-#if LLVM_USE_RVALUE_REFERENCES
- Optional(T &&y) : x(std::forward<T>(y)), hasVal(true) {}
-#endif
+ Optional(NoneType) : hasVal(false) {}
+ explicit Optional() : hasVal(false) {}
+ Optional(const T &y) : hasVal(true) {
+ new (storage.buffer) T(y);
+ }
+ Optional(const Optional &O) : hasVal(O.hasVal) {
+ if (hasVal)
+ new (storage.buffer) T(*O);
+ }
+
+ Optional(T &&y) : hasVal(true) {
+ new (storage.buffer) T(std::forward<T>(y));
+ }
+ Optional(Optional<T> &&O) : hasVal(O) {
+ if (O) {
+ new (storage.buffer) T(std::move(*O));
+ O.reset();
+ }
+ }
+ Optional &operator=(T &&y) {
+ if (hasVal)
+ **this = std::move(y);
+ else {
+ new (storage.buffer) T(std::move(y));
+ hasVal = true;
+ }
+ return *this;
+ }
+ Optional &operator=(Optional &&O) {
+ if (!O)
+ reset();
+ else {
+ *this = std::move(*O);
+ O.reset();
+ }
+ return *this;
+ }
+
+ /// Create a new object by constructing it in place with the given arguments.
+ template<typename ...ArgTypes>
+ void emplace(ArgTypes &&...Args) {
+ reset();
+ hasVal = true;
+ new (storage.buffer) T(std::forward<ArgTypes>(Args)...);
+ }