xref: /netbsd-src/external/apache2/llvm/dist/libcxx/include/utility (revision 4d6fc14bc9b0c5bf3e30be318c143ee82cadd108)
1// -*- C++ -*-
2//===-------------------------- utility -----------------------------------===//
3//
4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5// See https://llvm.org/LICENSE.txt for license information.
6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef _LIBCPP_UTILITY
11#define _LIBCPP_UTILITY
12
13/*
14    utility synopsis
15
16#include <initializer_list>
17
18namespace std
19{
20
21template <class T>
22    void
23    swap(T& a, T& b);
24
25namespace rel_ops
26{
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    template<class T> bool operator>=(const T&, const T&);
31}
32
33template<class T>
34void
35swap(T& a, T& b) noexcept(is_nothrow_move_constructible<T>::value &&
36                          is_nothrow_move_assignable<T>::value);
37
38template <class T, size_t N>
39void
40swap(T (&a)[N], T (&b)[N]) noexcept(noexcept(swap(*a, *b)));
41
42template <class T> T&& forward(typename remove_reference<T>::type& t) noexcept;  // constexpr in C++14
43template <class T> T&& forward(typename remove_reference<T>::type&& t) noexcept; // constexpr in C++14
44
45template <class T> typename remove_reference<T>::type&& move(T&&) noexcept;      // constexpr in C++14
46
47template <class T>
48    typename conditional
49    <
50        !is_nothrow_move_constructible<T>::value && is_copy_constructible<T>::value,
51        const T&,
52        T&&
53    >::type
54    move_if_noexcept(T& x) noexcept; // constexpr in C++14
55
56template <class T> constexpr add_const_t<T>& as_const(T& t) noexcept;      // C++17
57template <class T>                      void as_const(const T&&) = delete; // C++17
58
59template <class T> typename add_rvalue_reference<T>::type declval() noexcept;
60
61template<class T, class U> constexpr bool cmp_equal(T t, U u) noexcept;         // C++20
62template<class T, class U> constexpr bool cmp_not_equal(T t, U u) noexcept;     // C++20
63template<class T, class U> constexpr bool cmp_less(T t, U u) noexcept;          // C++20
64template<class T, class U> constexpr bool cmp_greater(T t, U u) noexcept;       // C++20
65template<class T, class U> constexpr bool cmp_less_equal(T t, U u) noexcept;    // C++20
66template<class T, class U> constexpr bool cmp_greater_equal(T t, U u) noexcept; // C++20
67template<class R, class T> constexpr bool in_range(T t) noexcept;               // C++20
68
69template <class T1, class T2>
70struct pair
71{
72    typedef T1 first_type;
73    typedef T2 second_type;
74
75    T1 first;
76    T2 second;
77
78    pair(const pair&) = default;
79    pair(pair&&) = default;
80    explicit(see-below) constexpr pair();
81    explicit(see-below) pair(const T1& x, const T2& y);                          // constexpr in C++14
82    template <class U, class V> explicit(see-below) pair(U&& x, V&& y);          // constexpr in C++14
83    template <class U, class V> explicit(see-below) pair(const pair<U, V>& p);   // constexpr in C++14
84    template <class U, class V> explicit(see-below) pair(pair<U, V>&& p);        // constexpr in C++14
85    template <class... Args1, class... Args2>
86        pair(piecewise_construct_t, tuple<Args1...> first_args,
87             tuple<Args2...> second_args);                                       // constexpr in C++20
88
89    template <class U, class V> pair& operator=(const pair<U, V>& p);            // constexpr in C++20
90    pair& operator=(pair&& p) noexcept(is_nothrow_move_assignable<T1>::value &&
91                                       is_nothrow_move_assignable<T2>::value);   // constexpr in C++20
92    template <class U, class V> pair& operator=(pair<U, V>&& p);                 // constexpr in C++20
93
94    void swap(pair& p) noexcept(is_nothrow_swappable_v<T1> &&
95                                is_nothrow_swappable_v<T2>);                     // constexpr in C++20
96};
97
98template <class T1, class T2> bool operator==(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
99template <class T1, class T2> bool operator!=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
100template <class T1, class T2> bool operator< (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
101template <class T1, class T2> bool operator> (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
102template <class T1, class T2> bool operator>=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
103template <class T1, class T2> bool operator<=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
104
105template <class T1, class T2> pair<V1, V2> make_pair(T1&&, T2&&);                // constexpr in C++14
106template <class T1, class T2>
107void
108swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));            // constexpr in C++20
109
110struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
111inline constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
112
113template <class T> struct tuple_size;
114template <size_t I, class T> struct tuple_element;
115
116template <class T1, class T2> struct tuple_size<pair<T1, T2> >;
117template <class T1, class T2> struct tuple_element<0, pair<T1, T2> >;
118template <class T1, class T2> struct tuple_element<1, pair<T1, T2> >;
119
120template<size_t I, class T1, class T2>
121    typename tuple_element<I, pair<T1, T2> >::type&
122    get(pair<T1, T2>&) noexcept; // constexpr in C++14
123
124template<size_t I, class T1, class T2>
125    const typename tuple_element<I, pair<T1, T2> >::type&
126    get(const pair<T1, T2>&) noexcept; // constexpr in C++14
127
128template<size_t I, class T1, class T2>
129    typename tuple_element<I, pair<T1, T2> >::type&&
130    get(pair<T1, T2>&&) noexcept; // constexpr in C++14
131
132template<size_t I, class T1, class T2>
133    const typename tuple_element<I, pair<T1, T2> >::type&&
134    get(const pair<T1, T2>&&) noexcept; // constexpr in C++14
135
136template<class T1, class T2>
137    constexpr T1& get(pair<T1, T2>&) noexcept; // C++14
138
139template<class T1, class T2>
140    constexpr const T1& get(const pair<T1, T2>&) noexcept; // C++14
141
142template<class T1, class T2>
143    constexpr T1&& get(pair<T1, T2>&&) noexcept; // C++14
144
145template<class T1, class T2>
146    constexpr const T1&& get(const pair<T1, T2>&&) noexcept; // C++14
147
148template<class T1, class T2>
149    constexpr T1& get(pair<T2, T1>&) noexcept; // C++14
150
151template<class T1, class T2>
152    constexpr const T1& get(const pair<T2, T1>&) noexcept; // C++14
153
154template<class T1, class T2>
155    constexpr T1&& get(pair<T2, T1>&&) noexcept; // C++14
156
157template<class T1, class T2>
158    constexpr const T1&& get(const pair<T2, T1>&&) noexcept; // C++14
159
160// C++14
161
162template<class T, T... I>
163struct integer_sequence
164{
165    typedef T value_type;
166
167    static constexpr size_t size() noexcept;
168};
169
170template<size_t... I>
171  using index_sequence = integer_sequence<size_t, I...>;
172
173template<class T, T N>
174  using make_integer_sequence = integer_sequence<T, 0, 1, ..., N-1>;
175template<size_t N>
176  using make_index_sequence = make_integer_sequence<size_t, N>;
177
178template<class... T>
179  using index_sequence_for = make_index_sequence<sizeof...(T)>;
180
181template<class T, class U=T>
182    T exchange(T& obj, U&& new_value);
183
184// 20.2.7, in-place construction // C++17
185struct in_place_t {
186  explicit in_place_t() = default;
187};
188inline constexpr in_place_t in_place{};
189template <class T>
190  struct in_place_type_t {
191    explicit in_place_type_t() = default;
192  };
193template <class T>
194  inline constexpr in_place_type_t<T> in_place_type{};
195template <size_t I>
196  struct in_place_index_t {
197    explicit in_place_index_t() = default;
198  };
199template <size_t I>
200  inline constexpr in_place_index_t<I> in_place_index{};
201
202// [utility.underlying], to_underlying
203template <class T>
204    constexpr underlying_type_t<T> to_underlying( T value ) noexcept; // C++2b
205
206}  // std
207
208*/
209
210#include <__config>
211#include <__tuple>
212#include <__utility/to_underlying.h>
213#include <compare>
214#include <type_traits>
215#include <initializer_list>
216#include <cstddef>
217#include <cstring>
218#include <cstdint>
219#include <limits>
220#include <version>
221#include <__debug>
222
223#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
224#pragma GCC system_header
225#endif
226
227_LIBCPP_PUSH_MACROS
228#include <__undef_macros>
229
230_LIBCPP_BEGIN_NAMESPACE_STD
231
232namespace rel_ops
233{
234
235template<class _Tp>
236inline _LIBCPP_INLINE_VISIBILITY
237bool
238operator!=(const _Tp& __x, const _Tp& __y)
239{
240    return !(__x == __y);
241}
242
243template<class _Tp>
244inline _LIBCPP_INLINE_VISIBILITY
245bool
246operator> (const _Tp& __x, const _Tp& __y)
247{
248    return __y < __x;
249}
250
251template<class _Tp>
252inline _LIBCPP_INLINE_VISIBILITY
253bool
254operator<=(const _Tp& __x, const _Tp& __y)
255{
256    return !(__y < __x);
257}
258
259template<class _Tp>
260inline _LIBCPP_INLINE_VISIBILITY
261bool
262operator>=(const _Tp& __x, const _Tp& __y)
263{
264    return !(__x < __y);
265}
266
267}  // rel_ops
268
269// swap_ranges is defined in <type_traits>`
270
271// swap is defined in <type_traits>
272
273// move_if_noexcept
274
275template <class _Tp>
276_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
277#ifndef _LIBCPP_CXX03_LANG
278typename conditional
279<
280    !is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value,
281    const _Tp&,
282    _Tp&&
283>::type
284#else  // _LIBCPP_CXX03_LANG
285const _Tp&
286#endif
287move_if_noexcept(_Tp& __x) _NOEXCEPT
288{
289    return _VSTD::move(__x);
290}
291
292#if _LIBCPP_STD_VER > 14
293template <class _Tp>
294_LIBCPP_NODISCARD_EXT constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
295
296template <class _Tp>
297void as_const(const _Tp&&) = delete;
298#endif
299
300#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
301template<class _Tp, class... _Up>
302struct _IsSameAsAny : _Or<_IsSame<_Tp, _Up>...> {};
303
304template<class _Tp>
305concept __is_safe_integral_cmp = is_integral_v<_Tp> &&
306                      !_IsSameAsAny<_Tp, bool, char,
307#ifndef _LIBCPP_HAS_NO_CHAR8_T
308                                    char8_t,
309#endif
310#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
311                                    char16_t, char32_t,
312#endif
313                                    wchar_t>::value;
314
315template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
316_LIBCPP_INLINE_VISIBILITY constexpr
317bool cmp_equal(_Tp __t, _Up __u) noexcept
318{
319  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
320    return __t == __u;
321  else if constexpr (is_signed_v<_Tp>)
322    return __t < 0 ? false : make_unsigned_t<_Tp>(__t) == __u;
323  else
324    return __u < 0 ? false : __t == make_unsigned_t<_Up>(__u);
325}
326
327template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
328_LIBCPP_INLINE_VISIBILITY constexpr
329bool cmp_not_equal(_Tp __t, _Up __u) noexcept
330{
331  return !_VSTD::cmp_equal(__t, __u);
332}
333
334template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
335_LIBCPP_INLINE_VISIBILITY constexpr
336bool cmp_less(_Tp __t, _Up __u) noexcept
337{
338  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
339    return __t < __u;
340  else if constexpr (is_signed_v<_Tp>)
341    return __t < 0 ? true : make_unsigned_t<_Tp>(__t) < __u;
342  else
343    return __u < 0 ? false : __t < make_unsigned_t<_Up>(__u);
344}
345
346template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
347_LIBCPP_INLINE_VISIBILITY constexpr
348bool cmp_greater(_Tp __t, _Up __u) noexcept
349{
350  return _VSTD::cmp_less(__u, __t);
351}
352
353template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
354_LIBCPP_INLINE_VISIBILITY constexpr
355bool cmp_less_equal(_Tp __t, _Up __u) noexcept
356{
357  return !_VSTD::cmp_greater(__t, __u);
358}
359
360template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
361_LIBCPP_INLINE_VISIBILITY constexpr
362bool cmp_greater_equal(_Tp __t, _Up __u) noexcept
363{
364  return !_VSTD::cmp_less(__t, __u);
365}
366
367template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
368_LIBCPP_INLINE_VISIBILITY constexpr
369bool in_range(_Up __u) noexcept
370{
371  return _VSTD::cmp_less_equal(__u, numeric_limits<_Tp>::max()) &&
372         _VSTD::cmp_greater_equal(__u, numeric_limits<_Tp>::min());
373}
374#endif
375
376struct _LIBCPP_TEMPLATE_VIS piecewise_construct_t { explicit piecewise_construct_t() = default; };
377#if defined(_LIBCPP_CXX03_LANG) || defined(_LIBCPP_BUILDING_LIBRARY)
378extern _LIBCPP_EXPORTED_FROM_ABI const piecewise_construct_t piecewise_construct;// = piecewise_construct_t();
379#else
380/* _LIBCPP_INLINE_VAR */ constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
381#endif
382
383#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
384template <class, class>
385struct __non_trivially_copyable_base {
386  _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
387  __non_trivially_copyable_base() _NOEXCEPT {}
388  _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
389  __non_trivially_copyable_base(__non_trivially_copyable_base const&) _NOEXCEPT {}
390};
391#endif
392
393template <class _T1, class _T2>
394struct _LIBCPP_TEMPLATE_VIS pair
395#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
396: private __non_trivially_copyable_base<_T1, _T2>
397#endif
398{
399    typedef _T1 first_type;
400    typedef _T2 second_type;
401
402    _T1 first;
403    _T2 second;
404
405#if !defined(_LIBCPP_CXX03_LANG)
406    pair(pair const&) = default;
407    pair(pair&&) = default;
408#else
409  // Use the implicitly declared copy constructor in C++03
410#endif
411
412#ifdef _LIBCPP_CXX03_LANG
413    _LIBCPP_INLINE_VISIBILITY
414    pair() : first(), second() {}
415
416    _LIBCPP_INLINE_VISIBILITY
417    pair(_T1 const& __t1, _T2 const& __t2) : first(__t1), second(__t2) {}
418
419    template <class _U1, class _U2>
420    _LIBCPP_INLINE_VISIBILITY
421    pair(const pair<_U1, _U2>& __p) : first(__p.first), second(__p.second) {}
422
423    _LIBCPP_INLINE_VISIBILITY
424    pair& operator=(pair const& __p) {
425        first = __p.first;
426        second = __p.second;
427        return *this;
428    }
429#else
430    template <bool _Val>
431    using _EnableB _LIBCPP_NODEBUG_TYPE = typename enable_if<_Val, bool>::type;
432
433    struct _CheckArgs {
434      template <int&...>
435      static constexpr bool __enable_explicit_default() {
436          return is_default_constructible<_T1>::value
437              && is_default_constructible<_T2>::value
438              && !__enable_implicit_default<>();
439      }
440
441      template <int&...>
442      static constexpr bool __enable_implicit_default() {
443          return __is_implicitly_default_constructible<_T1>::value
444              && __is_implicitly_default_constructible<_T2>::value;
445      }
446
447      template <class _U1, class _U2>
448      static constexpr bool __enable_explicit() {
449          return is_constructible<first_type, _U1>::value
450              && is_constructible<second_type, _U2>::value
451              && (!is_convertible<_U1, first_type>::value
452                  || !is_convertible<_U2, second_type>::value);
453      }
454
455      template <class _U1, class _U2>
456      static constexpr bool __enable_implicit() {
457          return is_constructible<first_type, _U1>::value
458              && is_constructible<second_type, _U2>::value
459              && is_convertible<_U1, first_type>::value
460              && is_convertible<_U2, second_type>::value;
461      }
462    };
463
464    template <bool _MaybeEnable>
465    using _CheckArgsDep _LIBCPP_NODEBUG_TYPE = typename conditional<
466      _MaybeEnable, _CheckArgs, __check_tuple_constructor_fail>::type;
467
468    struct _CheckTupleLikeConstructor {
469        template <class _Tuple>
470        static constexpr bool __enable_implicit() {
471            return __tuple_convertible<_Tuple, pair>::value;
472        }
473
474        template <class _Tuple>
475        static constexpr bool __enable_explicit() {
476            return __tuple_constructible<_Tuple, pair>::value
477               && !__tuple_convertible<_Tuple, pair>::value;
478        }
479
480        template <class _Tuple>
481        static constexpr bool __enable_assign() {
482            return __tuple_assignable<_Tuple, pair>::value;
483        }
484    };
485
486    template <class _Tuple>
487    using _CheckTLC _LIBCPP_NODEBUG_TYPE = typename conditional<
488        __tuple_like_with_size<_Tuple, 2>::value
489            && !is_same<typename decay<_Tuple>::type, pair>::value,
490        _CheckTupleLikeConstructor,
491        __check_tuple_constructor_fail
492    >::type;
493
494    template<bool _Dummy = true, _EnableB<
495            _CheckArgsDep<_Dummy>::__enable_explicit_default()
496    > = false>
497    explicit _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
498    pair() _NOEXCEPT_(is_nothrow_default_constructible<first_type>::value &&
499                      is_nothrow_default_constructible<second_type>::value)
500        : first(), second() {}
501
502    template<bool _Dummy = true, _EnableB<
503            _CheckArgsDep<_Dummy>::__enable_implicit_default()
504    > = false>
505    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
506    pair() _NOEXCEPT_(is_nothrow_default_constructible<first_type>::value &&
507                      is_nothrow_default_constructible<second_type>::value)
508        : first(), second() {}
509
510    template <bool _Dummy = true, _EnableB<
511             _CheckArgsDep<_Dummy>::template __enable_explicit<_T1 const&, _T2 const&>()
512    > = false>
513    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
514    explicit pair(_T1 const& __t1, _T2 const& __t2)
515        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
516                   is_nothrow_copy_constructible<second_type>::value)
517        : first(__t1), second(__t2) {}
518
519    template<bool _Dummy = true, _EnableB<
520            _CheckArgsDep<_Dummy>::template __enable_implicit<_T1 const&, _T2 const&>()
521    > = false>
522    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
523    pair(_T1 const& __t1, _T2 const& __t2)
524        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
525                   is_nothrow_copy_constructible<second_type>::value)
526        : first(__t1), second(__t2) {}
527
528    template<class _U1, class _U2, _EnableB<
529             _CheckArgs::template __enable_explicit<_U1, _U2>()
530    > = false>
531    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
532    explicit pair(_U1&& __u1, _U2&& __u2)
533        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1>::value &&
534                    is_nothrow_constructible<second_type, _U2>::value))
535        : first(_VSTD::forward<_U1>(__u1)), second(_VSTD::forward<_U2>(__u2)) {}
536
537    template<class _U1, class _U2, _EnableB<
538            _CheckArgs::template __enable_implicit<_U1, _U2>()
539    > = false>
540    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
541    pair(_U1&& __u1, _U2&& __u2)
542        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1>::value &&
543                    is_nothrow_constructible<second_type, _U2>::value))
544        : first(_VSTD::forward<_U1>(__u1)), second(_VSTD::forward<_U2>(__u2)) {}
545
546    template<class _U1, class _U2, _EnableB<
547            _CheckArgs::template __enable_explicit<_U1 const&, _U2 const&>()
548    > = false>
549    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
550    explicit pair(pair<_U1, _U2> const& __p)
551        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1 const&>::value &&
552                    is_nothrow_constructible<second_type, _U2 const&>::value))
553        : first(__p.first), second(__p.second) {}
554
555    template<class _U1, class _U2, _EnableB<
556            _CheckArgs::template __enable_implicit<_U1 const&, _U2 const&>()
557    > = false>
558    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
559    pair(pair<_U1, _U2> const& __p)
560        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1 const&>::value &&
561                    is_nothrow_constructible<second_type, _U2 const&>::value))
562        : first(__p.first), second(__p.second) {}
563
564    template<class _U1, class _U2, _EnableB<
565            _CheckArgs::template __enable_explicit<_U1, _U2>()
566    > = false>
567    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
568    explicit pair(pair<_U1, _U2>&&__p)
569        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1&&>::value &&
570                    is_nothrow_constructible<second_type, _U2&&>::value))
571        : first(_VSTD::forward<_U1>(__p.first)), second(_VSTD::forward<_U2>(__p.second)) {}
572
573    template<class _U1, class _U2, _EnableB<
574            _CheckArgs::template __enable_implicit<_U1, _U2>()
575    > = false>
576    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
577    pair(pair<_U1, _U2>&& __p)
578        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1&&>::value &&
579                    is_nothrow_constructible<second_type, _U2&&>::value))
580        : first(_VSTD::forward<_U1>(__p.first)), second(_VSTD::forward<_U2>(__p.second)) {}
581
582    template<class _Tuple, _EnableB<
583            _CheckTLC<_Tuple>::template __enable_explicit<_Tuple>()
584    > = false>
585    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
586    explicit pair(_Tuple&& __p)
587        : first(_VSTD::get<0>(_VSTD::forward<_Tuple>(__p))),
588          second(_VSTD::get<1>(_VSTD::forward<_Tuple>(__p))) {}
589
590    template<class _Tuple, _EnableB<
591            _CheckTLC<_Tuple>::template __enable_implicit<_Tuple>()
592    > = false>
593    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
594    pair(_Tuple&& __p)
595        : first(_VSTD::get<0>(_VSTD::forward<_Tuple>(__p))),
596          second(_VSTD::get<1>(_VSTD::forward<_Tuple>(__p))) {}
597
598    template <class... _Args1, class... _Args2>
599    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
600    pair(piecewise_construct_t __pc,
601         tuple<_Args1...> __first_args, tuple<_Args2...> __second_args)
602        _NOEXCEPT_((is_nothrow_constructible<first_type, _Args1...>::value &&
603                    is_nothrow_constructible<second_type, _Args2...>::value))
604        : pair(__pc, __first_args, __second_args,
605                typename __make_tuple_indices<sizeof...(_Args1)>::type(),
606                typename __make_tuple_indices<sizeof...(_Args2) >::type()) {}
607
608    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
609    pair& operator=(typename conditional<
610                        is_copy_assignable<first_type>::value &&
611                        is_copy_assignable<second_type>::value,
612                    pair, __nat>::type const& __p)
613        _NOEXCEPT_(is_nothrow_copy_assignable<first_type>::value &&
614                   is_nothrow_copy_assignable<second_type>::value)
615    {
616        first = __p.first;
617        second = __p.second;
618        return *this;
619    }
620
621    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
622    pair& operator=(typename conditional<
623                        is_move_assignable<first_type>::value &&
624                        is_move_assignable<second_type>::value,
625                    pair, __nat>::type&& __p)
626        _NOEXCEPT_(is_nothrow_move_assignable<first_type>::value &&
627                   is_nothrow_move_assignable<second_type>::value)
628    {
629        first = _VSTD::forward<first_type>(__p.first);
630        second = _VSTD::forward<second_type>(__p.second);
631        return *this;
632    }
633
634    template <class _Tuple, _EnableB<
635            _CheckTLC<_Tuple>::template __enable_assign<_Tuple>()
636     > = false>
637    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
638    pair& operator=(_Tuple&& __p) {
639        first = _VSTD::get<0>(_VSTD::forward<_Tuple>(__p));
640        second = _VSTD::get<1>(_VSTD::forward<_Tuple>(__p));
641        return *this;
642    }
643#endif
644
645    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
646    void
647    swap(pair& __p) _NOEXCEPT_(__is_nothrow_swappable<first_type>::value &&
648                               __is_nothrow_swappable<second_type>::value)
649    {
650        using _VSTD::swap;
651        swap(first,  __p.first);
652        swap(second, __p.second);
653    }
654private:
655
656#ifndef _LIBCPP_CXX03_LANG
657    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
658    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
659    pair(piecewise_construct_t,
660         tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
661         __tuple_indices<_I1...>, __tuple_indices<_I2...>);
662#endif
663};
664
665#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
666template<class _T1, class _T2>
667pair(_T1, _T2) -> pair<_T1, _T2>;
668#endif // _LIBCPP_HAS_NO_DEDUCTION_GUIDES
669
670template <class _T1, class _T2>
671inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
672bool
673operator==(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
674{
675    return __x.first == __y.first && __x.second == __y.second;
676}
677
678template <class _T1, class _T2>
679inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
680bool
681operator!=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
682{
683    return !(__x == __y);
684}
685
686template <class _T1, class _T2>
687inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
688bool
689operator< (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
690{
691    return __x.first < __y.first || (!(__y.first < __x.first) && __x.second < __y.second);
692}
693
694template <class _T1, class _T2>
695inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
696bool
697operator> (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
698{
699    return __y < __x;
700}
701
702template <class _T1, class _T2>
703inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
704bool
705operator>=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
706{
707    return !(__x < __y);
708}
709
710template <class _T1, class _T2>
711inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
712bool
713operator<=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
714{
715    return !(__y < __x);
716}
717
718template <class _T1, class _T2>
719inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
720typename enable_if
721<
722    __is_swappable<_T1>::value &&
723    __is_swappable<_T2>::value,
724    void
725>::type
726swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
727                     _NOEXCEPT_((__is_nothrow_swappable<_T1>::value &&
728                                 __is_nothrow_swappable<_T2>::value))
729{
730    __x.swap(__y);
731}
732
733template <class _Tp>
734struct __unwrap_reference { typedef _LIBCPP_NODEBUG_TYPE _Tp type; };
735
736template <class _Tp>
737struct __unwrap_reference<reference_wrapper<_Tp> > { typedef _LIBCPP_NODEBUG_TYPE _Tp& type; };
738
739#if _LIBCPP_STD_VER > 17
740template <class _Tp>
741struct unwrap_reference : __unwrap_reference<_Tp> { };
742
743template <class _Tp>
744struct unwrap_ref_decay : unwrap_reference<typename decay<_Tp>::type> { };
745#endif // > C++17
746
747template <class _Tp>
748struct __unwrap_ref_decay
749#if _LIBCPP_STD_VER > 17
750    : unwrap_ref_decay<_Tp>
751#else
752    : __unwrap_reference<typename decay<_Tp>::type>
753#endif
754{ };
755
756#ifndef _LIBCPP_CXX03_LANG
757
758template <class _T1, class _T2>
759inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
760pair<typename __unwrap_ref_decay<_T1>::type, typename __unwrap_ref_decay<_T2>::type>
761make_pair(_T1&& __t1, _T2&& __t2)
762{
763    return pair<typename __unwrap_ref_decay<_T1>::type, typename __unwrap_ref_decay<_T2>::type>
764               (_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
765}
766
767#else  // _LIBCPP_CXX03_LANG
768
769template <class _T1, class _T2>
770inline _LIBCPP_INLINE_VISIBILITY
771pair<_T1,_T2>
772make_pair(_T1 __x, _T2 __y)
773{
774    return pair<_T1, _T2>(__x, __y);
775}
776
777#endif // _LIBCPP_CXX03_LANG
778
779template <class _T1, class _T2>
780  struct _LIBCPP_TEMPLATE_VIS tuple_size<pair<_T1, _T2> >
781    : public integral_constant<size_t, 2> {};
782
783template <size_t _Ip, class _T1, class _T2>
784struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, pair<_T1, _T2> >
785{
786    static_assert(_Ip < 2, "Index out of bounds in std::tuple_element<std::pair<T1, T2>>");
787};
788
789template <class _T1, class _T2>
790struct _LIBCPP_TEMPLATE_VIS tuple_element<0, pair<_T1, _T2> >
791{
792    typedef _LIBCPP_NODEBUG_TYPE _T1 type;
793};
794
795template <class _T1, class _T2>
796struct _LIBCPP_TEMPLATE_VIS tuple_element<1, pair<_T1, _T2> >
797{
798    typedef _LIBCPP_NODEBUG_TYPE _T2 type;
799};
800
801template <size_t _Ip> struct __get_pair;
802
803template <>
804struct __get_pair<0>
805{
806    template <class _T1, class _T2>
807    static
808    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
809    _T1&
810    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
811
812    template <class _T1, class _T2>
813    static
814    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
815    const _T1&
816    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
817
818#ifndef _LIBCPP_CXX03_LANG
819    template <class _T1, class _T2>
820    static
821    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
822    _T1&&
823    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
824
825    template <class _T1, class _T2>
826    static
827    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
828    const _T1&&
829    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T1>(__p.first);}
830#endif // _LIBCPP_CXX03_LANG
831};
832
833template <>
834struct __get_pair<1>
835{
836    template <class _T1, class _T2>
837    static
838    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
839    _T2&
840    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
841
842    template <class _T1, class _T2>
843    static
844    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
845    const _T2&
846    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
847
848#ifndef _LIBCPP_CXX03_LANG
849    template <class _T1, class _T2>
850    static
851    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
852    _T2&&
853    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
854
855    template <class _T1, class _T2>
856    static
857    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
858    const _T2&&
859    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T2>(__p.second);}
860#endif // _LIBCPP_CXX03_LANG
861};
862
863template <size_t _Ip, class _T1, class _T2>
864inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
865typename tuple_element<_Ip, pair<_T1, _T2> >::type&
866get(pair<_T1, _T2>& __p) _NOEXCEPT
867{
868    return __get_pair<_Ip>::get(__p);
869}
870
871template <size_t _Ip, class _T1, class _T2>
872inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
873const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
874get(const pair<_T1, _T2>& __p) _NOEXCEPT
875{
876    return __get_pair<_Ip>::get(__p);
877}
878
879#ifndef _LIBCPP_CXX03_LANG
880template <size_t _Ip, class _T1, class _T2>
881inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
882typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
883get(pair<_T1, _T2>&& __p) _NOEXCEPT
884{
885    return __get_pair<_Ip>::get(_VSTD::move(__p));
886}
887
888template <size_t _Ip, class _T1, class _T2>
889inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
890const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
891get(const pair<_T1, _T2>&& __p) _NOEXCEPT
892{
893    return __get_pair<_Ip>::get(_VSTD::move(__p));
894}
895#endif // _LIBCPP_CXX03_LANG
896
897#if _LIBCPP_STD_VER > 11
898template <class _T1, class _T2>
899inline _LIBCPP_INLINE_VISIBILITY
900constexpr _T1 & get(pair<_T1, _T2>& __p) _NOEXCEPT
901{
902    return __get_pair<0>::get(__p);
903}
904
905template <class _T1, class _T2>
906inline _LIBCPP_INLINE_VISIBILITY
907constexpr _T1 const & get(pair<_T1, _T2> const& __p) _NOEXCEPT
908{
909    return __get_pair<0>::get(__p);
910}
911
912template <class _T1, class _T2>
913inline _LIBCPP_INLINE_VISIBILITY
914constexpr _T1 && get(pair<_T1, _T2>&& __p) _NOEXCEPT
915{
916    return __get_pair<0>::get(_VSTD::move(__p));
917}
918
919template <class _T1, class _T2>
920inline _LIBCPP_INLINE_VISIBILITY
921constexpr _T1 const && get(pair<_T1, _T2> const&& __p) _NOEXCEPT
922{
923    return __get_pair<0>::get(_VSTD::move(__p));
924}
925
926template <class _T1, class _T2>
927inline _LIBCPP_INLINE_VISIBILITY
928constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
929{
930    return __get_pair<1>::get(__p);
931}
932
933template <class _T1, class _T2>
934inline _LIBCPP_INLINE_VISIBILITY
935constexpr _T1 const & get(pair<_T2, _T1> const& __p) _NOEXCEPT
936{
937    return __get_pair<1>::get(__p);
938}
939
940template <class _T1, class _T2>
941inline _LIBCPP_INLINE_VISIBILITY
942constexpr _T1 && get(pair<_T2, _T1>&& __p) _NOEXCEPT
943{
944    return __get_pair<1>::get(_VSTD::move(__p));
945}
946
947template <class _T1, class _T2>
948inline _LIBCPP_INLINE_VISIBILITY
949constexpr _T1 const && get(pair<_T2, _T1> const&& __p) _NOEXCEPT
950{
951    return __get_pair<1>::get(_VSTD::move(__p));
952}
953
954#endif
955
956#if _LIBCPP_STD_VER > 11
957
958template<class _Tp, _Tp... _Ip>
959struct _LIBCPP_TEMPLATE_VIS integer_sequence
960{
961    typedef _Tp value_type;
962    static_assert( is_integral<_Tp>::value,
963                  "std::integer_sequence can only be instantiated with an integral type" );
964    static
965    _LIBCPP_INLINE_VISIBILITY
966    constexpr
967    size_t
968    size() noexcept { return sizeof...(_Ip); }
969};
970
971template<size_t... _Ip>
972    using index_sequence = integer_sequence<size_t, _Ip...>;
973
974#if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
975
976template <class _Tp, _Tp _Ep>
977using __make_integer_sequence _LIBCPP_NODEBUG_TYPE = __make_integer_seq<integer_sequence, _Tp, _Ep>;
978
979#else
980
981template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked _LIBCPP_NODEBUG_TYPE  =
982  typename __detail::__make<_Np>::type::template __convert<integer_sequence, _Tp>;
983
984template <class _Tp, _Tp _Ep>
985struct __make_integer_sequence_checked
986{
987    static_assert(is_integral<_Tp>::value,
988                  "std::make_integer_sequence can only be instantiated with an integral type" );
989    static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length");
990    // Workaround GCC bug by preventing bad installations when 0 <= _Ep
991    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929
992    typedef _LIBCPP_NODEBUG_TYPE  __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type;
993};
994
995template <class _Tp, _Tp _Ep>
996using __make_integer_sequence _LIBCPP_NODEBUG_TYPE = typename __make_integer_sequence_checked<_Tp, _Ep>::type;
997
998#endif
999
1000template<class _Tp, _Tp _Np>
1001    using make_integer_sequence = __make_integer_sequence<_Tp, _Np>;
1002
1003template<size_t _Np>
1004    using make_index_sequence = make_integer_sequence<size_t, _Np>;
1005
1006template<class... _Tp>
1007    using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
1008
1009#endif // _LIBCPP_STD_VER > 11
1010
1011#if _LIBCPP_STD_VER > 11
1012template<class _T1, class _T2 = _T1>
1013inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1014_T1 exchange(_T1& __obj, _T2 && __new_value)
1015{
1016    _T1 __old_value = _VSTD::move(__obj);
1017    __obj = _VSTD::forward<_T2>(__new_value);
1018    return __old_value;
1019}
1020#endif // _LIBCPP_STD_VER > 11
1021
1022#if _LIBCPP_STD_VER > 14
1023
1024struct _LIBCPP_TYPE_VIS in_place_t {
1025    explicit in_place_t() = default;
1026};
1027_LIBCPP_INLINE_VAR constexpr in_place_t in_place{};
1028
1029template <class _Tp>
1030struct _LIBCPP_TEMPLATE_VIS in_place_type_t {
1031    explicit in_place_type_t() = default;
1032};
1033template <class _Tp>
1034_LIBCPP_INLINE_VAR constexpr in_place_type_t<_Tp> in_place_type{};
1035
1036template <size_t _Idx>
1037struct _LIBCPP_TEMPLATE_VIS in_place_index_t {
1038    explicit in_place_index_t() = default;
1039};
1040template <size_t _Idx>
1041_LIBCPP_INLINE_VAR constexpr in_place_index_t<_Idx> in_place_index{};
1042
1043template <class _Tp> struct __is_inplace_type_imp : false_type {};
1044template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_type {};
1045
1046template <class _Tp>
1047using __is_inplace_type = __is_inplace_type_imp<__uncvref_t<_Tp>>;
1048
1049template <class _Tp> struct __is_inplace_index_imp : false_type {};
1050template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
1051
1052template <class _Tp>
1053using __is_inplace_index = __is_inplace_index_imp<__uncvref_t<_Tp>>;
1054
1055#endif // _LIBCPP_STD_VER > 14
1056
1057template <class _Arg, class _Result>
1058struct _LIBCPP_TEMPLATE_VIS unary_function
1059{
1060    typedef _Arg    argument_type;
1061    typedef _Result result_type;
1062};
1063
1064template <class _Size>
1065inline _LIBCPP_INLINE_VISIBILITY
1066_Size
1067__loadword(const void* __p)
1068{
1069    _Size __r;
1070    _VSTD::memcpy(&__r, __p, sizeof(__r));
1071    return __r;
1072}
1073
1074// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t
1075// is 64 bits.  This is because cityhash64 uses 64bit x 64bit
1076// multiplication, which can be very slow on 32-bit systems.
1077template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__>
1078struct __murmur2_or_cityhash;
1079
1080template <class _Size>
1081struct __murmur2_or_cityhash<_Size, 32>
1082{
1083    inline _Size operator()(const void* __key, _Size __len)
1084         _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK;
1085};
1086
1087// murmur2
1088template <class _Size>
1089_Size
1090__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len)
1091{
1092    const _Size __m = 0x5bd1e995;
1093    const _Size __r = 24;
1094    _Size __h = __len;
1095    const unsigned char* __data = static_cast<const unsigned char*>(__key);
1096    for (; __len >= 4; __data += 4, __len -= 4)
1097    {
1098        _Size __k = __loadword<_Size>(__data);
1099        __k *= __m;
1100        __k ^= __k >> __r;
1101        __k *= __m;
1102        __h *= __m;
1103        __h ^= __k;
1104    }
1105    switch (__len)
1106    {
1107    case 3:
1108        __h ^= __data[2] << 16;
1109        _LIBCPP_FALLTHROUGH();
1110    case 2:
1111        __h ^= __data[1] << 8;
1112        _LIBCPP_FALLTHROUGH();
1113    case 1:
1114        __h ^= __data[0];
1115        __h *= __m;
1116    }
1117    __h ^= __h >> 13;
1118    __h *= __m;
1119    __h ^= __h >> 15;
1120    return __h;
1121}
1122
1123template <class _Size>
1124struct __murmur2_or_cityhash<_Size, 64>
1125{
1126    inline _Size operator()(const void* __key, _Size __len)  _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK;
1127
1128 private:
1129  // Some primes between 2^63 and 2^64.
1130  static const _Size __k0 = 0xc3a5c85c97cb3127ULL;
1131  static const _Size __k1 = 0xb492b66fbe98f273ULL;
1132  static const _Size __k2 = 0x9ae16a3b2f90404fULL;
1133  static const _Size __k3 = 0xc949d7c7509e6557ULL;
1134
1135  static _Size __rotate(_Size __val, int __shift) {
1136    return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift)));
1137  }
1138
1139  static _Size __rotate_by_at_least_1(_Size __val, int __shift) {
1140    return (__val >> __shift) | (__val << (64 - __shift));
1141  }
1142
1143  static _Size __shift_mix(_Size __val) {
1144    return __val ^ (__val >> 47);
1145  }
1146
1147  static _Size __hash_len_16(_Size __u, _Size __v)
1148     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1149  {
1150    const _Size __mul = 0x9ddfea08eb382d69ULL;
1151    _Size __a = (__u ^ __v) * __mul;
1152    __a ^= (__a >> 47);
1153    _Size __b = (__v ^ __a) * __mul;
1154    __b ^= (__b >> 47);
1155    __b *= __mul;
1156    return __b;
1157  }
1158
1159  static _Size __hash_len_0_to_16(const char* __s, _Size __len)
1160     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1161  {
1162    if (__len > 8) {
1163      const _Size __a = __loadword<_Size>(__s);
1164      const _Size __b = __loadword<_Size>(__s + __len - 8);
1165      return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b;
1166    }
1167    if (__len >= 4) {
1168      const uint32_t __a = __loadword<uint32_t>(__s);
1169      const uint32_t __b = __loadword<uint32_t>(__s + __len - 4);
1170      return __hash_len_16(__len + (__a << 3), __b);
1171    }
1172    if (__len > 0) {
1173      const unsigned char __a = __s[0];
1174      const unsigned char __b = __s[__len >> 1];
1175      const unsigned char __c = __s[__len - 1];
1176      const uint32_t __y = static_cast<uint32_t>(__a) +
1177                           (static_cast<uint32_t>(__b) << 8);
1178      const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
1179      return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
1180    }
1181    return __k2;
1182  }
1183
1184  static _Size __hash_len_17_to_32(const char *__s, _Size __len)
1185     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1186  {
1187    const _Size __a = __loadword<_Size>(__s) * __k1;
1188    const _Size __b = __loadword<_Size>(__s + 8);
1189    const _Size __c = __loadword<_Size>(__s + __len - 8) * __k2;
1190    const _Size __d = __loadword<_Size>(__s + __len - 16) * __k0;
1191    return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
1192                         __a + __rotate(__b ^ __k3, 20) - __c + __len);
1193  }
1194
1195  // Return a 16-byte hash for 48 bytes.  Quick and dirty.
1196  // Callers do best to use "random-looking" values for a and b.
1197  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
1198      _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b)
1199        _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1200  {
1201    __a += __w;
1202    __b = __rotate(__b + __a + __z, 21);
1203    const _Size __c = __a;
1204    __a += __x;
1205    __a += __y;
1206    __b += __rotate(__a, 44);
1207    return pair<_Size, _Size>(__a + __z, __b + __c);
1208  }
1209
1210  // Return a 16-byte hash for s[0] ... s[31], a, and b.  Quick and dirty.
1211  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
1212      const char* __s, _Size __a, _Size __b)
1213    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1214  {
1215    return __weak_hash_len_32_with_seeds(__loadword<_Size>(__s),
1216                                         __loadword<_Size>(__s + 8),
1217                                         __loadword<_Size>(__s + 16),
1218                                         __loadword<_Size>(__s + 24),
1219                                         __a,
1220                                         __b);
1221  }
1222
1223  // Return an 8-byte hash for 33 to 64 bytes.
1224  static _Size __hash_len_33_to_64(const char *__s, size_t __len)
1225    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1226  {
1227    _Size __z = __loadword<_Size>(__s + 24);
1228    _Size __a = __loadword<_Size>(__s) +
1229                (__len + __loadword<_Size>(__s + __len - 16)) * __k0;
1230    _Size __b = __rotate(__a + __z, 52);
1231    _Size __c = __rotate(__a, 37);
1232    __a += __loadword<_Size>(__s + 8);
1233    __c += __rotate(__a, 7);
1234    __a += __loadword<_Size>(__s + 16);
1235    _Size __vf = __a + __z;
1236    _Size __vs = __b + __rotate(__a, 31) + __c;
1237    __a = __loadword<_Size>(__s + 16) + __loadword<_Size>(__s + __len - 32);
1238    __z += __loadword<_Size>(__s + __len - 8);
1239    __b = __rotate(__a + __z, 52);
1240    __c = __rotate(__a, 37);
1241    __a += __loadword<_Size>(__s + __len - 24);
1242    __c += __rotate(__a, 7);
1243    __a += __loadword<_Size>(__s + __len - 16);
1244    _Size __wf = __a + __z;
1245    _Size __ws = __b + __rotate(__a, 31) + __c;
1246    _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
1247    return __shift_mix(__r * __k0 + __vs) * __k2;
1248  }
1249};
1250
1251// cityhash64
1252template <class _Size>
1253_Size
1254__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
1255{
1256  const char* __s = static_cast<const char*>(__key);
1257  if (__len <= 32) {
1258    if (__len <= 16) {
1259      return __hash_len_0_to_16(__s, __len);
1260    } else {
1261      return __hash_len_17_to_32(__s, __len);
1262    }
1263  } else if (__len <= 64) {
1264    return __hash_len_33_to_64(__s, __len);
1265  }
1266
1267  // For strings over 64 bytes we hash the end first, and then as we
1268  // loop we keep 56 bytes of state: v, w, x, y, and z.
1269  _Size __x = __loadword<_Size>(__s + __len - 40);
1270  _Size __y = __loadword<_Size>(__s + __len - 16) +
1271              __loadword<_Size>(__s + __len - 56);
1272  _Size __z = __hash_len_16(__loadword<_Size>(__s + __len - 48) + __len,
1273                          __loadword<_Size>(__s + __len - 24));
1274  pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
1275  pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
1276  __x = __x * __k1 + __loadword<_Size>(__s);
1277
1278  // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
1279  __len = (__len - 1) & ~static_cast<_Size>(63);
1280  do {
1281    __x = __rotate(__x + __y + __v.first + __loadword<_Size>(__s + 8), 37) * __k1;
1282    __y = __rotate(__y + __v.second + __loadword<_Size>(__s + 48), 42) * __k1;
1283    __x ^= __w.second;
1284    __y += __v.first + __loadword<_Size>(__s + 40);
1285    __z = __rotate(__z + __w.first, 33) * __k1;
1286    __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
1287    __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
1288                                        __y + __loadword<_Size>(__s + 16));
1289    _VSTD::swap(__z, __x);
1290    __s += 64;
1291    __len -= 64;
1292  } while (__len != 0);
1293  return __hash_len_16(
1294      __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
1295      __hash_len_16(__v.second, __w.second) + __x);
1296}
1297
1298template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
1299struct __scalar_hash;
1300
1301template <class _Tp>
1302struct __scalar_hash<_Tp, 0>
1303    : public unary_function<_Tp, size_t>
1304{
1305    _LIBCPP_INLINE_VISIBILITY
1306    size_t operator()(_Tp __v) const _NOEXCEPT
1307    {
1308        union
1309        {
1310            _Tp    __t;
1311            size_t __a;
1312        } __u;
1313        __u.__a = 0;
1314        __u.__t = __v;
1315        return __u.__a;
1316    }
1317};
1318
1319template <class _Tp>
1320struct __scalar_hash<_Tp, 1>
1321    : public unary_function<_Tp, size_t>
1322{
1323    _LIBCPP_INLINE_VISIBILITY
1324    size_t operator()(_Tp __v) const _NOEXCEPT
1325    {
1326        union
1327        {
1328            _Tp    __t;
1329            size_t __a;
1330        } __u;
1331        __u.__t = __v;
1332        return __u.__a;
1333    }
1334};
1335
1336template <class _Tp>
1337struct __scalar_hash<_Tp, 2>
1338    : public unary_function<_Tp, size_t>
1339{
1340    _LIBCPP_INLINE_VISIBILITY
1341    size_t operator()(_Tp __v) const _NOEXCEPT
1342    {
1343        union
1344        {
1345            _Tp __t;
1346            struct
1347            {
1348                size_t __a;
1349                size_t __b;
1350            } __s;
1351        } __u;
1352        __u.__t = __v;
1353        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1354    }
1355};
1356
1357template <class _Tp>
1358struct __scalar_hash<_Tp, 3>
1359    : public unary_function<_Tp, size_t>
1360{
1361    _LIBCPP_INLINE_VISIBILITY
1362    size_t operator()(_Tp __v) const _NOEXCEPT
1363    {
1364        union
1365        {
1366            _Tp __t;
1367            struct
1368            {
1369                size_t __a;
1370                size_t __b;
1371                size_t __c;
1372            } __s;
1373        } __u;
1374        __u.__t = __v;
1375        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1376    }
1377};
1378
1379template <class _Tp>
1380struct __scalar_hash<_Tp, 4>
1381    : public unary_function<_Tp, size_t>
1382{
1383    _LIBCPP_INLINE_VISIBILITY
1384    size_t operator()(_Tp __v) const _NOEXCEPT
1385    {
1386        union
1387        {
1388            _Tp __t;
1389            struct
1390            {
1391                size_t __a;
1392                size_t __b;
1393                size_t __c;
1394                size_t __d;
1395            } __s;
1396        } __u;
1397        __u.__t = __v;
1398        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1399    }
1400};
1401
1402struct _PairT {
1403  size_t first;
1404  size_t second;
1405};
1406
1407_LIBCPP_INLINE_VISIBILITY
1408inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT {
1409    typedef __scalar_hash<_PairT> _HashT;
1410    const _PairT __p = {__lhs, __rhs};
1411    return _HashT()(__p);
1412}
1413
1414template<class _Tp>
1415struct _LIBCPP_TEMPLATE_VIS hash<_Tp*>
1416    : public unary_function<_Tp*, size_t>
1417{
1418    _LIBCPP_INLINE_VISIBILITY
1419    size_t operator()(_Tp* __v) const _NOEXCEPT
1420    {
1421        union
1422        {
1423            _Tp* __t;
1424            size_t __a;
1425        } __u;
1426        __u.__t = __v;
1427        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1428    }
1429};
1430
1431
1432template <>
1433struct _LIBCPP_TEMPLATE_VIS hash<bool>
1434    : public unary_function<bool, size_t>
1435{
1436    _LIBCPP_INLINE_VISIBILITY
1437    size_t operator()(bool __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1438};
1439
1440template <>
1441struct _LIBCPP_TEMPLATE_VIS hash<char>
1442    : public unary_function<char, size_t>
1443{
1444    _LIBCPP_INLINE_VISIBILITY
1445    size_t operator()(char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1446};
1447
1448template <>
1449struct _LIBCPP_TEMPLATE_VIS hash<signed char>
1450    : public unary_function<signed char, size_t>
1451{
1452    _LIBCPP_INLINE_VISIBILITY
1453    size_t operator()(signed char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1454};
1455
1456template <>
1457struct _LIBCPP_TEMPLATE_VIS hash<unsigned char>
1458    : public unary_function<unsigned char, size_t>
1459{
1460    _LIBCPP_INLINE_VISIBILITY
1461    size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1462};
1463
1464#ifndef _LIBCPP_HAS_NO_CHAR8_T
1465template <>
1466struct _LIBCPP_TEMPLATE_VIS hash<char8_t>
1467    : public unary_function<char8_t, size_t>
1468{
1469    _LIBCPP_INLINE_VISIBILITY
1470    size_t operator()(char8_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1471};
1472#endif // !_LIBCPP_HAS_NO_CHAR8_T
1473
1474#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
1475
1476template <>
1477struct _LIBCPP_TEMPLATE_VIS hash<char16_t>
1478    : public unary_function<char16_t, size_t>
1479{
1480    _LIBCPP_INLINE_VISIBILITY
1481    size_t operator()(char16_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1482};
1483
1484template <>
1485struct _LIBCPP_TEMPLATE_VIS hash<char32_t>
1486    : public unary_function<char32_t, size_t>
1487{
1488    _LIBCPP_INLINE_VISIBILITY
1489    size_t operator()(char32_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1490};
1491
1492#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
1493
1494template <>
1495struct _LIBCPP_TEMPLATE_VIS hash<wchar_t>
1496    : public unary_function<wchar_t, size_t>
1497{
1498    _LIBCPP_INLINE_VISIBILITY
1499    size_t operator()(wchar_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1500};
1501
1502template <>
1503struct _LIBCPP_TEMPLATE_VIS hash<short>
1504    : public unary_function<short, size_t>
1505{
1506    _LIBCPP_INLINE_VISIBILITY
1507    size_t operator()(short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1508};
1509
1510template <>
1511struct _LIBCPP_TEMPLATE_VIS hash<unsigned short>
1512    : public unary_function<unsigned short, size_t>
1513{
1514    _LIBCPP_INLINE_VISIBILITY
1515    size_t operator()(unsigned short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1516};
1517
1518template <>
1519struct _LIBCPP_TEMPLATE_VIS hash<int>
1520    : public unary_function<int, size_t>
1521{
1522    _LIBCPP_INLINE_VISIBILITY
1523    size_t operator()(int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1524};
1525
1526template <>
1527struct _LIBCPP_TEMPLATE_VIS hash<unsigned int>
1528    : public unary_function<unsigned int, size_t>
1529{
1530    _LIBCPP_INLINE_VISIBILITY
1531    size_t operator()(unsigned int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1532};
1533
1534template <>
1535struct _LIBCPP_TEMPLATE_VIS hash<long>
1536    : public unary_function<long, size_t>
1537{
1538    _LIBCPP_INLINE_VISIBILITY
1539    size_t operator()(long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1540};
1541
1542template <>
1543struct _LIBCPP_TEMPLATE_VIS hash<unsigned long>
1544    : public unary_function<unsigned long, size_t>
1545{
1546    _LIBCPP_INLINE_VISIBILITY
1547    size_t operator()(unsigned long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1548};
1549
1550template <>
1551struct _LIBCPP_TEMPLATE_VIS hash<long long>
1552    : public __scalar_hash<long long>
1553{
1554};
1555
1556template <>
1557struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long>
1558    : public __scalar_hash<unsigned long long>
1559{
1560};
1561
1562#ifndef _LIBCPP_HAS_NO_INT128
1563
1564template <>
1565struct _LIBCPP_TEMPLATE_VIS hash<__int128_t>
1566    : public __scalar_hash<__int128_t>
1567{
1568};
1569
1570template <>
1571struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t>
1572    : public __scalar_hash<__uint128_t>
1573{
1574};
1575
1576#endif
1577
1578template <>
1579struct _LIBCPP_TEMPLATE_VIS hash<float>
1580    : public __scalar_hash<float>
1581{
1582    _LIBCPP_INLINE_VISIBILITY
1583    size_t operator()(float __v) const _NOEXCEPT
1584    {
1585        // -0.0 and 0.0 should return same hash
1586       if (__v == 0.0f)
1587           return 0;
1588        return __scalar_hash<float>::operator()(__v);
1589    }
1590};
1591
1592template <>
1593struct _LIBCPP_TEMPLATE_VIS hash<double>
1594    : public __scalar_hash<double>
1595{
1596    _LIBCPP_INLINE_VISIBILITY
1597    size_t operator()(double __v) const _NOEXCEPT
1598    {
1599        // -0.0 and 0.0 should return same hash
1600       if (__v == 0.0)
1601           return 0;
1602        return __scalar_hash<double>::operator()(__v);
1603    }
1604};
1605
1606template <>
1607struct _LIBCPP_TEMPLATE_VIS hash<long double>
1608    : public __scalar_hash<long double>
1609{
1610    _LIBCPP_INLINE_VISIBILITY
1611    size_t operator()(long double __v) const _NOEXCEPT
1612    {
1613        // -0.0 and 0.0 should return same hash
1614        if (__v == 0.0L)
1615            return 0;
1616#if defined(__i386__) || (defined(__x86_64__) && defined(__ILP32__))
1617        // Zero out padding bits
1618        union
1619        {
1620            long double __t;
1621            struct
1622            {
1623                size_t __a;
1624                size_t __b;
1625                size_t __c;
1626                size_t __d;
1627            } __s;
1628        } __u;
1629        __u.__s.__a = 0;
1630        __u.__s.__b = 0;
1631        __u.__s.__c = 0;
1632        __u.__s.__d = 0;
1633        __u.__t = __v;
1634        return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d;
1635#elif defined(__x86_64__)
1636        // Zero out padding bits
1637        union
1638        {
1639            long double __t;
1640            struct
1641            {
1642                size_t __a;
1643                size_t __b;
1644            } __s;
1645        } __u;
1646        __u.__s.__a = 0;
1647        __u.__s.__b = 0;
1648        __u.__t = __v;
1649        return __u.__s.__a ^ __u.__s.__b;
1650#else
1651        return __scalar_hash<long double>::operator()(__v);
1652#endif
1653    }
1654};
1655
1656#if _LIBCPP_STD_VER > 11
1657
1658template <class _Tp, bool = is_enum<_Tp>::value>
1659struct _LIBCPP_TEMPLATE_VIS __enum_hash
1660    : public unary_function<_Tp, size_t>
1661{
1662    _LIBCPP_INLINE_VISIBILITY
1663    size_t operator()(_Tp __v) const _NOEXCEPT
1664    {
1665        typedef typename underlying_type<_Tp>::type type;
1666        return hash<type>{}(static_cast<type>(__v));
1667    }
1668};
1669template <class _Tp>
1670struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> {
1671    __enum_hash() = delete;
1672    __enum_hash(__enum_hash const&) = delete;
1673    __enum_hash& operator=(__enum_hash const&) = delete;
1674};
1675
1676template <class _Tp>
1677struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp>
1678{
1679};
1680#endif
1681
1682#if _LIBCPP_STD_VER > 14
1683
1684template <>
1685struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t>
1686  : public unary_function<nullptr_t, size_t>
1687{
1688  _LIBCPP_INLINE_VISIBILITY
1689  size_t operator()(nullptr_t) const _NOEXCEPT {
1690    return 662607004ull;
1691  }
1692};
1693#endif
1694
1695#ifndef _LIBCPP_CXX03_LANG
1696template <class _Key, class _Hash>
1697using __check_hash_requirements _LIBCPP_NODEBUG_TYPE  = integral_constant<bool,
1698    is_copy_constructible<_Hash>::value &&
1699    is_move_constructible<_Hash>::value &&
1700    __invokable_r<size_t, _Hash, _Key const&>::value
1701>;
1702
1703template <class _Key, class _Hash = hash<_Key> >
1704using __has_enabled_hash _LIBCPP_NODEBUG_TYPE = integral_constant<bool,
1705    __check_hash_requirements<_Key, _Hash>::value &&
1706    is_default_constructible<_Hash>::value
1707>;
1708
1709#if _LIBCPP_STD_VER > 14
1710template <class _Type, class>
1711using __enable_hash_helper_imp _LIBCPP_NODEBUG_TYPE  = _Type;
1712
1713template <class _Type, class ..._Keys>
1714using __enable_hash_helper _LIBCPP_NODEBUG_TYPE  = __enable_hash_helper_imp<_Type,
1715  typename enable_if<__all<__has_enabled_hash<_Keys>::value...>::value>::type
1716>;
1717#else
1718template <class _Type, class ...>
1719using __enable_hash_helper _LIBCPP_NODEBUG_TYPE = _Type;
1720#endif
1721
1722#endif // !_LIBCPP_CXX03_LANG
1723
1724_LIBCPP_END_NAMESPACE_STD
1725
1726_LIBCPP_POP_MACROS
1727
1728#endif // _LIBCPP_UTILITY
1729