114 	template <typename T>
115 	using is_trivially_destructible = std::has_trivial_destructor<T>;
131 template <class T>
134   constexpr static bool value = std::is_nothrow_constructible<T, T&&>::value;
138 template <class T, class U>
148   constexpr static bool value = has_assign<T, U>(true);
152 template <class T>
165   constexpr static bool value = has_nothrow_move_assign<T, is_assignable<T&, T&&>::value>::value;
175 template <class T> class optional;
178 template <class T> class optional<T&>;
182 template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type& …  in constexpr_forward()
184   return static_cast<T&&>(t);  in constexpr_forward()
187 template <class T> inline constexpr T&& constexpr_forward(typename std::remove_reference<T>::type&&…  in constexpr_forward()
189     static_assert(!std::is_lvalue_reference<T>::value, "!!");  in constexpr_forward()
190     return static_cast<T&&>(t);  in constexpr_forward()
193 template <class T> inline constexpr typename std::remove_reference<T>::type&& constexpr_move(T&& t)…  in constexpr_move()
195     return static_cast<typename std::remove_reference<T>::type&&>(t);  in constexpr_move()
210 template <typename T>
219   constexpr static bool value = has_overload<T>(true);
222 template <typename T, TR2_OPTIONAL_REQUIRES(!has_overloaded_addressof<T>)>
223 constexpr T* static_addressof(T& ref)  in static_addressof()
228 template <typename T, TR2_OPTIONAL_REQUIRES(has_overloaded_addressof<T>)>
229 T* static_addressof(T& ref)  in static_addressof()
266 template <class T>
270   T value_;
281 template <class T>
285     T value_;
296 template <class T>
300     storage_t<T> storage_;
304     explicit constexpr optional_base(const T& v) : init_(true), storage_(v) {}  in optional_base()
306     explicit constexpr optional_base(T&& v) : init_(true), storage_(constexpr_move(v)) {}  in optional_base()
311 …template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<…
315     ~optional_base() { if (init_) storage_.value_.T::~T(); }  in ~optional_base()
319 template <class T>
323     constexpr_storage_t<T> storage_;
327     explicit constexpr constexpr_optional_base(const T& v) : init_(true), storage_(v) {}  in constexpr_optional_base()
329     explicit constexpr constexpr_optional_base(T&& v) : init_(true), storage_(constexpr_move(v)) {}  in constexpr_optional_base()
334 …template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<…
341 template <class T>
343     is_trivially_destructible<T>::value,
344     constexpr_optional_base<T>,
345     optional_base<T>
350 template <class T>
351 class optional : private OptionalBase<T>
353   static_assert( !std::is_same<typename std::decay<T>::type, nullopt_t>::value, "bad T" );
354   static_assert( !std::is_same<typename std::decay<T>::type, in_place_t>::value, "bad T" );
357   constexpr bool initialized() const noexcept { return OptionalBase<T>::init_; }  in initialized()
358   T* dataptr() {  return std::addressof(OptionalBase<T>::storage_.value_); }  in dataptr()
359 …constexpr const T* dataptr() const { return detail_::static_addressof(OptionalBase<T>::storage_.va…  in dataptr()
362   constexpr const T& contained_val() const& { return OptionalBase<T>::storage_.value_; }  in contained_val()
364 …OPTIONAL_MUTABLE_CONSTEXPR T&& contained_val() && { return std::move(OptionalBase<T>::storage_.val…  in contained_val()
365   OPTIONAL_MUTABLE_CONSTEXPR T& contained_val() & { return OptionalBase<T>::storage_.value_; }  in contained_val()
367   T& contained_val() & { return OptionalBase<T>::storage_.value_; }  in contained_val()
368   T&& contained_val() && { return std::move(OptionalBase<T>::storage_.value_); }  in contained_val()
371   constexpr const T& contained_val() const { return OptionalBase<T>::storage_.value_; }  in contained_val()
372   T& contained_val() { return OptionalBase<T>::storage_.value_; }  in contained_val()
376     if (initialized()) dataptr()->T::~T();  in clear()
377     OptionalBase<T>::init_ = false;  in clear()
381   void initialize(Args&&... args) noexcept(noexcept(T(std::forward<Args>(args)...)))  in initialize()
383     assert(!OptionalBase<T>::init_);  in initialize()
384     ::new (static_cast<void*>(dataptr())) T(std::forward<Args>(args)...);  in initialize()
385     OptionalBase<T>::init_ = true;  in initialize()
389 …void initialize(std::initializer_list<U> il, Args&&... args) noexcept(noexcept(T(il, std::forward<…  in initialize()
391     assert(!OptionalBase<T>::init_);  in initialize()
392     ::new (static_cast<void*>(dataptr())) T(il, std::forward<Args>(args)...);  in initialize()
393     OptionalBase<T>::init_ = true;  in initialize()
397   typedef T value_type;
400   constexpr optional() noexcept : OptionalBase<T>()  {};  in optional()
401   constexpr optional(nullopt_t) noexcept : OptionalBase<T>() {};  in optional()
404   : OptionalBase<T>()  in optional()
407         ::new (static_cast<void*>(dataptr())) T(*rhs);  in optional()
408         OptionalBase<T>::init_ = true;  in optional()
412   optional(optional&& rhs) noexcept(is_nothrow_move_constructible<T>::value)  in optional()
413   : OptionalBase<T>()  in optional()
416         ::new (static_cast<void*>(dataptr())) T(std::move(*rhs));  in optional()
417         OptionalBase<T>::init_ = true;  in optional()
421   constexpr optional(const T& v) : OptionalBase<T>(v) {}  in optional()
423   constexpr optional(T&& v) : OptionalBase<T>(constexpr_move(v)) {}  in optional()
427   : OptionalBase<T>(in_place_t{}, constexpr_forward<Args>(args)...) {}  in optional()
429 …template <class U, class... Args, TR2_OPTIONAL_REQUIRES(is_constructible<T, std::initializer_list<…
431   : OptionalBase<T>(in_place_t{}, il, constexpr_forward<Args>(args)...) {}  in optional()
452   noexcept(is_nothrow_move_assignable<T>::value && is_nothrow_move_constructible<T>::value)  in operator =()
464     is_same<typename decay<U>::type, T>::value,  in operator =()
489 …void swap(optional<T>& rhs) noexcept(is_nothrow_move_constructible<T>::value && noexcept(swap(decl…  in swap()
500   constexpr T const* operator ->() const {  in operator ->()
506   OPTIONAL_MUTABLE_CONSTEXPR T* operator ->() {  in operator ->()
511   constexpr T const& operator *() const& {  in operator *()
515   OPTIONAL_MUTABLE_CONSTEXPR T& operator *() & {  in operator *()
520   OPTIONAL_MUTABLE_CONSTEXPR T&& operator *() && {  in operator *()
525   constexpr T const& value() const& {  in value()
529   OPTIONAL_MUTABLE_CONSTEXPR T& value() & {  in value()
533   OPTIONAL_MUTABLE_CONSTEXPR T&& value() && {  in value()
540   T* operator ->() {  in operator ->()
545   constexpr T const& operator *() const {  in operator *()
549   T& operator *() {  in operator *()
554   constexpr T const& value() const {  in value()
558   T& value() {  in value()
567   constexpr T value_or(V&& v) const&  in value_or()
569     return *this ? **this : detail_::convert<T>(constexpr_forward<V>(v));  in value_or()
575   OPTIONAL_MUTABLE_CONSTEXPR T value_or(V&& v) &&  in value_or()
577 …return *this ? constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<…  in value_or()
583   T value_or(V&& v) &&  in value_or()
585 …return *this ? constexpr_move(const_cast<optional<T>&>(*this).contained_val()) : detail_::convert<…  in value_or()
593   constexpr T value_or(V&& v) const  in value_or()
595     return *this ? **this : detail_::convert<T>(constexpr_forward<V>(v));  in value_or()
603 template <class T>
604 class optional<T&>
606   static_assert( !std::is_same<T, nullopt_t>::value, "bad T" );
607   static_assert( !std::is_same<T, in_place_t>::value, "bad T" );
608   T* ref;
617   constexpr optional(T& v) noexcept : ref(detail_::static_addressof(v)) {}  in optional()
619   optional(T&&) = delete;
623   explicit constexpr optional(in_place_t, T& v) noexcept : ref(detail_::static_addressof(v)) {}  in optional()
625   explicit optional(in_place_t, T&&) = delete;
649     is_same<typename decay<U>::type, optional<T&>>::value,  in operator =()
661     !is_same<typename decay<U>::type, optional<T&>>::value,
666   void emplace(T& v) noexcept {  in emplace()
670   void emplace(T&&) = delete;
673   void swap(optional<T&>& rhs) noexcept  in swap()
679   constexpr T* operator->() const {  in operator ->()
683   constexpr T& operator*() const {  in operator *()
687   constexpr T& value() const {  in value()
696   constexpr typename decay<T>::type value_or(V&& v) const  in value_or()
698     return *this ? **this : detail_::convert<typename decay<T>::type>(constexpr_forward<V>(v));  in value_or()
703 template <class T>
704 class optional<T&&>
706   static_assert( sizeof(T) == 0, "optional rvalue references disallowed" );
711 template <class T> constexpr bool operator==(const optional<T>& x, const optional<T>& y)  in operator ==()
716 template <class T> constexpr bool operator!=(const optional<T>& x, const optional<T>& y)  in operator !=()
721 template <class T> constexpr bool operator<(const optional<T>& x, const optional<T>& y)  in operator <()
726 template <class T> constexpr bool operator>(const optional<T>& x, const optional<T>& y)  in operator >()
731 template <class T> constexpr bool operator<=(const optional<T>& x, const optional<T>& y)  in operator <=()
736 template <class T> constexpr bool operator>=(const optional<T>& x, const optional<T>& y)  in operator >=()
743 template <class T> constexpr bool operator==(const optional<T>& x, nullopt_t) noexcept  in operator ==()
748 template <class T> constexpr bool operator==(nullopt_t, const optional<T>& x) noexcept  in operator ==()
753 template <class T> constexpr bool operator!=(const optional<T>& x, nullopt_t) noexcept  in operator !=()
758 template <class T> constexpr bool operator!=(nullopt_t, const optional<T>& x) noexcept  in operator !=()
763 template <class T> constexpr bool operator<(const optional<T>&, nullopt_t) noexcept  in operator <()  argument
768 template <class T> constexpr bool operator<(nullopt_t, const optional<T>& x) noexcept  in operator <()
773 template <class T> constexpr bool operator<=(const optional<T>& x, nullopt_t) noexcept  in operator <=()
778 template <class T> constexpr bool operator<=(nullopt_t, const optional<T>&) noexcept  in operator <=()  argument
783 template <class T> constexpr bool operator>(const optional<T>& x, nullopt_t) noexcept  in operator >()
788 template <class T> constexpr bool operator>(nullopt_t, const optional<T>&) noexcept  in operator >()  argument
793 template <class T> constexpr bool operator>=(const optional<T>&, nullopt_t) noexcept  in operator >=()  argument
798 template <class T> constexpr bool operator>=(nullopt_t, const optional<T>& x) noexcept  in operator >=()
806 template <class T> constexpr bool operator==(const optional<T>& x, const T& v)  in operator ==()
811 template <class T> constexpr bool operator==(const T& v, const optional<T>& x)  in operator ==()
816 template <class T> constexpr bool operator!=(const optional<T>& x, const T& v)  in operator !=()
821 template <class T> constexpr bool operator!=(const T& v, const optional<T>& x)  in operator !=()
826 template <class T> constexpr bool operator<(const optional<T>& x, const T& v)  in operator <()
831 template <class T> constexpr bool operator>(const T& v, const optional<T>& x)  in operator >()
836 template <class T> constexpr bool operator>(const optional<T>& x, const T& v)  in operator >()
841 template <class T> constexpr bool operator<(const T& v, const optional<T>& x)  in operator <()
846 template <class T> constexpr bool operator>=(const optional<T>& x, const T& v)  in operator >=()
851 template <class T> constexpr bool operator<=(const T& v, const optional<T>& x)  in operator <=()
856 template <class T> constexpr bool operator<=(const optional<T>& x, const T& v)  in operator <=()
861 template <class T> constexpr bool operator>=(const T& v, const optional<T>& x)  in operator >=()
868 template <class T> constexpr bool operator==(const optional<T&>& x, const T& v)  in operator ==()
873 template <class T> constexpr bool operator==(const T& v, const optional<T&>& x)  in operator ==()
878 template <class T> constexpr bool operator!=(const optional<T&>& x, const T& v)  in operator !=()
883 template <class T> constexpr bool operator!=(const T& v, const optional<T&>& x)  in operator !=()
888 template <class T> constexpr bool operator<(const optional<T&>& x, const T& v)  in operator <()
893 template <class T> constexpr bool operator>(const T& v, const optional<T&>& x)  in operator >()
898 template <class T> constexpr bool operator>(const optional<T&>& x, const T& v)  in operator >()
903 template <class T> constexpr bool operator<(const T& v, const optional<T&>& x)  in operator <()
908 template <class T> constexpr bool operator>=(const optional<T&>& x, const T& v)  in operator >=()
913 template <class T> constexpr bool operator<=(const T& v, const optional<T&>& x)  in operator <=()
918 template <class T> constexpr bool operator<=(const optional<T&>& x, const T& v)  in operator <=()
923 template <class T> constexpr bool operator>=(const T& v, const optional<T&>& x)  in operator >=()
929 template <class T> constexpr bool operator==(const optional<const T&>& x, const T& v)  in operator ==()
934 template <class T> constexpr bool operator==(const T& v, const optional<const T&>& x)  in operator ==()
939 template <class T> constexpr bool operator!=(const optional<const T&>& x, const T& v)  in operator !=()
944 template <class T> constexpr bool operator!=(const T& v, const optional<const T&>& x)  in operator !=()
949 template <class T> constexpr bool operator<(const optional<const T&>& x, const T& v)  in operator <()
954 template <class T> constexpr bool operator>(const T& v, const optional<const T&>& x)  in operator >()
959 template <class T> constexpr bool operator>(const optional<const T&>& x, const T& v)  in operator >()
964 template <class T> constexpr bool operator<(const T& v, const optional<const T&>& x)  in operator <()
969 template <class T> constexpr bool operator>=(const optional<const T&>& x, const T& v)  in operator >=()
974 template <class T> constexpr bool operator<=(const T& v, const optional<const T&>& x)  in operator <=()
979 template <class T> constexpr bool operator<=(const optional<const T&>& x, const T& v)  in operator <=()
984 template <class T> constexpr bool operator>=(const T& v, const optional<const T&>& x)  in operator >=()
991 template <class T>
992 void swap(optional<T>& x, optional<T>& y) noexcept(noexcept(x.swap(y)))  in swap()
998 template <class T>
999 constexpr optional<typename decay<T>::type> make_optional(T&& v)  in make_optional()
1001   return optional<typename decay<T>::type>(constexpr_forward<T>(v));  in make_optional()
1016   template <typename T>
1017   struct hash<std::experimental::optional<T>>
1019     typedef typename hash<T>::result_type result_type;
1020     typedef std::experimental::optional<T> argument_type;
1023       return arg ? std::hash<T>{}(*arg) : result_type{};  in operator ()()
1027   template <typename T>
1028   struct hash<std::experimental::optional<T&>>
1030     typedef typename hash<T>::result_type result_type;
1031     typedef std::experimental::optional<T&> argument_type;
1034       return arg ? std::hash<T>{}(*arg) : result_type{};  in operator ()()