hgext/children.py

revlog: do revlog node->rev mapping by scanning

Now that the nodemap is lazily created, we use linear scanning back
from tip for typical node to rev mapping. Given that nodemap creation
is O(n log n) and revisions searched for are usually very close to
tip, this is often a significant performance win for a small number of
searches.

When we do end up building a nodemap for bulk lookups, the scanning
function is replaced with a hash lookup.

# 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 or any later version.

'''command to display child changesets'''

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)
    displayer.close()

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