前段時間封裝了一個意在跨平臺，且滿足自己需求的很light的LuaEngine，對于表參數(shù)和表返回值留了白，想找時間研究一下，近日終于弄好。
首先我對C++的參數(shù)和返回值做了一個封裝
enum
{
SD_NUMBER = 0, // 數(shù)字類型
SD_STRING, // 字符串類型
SD_TABLE, //表
};
struct SSDTable
{
int nNum;
void* pValue;
};
// 腳本參數(shù)對象
struct SScriptParamObj
{
int nType; // 參數(shù)類型, SD_NUMBER 或者 SD_STRING
union UScriptParam // 參數(shù)值
{
int nNumber; // 數(shù)字
char szString[64]; // 字符串
SSDTable stTable;
} unValue;
SScriptParamObj()
{
memset(this, 0, sizeof(*this));
}
~SScriptParamObj()
{
}
void operator = (int nValue)
{
nType = SD_NUMBER;
unValue.nNumber = nValue;
}
void operator = (const char *str)
{
nType = SD_STRING;
unValue.szString[0] = 0;
if (str != NULL)
{
strncpy(unValue.szString, str, sizeof(unValue.szString));
}
}
void operator = ( SSDTable& pT )
{
nType = SD_TABLE;
unValue.stTable.nNum = pT.nNum;
unValue.stTable.pValue = (void *)pT.pValue;
}
};需要細心一點的就是，對于嵌套表的處理，不用說大家也就知道了--遞歸。
下面的這個函數(shù)是C++調(diào)用Lua的函數(shù)，Lua函數(shù)的參數(shù)和返回值都作為C++的參數(shù)
bool CLuaScript::CallFunction(const char *szFuncName, SScriptParamObj *pIn,
int nInNum, SScriptParamObj *pRet, int nRetNum)
{
if (szFuncName == NULL)
{
return false;
}
assert(m_pManager->GetMasterState());
assert(m_pThreadState);
lua_getglobal(m_pThreadState, szFuncName);
for (int i = 0; i < nInNum; i++)
{
// 參數(shù)的三種類型
switch (pIn[i].nType)
{
case SD_NUMBER:
lua_pushnumber(m_pThreadState, pIn[i].unValue.nNumber);
break;
case SD_STRING:
lua_pushstring(m_pThreadState, pIn[i].unValue.szString);
break;
case SD_TABLE:
// 現(xiàn)在棧頂創(chuàng)建一個新的表
lua_newtable(m_pThreadState);
int nSize = pIn[i].unValue.stTable.nNum;
SScriptParamObj* pData = (SScriptParamObj*)pIn[i].unValue.stTable.pValue;
PushTable(pData, nSize);
break;
}
}
int nStatus = lua_pcall(m_pThreadState, nInNum, nRetNum, 0);
for (int i = nRetNum - 1; i >= 0; i--)
{
// 參數(shù)的三種類型,pop的順序,完全靠直覺
switch (pRet[i].nType)
{
case SD_NUMBER:
pRet[i].unValue.nNumber = lua_tonumber(m_pThreadState, -1);
lua_pop(m_pThreadState, 1);
break;
case SD_STRING:
strcpy(pRet[i].unValue.szString, lua_tostring(m_pThreadState, -1));
lua_pop(m_pThreadState, 1);
break;
case SD_TABLE:
ReturnTable(&pRet[i]);
lua_pop(m_pThreadState, 1);
break;
}
}
if (nStatus != 0)
{
FormatError();
OutputError("Runtime Error:");
return false;
}
return true;
}
處理表作為輸入?yún)?shù)，對于嵌套表的處理，請大家詳細的看下代碼就明白了
void CLuaScript::PushTable(SScriptParamObj *pIn, int nInNum)
{
for (int i = 0; i < nInNum; i++)
{
// 參數(shù)的三種類型
switch (pIn[i].nType)
{
case SD_NUMBER:
// 添加key和value，下標(biāo)從1開始
lua_pushnumber(m_pThreadState, i + 1);
lua_pushnumber(m_pThreadState, pIn[i].unValue.nNumber);
lua_rawset(m_pThreadState, -3);
break;
case SD_STRING:
lua_pushnumber(m_pThreadState, i + 1);
lua_pushstring(m_pThreadState, pIn[i].unValue.szString);
lua_rawset(m_pThreadState, -3);
break;
case SD_TABLE:
lua_pushnumber(m_pThreadState, i + 1);
lua_newtable(m_pThreadState);
int nSize = pIn[i].unValue.stTable.nNum;
SScriptParamObj* pData = (SScriptParamObj*)pIn[i].unValue.stTable.pValue;
PushTable(pData, nSize);
lua_rawset(m_pThreadState, -3);
break;
}
}
}
表作為結(jié)果返回的時候，要注意下面的情況了是否返回表結(jié)構(gòu)的邏輯，程序員應(yīng)該知道的，如果是 表結(jié)構(gòu)，請務(wù)必手動刪除分配的內(nèi)存，而且
在多層的嵌套表結(jié)構(gòu)中，要逐層清理。大概意思就是在引擎中會new內(nèi)存，而這塊內(nèi)存，引擎并不知道在什么時候釋放，需要程序員去手動的釋放
void CLuaScript::ReturnTable(SScriptParamObj* pRet)
{
// 獲取到表的索引
int nNum = 0;
int nIndex = lua_gettop(m_pThreadState);
lua_pushnil(m_pThreadState);
// 先得到數(shù)組的長度
while (lua_next(m_pThreadState, nIndex) != 0)
{
nNum++;
//移除 'value' ；保留 'key' 做下一次迭代
lua_pop(m_pThreadState, 1);
}
nIndex = lua_gettop(m_pThreadState);
// 這時候棧頂還是表
lua_pushnil(m_pThreadState);
SScriptParamObj* pObject = new SScriptParamObj[nNum];
pRet->unValue.stTable.pValue = pObject;
pRet->unValue.stTable.nNum = nNum;
nNum = 0;
while (lua_next(m_pThreadState, nIndex) != 0)
{
// 'key' (索引-2) 和 'value' (索引-1)
// 只對Value感興趣
if (lua_type(m_pThreadState, -1) == LUA_TSTRING)
{
pObject[nNum++] = lua_tostring(m_pThreadState, -1);
}
else if (lua_type(m_pThreadState, -1) == LUA_TNUMBER)
{
pObject[nNum++] = (int)lua_tonumber(m_pThreadState, -1);
}
else if (lua_type(m_pThreadState, -1) == LUA_TTABLE)
{
ReturnTable(&pObject[nNum++]);
}
else
{
nNum++;
}
//移除 'value' ；保留 'key' 做下一次迭代
lua_pop(m_pThreadState, 1);
}
}