add recovery reference

src/Utils/Reference.cs

@@ -0,0 +1,61 @@
+using System.Runtime.CompilerServices;
+using UnityEngine;
+
+namespace DCFApixels.DragonECS
+{
+    [System.Serializable]
+    public struct Reference<T>
+#if UNITY_EDITOR
+        : ISerializationCallbackReceiver
+#endif
+    {
+#if UNITY_EDITOR
+        [SerializeReference]
+        private T _value;
+        [SerializeField]
+        private string _json;
+        public T Value
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get { return _value; }
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            set { _value = value; }
+        }
+#else   
+        public T Value;
+#endif
+
+#if UNITY_EDITOR
+        private static System.Collections.Generic.Dictionary<string, System.Type> _metaIDTypePairs;
+        private static void InitRecoverCache()
+        {
+            if (_metaIDTypePairs == null) { return; }
+            _metaIDTypePairs = new System.Collections.Generic.Dictionary<string, System.Type>();
+        }
+        private static T TryRecoverReference(string metaID)
+        {
+            InitRecoverCache();
+            if (_metaIDTypePairs.TryGetValue(metaID, out System.Type type))
+            {
+                return (T)System.Activator.CreateInstance(type);
+            }
+            return default;
+        }
+        void ISerializationCallbackReceiver.OnAfterDeserialize()
+        {
+            if (_value == null)
+            {
+                int indexof = _json.IndexOf(',');
+                _value = TryRecoverReference(_json.Substring(0, indexof));
+                if (_value == null) { return; }
+                JsonUtility.FromJsonOverwrite(_json.Substring(indexof + 1), _value);
+                _json = null;
+            }
+        }
+        void ISerializationCallbackReceiver.OnBeforeSerialize()
+        {
+            _json = $"{_value.GetMeta().MetaID},{JsonUtility.ToJson(_value)}";
+        }
+#endif
+    }
+}

src/Utils/Reference.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 6399ac2dd5218444b98f4dcf3a359611
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: