pretty: support normalization options for %(trailers)

The interpret-trailers command recently learned some options
to make its output easier to parse (for a caller whose only
interested in picking out the trailer values). But it's not
very efficient for asking for the trailers of many commits
in a single invocation.

We already have "%(trailers)" to do that, but it doesn't
know about unfolding or omitting non-trailers. Let's plumb
those options through, so you can have the best of both.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 12 insertions, 3 deletions

diff --git a/pretty.c b/pretty.c
index 33054e2..0e23fe3 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1044,6 +1044,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 	const struct commit *commit = c->commit;
 	const char *msg = c->message;
 	struct commit_list *p;
+	const char *arg;
 	int ch;
 
 	/* these are independent of the commit */
@@ -1262,10 +1263,18 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		return 1;
 	}
 
-	if (starts_with(placeholder, "(trailers)")) {
+	if (skip_prefix(placeholder, "(trailers", &arg)) {
 		struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
-		format_trailers_from_commit(sb, msg + c->subject_off, &opts);
-		return strlen("(trailers)");
+		while (*arg == ':') {
+			if (skip_prefix(arg, ":only", &arg))
+				opts.only_trailers = 1;
+			else if (skip_prefix(arg, ":unfold", &arg))
+				opts.unfold = 1;
+		}
+		if (*arg == ')') {
+			format_trailers_from_commit(sb, msg + c->subject_off, &opts);
+			return arg - placeholder + 1;
+		}
 	}
 
 	return 0;	/* unknown placeholder */