Home | History | Annotate | Download | only in include
      1 // -*- C++ -*-
      2 //===-------------------------- utility -----------------------------------===//
      3 //
      4 //                     The LLVM Compiler Infrastructure
      5 //
      6 // This file is dual licensed under the MIT and the University of Illinois Open
      7 // Source Licenses. See LICENSE.TXT for details.
      8 //
      9 //===----------------------------------------------------------------------===//
     10 
     11 #ifndef _LIBCPP_UTILITY
     12 #define _LIBCPP_UTILITY
     13 
     14 /*
     15     utility synopsis
     16 
     17 namespace std
     18 {
     19 
     20 template <class T>
     21     void
     22     swap(T& a, T& b);
     23 
     24 namespace rel_ops
     25 {
     26     template<class T> bool operator!=(const T&, const T&);
     27     template<class T> bool operator> (const T&, const T&);
     28     template<class T> bool operator<=(const T&, const T&);
     29     template<class T> bool operator>=(const T&, const T&);
     30 }
     31 
     32 template<class T>
     33 void
     34 swap(T& a, T& b) noexcept(is_nothrow_move_constructible<T>::value &&
     35                           is_nothrow_move_assignable<T>::value);
     36 
     37 template <class T, size_t N>
     38 void
     39 swap(T (&a)[N], T (&b)[N]) noexcept(noexcept(swap(*a, *b)));
     40 
     41 template <class T> T&& forward(typename remove_reference<T>::type& t) noexcept;  // constexpr in C++14
     42 template <class T> T&& forward(typename remove_reference<T>::type&& t) noexcept; // constexpr in C++14
     43 
     44 template <class T> typename remove_reference<T>::type&& move(T&&) noexcept;      // constexpr in C++14
     45 
     46 template <class T>
     47     typename conditional
     48     <
     49         !is_nothrow_move_constructible<T>::value && is_copy_constructible<T>::value,
     50         const T&,
     51         T&&
     52     >::type
     53     move_if_noexcept(T& x) noexcept; // constexpr in C++14
     54 
     55 template <class T> typename add_rvalue_reference<T>::type declval() noexcept;
     56 
     57 template <class T1, class T2>
     58 struct pair
     59 {
     60     typedef T1 first_type;
     61     typedef T2 second_type;
     62 
     63     T1 first;
     64     T2 second;
     65 
     66     pair(const pair&) = default;
     67     pair(pair&&) = default;
     68     constexpr pair();
     69     pair(const T1& x, const T2& y);                          // constexpr in C++14
     70     template <class U, class V> pair(U&& x, V&& y);          // constexpr in C++14
     71     template <class U, class V> pair(const pair<U, V>& p);   // constexpr in C++14
     72     template <class U, class V> pair(pair<U, V>&& p);        // constexpr in C++14
     73     template <class... Args1, class... Args2>
     74         pair(piecewise_construct_t, tuple<Args1...> first_args,
     75              tuple<Args2...> second_args);
     76 
     77     template <class U, class V> pair& operator=(const pair<U, V>& p);
     78     pair& operator=(pair&& p) noexcept(is_nothrow_move_assignable<T1>::value &&
     79                                        is_nothrow_move_assignable<T2>::value);
     80     template <class U, class V> pair& operator=(pair<U, V>&& p);
     81 
     82     void swap(pair& p) noexcept(noexcept(swap(first, p.first)) &&
     83                                 noexcept(swap(second, p.second)));
     84 };
     85 
     86 template <class T1, class T2> bool operator==(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
     87 template <class T1, class T2> bool operator!=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
     88 template <class T1, class T2> bool operator< (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
     89 template <class T1, class T2> bool operator> (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
     90 template <class T1, class T2> bool operator>=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
     91 template <class T1, class T2> bool operator<=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
     92 
     93 template <class T1, class T2> pair<V1, V2> make_pair(T1&&, T2&&);   // constexpr in C++14
     94 template <class T1, class T2>
     95 void
     96 swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
     97 
     98 struct piecewise_construct_t { };
     99 constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
    100 
    101 template <class T> class tuple_size;
    102 template <size_t I, class T> class tuple_element;
    103 
    104 template <class T1, class T2> struct tuple_size<pair<T1, T2> >;
    105 template <class T1, class T2> struct tuple_element<0, pair<T1, T2> >;
    106 template <class T1, class T2> struct tuple_element<1, pair<T1, T2> >;
    107 
    108 template<size_t I, class T1, class T2>
    109     typename tuple_element<I, pair<T1, T2> >::type&
    110     get(pair<T1, T2>&) noexcept; // constexpr in C++14
    111 
    112 template<size_t I, class T1, class T2>
    113     const typename const tuple_element<I, pair<T1, T2> >::type&
    114     get(const pair<T1, T2>&) noexcept; // constexpr in C++14
    115 
    116 template<size_t I, class T1, class T2>
    117     typename tuple_element<I, pair<T1, T2> >::type&&
    118     get(pair<T1, T2>&&) noexcept; // constexpr in C++14
    119 
    120 template<class T1, class T2>
    121     constexpr T1& get(pair<T1, T2>&) noexcept; // C++14
    122 
    123 template<size_t I, class T1, class T2>
    124     constexpr T1 const& get(pair<T1, T2> const &) noexcept; // C++14
    125 
    126 template<size_t I, class T1, class T2>
    127     constexpr T1&& get(pair<T1, T2>&&) noexcept; // C++14
    128 
    129 // C++14
    130 
    131 template<class T, T... I>
    132 struct integer_sequence
    133 {
    134     typedef T value_type;
    135 
    136     static constexpr size_t size() noexcept;
    137 };
    138 
    139 template<size_t... I>
    140   using index_sequence = integer_sequence<size_t, I...>;
    141 
    142 template<class T, T N>
    143   using make_integer_sequence = integer_sequence<T, 0, 1, ..., N-1>;
    144 template<size_t N>
    145   using make_index_sequence = make_integer_sequence<size_t, N>;
    146 
    147 template<class... T>
    148   using index_sequence_for = make_index_sequence<sizeof...(T)>;
    149 
    150 template<class T, class U=T> 
    151     T exchange(T& obj, U&& new_value);
    152 }  // std
    153 
    154 */
    155 
    156 #include <__config>
    157 #include <__tuple>
    158 #include <type_traits>
    159 
    160 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
    161 #pragma GCC system_header
    162 #endif
    163 
    164 _LIBCPP_BEGIN_NAMESPACE_STD
    165 
    166 namespace rel_ops
    167 {
    168 
    169 template<class _Tp>
    170 inline _LIBCPP_INLINE_VISIBILITY
    171 bool
    172 operator!=(const _Tp& __x, const _Tp& __y)
    173 {
    174     return !(__x == __y);
    175 }
    176 
    177 template<class _Tp>
    178 inline _LIBCPP_INLINE_VISIBILITY
    179 bool
    180 operator> (const _Tp& __x, const _Tp& __y)
    181 {
    182     return __y < __x;
    183 }
    184 
    185 template<class _Tp>
    186 inline _LIBCPP_INLINE_VISIBILITY
    187 bool
    188 operator<=(const _Tp& __x, const _Tp& __y)
    189 {
    190     return !(__y < __x);
    191 }
    192 
    193 template<class _Tp>
    194 inline _LIBCPP_INLINE_VISIBILITY
    195 bool
    196 operator>=(const _Tp& __x, const _Tp& __y)
    197 {
    198     return !(__x < __y);
    199 }
    200 
    201 }  // rel_ops
    202 
    203 // swap_ranges
    204 
    205 template <class _ForwardIterator1, class _ForwardIterator2>
    206 inline _LIBCPP_INLINE_VISIBILITY
    207 _ForwardIterator2
    208 swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
    209 {
    210     for(; __first1 != __last1; ++__first1, ++__first2)
    211         swap(*__first1, *__first2);
    212     return __first2;
    213 }
    214 
    215 template<class _Tp, size_t _Np>
    216 inline _LIBCPP_INLINE_VISIBILITY
    217 void
    218 swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value)
    219 {
    220     _VSTD::swap_ranges(__a, __a + _Np, __b);
    221 }
    222 
    223 template <class _Tp>
    224 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    225 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    226 typename conditional
    227 <
    228     !is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value,
    229     const _Tp&,
    230     _Tp&&
    231 >::type
    232 #else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    233 const _Tp&
    234 #endif
    235 move_if_noexcept(_Tp& __x) _NOEXCEPT
    236 {
    237     return _VSTD::move(__x);
    238 }
    239 
    240 struct _LIBCPP_TYPE_VIS_ONLY piecewise_construct_t { };
    241 #if defined(_LIBCPP_HAS_NO_CONSTEXPR) || defined(_LIBCPP_BUILDING_UTILITY)
    242 extern const piecewise_construct_t piecewise_construct;// = piecewise_construct_t();
    243 #else
    244 constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
    245 #endif
    246 
    247 template <class _T1, class _T2>
    248 struct _LIBCPP_TYPE_VIS_ONLY pair
    249 {
    250     typedef _T1 first_type;
    251     typedef _T2 second_type;
    252 
    253     _T1 first;
    254     _T2 second;
    255 
    256     // pair(const pair&) = default;
    257     // pair(pair&&) = default;
    258 
    259     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR pair() : first(), second() {}
    260 
    261     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    262     pair(const _T1& __x, const _T2& __y)
    263         : first(__x), second(__y) {}
    264 
    265     template<class _U1, class _U2>
    266         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    267         pair(const pair<_U1, _U2>& __p
    268 #ifndef _LIBCPP_HAS_NO_ADVANCED_SFINAE
    269                  ,typename enable_if<is_convertible<const _U1&, _T1>::value &&
    270                                     is_convertible<const _U2&, _T2>::value>::type* = 0
    271 #endif
    272                                       )
    273             : first(__p.first), second(__p.second) {}
    274 
    275 #if !defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && _LIBCPP_TRIVIAL_PAIR_COPY_CTOR
    276     _LIBCPP_INLINE_VISIBILITY
    277     pair(const pair& __p) = default;
    278 #elif !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) || !_LIBCPP_TRIVIAL_PAIR_COPY_CTOR
    279     _LIBCPP_INLINE_VISIBILITY
    280     pair(const pair& __p)
    281         _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
    282                    is_nothrow_copy_constructible<second_type>::value)
    283         : first(__p.first),
    284           second(__p.second)
    285     {
    286     }
    287 #endif
    288 
    289     _LIBCPP_INLINE_VISIBILITY
    290     pair& operator=(const pair& __p)
    291         _NOEXCEPT_(is_nothrow_copy_assignable<first_type>::value &&
    292                    is_nothrow_copy_assignable<second_type>::value)
    293     {
    294         first = __p.first;
    295         second = __p.second;
    296         return *this;
    297     }
    298 
    299 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    300 
    301     template <class _U1, class _U2,
    302               class = typename enable_if<is_convertible<_U1, first_type>::value &&
    303                                          is_convertible<_U2, second_type>::value>::type>
    304         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    305         pair(_U1&& __u1, _U2&& __u2)
    306             : first(_VSTD::forward<_U1>(__u1)),
    307               second(_VSTD::forward<_U2>(__u2))
    308             {}
    309 
    310     template<class _U1, class _U2>
    311         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    312         pair(pair<_U1, _U2>&& __p,
    313                  typename enable_if<is_convertible<_U1, _T1>::value &&
    314                                     is_convertible<_U2, _T2>::value>::type* = 0)
    315             : first(_VSTD::forward<_U1>(__p.first)),
    316               second(_VSTD::forward<_U2>(__p.second)) {}
    317 
    318 #ifndef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
    319     _LIBCPP_INLINE_VISIBILITY
    320     pair(pair&& __p) = default;
    321 #else
    322     _LIBCPP_INLINE_VISIBILITY
    323     pair(pair&& __p) _NOEXCEPT_(is_nothrow_move_constructible<first_type>::value &&
    324                                 is_nothrow_move_constructible<second_type>::value)
    325         : first(_VSTD::forward<first_type>(__p.first)),
    326           second(_VSTD::forward<second_type>(__p.second))
    327     {
    328     }
    329 #endif
    330 
    331     _LIBCPP_INLINE_VISIBILITY
    332     pair&
    333     operator=(pair&& __p) _NOEXCEPT_(is_nothrow_move_assignable<first_type>::value &&
    334                                      is_nothrow_move_assignable<second_type>::value)
    335     {
    336         first = _VSTD::forward<first_type>(__p.first);
    337         second = _VSTD::forward<second_type>(__p.second);
    338         return *this;
    339     }
    340 
    341 #ifndef _LIBCPP_HAS_NO_VARIADICS
    342 
    343     template<class _Tuple,
    344              class = typename enable_if<__tuple_convertible<_Tuple, pair>::value>::type>
    345         _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    346         pair(_Tuple&& __p)
    347             : first(_VSTD::forward<typename tuple_element<0,
    348                                   typename __make_tuple_types<_Tuple>::type>::type>(get<0>(__p))),
    349               second(_VSTD::forward<typename tuple_element<1,
    350                                    typename __make_tuple_types<_Tuple>::type>::type>(get<1>(__p)))
    351             {}
    352 
    353 
    354 
    355     template <class... _Args1, class... _Args2>
    356         _LIBCPP_INLINE_VISIBILITY
    357         pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
    358                                     tuple<_Args2...> __second_args)
    359             : pair(__pc, __first_args, __second_args,
    360                    typename __make_tuple_indices<sizeof...(_Args1)>::type(),
    361                    typename __make_tuple_indices<sizeof...(_Args2) >::type())
    362             {}
    363 
    364     template <class _Tuple,
    365               class = typename enable_if<__tuple_assignable<_Tuple, pair>::value>::type>
    366         _LIBCPP_INLINE_VISIBILITY
    367         pair&
    368         operator=(_Tuple&& __p)
    369         {
    370             typedef typename __make_tuple_types<_Tuple>::type _TupleRef;
    371             typedef typename tuple_element<0, _TupleRef>::type _U0;
    372             typedef typename tuple_element<1, _TupleRef>::type _U1;
    373             first  = _VSTD::forward<_U0>(_VSTD::get<0>(__p));
    374             second = _VSTD::forward<_U1>(_VSTD::get<1>(__p));
    375             return *this;
    376         }
    377 
    378 #endif  // _LIBCPP_HAS_NO_VARIADICS
    379 
    380 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    381     _LIBCPP_INLINE_VISIBILITY
    382     void
    383     swap(pair& __p) _NOEXCEPT_(__is_nothrow_swappable<first_type>::value &&
    384                                __is_nothrow_swappable<second_type>::value)
    385     {
    386         _VSTD::iter_swap(&first, &__p.first);
    387         _VSTD::iter_swap(&second, &__p.second);
    388     }
    389 private:
    390 
    391 #ifndef _LIBCPP_HAS_NO_VARIADICS
    392     template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
    393         _LIBCPP_INLINE_VISIBILITY
    394         pair(piecewise_construct_t,
    395              tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
    396              __tuple_indices<_I1...>, __tuple_indices<_I2...>);
    397 #endif  // _LIBCPP_HAS_NO_VARIADICS
    398 };
    399 
    400 template <class _T1, class _T2>
    401 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    402 bool
    403 operator==(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
    404 {
    405     return __x.first == __y.first && __x.second == __y.second;
    406 }
    407 
    408 template <class _T1, class _T2>
    409 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    410 bool
    411 operator!=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
    412 {
    413     return !(__x == __y);
    414 }
    415 
    416 template <class _T1, class _T2>
    417 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    418 bool
    419 operator< (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
    420 {
    421     return __x.first < __y.first || (!(__y.first < __x.first) && __x.second < __y.second);
    422 }
    423 
    424 template <class _T1, class _T2>
    425 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    426 bool
    427 operator> (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
    428 {
    429     return __y < __x;
    430 }
    431 
    432 template <class _T1, class _T2>
    433 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    434 bool
    435 operator>=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
    436 {
    437     return !(__x < __y);
    438 }
    439 
    440 template <class _T1, class _T2>
    441 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    442 bool
    443 operator<=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
    444 {
    445     return !(__y < __x);
    446 }
    447 
    448 template <class _T1, class _T2>
    449 inline _LIBCPP_INLINE_VISIBILITY
    450 typename enable_if
    451 <
    452     __is_swappable<_T1>::value &&
    453     __is_swappable<_T2>::value,
    454     void
    455 >::type
    456 swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
    457                      _NOEXCEPT_((__is_nothrow_swappable<_T1>::value &&
    458                                  __is_nothrow_swappable<_T2>::value))
    459 {
    460     __x.swap(__y);
    461 }
    462 
    463 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    464 
    465 template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
    466 
    467 template <class _Tp>
    468 struct __make_pair_return_impl
    469 {
    470     typedef _Tp type;
    471 };
    472 
    473 template <class _Tp>
    474 struct __make_pair_return_impl<reference_wrapper<_Tp>>
    475 {
    476     typedef _Tp& type;
    477 };
    478 
    479 template <class _Tp>
    480 struct __make_pair_return
    481 {
    482     typedef typename __make_pair_return_impl<typename decay<_Tp>::type>::type type;
    483 };
    484 
    485 template <class _T1, class _T2>
    486 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    487 pair<typename __make_pair_return<_T1>::type, typename __make_pair_return<_T2>::type>
    488 make_pair(_T1&& __t1, _T2&& __t2)
    489 {
    490     return pair<typename __make_pair_return<_T1>::type, typename __make_pair_return<_T2>::type>
    491                (_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
    492 }
    493 
    494 #else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    495 
    496 template <class _T1, class _T2>
    497 inline _LIBCPP_INLINE_VISIBILITY
    498 pair<_T1,_T2>
    499 make_pair(_T1 __x, _T2 __y)
    500 {
    501     return pair<_T1, _T2>(__x, __y);
    502 }
    503 
    504 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    505 
    506 template <class _T1, class _T2>
    507   class _LIBCPP_TYPE_VIS_ONLY tuple_size<pair<_T1, _T2> >
    508     : public integral_constant<size_t, 2> {};
    509 
    510 template <class _T1, class _T2>
    511   class _LIBCPP_TYPE_VIS_ONLY tuple_size<const pair<_T1, _T2> >
    512     : public integral_constant<size_t, 2> {};
    513 
    514 template <class _T1, class _T2>
    515 class _LIBCPP_TYPE_VIS_ONLY tuple_element<0, pair<_T1, _T2> >
    516 {
    517 public:
    518     typedef _T1 type;
    519 };
    520 
    521 template <class _T1, class _T2>
    522 class _LIBCPP_TYPE_VIS_ONLY tuple_element<1, pair<_T1, _T2> >
    523 {
    524 public:
    525     typedef _T2 type;
    526 };
    527 
    528 template <class _T1, class _T2>
    529 class _LIBCPP_TYPE_VIS_ONLY tuple_element<0, const pair<_T1, _T2> >
    530 {
    531 public:
    532     typedef const _T1 type;
    533 };
    534 
    535 template <class _T1, class _T2>
    536 class _LIBCPP_TYPE_VIS_ONLY tuple_element<1, const pair<_T1, _T2> >
    537 {
    538 public:
    539     typedef const _T2 type;
    540 };
    541 
    542 template <size_t _Ip> struct __get_pair;
    543 
    544 template <>
    545 struct __get_pair<0>
    546 {
    547     template <class _T1, class _T2>
    548     static
    549     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    550     _T1&
    551     get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
    552 
    553     template <class _T1, class _T2>
    554     static
    555     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    556     const _T1&
    557     get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
    558 
    559 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    560 
    561     template <class _T1, class _T2>
    562     static
    563     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    564     _T1&&
    565     get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
    566 
    567 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    568 };
    569 
    570 template <>
    571 struct __get_pair<1>
    572 {
    573     template <class _T1, class _T2>
    574     static
    575     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    576     _T2&
    577     get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
    578 
    579     template <class _T1, class _T2>
    580     static
    581     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    582     const _T2&
    583     get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
    584 
    585 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    586 
    587     template <class _T1, class _T2>
    588     static
    589     _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    590     _T2&&
    591     get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
    592 
    593 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    594 };
    595 
    596 template <size_t _Ip, class _T1, class _T2>
    597 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    598 typename tuple_element<_Ip, pair<_T1, _T2> >::type&
    599 get(pair<_T1, _T2>& __p) _NOEXCEPT
    600 {
    601     return __get_pair<_Ip>::get(__p);
    602 }
    603 
    604 template <size_t _Ip, class _T1, class _T2>
    605 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    606 const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
    607 get(const pair<_T1, _T2>& __p) _NOEXCEPT
    608 {
    609     return __get_pair<_Ip>::get(__p);
    610 }
    611 
    612 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
    613 
    614 template <size_t _Ip, class _T1, class _T2>
    615 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
    616 typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
    617 get(pair<_T1, _T2>&& __p) _NOEXCEPT
    618 {
    619     return __get_pair<_Ip>::get(_VSTD::move(__p));
    620 }
    621 
    622 #endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
    623 
    624 #if _LIBCPP_STD_VER > 11
    625 template <class _T1, class _T2>
    626 inline _LIBCPP_INLINE_VISIBILITY
    627 constexpr _T1 & get(pair<_T1, _T2>& __p) _NOEXCEPT
    628 {
    629     return __get_pair<0>::get(__p);
    630 }
    631 
    632 template <class _T1, class _T2>
    633 inline _LIBCPP_INLINE_VISIBILITY
    634 constexpr _T1 const & get(pair<_T1, _T2> const& __p) _NOEXCEPT
    635 {
    636     return __get_pair<0>::get(__p);
    637 }
    638 
    639 template <class _T1, class _T2>
    640 inline _LIBCPP_INLINE_VISIBILITY
    641 constexpr _T1 && get(pair<_T1, _T2>&& __p) _NOEXCEPT
    642 {
    643     return __get_pair<0>::get(_VSTD::move(__p));
    644 }
    645 
    646 template <class _T1, class _T2>
    647 inline _LIBCPP_INLINE_VISIBILITY
    648 constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
    649 {
    650     return __get_pair<1>::get(__p);
    651 }
    652 
    653 template <class _T1, class _T2>
    654 inline _LIBCPP_INLINE_VISIBILITY
    655 constexpr _T1 const & get(pair<_T2, _T1> const& __p) _NOEXCEPT
    656 {
    657     return __get_pair<1>::get(__p);
    658 }
    659 
    660 template <class _T1, class _T2>
    661 inline _LIBCPP_INLINE_VISIBILITY
    662 constexpr _T1 && get(pair<_T2, _T1>&& __p) _NOEXCEPT
    663 {
    664     return __get_pair<1>::get(_VSTD::move(__p));
    665 }
    666 
    667 #endif
    668 
    669 #if _LIBCPP_STD_VER > 11
    670 
    671 template<class _Tp, _Tp... _Ip>
    672 struct _LIBCPP_TYPE_VIS_ONLY integer_sequence
    673 {
    674     typedef _Tp value_type;
    675     static_assert( is_integral<_Tp>::value,
    676                   "std::integer_sequence can only be instantiated with an integral type" );
    677     static
    678     _LIBCPP_INLINE_VISIBILITY
    679     constexpr
    680     size_t
    681     size() noexcept { return sizeof...(_Ip); }
    682 };
    683 
    684 template<size_t... _Ip>
    685     using index_sequence = integer_sequence<size_t, _Ip...>;
    686 
    687 namespace __detail {
    688 
    689 template<typename _Tp, size_t ..._Extra> struct __repeat;
    690 template<typename _Tp, _Tp ..._Np, size_t ..._Extra> struct __repeat<integer_sequence<_Tp, _Np...>, _Extra...> {
    691   typedef integer_sequence<_Tp,
    692                            _Np...,
    693                            sizeof...(_Np) + _Np...,
    694                            2 * sizeof...(_Np) + _Np...,
    695                            3 * sizeof...(_Np) + _Np...,
    696                            4 * sizeof...(_Np) + _Np...,
    697                            5 * sizeof...(_Np) + _Np...,
    698                            6 * sizeof...(_Np) + _Np...,
    699                            7 * sizeof...(_Np) + _Np...,
    700                            _Extra...> type;
    701 };
    702 
    703 template<size_t _Np> struct __parity;
    704 template<size_t _Np> struct __make : __parity<_Np % 8>::template __pmake<_Np> {};
    705 
    706 template<> struct __make<0> { typedef integer_sequence<size_t> type; };
    707 template<> struct __make<1> { typedef integer_sequence<size_t, 0> type; };
    708 template<> struct __make<2> { typedef integer_sequence<size_t, 0, 1> type; };
    709 template<> struct __make<3> { typedef integer_sequence<size_t, 0, 1, 2> type; };
    710 template<> struct __make<4> { typedef integer_sequence<size_t, 0, 1, 2, 3> type; };
    711 template<> struct __make<5> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4> type; };
    712 template<> struct __make<6> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4, 5> type; };
    713 template<> struct __make<7> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6> type; };
    714 
    715 template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; };
    716 template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; };
    717 template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; };
    718 template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; };
    719 template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
    720 template<> struct __parity<5> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
    721 template<> struct __parity<6> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
    722 template<> struct __parity<7> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 7, _Np - 6, _Np - 5, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
    723 
    724 template<typename _Tp, typename _Up> struct __convert {
    725   template<typename> struct __result;
    726   template<_Tp ..._Np> struct __result<integer_sequence<_Tp, _Np...> > { typedef integer_sequence<_Up, _Np...> type; };
    727 };
    728 template<typename _Tp> struct __convert<_Tp, _Tp> { template<typename _Up> struct __result { typedef _Up type; }; };
    729 
    730 }
    731 
    732 template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked =
    733   typename __detail::__convert<size_t, _Tp>::template __result<typename __detail::__make<_Np>::type>::type;
    734 
    735 template <class _Tp, _Tp _Ep>
    736 struct __make_integer_sequence
    737 {
    738     static_assert(is_integral<_Tp>::value,
    739                   "std::make_integer_sequence can only be instantiated with an integral type" );
    740     static_assert(0 <= _Ep, "std::make_integer_sequence input shall not be negative");
    741     typedef __make_integer_sequence_unchecked<_Tp, _Ep> type;
    742 };
    743 
    744 template<class _Tp, _Tp _Np>
    745     using make_integer_sequence = typename __make_integer_sequence<_Tp, _Np>::type;
    746 
    747 template<size_t _Np>
    748     using make_index_sequence = make_integer_sequence<size_t, _Np>;
    749 
    750 template<class... _Tp>
    751     using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
    752   
    753 #endif  // _LIBCPP_STD_VER > 11
    754 
    755 #if _LIBCPP_STD_VER > 11
    756 template<class _T1, class _T2 = _T1>
    757 inline _LIBCPP_INLINE_VISIBILITY
    758 _T1 exchange(_T1& __obj, _T2 && __new_value)
    759 {
    760     _T1 __old_value = _VSTD::move(__obj);
    761     __obj = _VSTD::forward<_T2>(__new_value);
    762     return __old_value;
    763 }    
    764 #endif  // _LIBCPP_STD_VER > 11
    765 
    766 _LIBCPP_END_NAMESPACE_STD
    767 
    768 #endif  // _LIBCPP_UTILITY
    769