meta-meta table is functioning correctly

rsc/scripts/setup_server.lua

@@ -37,7 +37,13 @@ roomAPI.Initialize(underworld, mapSaver.Load, mapSaver.Save, mapMaker.DebugGrass
 doorUtility.createDoorPair("pair 1", overworld, 0, -64, underworld, 0, 0)
 
 --testing the metatables
-local meta = getmetatable(underworld)
-print("", "userdata metatable: ", meta)
+print("debug")
+overworld["key"] = "value"
+local key = overworld["key"]
+print("", "result: ", key)
+
+local key = underworld["key"]
+print("", "result: ", key)
+--end test
 
 print("Finished the lua script")

server/userdata.cpp

@@ -23,13 +23,71 @@
 
 #include <iostream>
 
+#define METAMETA "__metameta"
+
 static int index(lua_State* L) {
-	std::cout << "WARNING: userdataIndex called" << std::endl;
+	std::cout << "debug: index" << std::endl;
+
+	//get __metameta
+	lua_getmetatable(L, 1); //get the userdata metatable
+	lua_pushstring(L, METAMETA); //push the __metameta name
+	lua_gettable(L, -2); //get the __metameta field from the metatable
+
+	//get __metameta[userdata]
+	lua_pushvalue(L, 1); //copy of the userdata
+	lua_gettable(L, -2); //get the table at __metameta[userdata]
+
+	//table doesn't exist yet
+	if (lua_isnil(L, -1)) {
+		std::cout << "debug: index (no table)" << std::endl;
+		return 1;
+	}
+
+	//get the value at __metameta[userdata][key]
+	lua_pushvalue(L, 2); //copy the key
+	lua_gettable(L, -2); //get value from the deepest table
+
+	//return
+	return 1;
+}
+
+static int newindex(lua_State* L) {
+	std::cout << "debug: newindex" << std::endl;
+
+	//get __metameta
+	lua_getmetatable(L, 1); //get the userdata metatable
+	lua_pushstring(L, METAMETA); //push the __metameta name
+	lua_gettable(L, -2); //get the __metameta field from the metatable
+
+	//get __metameta[userdata]
+	lua_pushvalue(L, 1); //copy of the userdata
+	lua_gettable(L, -2); //get the table at __metameta[userdata]
+
+	//if this table doesn't exist yet
+	if (lua_isnil(L, -1)) {
+		std::cout << "debug: newindex (new table)" << std::endl;
+		lua_pop(L, 1); //pop nil
+
+		lua_pushvalue(L, 1); //copy userdata (key)
+		lua_createtable(L, 0, 0); //new table (value)
+		lua_settable(L, -3); //create the new table in __metameta
+
+		lua_pushvalue(L, 1); //copy userdata (key)
+		lua_gettable(L, -2); //get the newly created table
+	}
+
+	//set the value at __metameta[userdata][key] = value
+	lua_pushvalue(L, 2); //copy the key
+	lua_pushvalue(L, 3); //copy the value
+	lua_settable(L, -3); //set value in the deepest table
+
+	//return
 	return 0;
 }
 
 static luaL_Reg metatable[] = {
 	{"__index", index},
+	{"__newindex", newindex},
 	{nullptr, nullptr}
 };
 
@@ -38,6 +96,17 @@ int createUserdataMetatable(lua_State* L) {
 	lua_pushlightuserdata(L, nullptr); //anon userdata
 	lua_createtable(L, 0, 0); //table
 
+	//insert meta-metatable
+	lua_pushstring(L, METAMETA);
+	lua_createtable(L, 0, 0);
+	lua_settable(L, -3);
+
+	//insert metatable blocker
+	lua_pushstring(L, "__metatable");
+	lua_createtable(L, 0, 0);
+	lua_settable(L, -3);
+
+	//insert metamethods
 	for (luaL_Reg* it = metatable; it->name; it++) {
 		lua_pushstring(L, it->name);
 		lua_pushcfunction(L, it->func);