Question

如何将c结构数据传给lua

Answer 1

利用lightuserdata和metatable来协调解决这个问题。也即将数据指针给lua，另外告诉它一个如何操作这些数据的metamethods即可。
typedef struct
{
int x;
int y;
int z;
}TData;

static int getAttribute(lua_State* L)
{
TData *data = (TData*)lua_touserdata(L, 1);
std::string attribute = luaL_checkstring(L, 2);
int result = 0;
if(attribute == "x")
{
result = data->x;
}
else if(attribute == "y")
{
result = data->y;
}
else
{
result = data->z;
}
lua_pushnumber(L, result);
return 1;
}

static struct luaL_reg dataLib[] = {
{"__index", getAttribute},
{NULL, NULL}
};

void getMetaTable(lua_State* L, luaL_reg* methods)
{
lua_pushlightuserdata(L, methods);
lua_gettable(L, LUA_REGISTRYINDEX);
if (lua_isnil(L, -1)) {
/* not found */
lua_pop(L, 1);

lua_newtable(L);
luaL_register(L, NULL, methods);

lua_pushlightuserdata(L, methods);
lua_pushvalue(L, -2);
lua_settable(L, LUA_REGISTRYINDEX);
}
}

int main()
{
const char* filename = "test.lua";
lua_State *lua = lua_open();
if (lua == NULL)
{
fprintf(stderr, "open lua failed");
return -1;
}
luaL_openlibs(lua);

TData input = {1, 2, 3};
lua_pushlightuserdata(lua, &input);
getMetaTable(lua, dataLib);
lua_setmetatable(lua, -2);
lua_setglobal(lua, "input");
if (luaL_dofile(lua, filename))
{
luaError(lua, "load file %s failed", filename);
}
lua_getglobal(lua, "data");
int output = lua_tointeger(lua, 0);
std::cout << output << std::endl;
return 0;
}