[PATCH 2 of 5] graphlog: add a way to test the 'topotier' function

[Pierre-Yves David]

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david at fb.com>
# Date 1415986679 0
#      Fri Nov 14 17:37:59 2014 +0000
# Node ID 7dd889a1feade274094952d4d2246d7190225c16
# Parent  06767ea27aca31cd1e65ccd32c22c45c1ebab83d
graphlog: add a way to test the 'topotier' function

We add an experimental config option to use the topological sorting. I first
tried to hook the 'topoiter' function in the 'sort' revset but this was useless
because graphlog enforce revision number sorting :(

As the goal is to advance on the topological iteration logic, I see this
experimental option as a good way to move forward.

We have to use turn the iterator into a list because the graphlog is apparently
not ready for pure iterator input yet.

diff --git a/mercurial/graphmod.py b/mercurial/graphmod.py
--- a/mercurial/graphmod.py
+++ b/mercurial/graphmod.py
@@ -185,10 +185,13 @@ def dagwalker(repo, revs):
 
     cl = repo.changelog
     lowestrev = revs.min()
     gpcache = {}
 
+    if repo.ui.configbool('experimental', 'graph-topological', False):
+        revs = list(topoiter(revs, repo.changelog.parentrevs))
+
     for rev in revs:
         ctx = repo[rev]
         parents = sorted(set([p.rev() for p in ctx.parents()
                               if p.rev() in revs]))
         mpars = [p.rev() for p in ctx.parents() if
diff --git a/tests/test-glog-topological.t b/tests/test-glog-topological.t
new file mode 100644
--- /dev/null
+++ b/tests/test-glog-topological.t
@@ -0,0 +1,58 @@
+This test file aims at test topological iteration and the various configuration it can has.
+
+  $ cat >> $HGRCPATH << EOF
+  > [ui]
+  > logtemplate={rev}\n
+  > EOF
+
+On this simple example, all topological branch are displayed in turn until we
+can finally display 0. this implies skipping from 8 to 3 and coming back to 7
+later.
+
+  $ hg init test01
+  $ cd test01
+  $ hg unbundle $TESTDIR/bundles/remote.hg
+  adding changesets
+  adding manifests
+  adding file changes
+  added 9 changesets with 7 changes to 4 files (+1 heads)
+  (run 'hg heads' to see heads, 'hg merge' to merge)
+
+  $ hg log -G
+  o  8
+  |
+  | o  7
+  | |
+  | o  6
+  | |
+  | o  5
+  | |
+  | o  4
+  | |
+  o |  3
+  | |
+  o |  2
+  | |
+  o |  1
+  |/
+  o  0
+  
+  $ hg --config experimental.graph-topological=1 log -G
+  o  8
+  |
+  o  3
+  |
+  o  2
+  |
+  o  1
+  |
+  | o  7
+  | |
+  | o  6
+  | |
+  | o  5
+  | |
+  | o  4
+  |/
+  o  0
+