+ void clear() noexcept {
+ reset();
+ }
+
+ void swap(Optional& that) noexcept(IsNothrowSwappable<Value>::value) {
+ if (hasValue() && that.hasValue()) {
+ using std::swap;
+ swap(value(), that.value());
+ } else if (hasValue()) {
+ that.emplace(std::move(value()));
+ reset();
+ } else if (that.hasValue()) {
+ emplace(std::move(that.value()));
+ that.reset();
+ }
+ }
+
+ FOLLY_CPP14_CONSTEXPR const Value& value() const & {