Introduce new pretty formats %g[sdD] for reflog information

Add three new --pretty=format escapes:

  %gD  long  reflog descriptor (e.g. refs/stash@{0})
  %gd  short reflog descriptor (e.g. stash@{0})
  %gs  reflog message

This is achieved by passing down the reflog info, if any, inside the
pretty_print_context struct.

We use the newly refactored get_reflog_selector(), and give it some
extra functionality to extract a shortened ref.  The shortening is
cached inside the commit_reflogs struct; the only allocation of it
happens in read_complete_reflog(), where it is initialised to 0.  Also
add another helper get_reflog_message() for the message extraction.

Note that the --format="%h %gD: %gs" tests may not work in real
repositories, as the --pretty formatter doesn't know to leave away the
": " on the last commit in an incomplete (because git-gc removed the
old part) reflog.  This equivalence is nevertheless the main goal of
this patch.

Thanks to Jeff King for reviews, the %gd testcase and documentation.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index 59d1f6283b..7f61ab0e52 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -162,4 +162,22 @@ test_expect_success 'empty email' '
 	}
 '
 
+test_expect_success '"%h %gD: %gs" is same as git-reflog' '
+	git reflog >expect &&
+	git log -g --format="%h %gD: %gs" >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '"%h %gD: %gs" is same as git-reflog (with date)' '
+	git reflog --date=raw >expect &&
+	git log -g --format="%h %gD: %gs" --date=raw >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '%gd shortens ref name' '
+	echo "master@{0}" >expect.gd-short &&
+	git log -g -1 --format=%gd refs/heads/master >actual.gd-short &&
+	test_cmp expect.gd-short actual.gd-short
+'
+
 test_done