diff tests/test-revset.t @ 33003:f63d111258da

revset: add startdepth limit to ancestors() as internal option

This is necessary to implement the set{gen} (set subscript) operator. For
example, set{-n} will be translated to ancestors(set, depth=n, startdepth=n).

https://www.mercurial-scm.org/wiki/RevsetOperatorPlan#ideas_from_mpm

The UI is undecided and I doubt if the startdepth option would be actually
useful, so the option is hidden for now. 'depth' could be extended to take
min:max range, in which case, integer depth should select a single generation.

  ancestors(set, depth=:y)  # scan up to y-th generation
  ancestors(set, depth=x:)  # skip until (x-1)-th generation
  ancestors(set, depth=x)   # select only x-th generation

Any ideas are welcomed.

  # reverse(ancestors(tip)) using hg repo
  3) 0.075951
  4) 0.076175

--- a/tests/test-revset.t	Sun Jun 18 00:22:41 2017 +0900
+++ b/tests/test-revset.t	Sun Jun 18 00:40:58 2017 +0900
@@ -903,6 +903,29 @@
   6
   5
 
+ (walk 2nd and 3rd ancestors)
+
+  $ log 'reverse(ancestors(7, depth=3, startdepth=2))'
+  5
+  4
+  3
+  2
+
+ (interleaved: '4' would be missing if higher-depth ancestors weren't scanned)
+
+  $ log 'reverse(ancestors(7+8, depth=2, startdepth=2))'
+  5
+  4
+  2
+
+ (note that 'ancestors(x, depth=y, startdepth=z)' does not identical to
+ 'ancestors(x, depth=y) - ancestors(x, depth=z-1)' because a node may have
+ multiple depths)
+
+  $ log 'reverse(ancestors(7+8, depth=2) - ancestors(7+8, depth=1))'
+  5
+  2
+
 test bad arguments passed to ancestors()
 
   $ log 'ancestors(., depth=-1)'