cpgf如何实现lua script binding的？

Lib：

https://github.com/cpgf/cpgf/tree/master

代码

以下是operator的实现函数

int UserData_operator(lua_State * L)
{
    ENTER_LUA()
    
    GOperatorGlueDataPointer glueData = static_cast<GGlueDataWrapper *>(lua_touserdata(L, lua_upvalueindex(1)))->getAs<GOperatorGlueData>();

    return invokeOperator(glueData->getBindingContext(), glueData->getObjectData(), glueData->getMetaClass(), glueData->getOp());
    
    LEAVE_LUA(L, return 0)
}

可见cpgf 设置 一个GGlueDataWrapper *指针作为upvalue，从而可以方便的调用相关实现

而注册函数如下

由于对lua api不很熟悉，这段代码还没有完全搞懂

有时间仔细研究下

void helperBindOperator(const GContextPointer & context, const GObjectGlueDataPointer & objectData, IMetaClass * metaClass, GMetaOpType op)
{
	lua_State * L = getLuaState(context);

	for(size_t i = 0; i < sizeof(metaOpTypes) / sizeof(metaOpTypes[0]); ++i) {
		if(metaOpTypes[i] == op) {
			GOperatorGlueDataPointer operatorData(context->newOperatorGlueData(objectData, metaClass, op));
			GLuaRefUserData * glueUserData = operatorData->getUserDataAs<GLuaRefUserData>();
			if(glueUserData != nullptr) {
				glueUserData->get();
				if(! lua_isnil(L, -1)) {
					return;
				}
				lua_pop(L, 1);
			}

			lua_pushstring(L, luaOperators[i]);
			void * userData = lua_newuserdata(L, getGlueDataWrapperSize<GOperatorGlueData>());
			newGlueDataWrapper(userData, operatorData);

			lua_newtable(L);
			setMetaTableSignature(L);
			setMetaTableGC(L);
			lua_setmetatable(L, -2);

			lua_pushcclosure(L, &UserData_operator, 1);
			lua_rawset(L, -3);

			glueUserData = new GLuaRefUserData(L, false);
			operatorData->setUserData(glueUserData);
			glueUserData->retainAndPop();

			glueUserData->get();

			return;
		}
	}
}