allow custom checker (#857)

Author: Domain

Assets/XLua/Src/ObjectCasters.cs

@@ -191,6 +191,11 @@ public ObjectCheck genNullableChecker(ObjectCheck oc)
             };
         }
 
+        public void AddChecker(Type type, ObjectCheck oc)
+        {
+            checkersMap[type] = oc;
+        }
+
         public ObjectCheck GetChecker(Type type)
         {
             if (type.IsByRef) type = type.GetElementType();

Assets/XLua/Src/ObjectTranslator.cs

@@ -1606,7 +1606,7 @@ bool tryGetGetFuncByType<T>(Type type, out T func) where T : class
             }
         }
 
-
+        public delegate bool CheckFunc<T>(RealStatePtr L, int idx);
         public delegate void GetFunc<T>(RealStatePtr L, int idx,  out T val);
 
         public void RegisterPushAndGetAndUpdate<T>(Action<RealStatePtr, T> push, GetFunc<T> get, Action<RealStatePtr, int, T> update)
@@ -1640,6 +1640,14 @@ public void RegisterPushAndGetAndUpdate<T>(Action<RealStatePtr, T> push, GetFunc
             );
         }
 
+        public void RegisterChecker<T>(CheckFunc<T> check)
+        {
+            objectCheckers.AddChecker(typeof(T), (L, idx) =>
+            {
+                return check(L, idx);
+            });
+        }
+
         public void RegisterCaster<T>(GetFunc<T> get)
         {
             objectCasters.AddCaster(typeof(T), (L, idx, o) =>