[PATCH RFC] templater: switch ctx of list expression to rev of revset() (BC)

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1441984901 -32400
#      Sat Sep 12 00:21:41 2015 +0900
# Node ID c84a1730514ee190526966250110fe4cf740d8d1
# Parent  efebefe162e98aa79438daaea9aaee47c7de33bb
templater: switch ctx of list expression to rev of revset() (BC)

Because revset() function generates a list of revisions, it seems sensible
to switch the ctx as well where a list expression will be evaluated. I think
"{revset(...) % "..."}" expression wasn't considered well when it was
introduced at cda9d2b6beab.

diff --git a/mercurial/help/templates.txt b/mercurial/help/templates.txt
--- a/mercurial/help/templates.txt
+++ b/mercurial/help/templates.txt
@@ -106,6 +106,10 @@ Some sample command line templates:
 
    $ hg log --template "{ifcontains(rev, revset('.'), '@')}\n"
 
+- Show details of parent revisions::
+
+   $ hg log --template "{revset('parents(%d)', rev) % '{desc|firstline}\n'}"
+
 - Show only commit descriptions that start with "template"::
 
    $ hg log --template "{startswith('template', firstline(desc))}\n"
diff --git a/mercurial/templatekw.py b/mercurial/templatekw.py
--- a/mercurial/templatekw.py
+++ b/mercurial/templatekw.py
@@ -409,6 +409,14 @@ def showrev(repo, ctx, templ, **args):
     """:rev: Integer. The repository-local changeset revision number."""
     return scmutil.intrev(ctx.rev())
 
+def showrevslist(name, revs, **args):
+    """helper to generate a list of revisions in which a mapped template will
+    be evaluated"""
+    repo = args['ctx'].repo()
+    f = _showlist(name, revs, **args)
+    return _hybrid(f, revs,
+                   lambda x: {name: x, 'ctx': repo[x], 'revcache': {}})
+
 def showsubrepos(**args):
     """:subrepos: List of strings. Updated subrepositories in the changeset."""
     ctx = args['ctx']
diff --git a/mercurial/templater.py b/mercurial/templater.py
--- a/mercurial/templater.py
+++ b/mercurial/templater.py
@@ -575,7 +575,7 @@ def revset(context, mapping, args):
             revs = list([str(r) for r in revs])
             revsetcache[raw] = revs
 
-    return templatekw.showlist("revision", revs, **mapping)
+    return templatekw.showrevslist("revision", revs, **mapping)
 
 def rstdoc(context, mapping, args):
     """:rstdoc(text, style): Format ReStructuredText."""
diff --git a/tests/test-command-template.t b/tests/test-command-template.t
--- a/tests/test-command-template.t
+++ b/tests/test-command-template.t
@@ -3234,6 +3234,23 @@ Test revset function
   $ hg log --template '{revset("TIP"|lower)}\n' -l1
   2
 
+ a list template is evaluated for each item of revset
+
+  $ hg log -T '{rev} p: {revset("p1(%s)", rev) % "{rev}:{node|short}"}\n'
+  2 p: 1:bcc7ff960b8e
+  1 p: 0:f7769ec2ab97
+  0 p: 
+
+ therefore, 'revcache' should be recreated for each rev
+
+  $ hg log -T '{rev} {file_adds}\np {revset("p1(%s)", rev) % "{file_adds}"}\n'
+  2 aa b
+  p 
+  1 
+  p a
+  0 a
+  p 
+
 Test active bookmark templating
 
   $ hg book foo