[PATCH 4 of 4] tags: unblock log-like template keywords and functions

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1528463783 -32400
#      Fri Jun 08 22:16:23 2018 +0900
# Node ID a7593c4a8c90d1182f21fa1b802ef1bea63a5c14
# Parent  e669b5c1e8a6d4d36d38b0f9c525cfd05846cec8
tags: unblock log-like template keywords and functions

It checks if ctx will be used in template since loading ctx per revision
could take extra 10-100msec in total depending on the number of tags.

diff --git a/mercurial/commands.py b/mercurial/commands.py
--- a/mercurial/commands.py
+++ b/mercurial/commands.py
@@ -5435,6 +5435,7 @@ def tags(ui, repo, **opts):
     opts = pycompat.byteskwargs(opts)
     ui.pager('tags')
     fm = ui.formatter('tags', opts)
+    contexthint = fm.contexthint('tag rev node type')
     hexfunc = fm.hexfunc
     tagtype = ""
 
@@ -5447,6 +5448,8 @@ def tags(ui, repo, **opts):
             tagtype = 'local'
 
         fm.startitem()
+        if 'ctx' in contexthint:
+            fm.context(ctx=repo[n])
         fm.write('tag', '%s', t, label=label)
         fmt = " " * (30 - encoding.colwidth(t)) + ' %5d:%s'
         fm.condwrite(not ui.quiet, 'rev node', fmt,
diff --git a/tests/test-tags.t b/tests/test-tags.t
--- a/tests/test-tags.t
+++ b/tests/test-tags.t
@@ -610,6 +610,27 @@ to remove a tag of type X which actually
   localtag                           0:bbd179dfa0a7 local
   globaltag                          0:bbd179dfa0a7
 
+Templated output:
+
+ (immediate values)
+
+  $ hg tags -T '{pad(tag, 9)} {rev}:{node} ({type})\n'
+  tip       1:a0b6fe111088c8c29567d3876cc466aa02927cae ()
+  localtag  0:bbd179dfa0a71671c253b3ae0aa1513b60d199fa (local)
+  globaltag 0:bbd179dfa0a71671c253b3ae0aa1513b60d199fa ()
+
+ (ctx/revcache dependent)
+
+  $ hg tags -T '{pad(tag, 9)} {rev} {file_adds}\n'
+  tip       1 .hgtags
+  localtag  0 foo
+  globaltag 0 foo
+
+  $ hg tags -T '{pad(tag, 9)} {rev}:{node|shortest}\n'
+  tip       1:a0b6
+  localtag  0:bbd1
+  globaltag 0:bbd1
+
 Test for issue3911
 
   $ hg tag -r 0 -l localtag2