Add OsuJsonDecoder

osu.Game/Beatmaps/Formats/OsuJsonDecoder.cs

@@ -0,0 +1,25 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System.IO;
+using osu.Game.IO.Serialization;
+
+namespace osu.Game.Beatmaps.Formats
+{
+    public class OsuJsonDecoder : BeatmapDecoder
+    {
+        public static void Register()
+        {
+            AddDecoder<OsuJsonDecoder>("{");
+        }
+
+        protected override void ParseFile(StreamReader stream, Beatmap beatmap)
+        {
+            stream.BaseStream.Position = 0;
+            stream.DiscardBufferedData();
+
+            string fullText = stream.ReadToEnd();
+            fullText.DeserializeInto(beatmap);
+        }
+    }
+}