# HG changeset patch
# User Boris Feld <boris.feld@octobus.net>
# Date 2017-06-26 13:46:24
# Node ID 4ecc6047d45f9ca18f7d13347fa8d1652bbaaad6
# Parent  4d780d510b44ad2ae3bb39f3816c95598704d1eb

log: add an extension hook-point in changeset_printer

Extensions sometimes wants to add other information in the default log output
format (when no templating is used).

Add an empty function named '_exthook' for easing the extension life.
Extensions will be able to wrap this function and collaborate to display
additional information.

Exthook is called after displaying troubles and just before displaying the
files, extra and description.

Add a new test file to test it and not pollute other test files.

diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -1411,6 +1411,8 @@ class changeset_printer(object):
             self.ui.write(_("trouble:     %s\n") % ', '.join(ctx.troubles()),
                           label='log.trouble')
 
+        self._exthook(ctx)
+
         if self.ui.debugflag:
             files = ctx.p1().status(ctx)[:3]
             for key, value in zip([# i18n: column positioning for "hg log"
@@ -1457,6 +1459,11 @@ class changeset_printer(object):
 
         self.showpatch(ctx, matchfn)
 
+    def _exthook(self, ctx):
+        '''empty method used by extension as a hook point
+        '''
+        pass
+
     def showpatch(self, ctx, matchfn):
         if not matchfn:
             matchfn = self.matchfn
diff --git a/tests/test-log-exthook.t b/tests/test-log-exthook.t
new file mode 100644
--- /dev/null
+++ b/tests/test-log-exthook.t
@@ -0,0 +1,56 @@
+Test hg log changeset printer external hook
+-------------------------------------------
+
+  $ cat > $TESTTMP/logexthook.py <<EOF
+  > from mercurial import repair, commands
+  > from mercurial import cmdutil
+  > def rot13description(self, ctx):
+  >     summary = "summary".encode('rot13')
+  >     description = ctx.description().strip().splitlines()[0].encode('rot13')
+  >     self.ui.write("%s:     %s\n" % (summary, description))
+  > def reposetup(ui, repo):
+  >     cmdutil.changeset_printer._exthook = rot13description
+  > EOF
+
+Prepare the repository
+
+  $ hg init empty
+  $ cd empty
+  $ touch ROOT
+  $ hg commit -A -m "Root" ROOT
+
+  $ touch a b c
+  $ hg commit -A -m "Add A, B, C" a b c
+
+Check the log
+
+  $ hg log --config extensions.t=$TESTTMP/logexthook.py
+  changeset:   1:70fc82b23320
+  tag:         tip
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  fhzznel:     Nqq N, O, P
+  summary:     Add A, B, C
+  
+  changeset:   0:b00443a54871
+  user:        test
+  date:        Thu Jan 01 00:00:00 1970 +0000
+  fhzznel:     Ebbg
+  summary:     Root
+  
+Check that exthook is working with graph log too
+
+  $ hg log -G --config extensions.t=$TESTTMP/logexthook.py
+  @  changeset:   1:70fc82b23320
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  fhzznel:     Nqq N, O, P
+  |  summary:     Add A, B, C
+  |
+  o  changeset:   0:b00443a54871
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     fhzznel:     Ebbg
+     summary:     Root
+