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, LUA_REGISTRYINDEX);        lua_pushstring(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",0);        tolua_beginmodule(L,"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"] = trueLUA_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"] = mtLUA_REGISTRYINDEX[mt] = "tolua_commonclass"tolua_classevents(mt)tolua_module(L,NULL,0);确保拥有该模块， 该木块没有 moduleevent __index, __newindextolua_beginmodule(L,NULL); push _G (not .isclass, a normal table not mt) tolua_module(L,"tolua",0); _G["tolua"] = {}tolua_beginmodule(L,"tolua");push _G["tolua"]tolua_function(L,"type",tolua_bnd_type); _G["tolua"]["type"] = tolua_bnd_type...tolua_endmodule(L); poptolua_endmodule(L); poprestore 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,"cc",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* name, const char* base, lua_CFunction col):mapinheritance(L,name,base);mapinheritance(L,cname,name);mapinheritance (lua_State* L, const char* name, const char* base)push mt_name as mtpush mt_base or LUA_REGISTRYINDEX["tolua_commonclass"] as base_mtset_ubox(L);:mt["tolua_ubox"] = base_mt["tolua_ubox"] or setmetatable({}, {__mode = v})setmetatable(mt, base_mt)mapsuper(L,cname,cbase);mapsuper(L,name,base);LUA_REGISTRYINDEX[name][".collector"] = colLUA_REGISTRYINDEX[cname][".collector"] = colmodule[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。