Function IsCallbackInstanceValid

engine/script/src/script.cpp:1789–1866

     }

    static bool IsCallbackInstanceValid(LuaCallbackInfo* cbk)
    {
        if (cbk->m_UniqueScriptId == INVALID_SCRIPT_ID)
        {
            return false;
        }
        lua_State* L = cbk->m_L;
        DM_LUA_STACK_CHECK(L, 0);

        GetInstance(L);
        // [-1] old instance
        lua_rawgeti(L, LUA_REGISTRYINDEX, cbk->m_ContextTableRef);
        // [-2] old instance
        // [-1] context table
        if (lua_type(L, -1) != LUA_TTABLE)
        {
            lua_pop(L, 2);
            cbk->m_UniqueScriptId  = INVALID_SCRIPT_ID;
            return false;
        }

        const int context_table_stack_index = lua_gettop(L);
        lua_rawgeti(L, context_table_stack_index, cbk->m_Self);
        // [-3] old instance
        // [-2] context table
        // [-1] instance
        if (lua_isnil(L, -1))
        {
            lua_pop(L, 3);
            cbk->m_UniqueScriptId = INVALID_SCRIPT_ID;
            return false;
        }

        lua_pushvalue(L, -1);
        // [-4] old instance
        // [-3] context table
        // [-2] instance
        // [-1] instance
        SetInstance(L);
        // [-3] old instance
        // [-2] context table
        // [-1] instance
        uint32_t unique_script_id = INVALID_SCRIPT_ID;
        if (GetMetaFunction(L, -1, META_GET_UNIQUE_SCRIPT_ID, sizeof(META_GET_UNIQUE_SCRIPT_ID) - 1))
        {
            // [-4] old instance
            // [-3] context table
            // [-2] instance
            // [-1] META_GET_UNIQUE_SCRIPT_ID()
            lua_pushvalue(L, -2);
            // [-5] old instance
            // [-4] context table
            // [-3] instance
            // [-2] META_GET_UNIQUE_SCRIPT_ID()
            // [-1] instance
            lua_call(L, 1, 1);
            // [-4] old instance
            // [-3] context table