Add Il2CppEqualityComparer

Reactor/Il2CppEqualityComparer.cs

@@ -0,0 +1,38 @@
+using System.Collections.Generic;
+using Il2CppSystem.Runtime.CompilerServices;
+
+namespace Reactor
+{
+    public sealed class Il2CppEqualityComparer<T> : IEqualityComparer<T> where T : Il2CppSystem.Object
+    {
+        private static Il2CppEqualityComparer<T> _instance;
+
+        public static Il2CppEqualityComparer<T> Instance
+        {
+            get
+            {
+                _instance ??= new Il2CppEqualityComparer<T>();
+                return _instance;
+            }
+        }
+
+        private Il2CppEqualityComparer()
+        {
+        }
+
+        public int GetHashCode(T value)
+        {
+            return RuntimeHelpers.GetHashCode(value);
+        }
+
+        public bool Equals(T left, T right)
+        {
+            if (left == null || right == null)
+            {
+                return left == null && right == null;
+            }
+
+            return left.Equals(right);
+        }
+    }
+}