--- a/mercurial/revset.py Sat Jul 08 13:07:59 2017 +0900
+++ b/mercurial/revset.py Sat Jul 08 13:15:17 2017 +0900
@@ -155,7 +155,23 @@
raise error.ParseError(_("can't use a relation in this context"))
def relsubscriptset(repo, subset, x, y, z, order):
- raise error.ParseError(_("can't use a relation in this context"))
+ # this is pretty basic implementation of 'x#y[z]' operator, still
+ # experimental so undocumented. see the wiki for further ideas.
+ # https://www.mercurial-scm.org/wiki/RevsetOperatorPlan
+ rel = getsymbol(y)
+ n = getinteger(z, _("relation subscript must be an integer"))
+
+ # TODO: perhaps this should be a table of relation functions
+ if rel in ('g', 'generations'):
+ # TODO: support range, rewrite tests, and drop startdepth argument
+ # from ancestors() and descendants() predicates
+ if n <= 0:
+ n = -n
+ return _ancestors(repo, subset, x, startdepth=n, stopdepth=n + 1)
+ else:
+ return _descendants(repo, subset, x, startdepth=n, stopdepth=n + 1)
+
+ raise error.UnknownIdentifier(rel, ['generations'])
def subscriptset(repo, subset, x, y, order):
raise error.ParseError(_("can't use a subscript in this context"))