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
17namespace std
18{
19
20template <class T>
21    void
22    swap(T& a, T& b);
23
24namespace 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
32template<class T>
33void
34swap(T& a, T& b) noexcept(is_nothrow_move_constructible<T>::value &&
35                          is_nothrow_move_assignable<T>::value);
36
37template <class T, size_t N>
38void
39swap(T (&a)[N], T (&b)[N]) noexcept(noexcept(swap(*a, *b)));
40
41template <class T> T&& forward(typename remove_reference<T>::type& t) noexcept;  // constexpr in C++14
42template <class T> T&& forward(typename remove_reference<T>::type&& t) noexcept; // constexpr in C++14
43
44template <class T> typename remove_reference<T>::type&& move(T&&) noexcept;      // constexpr in C++14
45
46template <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
55template <class T> constexpr add_const<T>_t& as_const(T& t) noexcept;      // C++17
56template <class T>                      void as_const(const T&&) = delete; // C++17
57
58template <class T> typename add_rvalue_reference<T>::type declval() noexcept;
59
60template <class T1, class T2>
61struct pair
62{
63    typedef T1 first_type;
64    typedef T2 second_type;
65
66    T1 first;
67    T2 second;
68
69    pair(const pair&) = default;
70    pair(pair&&) = default;
71    constexpr pair();
72    pair(const T1& x, const T2& y);                          // constexpr in C++14
73    template <class U, class V> pair(U&& x, V&& y);          // constexpr in C++14
74    template <class U, class V> pair(const pair<U, V>& p);   // constexpr in C++14
75    template <class U, class V> pair(pair<U, V>&& p);        // constexpr in C++14
76    template <class... Args1, class... Args2>
77        pair(piecewise_construct_t, tuple<Args1...> first_args,
78             tuple<Args2...> second_args);
79
80    template <class U, class V> pair& operator=(const pair<U, V>& p);
81    pair& operator=(pair&& p) noexcept(is_nothrow_move_assignable<T1>::value &&
82                                       is_nothrow_move_assignable<T2>::value);
83    template <class U, class V> pair& operator=(pair<U, V>&& p);
84
85    void swap(pair& p) noexcept(noexcept(swap(first, p.first)) &&
86                                noexcept(swap(second, p.second)));
87};
88
89template <class T1, class T2> bool operator==(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
90template <class T1, class T2> bool operator!=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
91template <class T1, class T2> bool operator< (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
92template <class T1, class T2> bool operator> (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
93template <class T1, class T2> bool operator>=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
94template <class T1, class T2> bool operator<=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
95
96template <class T1, class T2> pair<V1, V2> make_pair(T1&&, T2&&);   // constexpr in C++14
97template <class T1, class T2>
98void
99swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
100
101struct piecewise_construct_t { };
102constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
103
104template <class T> class tuple_size;
105template <size_t I, class T> class tuple_element;
106
107template <class T1, class T2> struct tuple_size<pair<T1, T2> >;
108template <class T1, class T2> struct tuple_element<0, pair<T1, T2> >;
109template <class T1, class T2> struct tuple_element<1, pair<T1, T2> >;
110
111template<size_t I, class T1, class T2>
112    typename tuple_element<I, pair<T1, T2> >::type&
113    get(pair<T1, T2>&) noexcept; // constexpr in C++14
114
115template<size_t I, class T1, class T2>
116    const typename tuple_element<I, pair<T1, T2> >::type&
117    get(const pair<T1, T2>&) noexcept; // constexpr in C++14
118
119template<size_t I, class T1, class T2>
120    typename tuple_element<I, pair<T1, T2> >::type&&
121    get(pair<T1, T2>&&) noexcept; // constexpr in C++14
122
123template<size_t I, class T1, class T2>
124    const typename tuple_element<I, pair<T1, T2> >::type&&
125    get(const pair<T1, T2>&&) noexcept; // constexpr in C++14
126
127template<class T1, class T2>
128    constexpr T1& get(pair<T1, T2>&) noexcept; // C++14
129
130template<class T1, class T2>
131    constexpr const T1& get(const pair<T1, T2>&) noexcept; // C++14
132
133template<class T1, class T2>
134    constexpr T1&& get(pair<T1, T2>&&) noexcept; // C++14
135
136template<class T1, class T2>
137    constexpr const T1&& get(const pair<T1, T2>&&) noexcept; // C++14
138
139template<class T1, class T2>
140    constexpr T1& get(pair<T2, T1>&) noexcept; // C++14
141
142template<class T1, class T2>
143    constexpr const T1& get(const pair<T2, T1>&) noexcept; // C++14
144
145template<class T1, class T2>
146    constexpr T1&& get(pair<T2, T1>&&) noexcept; // C++14
147
148template<class T1, class T2>
149    constexpr const T1&& get(const pair<T2, T1>&&) noexcept; // C++14
150
151// C++14
152
153template<class T, T... I>
154struct integer_sequence
155{
156    typedef T value_type;
157
158    static constexpr size_t size() noexcept;
159};
160
161template<size_t... I>
162  using index_sequence = integer_sequence<size_t, I...>;
163
164template<class T, T N>
165  using make_integer_sequence = integer_sequence<T, 0, 1, ..., N-1>;
166template<size_t N>
167  using make_index_sequence = make_integer_sequence<size_t, N>;
168
169template<class... T>
170  using index_sequence_for = make_index_sequence<sizeof...(T)>;
171
172template<class T, class U=T> 
173    T exchange(T& obj, U&& new_value);
174}  // std
175
176*/
177
178#include <__config>
179#include <__tuple>
180#include <type_traits>
181
182#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
183#pragma GCC system_header
184#endif
185
186_LIBCPP_BEGIN_NAMESPACE_STD
187
188namespace rel_ops
189{
190
191template<class _Tp>
192inline _LIBCPP_INLINE_VISIBILITY
193bool
194operator!=(const _Tp& __x, const _Tp& __y)
195{
196    return !(__x == __y);
197}
198
199template<class _Tp>
200inline _LIBCPP_INLINE_VISIBILITY
201bool
202operator> (const _Tp& __x, const _Tp& __y)
203{
204    return __y < __x;
205}
206
207template<class _Tp>
208inline _LIBCPP_INLINE_VISIBILITY
209bool
210operator<=(const _Tp& __x, const _Tp& __y)
211{
212    return !(__y < __x);
213}
214
215template<class _Tp>
216inline _LIBCPP_INLINE_VISIBILITY
217bool
218operator>=(const _Tp& __x, const _Tp& __y)
219{
220    return !(__x < __y);
221}
222
223}  // rel_ops
224
225// swap_ranges
226
227// forward
228template<class _Tp, size_t _Np>
229inline _LIBCPP_INLINE_VISIBILITY
230void swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value);
231
232template <class _ForwardIterator1, class _ForwardIterator2>
233inline _LIBCPP_INLINE_VISIBILITY
234_ForwardIterator2
235swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
236{
237    for(; __first1 != __last1; ++__first1, (void) ++__first2)
238        swap(*__first1, *__first2);
239    return __first2;
240}
241
242template<class _Tp, size_t _Np>
243inline _LIBCPP_INLINE_VISIBILITY
244void
245swap(_Tp (&__a)[_Np], _Tp (&__b)[_Np]) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value)
246{
247    _VSTD::swap_ranges(__a, __a + _Np, __b);
248}
249
250template <class _Tp>
251inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
252#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
253typename conditional
254<
255    !is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value,
256    const _Tp&,
257    _Tp&&
258>::type
259#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
260const _Tp&
261#endif
262move_if_noexcept(_Tp& __x) _NOEXCEPT
263{
264    return _VSTD::move(__x);
265}
266
267#if _LIBCPP_STD_VER > 14
268template <class _Tp> constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
269template <class _Tp>                        void as_const(const _Tp&&) = delete;
270#endif
271
272struct _LIBCPP_TYPE_VIS_ONLY piecewise_construct_t { };
273#if defined(_LIBCPP_HAS_NO_CONSTEXPR) || defined(_LIBCPP_BUILDING_UTILITY)
274extern const piecewise_construct_t piecewise_construct;// = piecewise_construct_t();
275#else
276constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
277#endif
278
279template <class _T1, class _T2>
280struct _LIBCPP_TYPE_VIS_ONLY pair
281{
282    typedef _T1 first_type;
283    typedef _T2 second_type;
284
285    _T1 first;
286    _T2 second;
287
288    // pair(const pair&) = default;
289    // pair(pair&&) = default;
290
291#ifndef _LIBCPP_HAS_NO_DEFAULT_FUNCTION_TEMPLATE_ARGS
292    template <bool _Dummy = true, class = typename enable_if<
293        __dependent_type<is_default_constructible<_T1>, _Dummy>::value &&
294        __dependent_type<is_default_constructible<_T2>, _Dummy>::value
295      >::type>
296#endif
297    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR pair() : first(), second() {}
298
299    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
300    pair(const _T1& __x, const _T2& __y)
301        : first(__x), second(__y) {}
302
303    template<class _U1, class _U2>
304        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
305        pair(const pair<_U1, _U2>& __p
306#ifndef _LIBCPP_HAS_NO_ADVANCED_SFINAE
307                 ,typename enable_if<is_convertible<const _U1&, _T1>::value &&
308                                    is_convertible<const _U2&, _T2>::value>::type* = 0
309#endif
310                                      )
311            : first(__p.first), second(__p.second) {}
312
313#if !defined(_LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS) && _LIBCPP_TRIVIAL_PAIR_COPY_CTOR
314    _LIBCPP_INLINE_VISIBILITY
315    pair(const pair& __p) = default;
316#elif !defined(_LIBCPP_HAS_NO_RVALUE_REFERENCES) || !_LIBCPP_TRIVIAL_PAIR_COPY_CTOR
317    _LIBCPP_INLINE_VISIBILITY
318    pair(const pair& __p)
319        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
320                   is_nothrow_copy_constructible<second_type>::value)
321        : first(__p.first),
322          second(__p.second)
323    {
324    }
325#endif
326
327    _LIBCPP_INLINE_VISIBILITY
328    pair& operator=(const pair& __p)
329        _NOEXCEPT_(is_nothrow_copy_assignable<first_type>::value &&
330                   is_nothrow_copy_assignable<second_type>::value)
331    {
332        first = __p.first;
333        second = __p.second;
334        return *this;
335    }
336
337#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
338
339    template <class _U1, class _U2,
340              class = typename enable_if<is_convertible<_U1, first_type>::value &&
341                                         is_convertible<_U2, second_type>::value>::type>
342        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
343        pair(_U1&& __u1, _U2&& __u2)
344            : first(_VSTD::forward<_U1>(__u1)),
345              second(_VSTD::forward<_U2>(__u2))
346            {}
347
348    template<class _U1, class _U2>
349        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
350        pair(pair<_U1, _U2>&& __p,
351                 typename enable_if<is_convertible<_U1, _T1>::value &&
352                                    is_convertible<_U2, _T2>::value>::type* = 0)
353            : first(_VSTD::forward<_U1>(__p.first)),
354              second(_VSTD::forward<_U2>(__p.second)) {}
355
356#ifndef _LIBCPP_HAS_NO_DEFAULTED_FUNCTIONS
357    _LIBCPP_INLINE_VISIBILITY
358    pair(pair&& __p) = default;
359#else
360    _LIBCPP_INLINE_VISIBILITY
361    pair(pair&& __p) _NOEXCEPT_(is_nothrow_move_constructible<first_type>::value &&
362                                is_nothrow_move_constructible<second_type>::value)
363        : first(_VSTD::forward<first_type>(__p.first)),
364          second(_VSTD::forward<second_type>(__p.second))
365    {
366    }
367#endif
368
369    _LIBCPP_INLINE_VISIBILITY
370    pair&
371    operator=(pair&& __p) _NOEXCEPT_(is_nothrow_move_assignable<first_type>::value &&
372                                     is_nothrow_move_assignable<second_type>::value)
373    {
374        first = _VSTD::forward<first_type>(__p.first);
375        second = _VSTD::forward<second_type>(__p.second);
376        return *this;
377    }
378
379#ifndef _LIBCPP_HAS_NO_VARIADICS
380
381    template<class _Tuple,
382             class = typename enable_if<__tuple_convertible<_Tuple, pair>::value>::type>
383        _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
384        pair(_Tuple&& __p)
385            : first(_VSTD::forward<typename tuple_element<0,
386                                  typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<0>(__p))),
387              second(_VSTD::forward<typename tuple_element<1,
388                                   typename __make_tuple_types<_Tuple>::type>::type>(_VSTD::get<1>(__p)))
389            {}
390
391
392
393    template <class... _Args1, class... _Args2>
394        _LIBCPP_INLINE_VISIBILITY
395        pair(piecewise_construct_t __pc, tuple<_Args1...> __first_args,
396                                    tuple<_Args2...> __second_args)
397            : pair(__pc, __first_args, __second_args,
398                   typename __make_tuple_indices<sizeof...(_Args1)>::type(),
399                   typename __make_tuple_indices<sizeof...(_Args2) >::type())
400            {}
401
402    template <class _Tuple,
403              class = typename enable_if<__tuple_assignable<_Tuple, pair>::value>::type>
404        _LIBCPP_INLINE_VISIBILITY
405        pair&
406        operator=(_Tuple&& __p)
407        {
408            typedef typename __make_tuple_types<_Tuple>::type _TupleRef;
409            typedef typename tuple_element<0, _TupleRef>::type _U0;
410            typedef typename tuple_element<1, _TupleRef>::type _U1;
411            first  = _VSTD::forward<_U0>(_VSTD::get<0>(__p));
412            second = _VSTD::forward<_U1>(_VSTD::get<1>(__p));
413            return *this;
414        }
415
416#endif  // _LIBCPP_HAS_NO_VARIADICS
417
418#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
419    _LIBCPP_INLINE_VISIBILITY
420    void
421    swap(pair& __p) _NOEXCEPT_(__is_nothrow_swappable<first_type>::value &&
422                               __is_nothrow_swappable<second_type>::value)
423    {
424        using _VSTD::swap;
425        swap(first,  __p.first);
426        swap(second, __p.second);
427    }
428private:
429
430#ifndef _LIBCPP_HAS_NO_VARIADICS
431    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
432        _LIBCPP_INLINE_VISIBILITY
433        pair(piecewise_construct_t,
434             tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
435             __tuple_indices<_I1...>, __tuple_indices<_I2...>);
436#endif  // _LIBCPP_HAS_NO_VARIADICS
437};
438
439template <class _T1, class _T2>
440inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
441bool
442operator==(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
443{
444    return __x.first == __y.first && __x.second == __y.second;
445}
446
447template <class _T1, class _T2>
448inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
449bool
450operator!=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
451{
452    return !(__x == __y);
453}
454
455template <class _T1, class _T2>
456inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
457bool
458operator< (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
459{
460    return __x.first < __y.first || (!(__y.first < __x.first) && __x.second < __y.second);
461}
462
463template <class _T1, class _T2>
464inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
465bool
466operator> (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
467{
468    return __y < __x;
469}
470
471template <class _T1, class _T2>
472inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
473bool
474operator>=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
475{
476    return !(__x < __y);
477}
478
479template <class _T1, class _T2>
480inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
481bool
482operator<=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
483{
484    return !(__y < __x);
485}
486
487template <class _T1, class _T2>
488inline _LIBCPP_INLINE_VISIBILITY
489typename enable_if
490<
491    __is_swappable<_T1>::value &&
492    __is_swappable<_T2>::value,
493    void
494>::type
495swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
496                     _NOEXCEPT_((__is_nothrow_swappable<_T1>::value &&
497                                 __is_nothrow_swappable<_T2>::value))
498{
499    __x.swap(__y);
500}
501
502#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
503
504template <class _Tp> class _LIBCPP_TYPE_VIS_ONLY reference_wrapper;
505
506template <class _Tp>
507struct __make_pair_return_impl
508{
509    typedef _Tp type;
510};
511
512template <class _Tp>
513struct __make_pair_return_impl<reference_wrapper<_Tp>>
514{
515    typedef _Tp& type;
516};
517
518template <class _Tp>
519struct __make_pair_return
520{
521    typedef typename __make_pair_return_impl<typename decay<_Tp>::type>::type type;
522};
523
524template <class _T1, class _T2>
525inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
526pair<typename __make_pair_return<_T1>::type, typename __make_pair_return<_T2>::type>
527make_pair(_T1&& __t1, _T2&& __t2)
528{
529    return pair<typename __make_pair_return<_T1>::type, typename __make_pair_return<_T2>::type>
530               (_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
531}
532
533#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
534
535template <class _T1, class _T2>
536inline _LIBCPP_INLINE_VISIBILITY
537pair<_T1,_T2>
538make_pair(_T1 __x, _T2 __y)
539{
540    return pair<_T1, _T2>(__x, __y);
541}
542
543#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
544
545template <class _T1, class _T2>
546  class _LIBCPP_TYPE_VIS_ONLY tuple_size<pair<_T1, _T2> >
547    : public integral_constant<size_t, 2> {};
548
549template <class _T1, class _T2>
550class _LIBCPP_TYPE_VIS_ONLY tuple_element<0, pair<_T1, _T2> >
551{
552public:
553    typedef _T1 type;
554};
555
556template <class _T1, class _T2>
557class _LIBCPP_TYPE_VIS_ONLY tuple_element<1, pair<_T1, _T2> >
558{
559public:
560    typedef _T2 type;
561};
562
563template <size_t _Ip> struct __get_pair;
564
565template <>
566struct __get_pair<0>
567{
568    template <class _T1, class _T2>
569    static
570    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
571    _T1&
572    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
573
574    template <class _T1, class _T2>
575    static
576    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
577    const _T1&
578    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
579
580#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
581
582    template <class _T1, class _T2>
583    static
584    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
585    _T1&&
586    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
587
588    template <class _T1, class _T2>
589    static
590    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
591    const _T1&&
592    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T1>(__p.first);}
593
594#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
595};
596
597template <>
598struct __get_pair<1>
599{
600    template <class _T1, class _T2>
601    static
602    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
603    _T2&
604    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
605
606    template <class _T1, class _T2>
607    static
608    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
609    const _T2&
610    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
611
612#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
613
614    template <class _T1, class _T2>
615    static
616    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
617    _T2&&
618    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
619
620    template <class _T1, class _T2>
621    static
622    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
623    const _T2&&
624    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T2>(__p.second);}
625
626#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
627};
628
629template <size_t _Ip, class _T1, class _T2>
630inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
631typename tuple_element<_Ip, pair<_T1, _T2> >::type&
632get(pair<_T1, _T2>& __p) _NOEXCEPT
633{
634    return __get_pair<_Ip>::get(__p);
635}
636
637template <size_t _Ip, class _T1, class _T2>
638inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
639const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
640get(const pair<_T1, _T2>& __p) _NOEXCEPT
641{
642    return __get_pair<_Ip>::get(__p);
643}
644
645#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
646
647template <size_t _Ip, class _T1, class _T2>
648inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
649typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
650get(pair<_T1, _T2>&& __p) _NOEXCEPT
651{
652    return __get_pair<_Ip>::get(_VSTD::move(__p));
653}
654
655template <size_t _Ip, class _T1, class _T2>
656inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
657const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
658get(const pair<_T1, _T2>&& __p) _NOEXCEPT
659{
660    return __get_pair<_Ip>::get(_VSTD::move(__p));
661}
662
663#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
664
665#if _LIBCPP_STD_VER > 11
666template <class _T1, class _T2>
667inline _LIBCPP_INLINE_VISIBILITY
668constexpr _T1 & get(pair<_T1, _T2>& __p) _NOEXCEPT
669{
670    return __get_pair<0>::get(__p);
671}
672
673template <class _T1, class _T2>
674inline _LIBCPP_INLINE_VISIBILITY
675constexpr _T1 const & get(pair<_T1, _T2> const& __p) _NOEXCEPT
676{
677    return __get_pair<0>::get(__p);
678}
679
680template <class _T1, class _T2>
681inline _LIBCPP_INLINE_VISIBILITY
682constexpr _T1 && get(pair<_T1, _T2>&& __p) _NOEXCEPT
683{
684    return __get_pair<0>::get(_VSTD::move(__p));
685}
686
687template <class _T1, class _T2>
688inline _LIBCPP_INLINE_VISIBILITY
689constexpr _T1 const && get(pair<_T1, _T2> const&& __p) _NOEXCEPT
690{
691    return __get_pair<0>::get(_VSTD::move(__p));
692}
693
694template <class _T1, class _T2>
695inline _LIBCPP_INLINE_VISIBILITY
696constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
697{
698    return __get_pair<1>::get(__p);
699}
700
701template <class _T1, class _T2>
702inline _LIBCPP_INLINE_VISIBILITY
703constexpr _T1 const & get(pair<_T2, _T1> const& __p) _NOEXCEPT
704{
705    return __get_pair<1>::get(__p);
706}
707
708template <class _T1, class _T2>
709inline _LIBCPP_INLINE_VISIBILITY
710constexpr _T1 && get(pair<_T2, _T1>&& __p) _NOEXCEPT
711{
712    return __get_pair<1>::get(_VSTD::move(__p));
713}
714
715template <class _T1, class _T2>
716inline _LIBCPP_INLINE_VISIBILITY
717constexpr _T1 const && get(pair<_T2, _T1> const&& __p) _NOEXCEPT
718{
719    return __get_pair<1>::get(_VSTD::move(__p));
720}
721
722#endif
723
724#if _LIBCPP_STD_VER > 11
725
726template<class _Tp, _Tp... _Ip>
727struct _LIBCPP_TYPE_VIS_ONLY integer_sequence
728{
729    typedef _Tp value_type;
730    static_assert( is_integral<_Tp>::value,
731                  "std::integer_sequence can only be instantiated with an integral type" );
732    static
733    _LIBCPP_INLINE_VISIBILITY
734    constexpr
735    size_t
736    size() noexcept { return sizeof...(_Ip); }
737};
738
739template<size_t... _Ip>
740    using index_sequence = integer_sequence<size_t, _Ip...>;
741
742#if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
743
744template <class _Tp, _Tp _Ep>
745struct __make_integer_sequence
746{
747    typedef __make_integer_seq<integer_sequence, _Tp, _Ep> type;
748};
749
750#else
751
752namespace __detail {
753
754template<typename _Tp, size_t ..._Extra> struct __repeat;
755template<typename _Tp, _Tp ..._Np, size_t ..._Extra> struct __repeat<integer_sequence<_Tp, _Np...>, _Extra...> {
756  typedef integer_sequence<_Tp,
757                           _Np...,
758                           sizeof...(_Np) + _Np...,
759                           2 * sizeof...(_Np) + _Np...,
760                           3 * sizeof...(_Np) + _Np...,
761                           4 * sizeof...(_Np) + _Np...,
762                           5 * sizeof...(_Np) + _Np...,
763                           6 * sizeof...(_Np) + _Np...,
764                           7 * sizeof...(_Np) + _Np...,
765                           _Extra...> type;
766};
767
768template<size_t _Np> struct __parity;
769template<size_t _Np> struct __make : __parity<_Np % 8>::template __pmake<_Np> {};
770
771template<> struct __make<0> { typedef integer_sequence<size_t> type; };
772template<> struct __make<1> { typedef integer_sequence<size_t, 0> type; };
773template<> struct __make<2> { typedef integer_sequence<size_t, 0, 1> type; };
774template<> struct __make<3> { typedef integer_sequence<size_t, 0, 1, 2> type; };
775template<> struct __make<4> { typedef integer_sequence<size_t, 0, 1, 2, 3> type; };
776template<> struct __make<5> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4> type; };
777template<> struct __make<6> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4, 5> type; };
778template<> struct __make<7> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6> type; };
779
780template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; };
781template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; };
782template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; };
783template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; };
784template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
785template<> 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> {}; };
786template<> 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> {}; };
787template<> 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> {}; };
788
789template<typename _Tp, typename _Up> struct __convert {
790  template<typename> struct __result;
791  template<_Tp ..._Np> struct __result<integer_sequence<_Tp, _Np...> > { typedef integer_sequence<_Up, _Np...> type; };
792};
793template<typename _Tp> struct __convert<_Tp, _Tp> { template<typename _Up> struct __result { typedef _Up type; }; };
794
795}
796
797template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked =
798  typename __detail::__convert<size_t, _Tp>::template __result<typename __detail::__make<_Np>::type>::type;
799
800template <class _Tp, _Tp _Ep>
801struct __make_integer_sequence
802{
803    static_assert(is_integral<_Tp>::value,
804                  "std::make_integer_sequence can only be instantiated with an integral type" );
805    static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length");
806    // Workaround GCC bug by preventing bad installations when 0 <= _Ep
807    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929
808    typedef __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type;
809};
810
811#endif
812
813template<class _Tp, _Tp _Np>
814    using make_integer_sequence = typename __make_integer_sequence<_Tp, _Np>::type;
815
816template<size_t _Np>
817    using make_index_sequence = make_integer_sequence<size_t, _Np>;
818
819template<class... _Tp>
820    using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
821  
822#endif  // _LIBCPP_STD_VER > 11
823
824#if _LIBCPP_STD_VER > 11
825template<class _T1, class _T2 = _T1>
826inline _LIBCPP_INLINE_VISIBILITY
827_T1 exchange(_T1& __obj, _T2 && __new_value)
828{
829    _T1 __old_value = _VSTD::move(__obj);
830    __obj = _VSTD::forward<_T2>(__new_value);
831    return __old_value;
832}    
833#endif  // _LIBCPP_STD_VER > 11
834
835_LIBCPP_END_NAMESPACE_STD
836
837#endif  // _LIBCPP_UTILITY
838