Update project to Unity 2021.x; implement SerializeReference-based context menu operations (Copy, Paster, Duplicate)

Author: arimger

Assets/Editor Toolbox/Editor/ContextMenu.meta

@@ -0,0 +1,14 @@
+using UnityEditor;
+using UnityEngine;
+
+namespace Toolbox.Editor.ContextMenu
+{
+    internal interface IContextMenuOperation
+    {
+        bool IsVisible(SerializedProperty property);
+        bool IsEnabled(SerializedProperty property);
+        void Perform(SerializedProperty property);
+
+        GUIContent Label { get; }
+    }
+}

Assets/Editor Toolbox/Editor/ContextMenu/IContextMenuOperation.cs

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+using System.Collections.Generic;
+
+using UnityEditor;
+
+namespace Toolbox.Editor.ContextMenu.Management
+{
+    using Toolbox.Editor.ContextMenu.Operations;
+
+    [InitializeOnLoad]
+    internal static class ToolboxContextMenuManager
+    {
+        private static readonly List<IContextMenuOperation> registeredOperations;
+
+        static ToolboxContextMenuManager()
+        {
+            registeredOperations = new List<IContextMenuOperation>()
+            {
+                new CopySerializeReferenceOperation(),
+                new PasteSerializeReferenceOperation(),
+                new DuplicateSerializeReferenceArrayElementOperation()
+            };
+
+            EditorApplication.contextualPropertyMenu -= OnContextMenuOpening;
+            EditorApplication.contextualPropertyMenu += OnContextMenuOpening;
+        }
+
+        public static void AppendOpertation(IContextMenuOperation operation)
+        {
+            registeredOperations.Add(operation);
+        }
+
+        public static bool RemoveOperation(IContextMenuOperation operation)
+        {
+            return registeredOperations.Remove(operation);
+        }
+
+        private static void OnContextMenuOpening(GenericMenu menu, SerializedProperty property)
+        {
+            foreach (var operation in registeredOperations)
+            {
+                if (!operation.IsVisible(property))
+                {
+                    continue;
+                }
+
+                var label = operation.Label;
+                if (!operation.IsEnabled(property))
+                {
+                    menu.AddDisabledItem(label);
+                    continue;
+                }
+
+                menu.AddItem(label, false, () =>
+                {
+                    operation.Perform(property);
+                });
+            }
+        }
+    }
+}

Assets/Editor Toolbox/Editor/ContextMenu/IContextMenuOperation.cs.meta

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+using UnityEditor;
+using UnityEngine;
+
+namespace Toolbox.Editor.ContextMenu.Operations
+{
+    internal class CopySerializeReferenceOperation : IContextMenuOperation
+    {
+        internal static CopySerializedRererenceCache Cache { get; private set; }
+
+        public bool IsVisible(SerializedProperty property)
+        {
+#if UNITY_2021_3_OR_NEWER
+            return property != null && property.propertyType == SerializedPropertyType.ManagedReference;
+#else
+            return false;
+#endif
+        }
+
+        public bool IsEnabled(SerializedProperty property)
+        {
+            return true;
+        }
+
+        public void Perform(SerializedProperty property)
+        {
+#if UNITY_2021_3_OR_NEWER
+            var value = property.managedReferenceValue;
+            if (value != null)
+            {
+                var referenceType = value.GetType();
+                var data = JsonUtility.ToJson(value);
+                Cache = new CopySerializedRererenceCache(referenceType, data);
+                return;
+            }
+
+            Cache = new CopySerializedRererenceCache(null, null);
+#endif
+        }
+
+        public GUIContent Label => new GUIContent("Copy Serialize Reference");
+
+        [InitializeOnLoadMethod]
+        private static void Initialize()
+        {
+            Cache = null;
+        }
+    }
+}