ref-filter.c: use trailer_opts to format trailers

Fill trailer_opts with "unfold" and "only" to match the sub-arguments
given to the "%(trailers)" atom. Then, let's use the filled trailer_opts
instance with 'format_trailers_from_commit' in order to format trailers
in the desired manner.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 68 insertions, 10 deletions

diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
index 1279b97330..4a2c851e6c 100644
--- a/Documentation/git-for-each-ref.txt
+++ b/Documentation/git-for-each-ref.txt
@@ -218,7 +218,10 @@ blank line.  The optional GPG signature is `contents:signature`.  The
 first `N` lines of the message is obtained using `contents:lines=N`.
 Additionally, the trailers as interpreted by linkgit:git-interpret-trailers[1]
 are obtained as `trailers` (or by using the historical alias
-`contents:trailers`).
+`contents:trailers`).  Non-trailer lines from the trailer block can be omitted
+with `trailers:only`. Whitespace-continuations can be removed from trailers so
+that each trailer appears on a line by itself with its full content with
+`trailers:unfold`. Both can be used together as `trailers:unfold,only`.
 
 For sorting purposes, fields with numeric values sort in numeric order
 (`objectsize`, `authordate`, `committerdate`, `creatordate`, `taggerdate`).
diff --git a/ref-filter.c b/ref-filter.c
index bc591f4f3d..43ed10a5e1 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -82,6 +82,7 @@ static struct used_atom {
 		} remote_ref;
 		struct {
 			enum { C_BARE, C_BODY, C_BODY_DEP, C_LINES, C_SIG, C_SUB, C_TRAILERS } option;
+			struct process_trailer_options trailer_opts;
 			unsigned int nlines;
 		} contents;
 		struct {
@@ -182,9 +183,23 @@ static void subject_atom_parser(const struct ref_format *format, struct used_ato
 
 static void trailers_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
 {
-	if (arg)
-		die(_("%%(trailers) does not take arguments"));
+	struct string_list params = STRING_LIST_INIT_DUP;
+	int i;
+
+	if (arg) {
+		string_list_split(&params, arg, ',', -1);
+		for (i = 0; i < params.nr; i++) {
+			const char *s = params.items[i].string;
+			if (!strcmp(s, "unfold"))
+				atom->u.contents.trailer_opts.unfold = 1;
+			else if (!strcmp(s, "only"))
+				atom->u.contents.trailer_opts.only_trailers = 1;
+			else
+				die(_("unknown %%(trailers) argument: %s"), s);
+		}
+	}
 	atom->u.contents.option = C_TRAILERS;
+	string_list_clear(&params, 0);
 }
 
 static void contents_atom_parser(const struct ref_format *format, struct used_atom *atom, const char *arg)
@@ -1042,7 +1057,7 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, struct obj
 			name++;
 		if (strcmp(name, "subject") &&
 		    strcmp(name, "body") &&
-		    strcmp(name, "trailers") &&
+		    !starts_with(name, "trailers") &&
 		    !starts_with(name, "contents"))
 			continue;
 		if (!subpos)
@@ -1067,13 +1082,12 @@ static void grab_sub_body_contents(struct atom_value *val, int deref, struct obj
 			append_lines(&s, subpos, contents_end - subpos, atom->u.contents.nlines);
 			v->s = strbuf_detach(&s, NULL);
 		} else if (atom->u.contents.option == C_TRAILERS) {
-			struct trailer_info info;
+			struct strbuf s = STRBUF_INIT;
 
-			/* Search for trailer info */
-			trailer_info_get(&info, subpos);
-			v->s = xmemdupz(info.trailer_start,
-					info.trailer_end - info.trailer_start);
-			trailer_info_release(&info);
+			/* Format the trailer info according to the trailer_opts given */
+			format_trailers_from_commit(&s, subpos, &atom->u.contents.trailer_opts);
+
+			v->s = strbuf_detach(&s, NULL);
 		} else if (atom->u.contents.option == C_BARE)
 			v->s = xstrdup(subpos);
 	}
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 39431908d5..64a0d9e170 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -610,6 +610,9 @@ Acked-by: A U Thor
   <author@example.com>
 EOF
 
+unfold () {
+	perl -0pe 's/\n\s+/ /g'
+}
 
 test_expect_success 'set up trailers for next test' '
 	echo "Some contents" > two &&
@@ -623,6 +626,44 @@ test_expect_success 'set up trailers for next test' '
 	EOF
 '
 
+test_expect_success '%(trailers:unfold) unfolds trailers' '
+	git for-each-ref --format="%(trailers:unfold)" refs/heads/master >actual &&
+	{
+		unfold <trailers
+		echo
+	} >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:only) shows only "key: value" trailers' '
+	git for-each-ref --format="%(trailers:only)" refs/heads/master >actual &&
+	{
+		grep -v patch.description <trailers &&
+		echo
+	} >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:only) and %(trailers:unfold) work together' '
+	git for-each-ref --format="%(trailers:only,unfold)" refs/heads/master >actual &&
+	git for-each-ref --format="%(trailers:unfold,only)" refs/heads/master >reverse &&
+	test_cmp actual reverse &&
+	{
+		grep -v patch.description <trailers | unfold &&
+		echo
+	} >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers) rejects unknown trailers arguments' '
+	# error message cannot be checked under i18n
+	cat >expect <<-EOF &&
+	fatal: unknown %(trailers) argument: unsupported
+	EOF
+	test_must_fail git for-each-ref --format="%(trailers:unsupported)" 2>actual &&
+	test_i18ncmp expect actual
+'
+
 test_expect_success 'basic atom: head contents:trailers' '
 	git for-each-ref --format="%(contents:trailers)" refs/heads/master >actual &&
 	sanitize_pgp <actual >actual.clean &&