Rework logic of TypedListConverter to remove extra converter for bindables

osu.Game/Beatmaps/ControlPoints/ControlPointGroup.cs

@@ -22,7 +22,7 @@ namespace osu.Game.Beatmaps.ControlPoints
         [JsonIgnore]
         public IBindableList<ControlPoint> ControlPoints => controlPoints;
 
-        [JsonConverter(typeof(BindableListConverter<ControlPoint>))]
+        [JsonConverter(typeof(TypedListConverter<ControlPoint>))]
         [JsonProperty]
         private readonly BindableList<ControlPoint> controlPoints = new BindableList<ControlPoint>();
 

osu.Game/IO/Serialization/Converters/BindableListConverter.cs

@@ -1,114 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-#nullable disable
-
-using System;
-using System.Collections.Generic;
-using Newtonsoft.Json;
-using Newtonsoft.Json.Linq;
-using osu.Framework.Bindables;
-using osu.Framework.Extensions.ObjectExtensions;
-
-namespace osu.Game.IO.Serialization.Converters
-{
-    /// <summary>
-    /// A type of <see cref="JsonConverter"/> that serializes an <see cref="IBindableList{T}"/> alongside
-    /// a lookup table for the types contained. The lookup table is used in deserialization to
-    /// reconstruct the objects with their original types.
-    /// </summary>
-    /// <typeparam name="T">The type of objects contained in the <see cref="IBindableList{T}"/> this attribute is attached to.</typeparam>
-    public class BindableListConverter<T> : JsonConverter<IBindableList<T>>
-    {
-        private readonly bool requiresTypeVersion;
-
-        /// <summary>
-        /// Constructs a new <see cref="BindableListConverter{T}"/>.
-        /// </summary>
-        // ReSharper disable once UnusedMember.Global
-        public BindableListConverter()
-        {
-        }
-
-        /// <summary>
-        /// Constructs a new <see cref="BindableListConverter{T}"/>.
-        /// </summary>
-        /// <param name="requiresTypeVersion">Whether the version of the type should be serialized.</param>
-        // ReSharper disable once UnusedMember.Global (Used in Beatmap)
-        public BindableListConverter(bool requiresTypeVersion)
-        {
-            this.requiresTypeVersion = requiresTypeVersion;
-        }
-
-        public override IBindableList<T> ReadJson(JsonReader reader, Type objectType, IBindableList<T> existingValue, bool hasExistingValue, JsonSerializer serializer)
-        {
-            var list = new BindableList<T>();
-
-            var obj = JObject.Load(reader);
-
-            if (obj["$lookup_table"] == null)
-                return list;
-
-            var lookupTable = serializer.Deserialize<List<string>>(obj["$lookup_table"].CreateReader());
-            if (lookupTable == null)
-                return list;
-
-            if (obj["$items"] == null)
-                return list;
-
-            foreach (var tok in obj["$items"])
-            {
-                var itemReader = tok.CreateReader();
-
-                if (tok["$type"] == null)
-                    throw new JsonException("Expected $type token.");
-
-                string typeName = lookupTable[(int)tok["$type"]];
-                var instance = (T)Activator.CreateInstance(Type.GetType(typeName).AsNonNull())!;
-                serializer.Populate(itemReader, instance);
-
-                list.Add(instance);
-            }
-
-            return list;
-        }
-
-        public override void WriteJson(JsonWriter writer, IBindableList<T> value, JsonSerializer serializer)
-        {
-            var lookupTable = new List<string>();
-            var objects = new List<JObject>();
-
-            foreach (var item in value)
-            {
-                var type = item.GetType();
-                var assemblyName = type.Assembly.GetName();
-
-                string typeString = $"{type.FullName}, {assemblyName.Name}";
-                if (requiresTypeVersion)
-                    typeString += $", {assemblyName.Version}";
-
-                int typeId = lookupTable.IndexOf(typeString);
-
-                if (typeId == -1)
-                {
-                    lookupTable.Add(typeString);
-                    typeId = lookupTable.Count - 1;
-                }
-
-                var itemObject = JObject.FromObject(item, serializer);
-                itemObject.AddFirst(new JProperty("$type", typeId));
-                objects.Add(itemObject);
-            }
-
-            writer.WriteStartObject();
-
-            writer.WritePropertyName("$lookup_table");
-            serializer.Serialize(writer, lookupTable);
-
-            writer.WritePropertyName("$items");
-            serializer.Serialize(writer, objects);
-
-            writer.WriteEndObject();
-        }
-    }
-}

osu.Game/IO/Serialization/Converters/TypedListConverter.cs

@@ -7,17 +7,18 @@ using System;
 using System.Collections.Generic;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
+using osu.Framework.Bindables;
 using osu.Framework.Extensions.ObjectExtensions;
 
 namespace osu.Game.IO.Serialization.Converters
 {
     /// <summary>
-    /// A type of <see cref="JsonConverter"/> that serializes an <see cref="IReadOnlyList{T}"/> alongside
+    /// A type of <see cref="JsonConverter"/> that serializes a list alongside
     /// a lookup table for the types contained. The lookup table is used in deserialization to
     /// reconstruct the objects with their original types.
     /// </summary>
-    /// <typeparam name="T">The type of objects contained in the <see cref="IReadOnlyList{T}"/> this attribute is attached to.</typeparam>
+    /// <typeparam name="T">The type of objects contained in the list this attribute is attached to.</typeparam>
-    public class TypedListConverter<T> : JsonConverter<IReadOnlyList<T>>
+    public class TypedListConverter<T> : JsonConverter
     {
         private readonly bool requiresTypeVersion;
 
@@ -39,10 +40,9 @@ namespace osu.Game.IO.Serialization.Converters
             this.requiresTypeVersion = requiresTypeVersion;
         }
 
-        public override IReadOnlyList<T> ReadJson(JsonReader reader, Type objectType, IReadOnlyList<T> existingValue, bool hasExistingValue, JsonSerializer serializer)
+        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
         {
             var list = new List<T>();
-
             var obj = JObject.Load(reader);
 
             if (obj["$lookup_table"] == null)
@@ -69,15 +69,25 @@ namespace osu.Game.IO.Serialization.Converters
                 list.Add(instance);
             }
 
+            if (objectType == typeof(IBindableList<T>) || objectType == typeof(BindableList<T>))
+                return new BindableList<T>(list);
+
+            if (objectType == typeof(IReadOnlyList<T>))
+                return list.AsReadOnly();
+
             return list;
         }
 
-        public override void WriteJson(JsonWriter writer, IReadOnlyList<T> value, JsonSerializer serializer)
+        public override bool CanConvert(Type objectType)
+            => objectType == typeof(IBindableList<T>) || objectType == typeof(BindableList<T>) || objectType == typeof(IReadOnlyList<T>) || objectType == typeof(List<T>);
+
+        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
         {
+            var enumerable = (IEnumerable<T>)value!;
             var lookupTable = new List<string>();
             var objects = new List<JObject>();
 
-            foreach (var item in value)
+            foreach (var item in enumerable)
             {
                 var type = item.GetType();
                 var assemblyName = type.Assembly.GetName();