// push onto the Lua stack a userdata containing a pointer to T object
static int push(lua_State *L, T *obj, bool gc=false) {
if (!obj) { lua_pushnil(L); return 0; }
luaL_getmetatable(L, ("Lunar_" + std::string(T::className)).c_str()); // lookup metatable in Lua registry
if (lua_isnil(L, -1)) luaL_error(L, "%s missing metatable", T::className);
int mt = lua_gettop(L);
subtable(L, mt, "userdata", "v");
userdataType *ud =
static_cast<userdataType*>(pushuserdata(L, obj, sizeof(userdataType)));
if (ud) {
ud->pT = obj; // store pointer to object in userdata
lua_pushvalue(L, mt);
lua_setmetatable(L, -2);
if (gc == false) {
lua_checkstack(L, 3);
subtable(L, mt, "do not trash", "k");
lua_pushvalue(L, -2);
lua_pushboolean(L, 1);
lua_settable(L, -3);
lua_pop(L, 1);
}
}
lua_replace(L, mt);
lua_settop(L, mt);
return mt; // index of userdata containing pointer to T object
}
// push onto the Lua stack a userdata containing a pointer to T object
static int push(lua_State *L, T *obj, bool gc = false) {
if (obj == nullptr) {
return 0;
}
luaL_getmetatable(L, T::className); // [-0,+1,-]
if (lua_isnil(L, -1)) {
return luaL_error(L, "'%s' missing metatable", T::className);
}
int l_mt = lua_gettop(L);
/* Was this pointer pushed already? Then pushuserdata pushed the existing copy */
if (!pushuserdata(L, obj)) {
return 1;
}
int l_ud = lua_gettop(L);
lua_pushvalue(L, l_mt); // dup(mt)
lua_setmetatable(L, l_ud); // mt(ud)=mt [-1,+0,-]
if (!gc) {
subtable(L, l_mt, "do not trash", "k");
lua_pushvalue(L, l_ud);
lua_pushboolean(L, true);
lua_rawset(L, -3);
}
lua_settop(L, l_ud);
lua_replace(L, l_mt);
int nresult = LunarWrapper::prep(obj, L);
if (nresult != 0) {
const char *msg = nullptr;
int err = lua_gettop(L);
if (err >= 0) {
msg = lua_tostring(L, err);
}
if (msg == nullptr) {
msg = "(unknown error)";
}
return luaL_error(L, "'%s' failed to prepare: %s", T::className, msg);
}
return 1;
}
