入手cocos2dx3.9笔记 3 tolua++解析

因为需求，最近又重新回忆了下tolua++的相关流程，以 3.9的 lua stack 的初始化相关代码开始解析：

    _state = lua_open();
    luaL_openlibs(_state);
    toluafix_open(_state);

    // Register our version of the global "print" function
    const luaL_reg global_functions [] = {
        {"print",lua_print},{"release_print",lua_release_print},{nullptr,nullptr}
    };
    luaL_register(_state,"_G",global_functions);

    g_luaType.clear();
    register_all_cocos2dx(_state);

register_all_cocos2dx 如下：

<pre name="code" class="cpp">TOLUA_API int register_all_cocos2dx(lua_State* tolua_S)
{
	tolua_open(tolua_S);
	
	tolua_module(tolua_S,"cc",0);
	tolua_beginmodule(tolua_S,"cc");

	lua_register_cocos2dx_Ref(tolua_S);

<span style="white-space:pre">	</span>...

<span style="white-space:pre">	</span>
	tolua_endmodule(tolua_S);

<span style="white-space:pre">	return 1;</span>

TOLUA_API void tolua_open (lua_State* L)
{
    int top = lua_gettop(L);
    lua_pushstring(L,"tolua_opened");
    lua_rawget(L,LUA_REGISTRYINDEX);
    if (!lua_isboolean(L,-1))
    {
        lua_pushstring(L,"tolua_opened");
        lua_pushboolean(L,1);
        lua_rawset(L,LUA_REGISTRYINDEX);
        
        // create value root table
        lua_pushstring(L,TOLUA_VALUE_ROOT);
        lua_newtable(L);
        lua_rawset(L,LUA_REGISTRYINDEX);

        /* create object ptr -> udata mapping table */
        lua_pushstring(L,"tolua_uBox");
        lua_newtable(L);
        /* make weak value Metatable for uBox table to allow userdata to be
           garbage-collected */
        lua_newtable(L);
        lua_pushliteral(L,"__mode");
        lua_pushliteral(L,"v");
        lua_rawset(L,-3);               /* stack: string uBox mt */
        lua_setMetatable(L,-2);  /* stack: string uBox */
        lua_rawset(L,LUA_REGISTRYINDEX);
        

        lua_pushstring(L,"tolua_super");
        lua_newtable(L);
        lua_rawset(L,LUA_REGISTRYINDEX);
        lua_pushstring(L,"tolua_gc");
        lua_newtable(L);
        lua_rawset(L,LUA_REGISTRYINDEX);

        /* create gc_event closure */
        lua_pushstring(L,"tolua_gc_event");
        lua_pushstring(L,"tolua_gc");
        lua_rawget(L,"tolua_super");
        lua_rawget(L,LUA_REGISTRYINDEX);
        lua_pushcclosure(L,class_gc_event,2);
        lua_rawset(L,LUA_REGISTRYINDEX);

        tolua_newMetatable(L,"tolua_commonclass");

        tolua_module(L,NULL,0);
        tolua_beginmodule(L,NULL);
        tolua_module(L,"tolua","tolua");
        tolua_function(L,"type",tolua_bnd_type);
        tolua_function(L,"takeownership",tolua_bnd_takeownership);
        tolua_function(L,"releaSEOwnership",tolua_bnd_releaSEOwnership);
        tolua_function(L,"cast",tolua_bnd_cast);
        tolua_function(L,"isnull",tolua_bnd_isnulluserdata);
        tolua_function(L,"inherit",tolua_bnd_inherit);
#ifdef LUA_VERSION_NUM /* lua 5.1 */
        tolua_function(L,"setpeer",tolua_bnd_setpeer);
        tolua_function(L,"getpeer",tolua_bnd_getpeer);
#endif
        tolua_function(L,"getcfunction",tolua_bnd_getcfunction);
        tolua_function(L,"iskindof",tolua_bnd_iskindof);

        tolua_endmodule(L);
        tolua_endmodule(L);
    }
    lua_settop(L,top);
}

对 tolua_open 解析如下：

tolua_open:
	LUA_REGISTRYINDEX["tolua_opened"] = true
	LUA_REGISTRYINDEX[TOLUA_VALUE_ROOT] = {}
	LUA_REGISTRYINDEX["tolua_uBox"] = setMetatable({},{__mode = v})
	LUA_REGISTRYINDEX["tolua_super"] = {}
	LUA_REGISTRYINDEX["tolua_gc"] = {}
	LUA_REGISTRYINDEX["tolua_gc_event"] = class_gc_event [closure: LUA_REGISTRYINDEX["tolua_gc"] LUA_REGISTRYINDEX["tolua_super"]]
	tolua_newMetatable(L,"tolua_commonclass")
		mt = {}
		LUA_REGISTRYINDEX["tolua_commonclass"] = mt
		LUA_REGISTRYINDEX[mt] = "tolua_commonclass"
		tolua_classevents(mt)
		
	tolua_module(L,0);						确保拥有该模块， 该木块没有 moduleevent __index,__newindex
	tolua_beginmodule(L,NULL); 					push _G (not .isclass,a normal table not mt) 
	tolua_module(L,0); 					_G["tolua"] = {}
	tolua_beginmodule(L,"tolua");				push _G["tolua"]
	tolua_function(L,tolua_bnd_type); 	_G["tolua"]["type"] = tolua_bnd_type
	...
	tolua_endmodule(L); 						pop
	tolua_endmodule(L); 						pop
		
	restore stack

需要留意的：
1.其中TOLUA_VALUE_ROOT 用于额外存放push到lua中的userdata 如果push的时候放入了这个table中，那么析构的时候需要从中移除

2.当push的 userdata 类的 mt 中没有 tolua_uBox 则这个userdata 会放入到这个全局 tolua_uBox 中

3.tolua_super 存储注册到lua中类的继承关系，例如 c_derived 继承 c_base 那么 tolua_super[mt_c_derived] = {cbaseName = true},cbaseName为c_base 在注册表的 class name

4.注册的lua类的基类都会索引 tolua_commonclass,他的 __index,__newindex,__gc 值得注意下，

其他流程用伪代码解析如下：

主流程调用：
register_all_cocos2dx: 						//栈顶已经有一个 _G 了
	tolua_open(tolua_S); 					//见核心一
	tolua_module(tolua_S,0); 			//确保拥有 _G["cc"]
	tolua_beginmodule(tolua_S,"cc"); 		//push _G["cc"]
	
	lua_register_cocos2dx_Ref(tolua_S);
	...
	tolua_endmodule(tolua_S); 				//pop
	

注册详细信息：
int lua_register_cocos2dx_Ref(lua_State* tolua_S)
{
    tolua_usertype(tolua_S,"cc.Ref");:
		tolua_newMetatable("cc.Ref")
		tolua_newMetatable("const cc.Ref")
		mapsuper(L,type,ctype);:
			mapsuper (lua_State* L,const char* name,const char* base)
				mt = LUA_REGISTRYINDEX[name]
				LUA_REGISTRYINDEX["tolua_super"][mt] = {$base = true}
				mtbase = LUA_REGISTRYINDEX[base]
				merge(LUA_REGISTRYINDEX["tolua_super"][mt],LUA_REGISTRYINDEX["tolua_super"][mtbase]) 右侧内容 merge 到左侧
				
				
    tolua_cclass(tolua_S,"Ref","cc.Ref","",nullptr);:
		tolua_cclass (lua_State* L,const char* lname,const char* base,lua_CFunction col):
			mapinheritance(L,name,base);
			mapinheritance(L,cname,name);
				mapinheritance (lua_State* L,const char* base)
					push mt_name 											as mt
					push mt_base or LUA_REGISTRYINDEX["tolua_commonclass"] 	as base_mt
					set_uBox(L);:
						mt["tolua_uBox"] = base_mt["tolua_uBox"] or setMetatable({},{__mode = v})
					setMetatable(mt,base_mt)
					
			mapsuper(L,cbase);
			mapsuper(L,base);
			LUA_REGISTRYINDEX[name][".collector"] = col
			LUA_REGISTRYINDEX[cname][".collector"] = col
			module[lname] = setMetatable({[".isclass"] = true},mt_name)
			// stack: module
			
    tolua_beginmodule(tolua_S,"Ref");
        tolua_function(tolua_S,"release",lua_cocos2dx_Ref_release);
		...
    tolua_endmodule(tolua_S);
    std::string typeName = typeid(cocos2d::Ref).name();
    g_luaType[typeName] = "cc.Ref";
    g_typeCast["Ref"] = "cc.Ref";
    return 1;
}

至于 cocos2dx 新增的 tolua_fix代码就不做笔记了，大概就是额外记录了下push 进lua的userdata,以及 function 相关的事情，确保当析构的时候 userdata 置 nil，让注册表functions 与对应索引id之类的事情。

OK,完毕，知道了这些，在 lua中扩充、派生那些注册进lua中的类就已经不是问题了。

干吧爹~，争取这几周内把框架搭建出来。

原文链接：/cocos2dx/340652.html

入手cocos2dx3.9笔记 3 tolua++解析

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