Add OsuJsonDecoder

osu.Game/Beatmaps/Formats/BeatmapDecoder.cs

@@ -14,6 +14,7 @@ namespace osu.Game.Beatmaps.Formats
         static BeatmapDecoder()
         {
             OsuLegacyDecoder.Register();
+            OsuJsonDecoder.Register();
         }
 
         public static BeatmapDecoder GetDecoder(StreamReader stream)
@@ -27,7 +28,16 @@ namespace osu.Game.Beatmaps.Formats
 
             if (line == null || !decoders.ContainsKey(line))
                 throw new IOException(@"Unknown file format");
-            return (BeatmapDecoder)Activator.CreateInstance(decoders[line], line);
+
+            try
+            {
+                return (BeatmapDecoder)Activator.CreateInstance(decoders[line], line);
+            }
+            catch
+            {
+                // As a default case, try a parameterless constructor
+                return (BeatmapDecoder)Activator.CreateInstance(decoders[line]);
+            }
         }
 
         protected static void AddDecoder<T>(string magic) where T : BeatmapDecoder

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);
+        }
+    }
+}

osu.Game/osu.Game.csproj

@@ -266,6 +266,7 @@
     <Compile Include="Beatmaps\Drawables\BeatmapPanel.cs" />
     <Compile Include="Beatmaps\Drawables\BeatmapSetCover.cs" />
     <Compile Include="Beatmaps\Drawables\BeatmapSetHeader.cs" />
+    <Compile Include="Beatmaps\Formats\OsuJsonDecoder.cs" />
     <Compile Include="Database\DatabaseContextFactory.cs" />
     <Compile Include="Database\IHasPrimaryKey.cs" />
     <Compile Include="Graphics\UserInterface\HoverClickSounds.cs" />