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本篇主题是C#如何调用lua的补充。
xLua交互知识
参考官方文档《programming in lua》的第24章开头,里面很详细地阐述了Lua和C++是如何实现交互的:栈操作。Lua API用一个抽象的栈在Lua与C之间交换值。栈中的每一条记录都可以保存任何 Lua 值。如果想要从Lua请求一个值(比如一个全局变量的值)则调用Lua,被请求的值将会被压入栈;如果想要传递一个值给 Lua,首先将这个值压入栈,然后调用 Lua(这个值就会被弹 出)。几乎所有的 API函数都用到了栈。而C#显而易见也可以和C++一侧进行交互,由此即可得出lua和C#可以通过C/C++这一层来进行通信,主要方法即是lua的堆栈操作。
C#获取Lua入口
首先写一段测试代码:
[LuaCallCSharp]
public class LuaTableTest
{public LuaTable tab = null;public Action<LuaTable> luaFunc = null;
}
然后经过Xlua Generate Code后可以观察Set方法,得到流程的起点:translator.GetObject
[MonoPInvokeCallbackAttribute(typeof(LuaCSFunction))]
static int _s_set_tab(RealStatePtr L)
{try {ObjectTranslator translator = ObjectTranslatorPool.Instance.Find(L);XluaTool.LuaTableTest gen_to_be_invoked = (XluaTool.LuaTableTest)translator.FastGetCSObj(L, 1);gen_to_be_invoked.tab = (XLua.LuaTable)translator.GetObject(L, 2, typeof(XLua.LuaTable));} catch(System.Exception gen_e) {return LuaAPI.luaL_error(L, "c# exception:" + gen_e);}return 0;
}[MonoPInvokeCallbackAttribute(typeof(LuaCSFunction))]
static int _s_set_luaFunc(RealStatePtr L)
{try {ObjectTranslator translator = ObjectTranslatorPool.Instance.Find(L);XluaTool.LuaTableTest gen_to_be_invoked = (XluaTool.LuaTableTest)translator.FastGetCSObj(L, 1);gen_to_be_invoked.luaFunc = translator.GetDelegate<System.Action<XLua.LuaTable>>(L, 2);} catch(System.Exception gen_e) {return LuaAPI.luaL_error(L, "c# exception:" + gen_e);}return 0;
}
可以看到,translator.GetObject负责把相应Lua类型转换成C#类型数据并返回。而GetObject内部是由GetCaster函数实现转换的:
public ObjectCast GetCaster(Type type)
{if (type.IsByRef) type = type.GetElementType();Type underlyingType = Nullable.GetUnderlyingType(type);if (underlyingType != null){return genNullableCaster(GetCaster(underlyingType)); }ObjectCast oc;if (!castersMap.TryGetValue(type, out oc)){oc = genCaster(type);castersMap.Add(type, oc);}return oc;
}
castersMap内部已经定义了各个类型的转换函数:
public ObjectCasters(ObjectTranslator translator)
{this.translator = translator;castersMap[typeof(char)] = charCaster;castersMap[typeof(sbyte)] = sbyteCaster;castersMap[typeof(byte)] = byteCaster;castersMap[typeof(short)] = shortCaster;castersMap[typeof(ushort)] = ushortCaster;castersMap[typeof(int)] = intCaster;castersMap[typeof(uint)] = uintCaster;castersMap[typeof(long)] = longCaster;castersMap[typeof(ulong)] = ulongCaster;castersMap[typeof(double)] = getDouble;castersMap[typeof(float)] = floatCaster;castersMap[typeof(decimal)] = decimalCaster;castersMap[typeof(bool)] = getBoolean;castersMap[typeof(string)] = getString;castersMap[typeof(object)] = getObject;castersMap[typeof(byte[])] = getBytes;castersMap[typeof(IntPtr)] = getIntptr;//special typecastersMap[typeof(LuaTable)] = getLuaTable;castersMap[typeof(LuaFunction)] = getLuaFunction;
}
所以接下来的任务无非就是研究getLuaTable和getLuaFunction如何实现的了。
C#获取Lua table
getLuaFunction实现如下:
private object getLuaTable(RealStatePtr L, int idx, object target)
{if (LuaAPI.lua_type(L, idx) == LuaTypes.LUA_TUSERDATA){object obj = translator.SafeGetCSObj(L, idx);return (obj != null && obj is LuaTable) ? obj : null;}if (!LuaAPI.lua_istable(L, idx)){return null;}LuaAPI.lua_pushvalue(L, idx);return new LuaTable(LuaAPI.luaL_ref(L), translator.luaEnv);
}
主要步骤即是通过luaL_ref添加到Lua注册表中并获取索引位置,创建一个C#侧的LuaTable对象用于管理。之后获取这个table即可直接用这个LuaTable对象即可。
如果使用测试代码
LuaTableTest.tab.Get<int>("testVal")
来获取相应变量信息,实际上内部执行的是table.Get接口:
public void Get<TKey, TValue>(TKey key, out TValue value)
{
#if THREAD_SAFE || HOTFIX_ENABLElock (luaEnv.luaEnvLock){
#endifvar L = luaEnv.L;var translator = luaEnv.translator;int oldTop = LuaAPI.lua_gettop(L);LuaAPI.lua_getref(L, luaReference);translator.PushByType(L, key);if (0 != LuaAPI.xlua_pgettable(L, -2)){string err = LuaAPI.lua_tostring(L, -1);LuaAPI.lua_settop(L, oldTop);throw new Exception("get field [" + key + "] error:" + err);}LuaTypes lua_type = LuaAPI.lua_type(L, -1);Type type_of_value = typeof(TValue);if (lua_type == LuaTypes.LUA_TNIL && type_of_value.IsValueType()){throw new InvalidCastException("can not assign nil to " + type_of_value.GetFriendlyName());}try{translator.Get(L, -1, out value);}catch (Exception e){throw e;}finally{LuaAPI.lua_settop(L, oldTop);}
#if THREAD_SAFE || HOTFIX_ENABLE}
#endif
}
可以看到,我们首先通过getref(之前new luaTable的时候已经做了添加ref的操作了)拿到table的reference,然后再通过这个reference查询到key的位置并取出,即可得到相应的数据了。
根据LuaTable获取变量
在Get代码中有一处细节:translator.Get,内部有提前封装好的基本类型对象转换,比如int、double、string类型等,这些都可以直接通过Lua API实现转换,LuaAPI.xlua_tointeger这些也仅仅是对原生API的简单封装。
public void Get<T>(RealStatePtr L, int index, out T v)
{Func<RealStatePtr, int, T> get_func;if (tryGetGetFuncByType(typeof(T), out get_func)){v = get_func(L, index);}else{v = (T)GetObject(L, index, typeof(T));}
}
bool tryGetGetFuncByType<T>(Type type, out T func) where T : class
{if (get_func_with_type == null){get_func_with_type = new Dictionary<Type, Delegate>(){{typeof(int), new Func<RealStatePtr, int, int>(LuaAPI.xlua_tointeger) },{typeof(double), new Func<RealStatePtr, int, double>(LuaAPI.lua_tonumber) },{typeof(string), new Func<RealStatePtr, int, string>(LuaAPI.lua_tostring) },{typeof(byte[]), new Func<RealStatePtr, int, byte[]>(LuaAPI.lua_tobytes) },{typeof(bool), new Func<RealStatePtr, int, bool>(LuaAPI.lua_toboolean) },{typeof(long), new Func<RealStatePtr, int, long>(LuaAPI.lua_toint64) },{typeof(ulong), new Func<RealStatePtr, int, ulong>(LuaAPI.lua_touint64) },{typeof(IntPtr), new Func<RealStatePtr, int, IntPtr>(LuaAPI.lua_touserdata) },{typeof(decimal), new Func<RealStatePtr, int, decimal>((L, idx) => {decimal ret;Get(L, idx, out ret);return ret;}) },{typeof(byte), new Func<RealStatePtr, int, byte>((L, idx) => (byte)LuaAPI.xlua_tointeger(L, idx) ) },{typeof(sbyte), new Func<RealStatePtr, int, sbyte>((L, idx) => (sbyte)LuaAPI.xlua_tointeger(L, idx) ) },{typeof(char), new Func<RealStatePtr, int, char>((L, idx) => (char)LuaAPI.xlua_tointeger(L, idx) ) },{typeof(short), new Func<RealStatePtr, int, short>((L, idx) => (short)LuaAPI.xlua_tointeger(L, idx) ) },{typeof(ushort), new Func<RealStatePtr, int, ushort>((L, idx) => (ushort)LuaAPI.xlua_tointeger(L, idx) ) },{typeof(uint), new Func<RealStatePtr, int, uint>(LuaAPI.xlua_touint) },{typeof(float), new Func<RealStatePtr, int, float>((L, idx) => (float)LuaAPI.lua_tonumber(L, idx) ) },};}Delegate obj;if (get_func_with_type.TryGetValue(type, out obj)){func = obj as T;return true;}else{func = null;return false;}
}
C#获取Function
以上已经说明,如果只是为了获取某个table内部的相关变量,其实走Get就已经满足需求,但是有些函数依然还需要调用,比如一些匿名函数:
XluaTool.LuaTableTest.luaFunc= function()
end
此时需要转换成delegate形式供C#侧调用,如第二段代码块中所示:
gen_to_be_invoked.luaFunc = translator.GetDelegate<System.Action<XLua.LuaTable>>(L, 2);
而跳转GetDelegate直到CreateDelegateBridge函数,会发现其中有一些代码和GetLuaTable非常相似,即会存储在lua注册表中,然后给出一个索引,最后通过DelegateBridgeBase类进行存储:
public object CreateDelegateBridge(RealStatePtr L, Type delegateType, int idx)
{......LuaAPI.lua_pushvalue(L, idx);int reference = LuaAPI.luaL_ref(L);LuaAPI.lua_pushvalue(L, idx);LuaAPI.lua_pushnumber(L, reference);LuaAPI.lua_rawset(L, LuaIndexes.LUA_REGISTRYINDEX);DelegateBridgeBase bridge;try{
#if (UNITY_EDITOR || XLUA_GENERAL) && !NET_STANDARD_2_0if (!DelegateBridge.Gen_Flag){bridge = Activator.CreateInstance(delegate_birdge_type, new object[] { reference, luaEnv }) as DelegateBridgeBase;}else
#endif{bridge = new DelegateBridge(reference, luaEnv);}}......
}
LuaBase Dispose
C#这边释放lua侧资源时需要调用相关接口,以防Lua侧一直认为C#侧持有lua相关资源。可以着重观察Xlua给的LuaBase析构函数的处理方式:
public void Dispose()
{Dispose(true);GC.SuppressFinalize(this);
}public virtual void Dispose(bool disposeManagedResources)
{if (!disposed){if (luaReference != 0){
#if THREAD_SAFE || HOTFIX_ENABLElock (luaEnv.luaEnvLock){
#endifbool is_delegate = this is DelegateBridgeBase;if (disposeManagedResources){luaEnv.translator.ReleaseLuaBase(luaEnv.L, luaReference, is_delegate);}else //will dispse by LuaEnv.GC{luaEnv.equeueGCAction(new LuaEnv.GCAction { Reference = luaReference, IsDelegate = is_delegate });}
#if THREAD_SAFE || HOTFIX_ENABLE}
#endif}disposed = true;}
}
调用Dispose接口,里面通知了translator此luaBase需要被释放,而translator则开始对lua注册表进行pop工作,尤其不要忘记之前的reference存储工作,也是要进行解绑的,如最后一句LuaAPI.lua_unref操作:
public void ReleaseLuaBase(RealStatePtr L, int reference, bool is_delegate)
{if(is_delegate){LuaAPI.xlua_rawgeti(L, LuaIndexes.LUA_REGISTRYINDEX, reference);if (LuaAPI.lua_isnil(L, -1)){LuaAPI.lua_pop(L, 1);}else{LuaAPI.lua_pushvalue(L, -1);LuaAPI.lua_rawget(L, LuaIndexes.LUA_REGISTRYINDEX);if (LuaAPI.lua_type(L, -1) == LuaTypes.LUA_TNUMBER && LuaAPI.xlua_tointeger(L, -1) == reference) //{//UnityEngine.Debug.LogWarning("release delegate ref = " + luaReference);LuaAPI.lua_pop(L, 1);// pop LUA_REGISTRYINDEX[func]LuaAPI.lua_pushnil(L);LuaAPI.lua_rawset(L, LuaIndexes.LUA_REGISTRYINDEX); // LUA_REGISTRYINDEX[func] = nil}else //another Delegate ref the function before the GC tick{LuaAPI.lua_pop(L, 2); // pop LUA_REGISTRYINDEX[func] & func}}LuaAPI.lua_unref(L, reference);delegate_bridges.Remove(reference);}else{LuaAPI.lua_unref(L, reference);}
}
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