reflog-walk: refactor the branch@{num} formatting

We'll use the same output in an upcoming commit, so refactor its
formatting (which was duplicated anyway) into a separate function.

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

reflog-walk.c

@@ -241,36 +241,46 @@ void fake_reflog_parent(struct reflog_walk_info *info, struct commit *commit)
 	commit->object.flags &= ~(ADDED | SEEN | SHOWN);
 }
 
-void show_reflog_message(struct reflog_walk_info *info, int oneline,
+void get_reflog_selector(struct strbuf *sb,
+			 struct reflog_walk_info *reflog_info,
+			 enum date_mode dmode)
+{
+	struct commit_reflog *commit_reflog = reflog_info->last_commit_reflog;
+	struct reflog_info *info;
+
+	if (!commit_reflog)
+		return;
+
+	strbuf_addf(sb, "%s@{", commit_reflog->reflogs->ref);
+	if (commit_reflog->flag || dmode) {
+		info = &commit_reflog->reflogs->items[commit_reflog->recno+1];
+		strbuf_addstr(sb, show_date(info->timestamp, info->tz, dmode));
+	} else {
+		strbuf_addf(sb, "%d", commit_reflog->reflogs->nr
+			    - 2 - commit_reflog->recno);
+	}
+
+	strbuf_addch(sb, '}');
+}
+
+void show_reflog_message(struct reflog_walk_info *reflog_info, int oneline,
 	enum date_mode dmode)
 {
-	if (info && info->last_commit_reflog) {
-		struct commit_reflog *commit_reflog = info->last_commit_reflog;
+	if (reflog_info && reflog_info->last_commit_reflog) {
+		struct commit_reflog *commit_reflog = reflog_info->last_commit_reflog;
 		struct reflog_info *info;
+		struct strbuf selector = STRBUF_INIT;
 
 		info = &commit_reflog->reflogs->items[commit_reflog->recno+1];
+		get_reflog_selector(&selector, reflog_info, dmode);
 		if (oneline) {
-			printf("%s@{", commit_reflog->reflogs->ref);
-			if (commit_reflog->flag || dmode)
-				printf("%s", show_date(info->timestamp,
-						       info->tz,
-						       dmode));
-			else
-				printf("%d", commit_reflog->reflogs->nr
-				       - 2 - commit_reflog->recno);
-			printf("}: %s", info->message);
+			printf("%s: %s", selector.buf, info->message);
 		}
 		else {
-			printf("Reflog: %s@{", commit_reflog->reflogs->ref);
-			if (commit_reflog->flag || dmode)
-				printf("%s", show_date(info->timestamp,
-							info->tz,
-							dmode));
-			else
-				printf("%d", commit_reflog->reflogs->nr
-				       - 2 - commit_reflog->recno);
-			printf("} (%s)\nReflog message: %s",
-			       info->email, info->message);
+			printf("Reflog: %s (%s)\nReflog message: %s",
+			       selector.buf, info->email, info->message);
 		}
+
+		strbuf_release(&selector);
 	}
 }