an editor to edit rules
 
     rules are in the format [ [act, ctx], ...] like in state.rules
     """
     rules = '\n'.join([makedesc(repo, act, rev) for [act, rev] in rules])
     rules += '\n\n'
     rules += editcomment
     rules = ui.edit(rules, ui.username())
 
     # Save edit rules in .hg/histedit-last-edit.txt in case
     # the user needs to ask for help after something
     # surprising happens.
     f = open(repo.join('histedit-last-edit.txt'), 'w')
     f.write(rules)
     f.close()
 
     return rules
 
 def verifyrules(rules, state, ctxs):
     """Verify that there exists exactly one edit rule per given changeset.
 
     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.
     """
-    known_constraints = ['noother', 'noduplicates']
     parsed = []
     expected = set(c.hex() for c in ctxs)
     seen = set()
     for r in rules:
         if ' ' not in r:
             raise error.Abort(_('malformed line "%s"') % r)
         verb, rest = r.split(' ', 1)
 
         if verb not in actiontable or verb.startswith('_'):
             raise error.Abort(_('unknown action "%s"') % verb)
         action = actiontable[verb].fromrule(state, rest)
         constraints = action.constraints()
         for constraint in constraints:
-            if constraint not in known_constraints:
+            if constraint not in _constraints.known():
                 error.Abort(_('unknown constraint "%s"') % constraint)
 
         nodetoverify = action.nodetoverify()
         if nodetoverify is not None:
             ha = node.hex(nodetoverify)
-            if 'noother' in constraints and ha not in expected:
+            if _constraints.noother in constraints and ha not in expected:
                 raise error.Abort(
                     _('may not use "%s" with changesets '
                       'other than the ones listed') % verb)
-            if 'forceother' in constraints and ha in expected:
+            if _constraints.forceother in constraints and ha in expected:
                 raise error.Abort(
                     _('may not use "%s" with changesets '
                       'within the edited list') % verb)
-            if 'noduplicates' in constraints and ha in seen:
+            if _constraints.noduplicates in constraints and ha in seen:
                 raise error.Abort(_('duplicated command for changeset %s') %
                         ha[:12])
             seen.add(ha)
             rest = ha
         parsed.append([verb, rest])
     missing = sorted(expected - seen)  # sort to stabilize output
     if missing:
         raise error.Abort(_('missing rules for changeset %s') %
                 missing[0][:12],
                 hint=_('do you want to use the drop action?'))
     return parsed
 
 def newnodestoabort(state):
     """process the list of replacements to return
 
     1) the list of final node
     2) the list of temporary node
 
     This meant to be used on abort as less data are required in this case.
     """
     replacements = state.replacements
     allsuccs = set()
     replaced = set()
     for rep in replacements:
         allsuccs.update(rep[1])
         replaced.add(rep[0])
     newnodes = allsuccs - replaced
     tmpnodes = allsuccs & replaced
     return newnodes, tmpnodes
 
 
 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 = 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 movebookmarks(ui, repo, mapping, oldtopmost, newtopmost):
     """Move bookmark from old to newly created node"""
     if not mapping:
         # if nothing got rewritten there is not purpose for this function
         return
     moves = []
     for bk, old in sorted(repo._bookmarks.iteritems()):
         if old == oldtopmost:
             # special case ensure bookmark stay on tip.
             #
             # 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.
             moves.append((bk, newtopmost))
             continue
         base = old
         new = mapping.get(base, None)
         if new is None:
             continue
         while not new:
             # base is killed, trying with parent
             base = repo[base].p1().node()
             new = mapping.get(base, (base,))
             # nothing to move
         moves.append((bk, new[-1]))
     if moves:
         lock = tr = None
         try:
             lock = repo.lock()
             tr = repo.transaction('histedit')
             marks = repo._bookmarks
             for mark, new in moves:
                 old = marks[mark]
                 ui.note(_('histedit: moving bookmarks %s from %s to %s\n')
                         % (mark, node.short(old), node.short(new)))
                 marks[mark] = new
             marks.recordchange(tr)
             tr.close()
         finally:
             release(tr, lock)
 
 def cleanupnode(ui, repo, name, nodes):
     """strip a group of nodes from the repository
 
     The set of node to strip may contains unknown nodes."""
     ui.debug('should strip %s nodes %s\n' %
              (name, ', '.join([node.short(n) for n in nodes])))
     lock = None
     try:
         lock = 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)]
         for c in roots:
             # We should process node in reverse order to strip tip most first.
             # but this trigger a bug in changegroup hook.
             # This would reduce bundle overhead
             repair.strip(ui, repo, c)
     finally:
         release(lock)
 
 def stripwrapper(orig, ui, repo, nodelist, *args, **kwargs):
     if isinstance(nodelist, str):
         nodelist = [nodelist]
     if os.path.exists(os.path.join(repo.path, 'histedit-state')):
         state = histeditstate(repo)
         state.read()
         histedit_nodes = set([repo[rulehash].node() for (action, rulehash)
                              in state.rules if rulehash in repo])
         strip_nodes = set([repo[n].node() for n in nodelist])
         common_nodes = histedit_nodes & strip_nodes
         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):
     if not os.path.exists(repo.join('histedit-state')):
         return
     state = histeditstate(repo)
     state.read()
     if state.rules:
         # i18n: column positioning for "hg summary"
         ui.write(_('hist:   %s (histedit --continue)\n') %
                  (ui.label(_('%d remaining'), 'histedit.remaining') %
                   len(state.rules)))
 
 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'")])
     if ui.configbool("experimental", "histeditng"):
         actiontable.update({'b': base, 'base': base})