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 <compare>
213#include <type_traits>
214#include <initializer_list>
215#include <cstddef>
216#include <cstring>
217#include <cstdint>
218#include <limits>
219#include <version>
220#include <__debug>
221
222#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
223#pragma GCC system_header
224#endif
225
226_LIBCPP_PUSH_MACROS
227#include <__undef_macros>
228
229_LIBCPP_BEGIN_NAMESPACE_STD
230
231namespace rel_ops
232{
233
234template<class _Tp>
235inline _LIBCPP_INLINE_VISIBILITY
236bool
237operator!=(const _Tp& __x, const _Tp& __y)
238{
239    return !(__x == __y);
240}
241
242template<class _Tp>
243inline _LIBCPP_INLINE_VISIBILITY
244bool
245operator> (const _Tp& __x, const _Tp& __y)
246{
247    return __y < __x;
248}
249
250template<class _Tp>
251inline _LIBCPP_INLINE_VISIBILITY
252bool
253operator<=(const _Tp& __x, const _Tp& __y)
254{
255    return !(__y < __x);
256}
257
258template<class _Tp>
259inline _LIBCPP_INLINE_VISIBILITY
260bool
261operator>=(const _Tp& __x, const _Tp& __y)
262{
263    return !(__x < __y);
264}
265
266}  // rel_ops
267
268// swap_ranges is defined in <type_traits>`
269
270// swap is defined in <type_traits>
271
272// move_if_noexcept
273
274template <class _Tp>
275_LIBCPP_NODISCARD_EXT inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
276#ifndef _LIBCPP_CXX03_LANG
277typename conditional
278<
279    !is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value,
280    const _Tp&,
281    _Tp&&
282>::type
283#else  // _LIBCPP_CXX03_LANG
284const _Tp&
285#endif
286move_if_noexcept(_Tp& __x) _NOEXCEPT
287{
288    return _VSTD::move(__x);
289}
290
291#if _LIBCPP_STD_VER > 14
292template <class _Tp>
293_LIBCPP_NODISCARD_EXT constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
294
295template <class _Tp>
296void as_const(const _Tp&&) = delete;
297#endif
298
299#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_CONCEPTS)
300template<class _Tp, class... _Up>
301struct _IsSameAsAny : _Or<_IsSame<_Tp, _Up>...> {};
302
303template<class _Tp>
304concept __is_safe_integral_cmp = is_integral_v<_Tp> &&
305                      !_IsSameAsAny<_Tp, bool, char,
306#ifndef _LIBCPP_NO_HAS_CHAR8_T
307                                    char8_t,
308#endif
309#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
310                                    char16_t, char32_t,
311#endif
312                                    wchar_t>::value;
313
314template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
315_LIBCPP_INLINE_VISIBILITY constexpr
316bool cmp_equal(_Tp __t, _Up __u) noexcept
317{
318  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
319    return __t == __u;
320  else if constexpr (is_signed_v<_Tp>)
321    return __t < 0 ? false : make_unsigned_t<_Tp>(__t) == __u;
322  else
323    return __u < 0 ? false : __t == make_unsigned_t<_Up>(__u);
324}
325
326template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
327_LIBCPP_INLINE_VISIBILITY constexpr
328bool cmp_not_equal(_Tp __t, _Up __u) noexcept
329{
330  return !_VSTD::cmp_equal(__t, __u);
331}
332
333template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
334_LIBCPP_INLINE_VISIBILITY constexpr
335bool cmp_less(_Tp __t, _Up __u) noexcept
336{
337  if constexpr (is_signed_v<_Tp> == is_signed_v<_Up>)
338    return __t < __u;
339  else if constexpr (is_signed_v<_Tp>)
340    return __t < 0 ? true : make_unsigned_t<_Tp>(__t) < __u;
341  else
342    return __u < 0 ? false : __t < make_unsigned_t<_Up>(__u);
343}
344
345template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
346_LIBCPP_INLINE_VISIBILITY constexpr
347bool cmp_greater(_Tp __t, _Up __u) noexcept
348{
349  return _VSTD::cmp_less(__u, __t);
350}
351
352template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
353_LIBCPP_INLINE_VISIBILITY constexpr
354bool cmp_less_equal(_Tp __t, _Up __u) noexcept
355{
356  return !_VSTD::cmp_greater(__t, __u);
357}
358
359template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
360_LIBCPP_INLINE_VISIBILITY constexpr
361bool cmp_greater_equal(_Tp __t, _Up __u) noexcept
362{
363  return !_VSTD::cmp_less(__t, __u);
364}
365
366template<__is_safe_integral_cmp _Tp, __is_safe_integral_cmp _Up>
367_LIBCPP_INLINE_VISIBILITY constexpr
368bool in_range(_Up __u) noexcept
369{
370  return _VSTD::cmp_less_equal(__u, numeric_limits<_Tp>::max()) &&
371         _VSTD::cmp_greater_equal(__u, numeric_limits<_Tp>::min());
372}
373#endif
374
375struct _LIBCPP_TEMPLATE_VIS piecewise_construct_t { explicit piecewise_construct_t() = default; };
376#if defined(_LIBCPP_CXX03_LANG) || defined(_LIBCPP_BUILDING_LIBRARY)
377extern _LIBCPP_EXPORTED_FROM_ABI const piecewise_construct_t piecewise_construct;// = piecewise_construct_t();
378#else
379/* _LIBCPP_INLINE_VAR */ constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
380#endif
381
382#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
383template <class, class>
384struct __non_trivially_copyable_base {
385  _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
386  __non_trivially_copyable_base() _NOEXCEPT {}
387  _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
388  __non_trivially_copyable_base(__non_trivially_copyable_base const&) _NOEXCEPT {}
389};
390#endif
391
392template <class _T1, class _T2>
393struct _LIBCPP_TEMPLATE_VIS pair
394#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
395: private __non_trivially_copyable_base<_T1, _T2>
396#endif
397{
398    typedef _T1 first_type;
399    typedef _T2 second_type;
400
401    _T1 first;
402    _T2 second;
403
404#if !defined(_LIBCPP_CXX03_LANG)
405    pair(pair const&) = default;
406    pair(pair&&) = default;
407#else
408  // Use the implicitly declared copy constructor in C++03
409#endif
410
411#ifdef _LIBCPP_CXX03_LANG
412    _LIBCPP_INLINE_VISIBILITY
413    pair() : first(), second() {}
414
415    _LIBCPP_INLINE_VISIBILITY
416    pair(_T1 const& __t1, _T2 const& __t2) : first(__t1), second(__t2) {}
417
418    template <class _U1, class _U2>
419    _LIBCPP_INLINE_VISIBILITY
420    pair(const pair<_U1, _U2>& __p) : first(__p.first), second(__p.second) {}
421
422    _LIBCPP_INLINE_VISIBILITY
423    pair& operator=(pair const& __p) {
424        first = __p.first;
425        second = __p.second;
426        return *this;
427    }
428#else
429    template <bool _Val>
430    using _EnableB _LIBCPP_NODEBUG_TYPE = typename enable_if<_Val, bool>::type;
431
432    struct _CheckArgs {
433      template <int&...>
434      static constexpr bool __enable_explicit_default() {
435          return is_default_constructible<_T1>::value
436              && is_default_constructible<_T2>::value
437              && !__enable_implicit_default<>();
438      }
439
440      template <int&...>
441      static constexpr bool __enable_implicit_default() {
442          return __is_implicitly_default_constructible<_T1>::value
443              && __is_implicitly_default_constructible<_T2>::value;
444      }
445
446      template <class _U1, class _U2>
447      static constexpr bool __enable_explicit() {
448          return is_constructible<first_type, _U1>::value
449              && is_constructible<second_type, _U2>::value
450              && (!is_convertible<_U1, first_type>::value
451                  || !is_convertible<_U2, second_type>::value);
452      }
453
454      template <class _U1, class _U2>
455      static constexpr bool __enable_implicit() {
456          return is_constructible<first_type, _U1>::value
457              && is_constructible<second_type, _U2>::value
458              && is_convertible<_U1, first_type>::value
459              && is_convertible<_U2, second_type>::value;
460      }
461    };
462
463    template <bool _MaybeEnable>
464    using _CheckArgsDep _LIBCPP_NODEBUG_TYPE = typename conditional<
465      _MaybeEnable, _CheckArgs, __check_tuple_constructor_fail>::type;
466
467    struct _CheckTupleLikeConstructor {
468        template <class _Tuple>
469        static constexpr bool __enable_implicit() {
470            return __tuple_convertible<_Tuple, pair>::value;
471        }
472
473        template <class _Tuple>
474        static constexpr bool __enable_explicit() {
475            return __tuple_constructible<_Tuple, pair>::value
476               && !__tuple_convertible<_Tuple, pair>::value;
477        }
478
479        template <class _Tuple>
480        static constexpr bool __enable_assign() {
481            return __tuple_assignable<_Tuple, pair>::value;
482        }
483    };
484
485    template <class _Tuple>
486    using _CheckTLC _LIBCPP_NODEBUG_TYPE = typename conditional<
487        __tuple_like_with_size<_Tuple, 2>::value
488            && !is_same<typename decay<_Tuple>::type, pair>::value,
489        _CheckTupleLikeConstructor,
490        __check_tuple_constructor_fail
491    >::type;
492
493    template<bool _Dummy = true, _EnableB<
494            _CheckArgsDep<_Dummy>::__enable_explicit_default()
495    > = false>
496    explicit _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
497    pair() _NOEXCEPT_(is_nothrow_default_constructible<first_type>::value &&
498                      is_nothrow_default_constructible<second_type>::value)
499        : first(), second() {}
500
501    template<bool _Dummy = true, _EnableB<
502            _CheckArgsDep<_Dummy>::__enable_implicit_default()
503    > = false>
504    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
505    pair() _NOEXCEPT_(is_nothrow_default_constructible<first_type>::value &&
506                      is_nothrow_default_constructible<second_type>::value)
507        : first(), second() {}
508
509    template <bool _Dummy = true, _EnableB<
510             _CheckArgsDep<_Dummy>::template __enable_explicit<_T1 const&, _T2 const&>()
511    > = false>
512    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
513    explicit pair(_T1 const& __t1, _T2 const& __t2)
514        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
515                   is_nothrow_copy_constructible<second_type>::value)
516        : first(__t1), second(__t2) {}
517
518    template<bool _Dummy = true, _EnableB<
519            _CheckArgsDep<_Dummy>::template __enable_implicit<_T1 const&, _T2 const&>()
520    > = false>
521    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
522    pair(_T1 const& __t1, _T2 const& __t2)
523        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
524                   is_nothrow_copy_constructible<second_type>::value)
525        : first(__t1), second(__t2) {}
526
527    template<class _U1, class _U2, _EnableB<
528             _CheckArgs::template __enable_explicit<_U1, _U2>()
529    > = false>
530    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
531    explicit pair(_U1&& __u1, _U2&& __u2)
532        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1>::value &&
533                    is_nothrow_constructible<second_type, _U2>::value))
534        : first(_VSTD::forward<_U1>(__u1)), second(_VSTD::forward<_U2>(__u2)) {}
535
536    template<class _U1, class _U2, _EnableB<
537            _CheckArgs::template __enable_implicit<_U1, _U2>()
538    > = false>
539    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
540    pair(_U1&& __u1, _U2&& __u2)
541        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1>::value &&
542                    is_nothrow_constructible<second_type, _U2>::value))
543        : first(_VSTD::forward<_U1>(__u1)), second(_VSTD::forward<_U2>(__u2)) {}
544
545    template<class _U1, class _U2, _EnableB<
546            _CheckArgs::template __enable_explicit<_U1 const&, _U2 const&>()
547    > = false>
548    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
549    explicit pair(pair<_U1, _U2> const& __p)
550        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1 const&>::value &&
551                    is_nothrow_constructible<second_type, _U2 const&>::value))
552        : first(__p.first), second(__p.second) {}
553
554    template<class _U1, class _U2, _EnableB<
555            _CheckArgs::template __enable_implicit<_U1 const&, _U2 const&>()
556    > = false>
557    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
558    pair(pair<_U1, _U2> const& __p)
559        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1 const&>::value &&
560                    is_nothrow_constructible<second_type, _U2 const&>::value))
561        : first(__p.first), second(__p.second) {}
562
563    template<class _U1, class _U2, _EnableB<
564            _CheckArgs::template __enable_explicit<_U1, _U2>()
565    > = false>
566    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
567    explicit pair(pair<_U1, _U2>&&__p)
568        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1&&>::value &&
569                    is_nothrow_constructible<second_type, _U2&&>::value))
570        : first(_VSTD::forward<_U1>(__p.first)), second(_VSTD::forward<_U2>(__p.second)) {}
571
572    template<class _U1, class _U2, _EnableB<
573            _CheckArgs::template __enable_implicit<_U1, _U2>()
574    > = false>
575    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
576    pair(pair<_U1, _U2>&& __p)
577        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1&&>::value &&
578                    is_nothrow_constructible<second_type, _U2&&>::value))
579        : first(_VSTD::forward<_U1>(__p.first)), second(_VSTD::forward<_U2>(__p.second)) {}
580
581    template<class _Tuple, _EnableB<
582            _CheckTLC<_Tuple>::template __enable_explicit<_Tuple>()
583    > = false>
584    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
585    explicit pair(_Tuple&& __p)
586        : first(_VSTD::get<0>(_VSTD::forward<_Tuple>(__p))),
587          second(_VSTD::get<1>(_VSTD::forward<_Tuple>(__p))) {}
588
589    template<class _Tuple, _EnableB<
590            _CheckTLC<_Tuple>::template __enable_implicit<_Tuple>()
591    > = false>
592    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
593    pair(_Tuple&& __p)
594        : first(_VSTD::get<0>(_VSTD::forward<_Tuple>(__p))),
595          second(_VSTD::get<1>(_VSTD::forward<_Tuple>(__p))) {}
596
597    template <class... _Args1, class... _Args2>
598    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
599    pair(piecewise_construct_t __pc,
600         tuple<_Args1...> __first_args, tuple<_Args2...> __second_args)
601        _NOEXCEPT_((is_nothrow_constructible<first_type, _Args1...>::value &&
602                    is_nothrow_constructible<second_type, _Args2...>::value))
603        : pair(__pc, __first_args, __second_args,
604                typename __make_tuple_indices<sizeof...(_Args1)>::type(),
605                typename __make_tuple_indices<sizeof...(_Args2) >::type()) {}
606
607    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
608    pair& operator=(typename conditional<
609                        is_copy_assignable<first_type>::value &&
610                        is_copy_assignable<second_type>::value,
611                    pair, __nat>::type const& __p)
612        _NOEXCEPT_(is_nothrow_copy_assignable<first_type>::value &&
613                   is_nothrow_copy_assignable<second_type>::value)
614    {
615        first = __p.first;
616        second = __p.second;
617        return *this;
618    }
619
620    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
621    pair& operator=(typename conditional<
622                        is_move_assignable<first_type>::value &&
623                        is_move_assignable<second_type>::value,
624                    pair, __nat>::type&& __p)
625        _NOEXCEPT_(is_nothrow_move_assignable<first_type>::value &&
626                   is_nothrow_move_assignable<second_type>::value)
627    {
628        first = _VSTD::forward<first_type>(__p.first);
629        second = _VSTD::forward<second_type>(__p.second);
630        return *this;
631    }
632
633    template <class _Tuple, _EnableB<
634            _CheckTLC<_Tuple>::template __enable_assign<_Tuple>()
635     > = false>
636    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
637    pair& operator=(_Tuple&& __p) {
638        first = _VSTD::get<0>(_VSTD::forward<_Tuple>(__p));
639        second = _VSTD::get<1>(_VSTD::forward<_Tuple>(__p));
640        return *this;
641    }
642#endif
643
644    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
645    void
646    swap(pair& __p) _NOEXCEPT_(__is_nothrow_swappable<first_type>::value &&
647                               __is_nothrow_swappable<second_type>::value)
648    {
649        using _VSTD::swap;
650        swap(first,  __p.first);
651        swap(second, __p.second);
652    }
653private:
654
655#ifndef _LIBCPP_CXX03_LANG
656    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
657    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
658    pair(piecewise_construct_t,
659         tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
660         __tuple_indices<_I1...>, __tuple_indices<_I2...>);
661#endif
662};
663
664#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
665template<class _T1, class _T2>
666pair(_T1, _T2) -> pair<_T1, _T2>;
667#endif // _LIBCPP_HAS_NO_DEDUCTION_GUIDES
668
669template <class _T1, class _T2>
670inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
671bool
672operator==(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
673{
674    return __x.first == __y.first && __x.second == __y.second;
675}
676
677template <class _T1, class _T2>
678inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
679bool
680operator!=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
681{
682    return !(__x == __y);
683}
684
685template <class _T1, class _T2>
686inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
687bool
688operator< (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
689{
690    return __x.first < __y.first || (!(__y.first < __x.first) && __x.second < __y.second);
691}
692
693template <class _T1, class _T2>
694inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
695bool
696operator> (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
697{
698    return __y < __x;
699}
700
701template <class _T1, class _T2>
702inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
703bool
704operator>=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
705{
706    return !(__x < __y);
707}
708
709template <class _T1, class _T2>
710inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
711bool
712operator<=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
713{
714    return !(__y < __x);
715}
716
717template <class _T1, class _T2>
718inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
719typename enable_if
720<
721    __is_swappable<_T1>::value &&
722    __is_swappable<_T2>::value,
723    void
724>::type
725swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
726                     _NOEXCEPT_((__is_nothrow_swappable<_T1>::value &&
727                                 __is_nothrow_swappable<_T2>::value))
728{
729    __x.swap(__y);
730}
731
732template <class _Tp>
733struct __unwrap_reference { typedef _LIBCPP_NODEBUG_TYPE _Tp type; };
734
735template <class _Tp>
736struct __unwrap_reference<reference_wrapper<_Tp> > { typedef _LIBCPP_NODEBUG_TYPE _Tp& type; };
737
738#if _LIBCPP_STD_VER > 17
739template <class _Tp>
740struct unwrap_reference : __unwrap_reference<_Tp> { };
741
742template <class _Tp>
743struct unwrap_ref_decay : unwrap_reference<typename decay<_Tp>::type> { };
744#endif // > C++17
745
746template <class _Tp>
747struct __unwrap_ref_decay
748#if _LIBCPP_STD_VER > 17
749    : unwrap_ref_decay<_Tp>
750#else
751    : __unwrap_reference<typename decay<_Tp>::type>
752#endif
753{ };
754
755#ifndef _LIBCPP_CXX03_LANG
756
757template <class _T1, class _T2>
758inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
759pair<typename __unwrap_ref_decay<_T1>::type, typename __unwrap_ref_decay<_T2>::type>
760make_pair(_T1&& __t1, _T2&& __t2)
761{
762    return pair<typename __unwrap_ref_decay<_T1>::type, typename __unwrap_ref_decay<_T2>::type>
763               (_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
764}
765
766#else  // _LIBCPP_CXX03_LANG
767
768template <class _T1, class _T2>
769inline _LIBCPP_INLINE_VISIBILITY
770pair<_T1,_T2>
771make_pair(_T1 __x, _T2 __y)
772{
773    return pair<_T1, _T2>(__x, __y);
774}
775
776#endif // _LIBCPP_CXX03_LANG
777
778template <class _T1, class _T2>
779  struct _LIBCPP_TEMPLATE_VIS tuple_size<pair<_T1, _T2> >
780    : public integral_constant<size_t, 2> {};
781
782template <size_t _Ip, class _T1, class _T2>
783struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, pair<_T1, _T2> >
784{
785    static_assert(_Ip < 2, "Index out of bounds in std::tuple_element<std::pair<T1, T2>>");
786};
787
788template <class _T1, class _T2>
789struct _LIBCPP_TEMPLATE_VIS tuple_element<0, pair<_T1, _T2> >
790{
791    typedef _LIBCPP_NODEBUG_TYPE _T1 type;
792};
793
794template <class _T1, class _T2>
795struct _LIBCPP_TEMPLATE_VIS tuple_element<1, pair<_T1, _T2> >
796{
797    typedef _LIBCPP_NODEBUG_TYPE _T2 type;
798};
799
800template <size_t _Ip> struct __get_pair;
801
802template <>
803struct __get_pair<0>
804{
805    template <class _T1, class _T2>
806    static
807    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
808    _T1&
809    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
810
811    template <class _T1, class _T2>
812    static
813    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
814    const _T1&
815    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
816
817#ifndef _LIBCPP_CXX03_LANG
818    template <class _T1, class _T2>
819    static
820    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
821    _T1&&
822    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
823
824    template <class _T1, class _T2>
825    static
826    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
827    const _T1&&
828    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T1>(__p.first);}
829#endif // _LIBCPP_CXX03_LANG
830};
831
832template <>
833struct __get_pair<1>
834{
835    template <class _T1, class _T2>
836    static
837    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
838    _T2&
839    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
840
841    template <class _T1, class _T2>
842    static
843    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
844    const _T2&
845    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
846
847#ifndef _LIBCPP_CXX03_LANG
848    template <class _T1, class _T2>
849    static
850    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
851    _T2&&
852    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
853
854    template <class _T1, class _T2>
855    static
856    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
857    const _T2&&
858    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T2>(__p.second);}
859#endif // _LIBCPP_CXX03_LANG
860};
861
862template <size_t _Ip, class _T1, class _T2>
863inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
864typename tuple_element<_Ip, pair<_T1, _T2> >::type&
865get(pair<_T1, _T2>& __p) _NOEXCEPT
866{
867    return __get_pair<_Ip>::get(__p);
868}
869
870template <size_t _Ip, class _T1, class _T2>
871inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
872const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
873get(const pair<_T1, _T2>& __p) _NOEXCEPT
874{
875    return __get_pair<_Ip>::get(__p);
876}
877
878#ifndef _LIBCPP_CXX03_LANG
879template <size_t _Ip, class _T1, class _T2>
880inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
881typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
882get(pair<_T1, _T2>&& __p) _NOEXCEPT
883{
884    return __get_pair<_Ip>::get(_VSTD::move(__p));
885}
886
887template <size_t _Ip, class _T1, class _T2>
888inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
889const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
890get(const pair<_T1, _T2>&& __p) _NOEXCEPT
891{
892    return __get_pair<_Ip>::get(_VSTD::move(__p));
893}
894#endif // _LIBCPP_CXX03_LANG
895
896#if _LIBCPP_STD_VER > 11
897template <class _T1, class _T2>
898inline _LIBCPP_INLINE_VISIBILITY
899constexpr _T1 & get(pair<_T1, _T2>& __p) _NOEXCEPT
900{
901    return __get_pair<0>::get(__p);
902}
903
904template <class _T1, class _T2>
905inline _LIBCPP_INLINE_VISIBILITY
906constexpr _T1 const & get(pair<_T1, _T2> const& __p) _NOEXCEPT
907{
908    return __get_pair<0>::get(__p);
909}
910
911template <class _T1, class _T2>
912inline _LIBCPP_INLINE_VISIBILITY
913constexpr _T1 && get(pair<_T1, _T2>&& __p) _NOEXCEPT
914{
915    return __get_pair<0>::get(_VSTD::move(__p));
916}
917
918template <class _T1, class _T2>
919inline _LIBCPP_INLINE_VISIBILITY
920constexpr _T1 const && get(pair<_T1, _T2> const&& __p) _NOEXCEPT
921{
922    return __get_pair<0>::get(_VSTD::move(__p));
923}
924
925template <class _T1, class _T2>
926inline _LIBCPP_INLINE_VISIBILITY
927constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
928{
929    return __get_pair<1>::get(__p);
930}
931
932template <class _T1, class _T2>
933inline _LIBCPP_INLINE_VISIBILITY
934constexpr _T1 const & get(pair<_T2, _T1> const& __p) _NOEXCEPT
935{
936    return __get_pair<1>::get(__p);
937}
938
939template <class _T1, class _T2>
940inline _LIBCPP_INLINE_VISIBILITY
941constexpr _T1 && get(pair<_T2, _T1>&& __p) _NOEXCEPT
942{
943    return __get_pair<1>::get(_VSTD::move(__p));
944}
945
946template <class _T1, class _T2>
947inline _LIBCPP_INLINE_VISIBILITY
948constexpr _T1 const && get(pair<_T2, _T1> const&& __p) _NOEXCEPT
949{
950    return __get_pair<1>::get(_VSTD::move(__p));
951}
952
953#endif
954
955#if _LIBCPP_STD_VER > 11
956
957template<class _Tp, _Tp... _Ip>
958struct _LIBCPP_TEMPLATE_VIS integer_sequence
959{
960    typedef _Tp value_type;
961    static_assert( is_integral<_Tp>::value,
962                  "std::integer_sequence can only be instantiated with an integral type" );
963    static
964    _LIBCPP_INLINE_VISIBILITY
965    constexpr
966    size_t
967    size() noexcept { return sizeof...(_Ip); }
968};
969
970template<size_t... _Ip>
971    using index_sequence = integer_sequence<size_t, _Ip...>;
972
973#if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
974
975template <class _Tp, _Tp _Ep>
976using __make_integer_sequence _LIBCPP_NODEBUG_TYPE = __make_integer_seq<integer_sequence, _Tp, _Ep>;
977
978#else
979
980template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked _LIBCPP_NODEBUG_TYPE  =
981  typename __detail::__make<_Np>::type::template __convert<integer_sequence, _Tp>;
982
983template <class _Tp, _Tp _Ep>
984struct __make_integer_sequence_checked
985{
986    static_assert(is_integral<_Tp>::value,
987                  "std::make_integer_sequence can only be instantiated with an integral type" );
988    static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length");
989    // Workaround GCC bug by preventing bad installations when 0 <= _Ep
990    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929
991    typedef _LIBCPP_NODEBUG_TYPE  __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type;
992};
993
994template <class _Tp, _Tp _Ep>
995using __make_integer_sequence _LIBCPP_NODEBUG_TYPE = typename __make_integer_sequence_checked<_Tp, _Ep>::type;
996
997#endif
998
999template<class _Tp, _Tp _Np>
1000    using make_integer_sequence = __make_integer_sequence<_Tp, _Np>;
1001
1002template<size_t _Np>
1003    using make_index_sequence = make_integer_sequence<size_t, _Np>;
1004
1005template<class... _Tp>
1006    using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
1007
1008#endif // _LIBCPP_STD_VER > 11
1009
1010#if _LIBCPP_STD_VER > 11
1011template<class _T1, class _T2 = _T1>
1012inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
1013_T1 exchange(_T1& __obj, _T2 && __new_value)
1014{
1015    _T1 __old_value = _VSTD::move(__obj);
1016    __obj = _VSTD::forward<_T2>(__new_value);
1017    return __old_value;
1018}
1019#endif // _LIBCPP_STD_VER > 11
1020
1021#if _LIBCPP_STD_VER > 14
1022
1023struct _LIBCPP_TYPE_VIS in_place_t {
1024    explicit in_place_t() = default;
1025};
1026_LIBCPP_INLINE_VAR constexpr in_place_t in_place{};
1027
1028template <class _Tp>
1029struct _LIBCPP_TEMPLATE_VIS in_place_type_t {
1030    explicit in_place_type_t() = default;
1031};
1032template <class _Tp>
1033_LIBCPP_INLINE_VAR constexpr in_place_type_t<_Tp> in_place_type{};
1034
1035template <size_t _Idx>
1036struct _LIBCPP_TEMPLATE_VIS in_place_index_t {
1037    explicit in_place_index_t() = default;
1038};
1039template <size_t _Idx>
1040_LIBCPP_INLINE_VAR constexpr in_place_index_t<_Idx> in_place_index{};
1041
1042template <class _Tp> struct __is_inplace_type_imp : false_type {};
1043template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_type {};
1044
1045template <class _Tp>
1046using __is_inplace_type = __is_inplace_type_imp<__uncvref_t<_Tp>>;
1047
1048template <class _Tp> struct __is_inplace_index_imp : false_type {};
1049template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
1050
1051template <class _Tp>
1052using __is_inplace_index = __is_inplace_index_imp<__uncvref_t<_Tp>>;
1053
1054#endif // _LIBCPP_STD_VER > 14
1055
1056template <class _Arg, class _Result>
1057struct _LIBCPP_TEMPLATE_VIS unary_function
1058{
1059    typedef _Arg    argument_type;
1060    typedef _Result result_type;
1061};
1062
1063template <class _Size>
1064inline _LIBCPP_INLINE_VISIBILITY
1065_Size
1066__loadword(const void* __p)
1067{
1068    _Size __r;
1069    _VSTD::memcpy(&__r, __p, sizeof(__r));
1070    return __r;
1071}
1072
1073// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t
1074// is 64 bits.  This is because cityhash64 uses 64bit x 64bit
1075// multiplication, which can be very slow on 32-bit systems.
1076template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__>
1077struct __murmur2_or_cityhash;
1078
1079template <class _Size>
1080struct __murmur2_or_cityhash<_Size, 32>
1081{
1082    inline _Size operator()(const void* __key, _Size __len)
1083         _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK;
1084};
1085
1086// murmur2
1087template <class _Size>
1088_Size
1089__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len)
1090{
1091    const _Size __m = 0x5bd1e995;
1092    const _Size __r = 24;
1093    _Size __h = __len;
1094    const unsigned char* __data = static_cast<const unsigned char*>(__key);
1095    for (; __len >= 4; __data += 4, __len -= 4)
1096    {
1097        _Size __k = __loadword<_Size>(__data);
1098        __k *= __m;
1099        __k ^= __k >> __r;
1100        __k *= __m;
1101        __h *= __m;
1102        __h ^= __k;
1103    }
1104    switch (__len)
1105    {
1106    case 3:
1107        __h ^= __data[2] << 16;
1108        _LIBCPP_FALLTHROUGH();
1109    case 2:
1110        __h ^= __data[1] << 8;
1111        _LIBCPP_FALLTHROUGH();
1112    case 1:
1113        __h ^= __data[0];
1114        __h *= __m;
1115    }
1116    __h ^= __h >> 13;
1117    __h *= __m;
1118    __h ^= __h >> 15;
1119    return __h;
1120}
1121
1122template <class _Size>
1123struct __murmur2_or_cityhash<_Size, 64>
1124{
1125    inline _Size operator()(const void* __key, _Size __len)  _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK;
1126
1127 private:
1128  // Some primes between 2^63 and 2^64.
1129  static const _Size __k0 = 0xc3a5c85c97cb3127ULL;
1130  static const _Size __k1 = 0xb492b66fbe98f273ULL;
1131  static const _Size __k2 = 0x9ae16a3b2f90404fULL;
1132  static const _Size __k3 = 0xc949d7c7509e6557ULL;
1133
1134  static _Size __rotate(_Size __val, int __shift) {
1135    return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift)));
1136  }
1137
1138  static _Size __rotate_by_at_least_1(_Size __val, int __shift) {
1139    return (__val >> __shift) | (__val << (64 - __shift));
1140  }
1141
1142  static _Size __shift_mix(_Size __val) {
1143    return __val ^ (__val >> 47);
1144  }
1145
1146  static _Size __hash_len_16(_Size __u, _Size __v)
1147     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1148  {
1149    const _Size __mul = 0x9ddfea08eb382d69ULL;
1150    _Size __a = (__u ^ __v) * __mul;
1151    __a ^= (__a >> 47);
1152    _Size __b = (__v ^ __a) * __mul;
1153    __b ^= (__b >> 47);
1154    __b *= __mul;
1155    return __b;
1156  }
1157
1158  static _Size __hash_len_0_to_16(const char* __s, _Size __len)
1159     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1160  {
1161    if (__len > 8) {
1162      const _Size __a = __loadword<_Size>(__s);
1163      const _Size __b = __loadword<_Size>(__s + __len - 8);
1164      return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b;
1165    }
1166    if (__len >= 4) {
1167      const uint32_t __a = __loadword<uint32_t>(__s);
1168      const uint32_t __b = __loadword<uint32_t>(__s + __len - 4);
1169      return __hash_len_16(__len + (__a << 3), __b);
1170    }
1171    if (__len > 0) {
1172      const unsigned char __a = __s[0];
1173      const unsigned char __b = __s[__len >> 1];
1174      const unsigned char __c = __s[__len - 1];
1175      const uint32_t __y = static_cast<uint32_t>(__a) +
1176                           (static_cast<uint32_t>(__b) << 8);
1177      const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
1178      return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
1179    }
1180    return __k2;
1181  }
1182
1183  static _Size __hash_len_17_to_32(const char *__s, _Size __len)
1184     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1185  {
1186    const _Size __a = __loadword<_Size>(__s) * __k1;
1187    const _Size __b = __loadword<_Size>(__s + 8);
1188    const _Size __c = __loadword<_Size>(__s + __len - 8) * __k2;
1189    const _Size __d = __loadword<_Size>(__s + __len - 16) * __k0;
1190    return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
1191                         __a + __rotate(__b ^ __k3, 20) - __c + __len);
1192  }
1193
1194  // Return a 16-byte hash for 48 bytes.  Quick and dirty.
1195  // Callers do best to use "random-looking" values for a and b.
1196  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
1197      _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b)
1198        _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1199  {
1200    __a += __w;
1201    __b = __rotate(__b + __a + __z, 21);
1202    const _Size __c = __a;
1203    __a += __x;
1204    __a += __y;
1205    __b += __rotate(__a, 44);
1206    return pair<_Size, _Size>(__a + __z, __b + __c);
1207  }
1208
1209  // Return a 16-byte hash for s[0] ... s[31], a, and b.  Quick and dirty.
1210  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
1211      const char* __s, _Size __a, _Size __b)
1212    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1213  {
1214    return __weak_hash_len_32_with_seeds(__loadword<_Size>(__s),
1215                                         __loadword<_Size>(__s + 8),
1216                                         __loadword<_Size>(__s + 16),
1217                                         __loadword<_Size>(__s + 24),
1218                                         __a,
1219                                         __b);
1220  }
1221
1222  // Return an 8-byte hash for 33 to 64 bytes.
1223  static _Size __hash_len_33_to_64(const char *__s, size_t __len)
1224    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1225  {
1226    _Size __z = __loadword<_Size>(__s + 24);
1227    _Size __a = __loadword<_Size>(__s) +
1228                (__len + __loadword<_Size>(__s + __len - 16)) * __k0;
1229    _Size __b = __rotate(__a + __z, 52);
1230    _Size __c = __rotate(__a, 37);
1231    __a += __loadword<_Size>(__s + 8);
1232    __c += __rotate(__a, 7);
1233    __a += __loadword<_Size>(__s + 16);
1234    _Size __vf = __a + __z;
1235    _Size __vs = __b + __rotate(__a, 31) + __c;
1236    __a = __loadword<_Size>(__s + 16) + __loadword<_Size>(__s + __len - 32);
1237    __z += __loadword<_Size>(__s + __len - 8);
1238    __b = __rotate(__a + __z, 52);
1239    __c = __rotate(__a, 37);
1240    __a += __loadword<_Size>(__s + __len - 24);
1241    __c += __rotate(__a, 7);
1242    __a += __loadword<_Size>(__s + __len - 16);
1243    _Size __wf = __a + __z;
1244    _Size __ws = __b + __rotate(__a, 31) + __c;
1245    _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
1246    return __shift_mix(__r * __k0 + __vs) * __k2;
1247  }
1248};
1249
1250// cityhash64
1251template <class _Size>
1252_Size
1253__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
1254{
1255  const char* __s = static_cast<const char*>(__key);
1256  if (__len <= 32) {
1257    if (__len <= 16) {
1258      return __hash_len_0_to_16(__s, __len);
1259    } else {
1260      return __hash_len_17_to_32(__s, __len);
1261    }
1262  } else if (__len <= 64) {
1263    return __hash_len_33_to_64(__s, __len);
1264  }
1265
1266  // For strings over 64 bytes we hash the end first, and then as we
1267  // loop we keep 56 bytes of state: v, w, x, y, and z.
1268  _Size __x = __loadword<_Size>(__s + __len - 40);
1269  _Size __y = __loadword<_Size>(__s + __len - 16) +
1270              __loadword<_Size>(__s + __len - 56);
1271  _Size __z = __hash_len_16(__loadword<_Size>(__s + __len - 48) + __len,
1272                          __loadword<_Size>(__s + __len - 24));
1273  pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
1274  pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
1275  __x = __x * __k1 + __loadword<_Size>(__s);
1276
1277  // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
1278  __len = (__len - 1) & ~static_cast<_Size>(63);
1279  do {
1280    __x = __rotate(__x + __y + __v.first + __loadword<_Size>(__s + 8), 37) * __k1;
1281    __y = __rotate(__y + __v.second + __loadword<_Size>(__s + 48), 42) * __k1;
1282    __x ^= __w.second;
1283    __y += __v.first + __loadword<_Size>(__s + 40);
1284    __z = __rotate(__z + __w.first, 33) * __k1;
1285    __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
1286    __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
1287                                        __y + __loadword<_Size>(__s + 16));
1288    _VSTD::swap(__z, __x);
1289    __s += 64;
1290    __len -= 64;
1291  } while (__len != 0);
1292  return __hash_len_16(
1293      __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
1294      __hash_len_16(__v.second, __w.second) + __x);
1295}
1296
1297template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
1298struct __scalar_hash;
1299
1300template <class _Tp>
1301struct __scalar_hash<_Tp, 0>
1302    : public unary_function<_Tp, size_t>
1303{
1304    _LIBCPP_INLINE_VISIBILITY
1305    size_t operator()(_Tp __v) const _NOEXCEPT
1306    {
1307        union
1308        {
1309            _Tp    __t;
1310            size_t __a;
1311        } __u;
1312        __u.__a = 0;
1313        __u.__t = __v;
1314        return __u.__a;
1315    }
1316};
1317
1318template <class _Tp>
1319struct __scalar_hash<_Tp, 1>
1320    : public unary_function<_Tp, size_t>
1321{
1322    _LIBCPP_INLINE_VISIBILITY
1323    size_t operator()(_Tp __v) const _NOEXCEPT
1324    {
1325        union
1326        {
1327            _Tp    __t;
1328            size_t __a;
1329        } __u;
1330        __u.__t = __v;
1331        return __u.__a;
1332    }
1333};
1334
1335template <class _Tp>
1336struct __scalar_hash<_Tp, 2>
1337    : public unary_function<_Tp, size_t>
1338{
1339    _LIBCPP_INLINE_VISIBILITY
1340    size_t operator()(_Tp __v) const _NOEXCEPT
1341    {
1342        union
1343        {
1344            _Tp __t;
1345            struct
1346            {
1347                size_t __a;
1348                size_t __b;
1349            } __s;
1350        } __u;
1351        __u.__t = __v;
1352        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1353    }
1354};
1355
1356template <class _Tp>
1357struct __scalar_hash<_Tp, 3>
1358    : public unary_function<_Tp, size_t>
1359{
1360    _LIBCPP_INLINE_VISIBILITY
1361    size_t operator()(_Tp __v) const _NOEXCEPT
1362    {
1363        union
1364        {
1365            _Tp __t;
1366            struct
1367            {
1368                size_t __a;
1369                size_t __b;
1370                size_t __c;
1371            } __s;
1372        } __u;
1373        __u.__t = __v;
1374        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1375    }
1376};
1377
1378template <class _Tp>
1379struct __scalar_hash<_Tp, 4>
1380    : public unary_function<_Tp, size_t>
1381{
1382    _LIBCPP_INLINE_VISIBILITY
1383    size_t operator()(_Tp __v) const _NOEXCEPT
1384    {
1385        union
1386        {
1387            _Tp __t;
1388            struct
1389            {
1390                size_t __a;
1391                size_t __b;
1392                size_t __c;
1393                size_t __d;
1394            } __s;
1395        } __u;
1396        __u.__t = __v;
1397        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1398    }
1399};
1400
1401struct _PairT {
1402  size_t first;
1403  size_t second;
1404};
1405
1406_LIBCPP_INLINE_VISIBILITY
1407inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT {
1408    typedef __scalar_hash<_PairT> _HashT;
1409    const _PairT __p = {__lhs, __rhs};
1410    return _HashT()(__p);
1411}
1412
1413template<class _Tp>
1414struct _LIBCPP_TEMPLATE_VIS hash<_Tp*>
1415    : public unary_function<_Tp*, size_t>
1416{
1417    _LIBCPP_INLINE_VISIBILITY
1418    size_t operator()(_Tp* __v) const _NOEXCEPT
1419    {
1420        union
1421        {
1422            _Tp* __t;
1423            size_t __a;
1424        } __u;
1425        __u.__t = __v;
1426        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1427    }
1428};
1429
1430
1431template <>
1432struct _LIBCPP_TEMPLATE_VIS hash<bool>
1433    : public unary_function<bool, size_t>
1434{
1435    _LIBCPP_INLINE_VISIBILITY
1436    size_t operator()(bool __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1437};
1438
1439template <>
1440struct _LIBCPP_TEMPLATE_VIS hash<char>
1441    : public unary_function<char, size_t>
1442{
1443    _LIBCPP_INLINE_VISIBILITY
1444    size_t operator()(char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1445};
1446
1447template <>
1448struct _LIBCPP_TEMPLATE_VIS hash<signed char>
1449    : public unary_function<signed char, size_t>
1450{
1451    _LIBCPP_INLINE_VISIBILITY
1452    size_t operator()(signed char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1453};
1454
1455template <>
1456struct _LIBCPP_TEMPLATE_VIS hash<unsigned char>
1457    : public unary_function<unsigned char, size_t>
1458{
1459    _LIBCPP_INLINE_VISIBILITY
1460    size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1461};
1462
1463#ifndef _LIBCPP_NO_HAS_CHAR8_T
1464template <>
1465struct _LIBCPP_TEMPLATE_VIS hash<char8_t>
1466    : public unary_function<char8_t, size_t>
1467{
1468    _LIBCPP_INLINE_VISIBILITY
1469    size_t operator()(char8_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1470};
1471#endif // !_LIBCPP_NO_HAS_CHAR8_T
1472
1473#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
1474
1475template <>
1476struct _LIBCPP_TEMPLATE_VIS hash<char16_t>
1477    : public unary_function<char16_t, size_t>
1478{
1479    _LIBCPP_INLINE_VISIBILITY
1480    size_t operator()(char16_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1481};
1482
1483template <>
1484struct _LIBCPP_TEMPLATE_VIS hash<char32_t>
1485    : public unary_function<char32_t, size_t>
1486{
1487    _LIBCPP_INLINE_VISIBILITY
1488    size_t operator()(char32_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1489};
1490
1491#endif // _LIBCPP_HAS_NO_UNICODE_CHARS
1492
1493template <>
1494struct _LIBCPP_TEMPLATE_VIS hash<wchar_t>
1495    : public unary_function<wchar_t, size_t>
1496{
1497    _LIBCPP_INLINE_VISIBILITY
1498    size_t operator()(wchar_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1499};
1500
1501template <>
1502struct _LIBCPP_TEMPLATE_VIS hash<short>
1503    : public unary_function<short, size_t>
1504{
1505    _LIBCPP_INLINE_VISIBILITY
1506    size_t operator()(short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1507};
1508
1509template <>
1510struct _LIBCPP_TEMPLATE_VIS hash<unsigned short>
1511    : public unary_function<unsigned short, size_t>
1512{
1513    _LIBCPP_INLINE_VISIBILITY
1514    size_t operator()(unsigned short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1515};
1516
1517template <>
1518struct _LIBCPP_TEMPLATE_VIS hash<int>
1519    : public unary_function<int, size_t>
1520{
1521    _LIBCPP_INLINE_VISIBILITY
1522    size_t operator()(int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1523};
1524
1525template <>
1526struct _LIBCPP_TEMPLATE_VIS hash<unsigned int>
1527    : public unary_function<unsigned int, size_t>
1528{
1529    _LIBCPP_INLINE_VISIBILITY
1530    size_t operator()(unsigned int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1531};
1532
1533template <>
1534struct _LIBCPP_TEMPLATE_VIS hash<long>
1535    : public unary_function<long, size_t>
1536{
1537    _LIBCPP_INLINE_VISIBILITY
1538    size_t operator()(long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1539};
1540
1541template <>
1542struct _LIBCPP_TEMPLATE_VIS hash<unsigned long>
1543    : public unary_function<unsigned long, size_t>
1544{
1545    _LIBCPP_INLINE_VISIBILITY
1546    size_t operator()(unsigned long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1547};
1548
1549template <>
1550struct _LIBCPP_TEMPLATE_VIS hash<long long>
1551    : public __scalar_hash<long long>
1552{
1553};
1554
1555template <>
1556struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long>
1557    : public __scalar_hash<unsigned long long>
1558{
1559};
1560
1561#ifndef _LIBCPP_HAS_NO_INT128
1562
1563template <>
1564struct _LIBCPP_TEMPLATE_VIS hash<__int128_t>
1565    : public __scalar_hash<__int128_t>
1566{
1567};
1568
1569template <>
1570struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t>
1571    : public __scalar_hash<__uint128_t>
1572{
1573};
1574
1575#endif
1576
1577template <>
1578struct _LIBCPP_TEMPLATE_VIS hash<float>
1579    : public __scalar_hash<float>
1580{
1581    _LIBCPP_INLINE_VISIBILITY
1582    size_t operator()(float __v) const _NOEXCEPT
1583    {
1584        // -0.0 and 0.0 should return same hash
1585       if (__v == 0.0f)
1586           return 0;
1587        return __scalar_hash<float>::operator()(__v);
1588    }
1589};
1590
1591template <>
1592struct _LIBCPP_TEMPLATE_VIS hash<double>
1593    : public __scalar_hash<double>
1594{
1595    _LIBCPP_INLINE_VISIBILITY
1596    size_t operator()(double __v) const _NOEXCEPT
1597    {
1598        // -0.0 and 0.0 should return same hash
1599       if (__v == 0.0)
1600           return 0;
1601        return __scalar_hash<double>::operator()(__v);
1602    }
1603};
1604
1605template <>
1606struct _LIBCPP_TEMPLATE_VIS hash<long double>
1607    : public __scalar_hash<long double>
1608{
1609    _LIBCPP_INLINE_VISIBILITY
1610    size_t operator()(long double __v) const _NOEXCEPT
1611    {
1612        // -0.0 and 0.0 should return same hash
1613        if (__v == 0.0L)
1614            return 0;
1615#if defined(__i386__) || (defined(__x86_64__) && defined(__ILP32__))
1616        // Zero out padding bits
1617        union
1618        {
1619            long double __t;
1620            struct
1621            {
1622                size_t __a;
1623                size_t __b;
1624                size_t __c;
1625                size_t __d;
1626            } __s;
1627        } __u;
1628        __u.__s.__a = 0;
1629        __u.__s.__b = 0;
1630        __u.__s.__c = 0;
1631        __u.__s.__d = 0;
1632        __u.__t = __v;
1633        return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d;
1634#elif defined(__x86_64__)
1635        // Zero out padding bits
1636        union
1637        {
1638            long double __t;
1639            struct
1640            {
1641                size_t __a;
1642                size_t __b;
1643            } __s;
1644        } __u;
1645        __u.__s.__a = 0;
1646        __u.__s.__b = 0;
1647        __u.__t = __v;
1648        return __u.__s.__a ^ __u.__s.__b;
1649#else
1650        return __scalar_hash<long double>::operator()(__v);
1651#endif
1652    }
1653};
1654
1655#if _LIBCPP_STD_VER > 11
1656
1657template <class _Tp, bool = is_enum<_Tp>::value>
1658struct _LIBCPP_TEMPLATE_VIS __enum_hash
1659    : public unary_function<_Tp, size_t>
1660{
1661    _LIBCPP_INLINE_VISIBILITY
1662    size_t operator()(_Tp __v) const _NOEXCEPT
1663    {
1664        typedef typename underlying_type<_Tp>::type type;
1665        return hash<type>{}(static_cast<type>(__v));
1666    }
1667};
1668template <class _Tp>
1669struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> {
1670    __enum_hash() = delete;
1671    __enum_hash(__enum_hash const&) = delete;
1672    __enum_hash& operator=(__enum_hash const&) = delete;
1673};
1674
1675template <class _Tp>
1676struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp>
1677{
1678};
1679#endif
1680
1681#if _LIBCPP_STD_VER > 14
1682
1683template <>
1684struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t>
1685  : public unary_function<nullptr_t, size_t>
1686{
1687  _LIBCPP_INLINE_VISIBILITY
1688  size_t operator()(nullptr_t) const _NOEXCEPT {
1689    return 662607004ull;
1690  }
1691};
1692#endif
1693
1694#ifndef _LIBCPP_CXX03_LANG
1695template <class _Key, class _Hash>
1696using __check_hash_requirements _LIBCPP_NODEBUG_TYPE  = integral_constant<bool,
1697    is_copy_constructible<_Hash>::value &&
1698    is_move_constructible<_Hash>::value &&
1699    __invokable_r<size_t, _Hash, _Key const&>::value
1700>;
1701
1702template <class _Key, class _Hash = hash<_Key> >
1703using __has_enabled_hash _LIBCPP_NODEBUG_TYPE = integral_constant<bool,
1704    __check_hash_requirements<_Key, _Hash>::value &&
1705    is_default_constructible<_Hash>::value
1706>;
1707
1708#if _LIBCPP_STD_VER > 14
1709template <class _Type, class>
1710using __enable_hash_helper_imp _LIBCPP_NODEBUG_TYPE  = _Type;
1711
1712template <class _Type, class ..._Keys>
1713using __enable_hash_helper _LIBCPP_NODEBUG_TYPE  = __enable_hash_helper_imp<_Type,
1714  typename enable_if<__all<__has_enabled_hash<_Keys>::value...>::value>::type
1715>;
1716#else
1717template <class _Type, class ...>
1718using __enable_hash_helper _LIBCPP_NODEBUG_TYPE = _Type;
1719#endif
1720
1721template <class _Tp>
1722_LIBCPP_INLINE_VISIBILITY constexpr typename underlying_type<_Tp>::type
1723__to_underlying(_Tp __val) noexcept {
1724  return static_cast<typename underlying_type<_Tp>::type>(__val);
1725}
1726#endif // !_LIBCPP_CXX03_LANG
1727
1728#if _LIBCPP_STD_VER > 20
1729template <class _Tp>
1730_LIBCPP_NODISCARD_EXT _LIBCPP_INLINE_VISIBILITY constexpr underlying_type_t<_Tp>
1731to_underlying(_Tp __val) noexcept {
1732  return _VSTD::__to_underlying(__val);
1733}
1734#endif
1735
1736_LIBCPP_END_NAMESPACE_STD
1737
1738_LIBCPP_POP_MACROS
1739
1740#endif // _LIBCPP_UTILITY
1741