hgext/children.py

dirstate: skip step 3 in walk if nothing new will match

nothing will ever match on match.never
nothing new will match on match.exact (all found in step 1)
nothing new will match on match.match when
  there is no pattern and
  there is no direcory in pats

# Mercurial extension to provide the 'hg children' command
#
# Copyright 2007 by Intevation GmbH <[e-mail]>
#
# Author(s):
# Thomas Arendsen Hein <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2, incorporated herein by reference.

from mercurial import cmdutil
from mercurial.commands import templateopts
from mercurial.i18n import _


def children(ui, repo, file_=None, **opts):
    """show the children of the given or working directory revision

    Print the children of the working directory's revisions. If a
    revision is given via -r/--rev, the children of that revision will
    be printed. If a file argument is given, revision in which the
    file was last changed (after the working directory revision or the
    argument to --rev if given) is printed.
    """
    rev = opts.get('rev')
    if file_:
        ctx = repo.filectx(file_, changeid=rev)
    else:
        ctx = repo[rev]

    displayer = cmdutil.show_changeset(ui, repo, opts)
    for cctx in ctx.children():
        displayer.show(cctx)


cmdtable = {
    "children":
        (children,
         [('r', 'rev', '', _('show children of the specified revision')),
         ] + templateopts,
         _('hg children [-r REV] [FILE]')),
}