PlaylistControl: move code to new method SeekSongOrder()

src/Playlist.hxx

@@ -234,6 +234,10 @@ public:
 
 	void PlayPrevious(PlayerControl &pc);
 
+	PlaylistResult SeekSongOrder(PlayerControl &pc,
+				     unsigned song_order,
+				     float seek_time);
+
 	PlaylistResult SeekSongPosition(PlayerControl &pc,
 					unsigned song_position,
 					float seek_time);

src/PlaylistControl.cxx

@@ -190,17 +190,12 @@ playlist::PlayPrevious(PlayerControl &pc)
 }
 
 PlaylistResult
-playlist::SeekSongPosition(PlayerControl &pc, unsigned song, float seek_time)
+playlist::SeekSongOrder(PlayerControl &pc, unsigned i, float seek_time)
 {
-	if (!queue.IsValidPosition(song))
-		return PlaylistResult::BAD_RANGE;
+	assert(queue.IsValidOrder(i));
 
 	const Song *queued_song = GetQueuedSong();
 
-	unsigned i = queue.random
-		? queue.PositionToOrder(song)
-		: song;
-
 	pc.ClearError();
 	stop_on_error = true;
 	error_count = 0;
@@ -229,6 +224,19 @@ playlist::SeekSongPosition(PlayerControl &pc, unsigned song, float seek_time)
 }
 
 PlaylistResult
+playlist::SeekSongPosition(PlayerControl &pc, unsigned song, float seek_time)
+{
+	if (!queue.IsValidPosition(song))
+		return PlaylistResult::BAD_RANGE;
+
+	unsigned i = queue.random
+		? queue.PositionToOrder(song)
+		: song;
+
+	return SeekSongOrder(pc, i, seek_time);
+}
+
+PlaylistResult
 playlist::SeekSongId(PlayerControl &pc, unsigned id, float seek_time)
 {
 	int song = queue.IdToPosition(id);