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