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(is_nothrow_swappable_v<T1> &&
86                                is_nothrow_swappable_v<T2>);
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#include <initializer_list>
182
183#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
184#pragma GCC system_header
185#endif
186
187_LIBCPP_BEGIN_NAMESPACE_STD
188
189namespace rel_ops
190{
191
192template<class _Tp>
193inline _LIBCPP_INLINE_VISIBILITY
194bool
195operator!=(const _Tp& __x, const _Tp& __y)
196{
197    return !(__x == __y);
198}
199
200template<class _Tp>
201inline _LIBCPP_INLINE_VISIBILITY
202bool
203operator> (const _Tp& __x, const _Tp& __y)
204{
205    return __y < __x;
206}
207
208template<class _Tp>
209inline _LIBCPP_INLINE_VISIBILITY
210bool
211operator<=(const _Tp& __x, const _Tp& __y)
212{
213    return !(__y < __x);
214}
215
216template<class _Tp>
217inline _LIBCPP_INLINE_VISIBILITY
218bool
219operator>=(const _Tp& __x, const _Tp& __y)
220{
221    return !(__x < __y);
222}
223
224}  // rel_ops
225
226// swap_ranges
227
228
229template <class _ForwardIterator1, class _ForwardIterator2>
230inline _LIBCPP_INLINE_VISIBILITY
231_ForwardIterator2
232swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
233{
234    for(; __first1 != __last1; ++__first1, (void) ++__first2)
235        swap(*__first1, *__first2);
236    return __first2;
237}
238
239// forward declared in <type_traits>
240template<class _Tp, size_t _Np>
241inline _LIBCPP_INLINE_VISIBILITY
242typename enable_if<
243    __is_swappable<_Tp>::value
244>::type
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
504
505template <class _Tp>
506struct __make_pair_return_impl
507{
508    typedef _Tp type;
509};
510
511template <class _Tp>
512struct __make_pair_return_impl<reference_wrapper<_Tp>>
513{
514    typedef _Tp& type;
515};
516
517template <class _Tp>
518struct __make_pair_return
519{
520    typedef typename __make_pair_return_impl<typename decay<_Tp>::type>::type type;
521};
522
523template <class _T1, class _T2>
524inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
525pair<typename __make_pair_return<_T1>::type, typename __make_pair_return<_T2>::type>
526make_pair(_T1&& __t1, _T2&& __t2)
527{
528    return pair<typename __make_pair_return<_T1>::type, typename __make_pair_return<_T2>::type>
529               (_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
530}
531
532#else  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
533
534template <class _T1, class _T2>
535inline _LIBCPP_INLINE_VISIBILITY
536pair<_T1,_T2>
537make_pair(_T1 __x, _T2 __y)
538{
539    return pair<_T1, _T2>(__x, __y);
540}
541
542#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
543
544template <class _T1, class _T2>
545  class _LIBCPP_TYPE_VIS_ONLY tuple_size<pair<_T1, _T2> >
546    : public integral_constant<size_t, 2> {};
547
548template <class _T1, class _T2>
549class _LIBCPP_TYPE_VIS_ONLY tuple_element<0, pair<_T1, _T2> >
550{
551public:
552    typedef _T1 type;
553};
554
555template <class _T1, class _T2>
556class _LIBCPP_TYPE_VIS_ONLY tuple_element<1, pair<_T1, _T2> >
557{
558public:
559    typedef _T2 type;
560};
561
562template <size_t _Ip> struct __get_pair;
563
564template <>
565struct __get_pair<0>
566{
567    template <class _T1, class _T2>
568    static
569    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
570    _T1&
571    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
572
573    template <class _T1, class _T2>
574    static
575    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
576    const _T1&
577    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
578
579#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
580
581    template <class _T1, class _T2>
582    static
583    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
584    _T1&&
585    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
586
587    template <class _T1, class _T2>
588    static
589    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
590    const _T1&&
591    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T1>(__p.first);}
592
593#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
594};
595
596template <>
597struct __get_pair<1>
598{
599    template <class _T1, class _T2>
600    static
601    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
602    _T2&
603    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
604
605    template <class _T1, class _T2>
606    static
607    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
608    const _T2&
609    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
610
611#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
612
613    template <class _T1, class _T2>
614    static
615    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
616    _T2&&
617    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
618
619    template <class _T1, class _T2>
620    static
621    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
622    const _T2&&
623    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T2>(__p.second);}
624
625#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
626};
627
628template <size_t _Ip, class _T1, class _T2>
629inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
630typename tuple_element<_Ip, pair<_T1, _T2> >::type&
631get(pair<_T1, _T2>& __p) _NOEXCEPT
632{
633    return __get_pair<_Ip>::get(__p);
634}
635
636template <size_t _Ip, class _T1, class _T2>
637inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
638const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
639get(const pair<_T1, _T2>& __p) _NOEXCEPT
640{
641    return __get_pair<_Ip>::get(__p);
642}
643
644#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
645
646template <size_t _Ip, class _T1, class _T2>
647inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
648typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
649get(pair<_T1, _T2>&& __p) _NOEXCEPT
650{
651    return __get_pair<_Ip>::get(_VSTD::move(__p));
652}
653
654template <size_t _Ip, class _T1, class _T2>
655inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
656const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
657get(const pair<_T1, _T2>&& __p) _NOEXCEPT
658{
659    return __get_pair<_Ip>::get(_VSTD::move(__p));
660}
661
662#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
663
664#if _LIBCPP_STD_VER > 11
665template <class _T1, class _T2>
666inline _LIBCPP_INLINE_VISIBILITY
667constexpr _T1 & get(pair<_T1, _T2>& __p) _NOEXCEPT
668{
669    return __get_pair<0>::get(__p);
670}
671
672template <class _T1, class _T2>
673inline _LIBCPP_INLINE_VISIBILITY
674constexpr _T1 const & get(pair<_T1, _T2> const& __p) _NOEXCEPT
675{
676    return __get_pair<0>::get(__p);
677}
678
679template <class _T1, class _T2>
680inline _LIBCPP_INLINE_VISIBILITY
681constexpr _T1 && get(pair<_T1, _T2>&& __p) _NOEXCEPT
682{
683    return __get_pair<0>::get(_VSTD::move(__p));
684}
685
686template <class _T1, class _T2>
687inline _LIBCPP_INLINE_VISIBILITY
688constexpr _T1 const && get(pair<_T1, _T2> const&& __p) _NOEXCEPT
689{
690    return __get_pair<0>::get(_VSTD::move(__p));
691}
692
693template <class _T1, class _T2>
694inline _LIBCPP_INLINE_VISIBILITY
695constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
696{
697    return __get_pair<1>::get(__p);
698}
699
700template <class _T1, class _T2>
701inline _LIBCPP_INLINE_VISIBILITY
702constexpr _T1 const & get(pair<_T2, _T1> const& __p) _NOEXCEPT
703{
704    return __get_pair<1>::get(__p);
705}
706
707template <class _T1, class _T2>
708inline _LIBCPP_INLINE_VISIBILITY
709constexpr _T1 && get(pair<_T2, _T1>&& __p) _NOEXCEPT
710{
711    return __get_pair<1>::get(_VSTD::move(__p));
712}
713
714template <class _T1, class _T2>
715inline _LIBCPP_INLINE_VISIBILITY
716constexpr _T1 const && get(pair<_T2, _T1> const&& __p) _NOEXCEPT
717{
718    return __get_pair<1>::get(_VSTD::move(__p));
719}
720
721#endif
722
723#if _LIBCPP_STD_VER > 11
724
725template<class _Tp, _Tp... _Ip>
726struct _LIBCPP_TYPE_VIS_ONLY integer_sequence
727{
728    typedef _Tp value_type;
729    static_assert( is_integral<_Tp>::value,
730                  "std::integer_sequence can only be instantiated with an integral type" );
731    static
732    _LIBCPP_INLINE_VISIBILITY
733    constexpr
734    size_t
735    size() noexcept { return sizeof...(_Ip); }
736};
737
738template<size_t... _Ip>
739    using index_sequence = integer_sequence<size_t, _Ip...>;
740
741#if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
742
743template <class _Tp, _Tp _Ep>
744struct __make_integer_sequence
745{
746    typedef __make_integer_seq<integer_sequence, _Tp, _Ep> type;
747};
748
749#else
750
751namespace __detail {
752
753template<typename _Tp, size_t ..._Extra> struct __repeat;
754template<typename _Tp, _Tp ..._Np, size_t ..._Extra> struct __repeat<integer_sequence<_Tp, _Np...>, _Extra...> {
755  typedef integer_sequence<_Tp,
756                           _Np...,
757                           sizeof...(_Np) + _Np...,
758                           2 * sizeof...(_Np) + _Np...,
759                           3 * sizeof...(_Np) + _Np...,
760                           4 * sizeof...(_Np) + _Np...,
761                           5 * sizeof...(_Np) + _Np...,
762                           6 * sizeof...(_Np) + _Np...,
763                           7 * sizeof...(_Np) + _Np...,
764                           _Extra...> type;
765};
766
767template<size_t _Np> struct __parity;
768template<size_t _Np> struct __make : __parity<_Np % 8>::template __pmake<_Np> {};
769
770template<> struct __make<0> { typedef integer_sequence<size_t> type; };
771template<> struct __make<1> { typedef integer_sequence<size_t, 0> type; };
772template<> struct __make<2> { typedef integer_sequence<size_t, 0, 1> type; };
773template<> struct __make<3> { typedef integer_sequence<size_t, 0, 1, 2> type; };
774template<> struct __make<4> { typedef integer_sequence<size_t, 0, 1, 2, 3> type; };
775template<> struct __make<5> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4> type; };
776template<> struct __make<6> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4, 5> type; };
777template<> struct __make<7> { typedef integer_sequence<size_t, 0, 1, 2, 3, 4, 5, 6> type; };
778
779template<> struct __parity<0> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type> {}; };
780template<> struct __parity<1> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 1> {}; };
781template<> struct __parity<2> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 2, _Np - 1> {}; };
782template<> struct __parity<3> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 3, _Np - 2, _Np - 1> {}; };
783template<> struct __parity<4> { template<size_t _Np> struct __pmake : __repeat<typename __make<_Np / 8>::type, _Np - 4, _Np - 3, _Np - 2, _Np - 1> {}; };
784template<> 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> {}; };
785template<> 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> {}; };
786template<> 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> {}; };
787
788template<typename _Tp, typename _Up> struct __convert {
789  template<typename> struct __result;
790  template<_Tp ..._Np> struct __result<integer_sequence<_Tp, _Np...> > { typedef integer_sequence<_Up, _Np...> type; };
791};
792template<typename _Tp> struct __convert<_Tp, _Tp> { template<typename _Up> struct __result { typedef _Up type; }; };
793
794}
795
796template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked =
797  typename __detail::__convert<size_t, _Tp>::template __result<typename __detail::__make<_Np>::type>::type;
798
799template <class _Tp, _Tp _Ep>
800struct __make_integer_sequence
801{
802    static_assert(is_integral<_Tp>::value,
803                  "std::make_integer_sequence can only be instantiated with an integral type" );
804    static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length");
805    // Workaround GCC bug by preventing bad installations when 0 <= _Ep
806    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929
807    typedef __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type;
808};
809
810#endif
811
812template<class _Tp, _Tp _Np>
813    using make_integer_sequence = typename __make_integer_sequence<_Tp, _Np>::type;
814
815template<size_t _Np>
816    using make_index_sequence = make_integer_sequence<size_t, _Np>;
817
818template<class... _Tp>
819    using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
820
821#endif  // _LIBCPP_STD_VER > 11
822
823#if _LIBCPP_STD_VER > 11
824template<class _T1, class _T2 = _T1>
825inline _LIBCPP_INLINE_VISIBILITY
826_T1 exchange(_T1& __obj, _T2 && __new_value)
827{
828    _T1 __old_value = _VSTD::move(__obj);
829    __obj = _VSTD::forward<_T2>(__new_value);
830    return __old_value;
831}
832#endif  // _LIBCPP_STD_VER > 11
833
834_LIBCPP_END_NAMESPACE_STD
835
836#endif  // _LIBCPP_UTILITY
837