trailer: add interface for iterating over commit trailers

The trailer code knows how to parse out the trailers and re-format them,
but there's no easy way to iterate over the trailers (you can use
trailer_info, but you have to then do a bunch of extra parsing).

Let's add an iteration interface that makes this easy to do.

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

1 files changed, 36 insertions, 0 deletions

diff --git a/trailer.c b/trailer.c
index 0c414f2fed..deee6551ce 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1185,3 +1185,39 @@ void format_trailers_from_commit(struct strbuf *out, const char *msg,
 	format_trailer_info(out, &info, opts);
 	trailer_info_release(&info);
 }
+
+void trailer_iterator_init(struct trailer_iterator *iter, const char *msg)
+{
+	struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
+	strbuf_init(&iter->key, 0);
+	strbuf_init(&iter->val, 0);
+	opts.no_divider = 1;
+	trailer_info_get(&iter->info, msg, &opts);
+	iter->cur = 0;
+}
+
+int trailer_iterator_advance(struct trailer_iterator *iter)
+{
+	while (iter->cur < iter->info.trailer_nr) {
+		char *trailer = iter->info.trailers[iter->cur++];
+		int separator_pos = find_separator(trailer, separators);
+
+		if (separator_pos < 1)
+			continue; /* not a real trailer */
+
+		strbuf_reset(&iter->key);
+		strbuf_reset(&iter->val);
+		parse_trailer(&iter->key, &iter->val, NULL,
+			      trailer, separator_pos);
+		unfold_value(&iter->val);
+		return 1;
+	}
+	return 0;
+}
+
+void trailer_iterator_release(struct trailer_iterator *iter)
+{
+	trailer_info_release(&iter->info);
+	strbuf_release(&iter->val);
+	strbuf_release(&iter->key);
+}