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 T1, class T2>
62struct pair
63{
64    typedef T1 first_type;
65    typedef T2 second_type;
66
67    T1 first;
68    T2 second;
69
70    pair(const pair&) = default;
71    pair(pair&&) = default;
72    explicit(see-below) constexpr pair();
73    explicit(see-below) pair(const T1& x, const T2& y);                          // constexpr in C++14
74    template <class U, class V> explicit(see-below) pair(U&& x, V&& y);          // constexpr in C++14
75    template <class U, class V> explicit(see-below) pair(const pair<U, V>& p);   // constexpr in C++14
76    template <class U, class V> explicit(see-below) pair(pair<U, V>&& p);        // constexpr in C++14
77    template <class... Args1, class... Args2>
78        pair(piecewise_construct_t, tuple<Args1...> first_args,
79             tuple<Args2...> second_args);                                       // constexpr in C++20
80
81    template <class U, class V> pair& operator=(const pair<U, V>& p);            // constexpr in C++20
82    pair& operator=(pair&& p) noexcept(is_nothrow_move_assignable<T1>::value &&
83                                       is_nothrow_move_assignable<T2>::value);   // constexpr in C++20
84    template <class U, class V> pair& operator=(pair<U, V>&& p);                 // constexpr in C++20
85
86    void swap(pair& p) noexcept(is_nothrow_swappable_v<T1> &&
87                                is_nothrow_swappable_v<T2>);                     // constexpr in C++20
88};
89
90template <class T1, class T2> bool operator==(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
91template <class T1, class T2> bool operator!=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
92template <class T1, class T2> bool operator< (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
93template <class T1, class T2> bool operator> (const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
94template <class T1, class T2> bool operator>=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
95template <class T1, class T2> bool operator<=(const pair<T1,T2>&, const pair<T1,T2>&); // constexpr in C++14
96
97template <class T1, class T2> pair<V1, V2> make_pair(T1&&, T2&&);                // constexpr in C++14
98template <class T1, class T2>
99void
100swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));            // constexpr in C++20
101
102struct piecewise_construct_t { explicit piecewise_construct_t() = default; };
103inline constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
104
105template <class T> struct tuple_size;
106template <size_t I, class T> struct tuple_element;
107
108template <class T1, class T2> struct tuple_size<pair<T1, T2> >;
109template <class T1, class T2> struct tuple_element<0, pair<T1, T2> >;
110template <class T1, class T2> struct tuple_element<1, pair<T1, T2> >;
111
112template<size_t I, class T1, class T2>
113    typename tuple_element<I, pair<T1, T2> >::type&
114    get(pair<T1, T2>&) noexcept; // constexpr in C++14
115
116template<size_t I, class T1, class T2>
117    const typename tuple_element<I, pair<T1, T2> >::type&
118    get(const pair<T1, T2>&) noexcept; // constexpr in C++14
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<class T1, class T2>
129    constexpr T1& get(pair<T1, T2>&) noexcept; // C++14
130
131template<class T1, class T2>
132    constexpr const T1& get(const pair<T1, T2>&) noexcept; // C++14
133
134template<class T1, class T2>
135    constexpr T1&& get(pair<T1, T2>&&) noexcept; // C++14
136
137template<class T1, class T2>
138    constexpr const T1&& get(const pair<T1, T2>&&) noexcept; // C++14
139
140template<class T1, class T2>
141    constexpr T1& get(pair<T2, T1>&) noexcept; // C++14
142
143template<class T1, class T2>
144    constexpr const T1& get(const pair<T2, T1>&) noexcept; // C++14
145
146template<class T1, class T2>
147    constexpr T1&& get(pair<T2, T1>&&) noexcept; // C++14
148
149template<class T1, class T2>
150    constexpr const T1&& get(const pair<T2, T1>&&) noexcept; // C++14
151
152// C++14
153
154template<class T, T... I>
155struct integer_sequence
156{
157    typedef T value_type;
158
159    static constexpr size_t size() noexcept;
160};
161
162template<size_t... I>
163  using index_sequence = integer_sequence<size_t, I...>;
164
165template<class T, T N>
166  using make_integer_sequence = integer_sequence<T, 0, 1, ..., N-1>;
167template<size_t N>
168  using make_index_sequence = make_integer_sequence<size_t, N>;
169
170template<class... T>
171  using index_sequence_for = make_index_sequence<sizeof...(T)>;
172
173template<class T, class U=T>
174    T exchange(T& obj, U&& new_value);
175
176// 20.2.7, in-place construction // C++17
177struct in_place_t {
178  explicit in_place_t() = default;
179};
180inline constexpr in_place_t in_place{};
181template <class T>
182  struct in_place_type_t {
183    explicit in_place_type_t() = default;
184  };
185template <class T>
186  inline constexpr in_place_type_t<T> in_place_type{};
187template <size_t I>
188  struct in_place_index_t {
189    explicit in_place_index_t() = default;
190  };
191template <size_t I>
192  inline constexpr in_place_index_t<I> in_place_index{};
193
194// [utility.underlying], to_underlying
195template <class T>
196    constexpr underlying_type_t<T> to_underlying( T value ) noexcept; // C++2b
197
198}  // std
199
200*/
201
202#include <__config>
203#include <__tuple>
204#include <compare>
205#include <type_traits>
206#include <initializer_list>
207#include <cstddef>
208#include <cstring>
209#include <cstdint>
210#include <version>
211#include <__debug>
212
213#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
214#pragma GCC system_header
215#endif
216
217_LIBCPP_BEGIN_NAMESPACE_STD
218
219namespace rel_ops
220{
221
222template<class _Tp>
223inline _LIBCPP_INLINE_VISIBILITY
224bool
225operator!=(const _Tp& __x, const _Tp& __y)
226{
227    return !(__x == __y);
228}
229
230template<class _Tp>
231inline _LIBCPP_INLINE_VISIBILITY
232bool
233operator> (const _Tp& __x, const _Tp& __y)
234{
235    return __y < __x;
236}
237
238template<class _Tp>
239inline _LIBCPP_INLINE_VISIBILITY
240bool
241operator<=(const _Tp& __x, const _Tp& __y)
242{
243    return !(__y < __x);
244}
245
246template<class _Tp>
247inline _LIBCPP_INLINE_VISIBILITY
248bool
249operator>=(const _Tp& __x, const _Tp& __y)
250{
251    return !(__x < __y);
252}
253
254}  // rel_ops
255
256// swap_ranges is defined in <type_traits>`
257
258// swap is defined in <type_traits>
259
260// move_if_noexcept
261
262template <class _Tp>
263inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
264#ifndef _LIBCPP_CXX03_LANG
265typename conditional
266<
267    !is_nothrow_move_constructible<_Tp>::value && is_copy_constructible<_Tp>::value,
268    const _Tp&,
269    _Tp&&
270>::type
271#else  // _LIBCPP_CXX03_LANG
272const _Tp&
273#endif
274move_if_noexcept(_Tp& __x) _NOEXCEPT
275{
276    return _VSTD::move(__x);
277}
278
279#if _LIBCPP_STD_VER > 14
280template <class _Tp> constexpr add_const_t<_Tp>& as_const(_Tp& __t) noexcept { return __t; }
281template <class _Tp>                        void as_const(const _Tp&&) = delete;
282#endif
283
284struct _LIBCPP_TEMPLATE_VIS piecewise_construct_t { explicit piecewise_construct_t() = default; };
285#if defined(_LIBCPP_CXX03_LANG) || defined(_LIBCPP_BUILDING_LIBRARY)
286extern _LIBCPP_EXPORTED_FROM_ABI const piecewise_construct_t piecewise_construct;// = piecewise_construct_t();
287#else
288/* _LIBCPP_INLINE_VAR */ constexpr piecewise_construct_t piecewise_construct = piecewise_construct_t();
289#endif
290
291#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
292template <class, class>
293struct __non_trivially_copyable_base {
294  _LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
295  __non_trivially_copyable_base() _NOEXCEPT {}
296  _LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
297  __non_trivially_copyable_base(__non_trivially_copyable_base const&) _NOEXCEPT {}
298};
299#endif
300
301template <class _T1, class _T2>
302struct _LIBCPP_TEMPLATE_VIS pair
303#if defined(_LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR)
304: private __non_trivially_copyable_base<_T1, _T2>
305#endif
306{
307    typedef _T1 first_type;
308    typedef _T2 second_type;
309
310    _T1 first;
311    _T2 second;
312
313#if !defined(_LIBCPP_CXX03_LANG)
314    pair(pair const&) = default;
315    pair(pair&&) = default;
316#else
317  // Use the implicitly declared copy constructor in C++03
318#endif
319
320#ifdef _LIBCPP_CXX03_LANG
321    _LIBCPP_INLINE_VISIBILITY
322    pair() : first(), second() {}
323
324    _LIBCPP_INLINE_VISIBILITY
325    pair(_T1 const& __t1, _T2 const& __t2) : first(__t1), second(__t2) {}
326
327    template <class _U1, class _U2>
328    _LIBCPP_INLINE_VISIBILITY
329    pair(const pair<_U1, _U2>& __p) : first(__p.first), second(__p.second) {}
330
331    _LIBCPP_INLINE_VISIBILITY
332    pair& operator=(pair const& __p) {
333        first = __p.first;
334        second = __p.second;
335        return *this;
336    }
337#else
338    template <bool _Val>
339    using _EnableB _LIBCPP_NODEBUG_TYPE = typename enable_if<_Val, bool>::type;
340
341    struct _CheckArgs {
342      template <int&...>
343      static constexpr bool __enable_explicit_default() {
344          return is_default_constructible<_T1>::value
345              && is_default_constructible<_T2>::value
346              && !__enable_implicit_default<>();
347      }
348
349      template <int&...>
350      static constexpr bool __enable_implicit_default() {
351          return __is_implicitly_default_constructible<_T1>::value
352              && __is_implicitly_default_constructible<_T2>::value;
353      }
354
355      template <class _U1, class _U2>
356      static constexpr bool __enable_explicit() {
357          return is_constructible<first_type, _U1>::value
358              && is_constructible<second_type, _U2>::value
359              && (!is_convertible<_U1, first_type>::value
360                  || !is_convertible<_U2, second_type>::value);
361      }
362
363      template <class _U1, class _U2>
364      static constexpr bool __enable_implicit() {
365          return is_constructible<first_type, _U1>::value
366              && is_constructible<second_type, _U2>::value
367              && is_convertible<_U1, first_type>::value
368              && is_convertible<_U2, second_type>::value;
369      }
370    };
371
372    template <bool _MaybeEnable>
373    using _CheckArgsDep _LIBCPP_NODEBUG_TYPE = typename conditional<
374      _MaybeEnable, _CheckArgs, __check_tuple_constructor_fail>::type;
375
376    struct _CheckTupleLikeConstructor {
377        template <class _Tuple>
378        static constexpr bool __enable_implicit() {
379            return __tuple_convertible<_Tuple, pair>::value;
380        }
381
382        template <class _Tuple>
383        static constexpr bool __enable_explicit() {
384            return __tuple_constructible<_Tuple, pair>::value
385               && !__tuple_convertible<_Tuple, pair>::value;
386        }
387
388        template <class _Tuple>
389        static constexpr bool __enable_assign() {
390            return __tuple_assignable<_Tuple, pair>::value;
391        }
392    };
393
394    template <class _Tuple>
395    using _CheckTLC _LIBCPP_NODEBUG_TYPE = typename conditional<
396        __tuple_like_with_size<_Tuple, 2>::value
397            && !is_same<typename decay<_Tuple>::type, pair>::value,
398        _CheckTupleLikeConstructor,
399        __check_tuple_constructor_fail
400    >::type;
401
402    template<bool _Dummy = true, _EnableB<
403            _CheckArgsDep<_Dummy>::__enable_explicit_default()
404    > = false>
405    explicit _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
406    pair() _NOEXCEPT_(is_nothrow_default_constructible<first_type>::value &&
407                      is_nothrow_default_constructible<second_type>::value)
408        : first(), second() {}
409
410    template<bool _Dummy = true, _EnableB<
411            _CheckArgsDep<_Dummy>::__enable_implicit_default()
412    > = false>
413    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR
414    pair() _NOEXCEPT_(is_nothrow_default_constructible<first_type>::value &&
415                      is_nothrow_default_constructible<second_type>::value)
416        : first(), second() {}
417
418    template <bool _Dummy = true, _EnableB<
419             _CheckArgsDep<_Dummy>::template __enable_explicit<_T1 const&, _T2 const&>()
420    > = false>
421    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
422    explicit pair(_T1 const& __t1, _T2 const& __t2)
423        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
424                   is_nothrow_copy_constructible<second_type>::value)
425        : first(__t1), second(__t2) {}
426
427    template<bool _Dummy = true, _EnableB<
428            _CheckArgsDep<_Dummy>::template __enable_implicit<_T1 const&, _T2 const&>()
429    > = false>
430    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
431    pair(_T1 const& __t1, _T2 const& __t2)
432        _NOEXCEPT_(is_nothrow_copy_constructible<first_type>::value &&
433                   is_nothrow_copy_constructible<second_type>::value)
434        : first(__t1), second(__t2) {}
435
436    template<class _U1, class _U2, _EnableB<
437             _CheckArgs::template __enable_explicit<_U1, _U2>()
438    > = false>
439    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
440    explicit pair(_U1&& __u1, _U2&& __u2)
441        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1>::value &&
442                    is_nothrow_constructible<second_type, _U2>::value))
443        : first(_VSTD::forward<_U1>(__u1)), second(_VSTD::forward<_U2>(__u2)) {}
444
445    template<class _U1, class _U2, _EnableB<
446            _CheckArgs::template __enable_implicit<_U1, _U2>()
447    > = false>
448    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
449    pair(_U1&& __u1, _U2&& __u2)
450        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1>::value &&
451                    is_nothrow_constructible<second_type, _U2>::value))
452        : first(_VSTD::forward<_U1>(__u1)), second(_VSTD::forward<_U2>(__u2)) {}
453
454    template<class _U1, class _U2, _EnableB<
455            _CheckArgs::template __enable_explicit<_U1 const&, _U2 const&>()
456    > = false>
457    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
458    explicit pair(pair<_U1, _U2> const& __p)
459        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1 const&>::value &&
460                    is_nothrow_constructible<second_type, _U2 const&>::value))
461        : first(__p.first), second(__p.second) {}
462
463    template<class _U1, class _U2, _EnableB<
464            _CheckArgs::template __enable_implicit<_U1 const&, _U2 const&>()
465    > = false>
466    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
467    pair(pair<_U1, _U2> const& __p)
468        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1 const&>::value &&
469                    is_nothrow_constructible<second_type, _U2 const&>::value))
470        : first(__p.first), second(__p.second) {}
471
472    template<class _U1, class _U2, _EnableB<
473            _CheckArgs::template __enable_explicit<_U1, _U2>()
474    > = false>
475    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
476    explicit pair(pair<_U1, _U2>&&__p)
477        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1&&>::value &&
478                    is_nothrow_constructible<second_type, _U2&&>::value))
479        : first(_VSTD::forward<_U1>(__p.first)), second(_VSTD::forward<_U2>(__p.second)) {}
480
481    template<class _U1, class _U2, _EnableB<
482            _CheckArgs::template __enable_implicit<_U1, _U2>()
483    > = false>
484    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
485    pair(pair<_U1, _U2>&& __p)
486        _NOEXCEPT_((is_nothrow_constructible<first_type, _U1&&>::value &&
487                    is_nothrow_constructible<second_type, _U2&&>::value))
488        : first(_VSTD::forward<_U1>(__p.first)), second(_VSTD::forward<_U2>(__p.second)) {}
489
490    template<class _Tuple, _EnableB<
491            _CheckTLC<_Tuple>::template __enable_explicit<_Tuple>()
492    > = false>
493    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
494    explicit pair(_Tuple&& __p)
495        : first(_VSTD::get<0>(_VSTD::forward<_Tuple>(__p))),
496          second(_VSTD::get<1>(_VSTD::forward<_Tuple>(__p))) {}
497
498    template<class _Tuple, _EnableB<
499            _CheckTLC<_Tuple>::template __enable_implicit<_Tuple>()
500    > = false>
501    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
502    pair(_Tuple&& __p)
503        : first(_VSTD::get<0>(_VSTD::forward<_Tuple>(__p))),
504          second(_VSTD::get<1>(_VSTD::forward<_Tuple>(__p))) {}
505
506    template <class... _Args1, class... _Args2>
507    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
508    pair(piecewise_construct_t __pc,
509         tuple<_Args1...> __first_args, tuple<_Args2...> __second_args)
510        _NOEXCEPT_((is_nothrow_constructible<first_type, _Args1...>::value &&
511                    is_nothrow_constructible<second_type, _Args2...>::value))
512        : pair(__pc, __first_args, __second_args,
513                typename __make_tuple_indices<sizeof...(_Args1)>::type(),
514                typename __make_tuple_indices<sizeof...(_Args2) >::type()) {}
515
516    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
517    pair& operator=(typename conditional<
518                        is_copy_assignable<first_type>::value &&
519                        is_copy_assignable<second_type>::value,
520                    pair, __nat>::type const& __p)
521        _NOEXCEPT_(is_nothrow_copy_assignable<first_type>::value &&
522                   is_nothrow_copy_assignable<second_type>::value)
523    {
524        first = __p.first;
525        second = __p.second;
526        return *this;
527    }
528
529    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
530    pair& operator=(typename conditional<
531                        is_move_assignable<first_type>::value &&
532                        is_move_assignable<second_type>::value,
533                    pair, __nat>::type&& __p)
534        _NOEXCEPT_(is_nothrow_move_assignable<first_type>::value &&
535                   is_nothrow_move_assignable<second_type>::value)
536    {
537        first = _VSTD::forward<first_type>(__p.first);
538        second = _VSTD::forward<second_type>(__p.second);
539        return *this;
540    }
541
542    template <class _Tuple, _EnableB<
543            _CheckTLC<_Tuple>::template __enable_assign<_Tuple>()
544     > = false>
545    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
546    pair& operator=(_Tuple&& __p) {
547        first = _VSTD::get<0>(_VSTD::forward<_Tuple>(__p));
548        second = _VSTD::get<1>(_VSTD::forward<_Tuple>(__p));
549        return *this;
550    }
551#endif
552
553    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
554    void
555    swap(pair& __p) _NOEXCEPT_(__is_nothrow_swappable<first_type>::value &&
556                               __is_nothrow_swappable<second_type>::value)
557    {
558        using _VSTD::swap;
559        swap(first,  __p.first);
560        swap(second, __p.second);
561    }
562private:
563
564#ifndef _LIBCPP_CXX03_LANG
565    template <class... _Args1, class... _Args2, size_t... _I1, size_t... _I2>
566    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
567    pair(piecewise_construct_t,
568         tuple<_Args1...>& __first_args, tuple<_Args2...>& __second_args,
569         __tuple_indices<_I1...>, __tuple_indices<_I2...>);
570#endif
571};
572
573#ifndef _LIBCPP_HAS_NO_DEDUCTION_GUIDES
574template<class _T1, class _T2>
575pair(_T1, _T2) -> pair<_T1, _T2>;
576#endif // _LIBCPP_HAS_NO_DEDUCTION_GUIDES
577
578template <class _T1, class _T2>
579inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
580bool
581operator==(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
582{
583    return __x.first == __y.first && __x.second == __y.second;
584}
585
586template <class _T1, class _T2>
587inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
588bool
589operator!=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
590{
591    return !(__x == __y);
592}
593
594template <class _T1, class _T2>
595inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
596bool
597operator< (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
598{
599    return __x.first < __y.first || (!(__y.first < __x.first) && __x.second < __y.second);
600}
601
602template <class _T1, class _T2>
603inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
604bool
605operator> (const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
606{
607    return __y < __x;
608}
609
610template <class _T1, class _T2>
611inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
612bool
613operator>=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
614{
615    return !(__x < __y);
616}
617
618template <class _T1, class _T2>
619inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
620bool
621operator<=(const pair<_T1,_T2>& __x, const pair<_T1,_T2>& __y)
622{
623    return !(__y < __x);
624}
625
626template <class _T1, class _T2>
627inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
628typename enable_if
629<
630    __is_swappable<_T1>::value &&
631    __is_swappable<_T2>::value,
632    void
633>::type
634swap(pair<_T1, _T2>& __x, pair<_T1, _T2>& __y)
635                     _NOEXCEPT_((__is_nothrow_swappable<_T1>::value &&
636                                 __is_nothrow_swappable<_T2>::value))
637{
638    __x.swap(__y);
639}
640
641template <class _Tp>
642struct __unwrap_reference { typedef _LIBCPP_NODEBUG_TYPE _Tp type; };
643
644template <class _Tp>
645struct __unwrap_reference<reference_wrapper<_Tp> > { typedef _LIBCPP_NODEBUG_TYPE _Tp& type; };
646
647#if _LIBCPP_STD_VER > 17
648template <class _Tp>
649struct unwrap_reference : __unwrap_reference<_Tp> { };
650
651template <class _Tp>
652struct unwrap_ref_decay : unwrap_reference<typename decay<_Tp>::type> { };
653#endif // > C++17
654
655template <class _Tp>
656struct __unwrap_ref_decay
657#if _LIBCPP_STD_VER > 17
658    : unwrap_ref_decay<_Tp>
659#else
660    : __unwrap_reference<typename decay<_Tp>::type>
661#endif
662{ };
663
664#ifndef _LIBCPP_CXX03_LANG
665
666template <class _T1, class _T2>
667inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
668pair<typename __unwrap_ref_decay<_T1>::type, typename __unwrap_ref_decay<_T2>::type>
669make_pair(_T1&& __t1, _T2&& __t2)
670{
671    return pair<typename __unwrap_ref_decay<_T1>::type, typename __unwrap_ref_decay<_T2>::type>
672               (_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
673}
674
675#else  // _LIBCPP_CXX03_LANG
676
677template <class _T1, class _T2>
678inline _LIBCPP_INLINE_VISIBILITY
679pair<_T1,_T2>
680make_pair(_T1 __x, _T2 __y)
681{
682    return pair<_T1, _T2>(__x, __y);
683}
684
685#endif  // _LIBCPP_CXX03_LANG
686
687template <class _T1, class _T2>
688  struct _LIBCPP_TEMPLATE_VIS tuple_size<pair<_T1, _T2> >
689    : public integral_constant<size_t, 2> {};
690
691template <size_t _Ip, class _T1, class _T2>
692struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, pair<_T1, _T2> >
693{
694    static_assert(_Ip < 2, "Index out of bounds in std::tuple_element<std::pair<T1, T2>>");
695};
696
697template <class _T1, class _T2>
698struct _LIBCPP_TEMPLATE_VIS tuple_element<0, pair<_T1, _T2> >
699{
700    typedef _LIBCPP_NODEBUG_TYPE _T1 type;
701};
702
703template <class _T1, class _T2>
704struct _LIBCPP_TEMPLATE_VIS tuple_element<1, pair<_T1, _T2> >
705{
706    typedef _LIBCPP_NODEBUG_TYPE _T2 type;
707};
708
709template <size_t _Ip> struct __get_pair;
710
711template <>
712struct __get_pair<0>
713{
714    template <class _T1, class _T2>
715    static
716    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
717    _T1&
718    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
719
720    template <class _T1, class _T2>
721    static
722    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
723    const _T1&
724    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.first;}
725
726#ifndef _LIBCPP_CXX03_LANG
727    template <class _T1, class _T2>
728    static
729    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
730    _T1&&
731    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T1>(__p.first);}
732
733    template <class _T1, class _T2>
734    static
735    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
736    const _T1&&
737    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T1>(__p.first);}
738#endif  // _LIBCPP_CXX03_LANG
739};
740
741template <>
742struct __get_pair<1>
743{
744    template <class _T1, class _T2>
745    static
746    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
747    _T2&
748    get(pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
749
750    template <class _T1, class _T2>
751    static
752    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
753    const _T2&
754    get(const pair<_T1, _T2>& __p) _NOEXCEPT {return __p.second;}
755
756#ifndef _LIBCPP_CXX03_LANG
757    template <class _T1, class _T2>
758    static
759    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
760    _T2&&
761    get(pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<_T2>(__p.second);}
762
763    template <class _T1, class _T2>
764    static
765    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
766    const _T2&&
767    get(const pair<_T1, _T2>&& __p) _NOEXCEPT {return _VSTD::forward<const _T2>(__p.second);}
768#endif  // _LIBCPP_CXX03_LANG
769};
770
771template <size_t _Ip, class _T1, class _T2>
772inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
773typename tuple_element<_Ip, pair<_T1, _T2> >::type&
774get(pair<_T1, _T2>& __p) _NOEXCEPT
775{
776    return __get_pair<_Ip>::get(__p);
777}
778
779template <size_t _Ip, class _T1, class _T2>
780inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
781const typename tuple_element<_Ip, pair<_T1, _T2> >::type&
782get(const pair<_T1, _T2>& __p) _NOEXCEPT
783{
784    return __get_pair<_Ip>::get(__p);
785}
786
787#ifndef _LIBCPP_CXX03_LANG
788template <size_t _Ip, class _T1, class _T2>
789inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
790typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
791get(pair<_T1, _T2>&& __p) _NOEXCEPT
792{
793    return __get_pair<_Ip>::get(_VSTD::move(__p));
794}
795
796template <size_t _Ip, class _T1, class _T2>
797inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
798const typename tuple_element<_Ip, pair<_T1, _T2> >::type&&
799get(const pair<_T1, _T2>&& __p) _NOEXCEPT
800{
801    return __get_pair<_Ip>::get(_VSTD::move(__p));
802}
803#endif  // _LIBCPP_CXX03_LANG
804
805#if _LIBCPP_STD_VER > 11
806template <class _T1, class _T2>
807inline _LIBCPP_INLINE_VISIBILITY
808constexpr _T1 & get(pair<_T1, _T2>& __p) _NOEXCEPT
809{
810    return __get_pair<0>::get(__p);
811}
812
813template <class _T1, class _T2>
814inline _LIBCPP_INLINE_VISIBILITY
815constexpr _T1 const & get(pair<_T1, _T2> const& __p) _NOEXCEPT
816{
817    return __get_pair<0>::get(__p);
818}
819
820template <class _T1, class _T2>
821inline _LIBCPP_INLINE_VISIBILITY
822constexpr _T1 && get(pair<_T1, _T2>&& __p) _NOEXCEPT
823{
824    return __get_pair<0>::get(_VSTD::move(__p));
825}
826
827template <class _T1, class _T2>
828inline _LIBCPP_INLINE_VISIBILITY
829constexpr _T1 const && get(pair<_T1, _T2> const&& __p) _NOEXCEPT
830{
831    return __get_pair<0>::get(_VSTD::move(__p));
832}
833
834template <class _T1, class _T2>
835inline _LIBCPP_INLINE_VISIBILITY
836constexpr _T1 & get(pair<_T2, _T1>& __p) _NOEXCEPT
837{
838    return __get_pair<1>::get(__p);
839}
840
841template <class _T1, class _T2>
842inline _LIBCPP_INLINE_VISIBILITY
843constexpr _T1 const & get(pair<_T2, _T1> const& __p) _NOEXCEPT
844{
845    return __get_pair<1>::get(__p);
846}
847
848template <class _T1, class _T2>
849inline _LIBCPP_INLINE_VISIBILITY
850constexpr _T1 && get(pair<_T2, _T1>&& __p) _NOEXCEPT
851{
852    return __get_pair<1>::get(_VSTD::move(__p));
853}
854
855template <class _T1, class _T2>
856inline _LIBCPP_INLINE_VISIBILITY
857constexpr _T1 const && get(pair<_T2, _T1> const&& __p) _NOEXCEPT
858{
859    return __get_pair<1>::get(_VSTD::move(__p));
860}
861
862#endif
863
864#if _LIBCPP_STD_VER > 11
865
866template<class _Tp, _Tp... _Ip>
867struct _LIBCPP_TEMPLATE_VIS integer_sequence
868{
869    typedef _Tp value_type;
870    static_assert( is_integral<_Tp>::value,
871                  "std::integer_sequence can only be instantiated with an integral type" );
872    static
873    _LIBCPP_INLINE_VISIBILITY
874    constexpr
875    size_t
876    size() noexcept { return sizeof...(_Ip); }
877};
878
879template<size_t... _Ip>
880    using index_sequence = integer_sequence<size_t, _Ip...>;
881
882#if __has_builtin(__make_integer_seq) && !defined(_LIBCPP_TESTING_FALLBACK_MAKE_INTEGER_SEQUENCE)
883
884template <class _Tp, _Tp _Ep>
885using __make_integer_sequence _LIBCPP_NODEBUG_TYPE = __make_integer_seq<integer_sequence, _Tp, _Ep>;
886
887#else
888
889template<typename _Tp, _Tp _Np> using __make_integer_sequence_unchecked _LIBCPP_NODEBUG_TYPE  =
890  typename __detail::__make<_Np>::type::template __convert<integer_sequence, _Tp>;
891
892template <class _Tp, _Tp _Ep>
893struct __make_integer_sequence_checked
894{
895    static_assert(is_integral<_Tp>::value,
896                  "std::make_integer_sequence can only be instantiated with an integral type" );
897    static_assert(0 <= _Ep, "std::make_integer_sequence must have a non-negative sequence length");
898    // Workaround GCC bug by preventing bad installations when 0 <= _Ep
899    // https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68929
900    typedef _LIBCPP_NODEBUG_TYPE  __make_integer_sequence_unchecked<_Tp, 0 <= _Ep ? _Ep : 0> type;
901};
902
903template <class _Tp, _Tp _Ep>
904using __make_integer_sequence _LIBCPP_NODEBUG_TYPE = typename __make_integer_sequence_checked<_Tp, _Ep>::type;
905
906#endif
907
908template<class _Tp, _Tp _Np>
909    using make_integer_sequence = __make_integer_sequence<_Tp, _Np>;
910
911template<size_t _Np>
912    using make_index_sequence = make_integer_sequence<size_t, _Np>;
913
914template<class... _Tp>
915    using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
916
917#endif  // _LIBCPP_STD_VER > 11
918
919#if _LIBCPP_STD_VER > 11
920template<class _T1, class _T2 = _T1>
921inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
922_T1 exchange(_T1& __obj, _T2 && __new_value)
923{
924    _T1 __old_value = _VSTD::move(__obj);
925    __obj = _VSTD::forward<_T2>(__new_value);
926    return __old_value;
927}
928#endif  // _LIBCPP_STD_VER > 11
929
930#if _LIBCPP_STD_VER > 14
931
932struct _LIBCPP_TYPE_VIS in_place_t {
933    explicit in_place_t() = default;
934};
935_LIBCPP_INLINE_VAR constexpr in_place_t in_place{};
936
937template <class _Tp>
938struct _LIBCPP_TEMPLATE_VIS in_place_type_t {
939    explicit in_place_type_t() = default;
940};
941template <class _Tp>
942_LIBCPP_INLINE_VAR constexpr in_place_type_t<_Tp> in_place_type{};
943
944template <size_t _Idx>
945struct _LIBCPP_TEMPLATE_VIS in_place_index_t {
946    explicit in_place_index_t() = default;
947};
948template <size_t _Idx>
949_LIBCPP_INLINE_VAR constexpr in_place_index_t<_Idx> in_place_index{};
950
951template <class _Tp> struct __is_inplace_type_imp : false_type {};
952template <class _Tp> struct __is_inplace_type_imp<in_place_type_t<_Tp>> : true_type {};
953
954template <class _Tp>
955using __is_inplace_type = __is_inplace_type_imp<__uncvref_t<_Tp>>;
956
957template <class _Tp> struct __is_inplace_index_imp : false_type {};
958template <size_t _Idx> struct __is_inplace_index_imp<in_place_index_t<_Idx>> : true_type {};
959
960template <class _Tp>
961using __is_inplace_index = __is_inplace_index_imp<__uncvref_t<_Tp>>;
962
963#endif // _LIBCPP_STD_VER > 14
964
965template <class _Arg, class _Result>
966struct _LIBCPP_TEMPLATE_VIS unary_function
967{
968    typedef _Arg    argument_type;
969    typedef _Result result_type;
970};
971
972template <class _Size>
973inline _LIBCPP_INLINE_VISIBILITY
974_Size
975__loadword(const void* __p)
976{
977    _Size __r;
978    _VSTD::memcpy(&__r, __p, sizeof(__r));
979    return __r;
980}
981
982// We use murmur2 when size_t is 32 bits, and cityhash64 when size_t
983// is 64 bits.  This is because cityhash64 uses 64bit x 64bit
984// multiplication, which can be very slow on 32-bit systems.
985template <class _Size, size_t = sizeof(_Size)*__CHAR_BIT__>
986struct __murmur2_or_cityhash;
987
988template <class _Size>
989struct __murmur2_or_cityhash<_Size, 32>
990{
991    inline _Size operator()(const void* __key, _Size __len)
992         _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK;
993};
994
995// murmur2
996template <class _Size>
997_Size
998__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len)
999{
1000    const _Size __m = 0x5bd1e995;
1001    const _Size __r = 24;
1002    _Size __h = __len;
1003    const unsigned char* __data = static_cast<const unsigned char*>(__key);
1004    for (; __len >= 4; __data += 4, __len -= 4)
1005    {
1006        _Size __k = __loadword<_Size>(__data);
1007        __k *= __m;
1008        __k ^= __k >> __r;
1009        __k *= __m;
1010        __h *= __m;
1011        __h ^= __k;
1012    }
1013    switch (__len)
1014    {
1015    case 3:
1016        __h ^= __data[2] << 16;
1017        _LIBCPP_FALLTHROUGH();
1018    case 2:
1019        __h ^= __data[1] << 8;
1020        _LIBCPP_FALLTHROUGH();
1021    case 1:
1022        __h ^= __data[0];
1023        __h *= __m;
1024    }
1025    __h ^= __h >> 13;
1026    __h *= __m;
1027    __h ^= __h >> 15;
1028    return __h;
1029}
1030
1031template <class _Size>
1032struct __murmur2_or_cityhash<_Size, 64>
1033{
1034    inline _Size operator()(const void* __key, _Size __len)  _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK;
1035
1036 private:
1037  // Some primes between 2^63 and 2^64.
1038  static const _Size __k0 = 0xc3a5c85c97cb3127ULL;
1039  static const _Size __k1 = 0xb492b66fbe98f273ULL;
1040  static const _Size __k2 = 0x9ae16a3b2f90404fULL;
1041  static const _Size __k3 = 0xc949d7c7509e6557ULL;
1042
1043  static _Size __rotate(_Size __val, int __shift) {
1044    return __shift == 0 ? __val : ((__val >> __shift) | (__val << (64 - __shift)));
1045  }
1046
1047  static _Size __rotate_by_at_least_1(_Size __val, int __shift) {
1048    return (__val >> __shift) | (__val << (64 - __shift));
1049  }
1050
1051  static _Size __shift_mix(_Size __val) {
1052    return __val ^ (__val >> 47);
1053  }
1054
1055  static _Size __hash_len_16(_Size __u, _Size __v)
1056     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1057  {
1058    const _Size __mul = 0x9ddfea08eb382d69ULL;
1059    _Size __a = (__u ^ __v) * __mul;
1060    __a ^= (__a >> 47);
1061    _Size __b = (__v ^ __a) * __mul;
1062    __b ^= (__b >> 47);
1063    __b *= __mul;
1064    return __b;
1065  }
1066
1067  static _Size __hash_len_0_to_16(const char* __s, _Size __len)
1068     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1069  {
1070    if (__len > 8) {
1071      const _Size __a = __loadword<_Size>(__s);
1072      const _Size __b = __loadword<_Size>(__s + __len - 8);
1073      return __hash_len_16(__a, __rotate_by_at_least_1(__b + __len, __len)) ^ __b;
1074    }
1075    if (__len >= 4) {
1076      const uint32_t __a = __loadword<uint32_t>(__s);
1077      const uint32_t __b = __loadword<uint32_t>(__s + __len - 4);
1078      return __hash_len_16(__len + (__a << 3), __b);
1079    }
1080    if (__len > 0) {
1081      const unsigned char __a = __s[0];
1082      const unsigned char __b = __s[__len >> 1];
1083      const unsigned char __c = __s[__len - 1];
1084      const uint32_t __y = static_cast<uint32_t>(__a) +
1085                           (static_cast<uint32_t>(__b) << 8);
1086      const uint32_t __z = __len + (static_cast<uint32_t>(__c) << 2);
1087      return __shift_mix(__y * __k2 ^ __z * __k3) * __k2;
1088    }
1089    return __k2;
1090  }
1091
1092  static _Size __hash_len_17_to_32(const char *__s, _Size __len)
1093     _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1094  {
1095    const _Size __a = __loadword<_Size>(__s) * __k1;
1096    const _Size __b = __loadword<_Size>(__s + 8);
1097    const _Size __c = __loadword<_Size>(__s + __len - 8) * __k2;
1098    const _Size __d = __loadword<_Size>(__s + __len - 16) * __k0;
1099    return __hash_len_16(__rotate(__a - __b, 43) + __rotate(__c, 30) + __d,
1100                         __a + __rotate(__b ^ __k3, 20) - __c + __len);
1101  }
1102
1103  // Return a 16-byte hash for 48 bytes.  Quick and dirty.
1104  // Callers do best to use "random-looking" values for a and b.
1105  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
1106      _Size __w, _Size __x, _Size __y, _Size __z, _Size __a, _Size __b)
1107        _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1108  {
1109    __a += __w;
1110    __b = __rotate(__b + __a + __z, 21);
1111    const _Size __c = __a;
1112    __a += __x;
1113    __a += __y;
1114    __b += __rotate(__a, 44);
1115    return pair<_Size, _Size>(__a + __z, __b + __c);
1116  }
1117
1118  // Return a 16-byte hash for s[0] ... s[31], a, and b.  Quick and dirty.
1119  static pair<_Size, _Size> __weak_hash_len_32_with_seeds(
1120      const char* __s, _Size __a, _Size __b)
1121    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1122  {
1123    return __weak_hash_len_32_with_seeds(__loadword<_Size>(__s),
1124                                         __loadword<_Size>(__s + 8),
1125                                         __loadword<_Size>(__s + 16),
1126                                         __loadword<_Size>(__s + 24),
1127                                         __a,
1128                                         __b);
1129  }
1130
1131  // Return an 8-byte hash for 33 to 64 bytes.
1132  static _Size __hash_len_33_to_64(const char *__s, size_t __len)
1133    _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
1134  {
1135    _Size __z = __loadword<_Size>(__s + 24);
1136    _Size __a = __loadword<_Size>(__s) +
1137                (__len + __loadword<_Size>(__s + __len - 16)) * __k0;
1138    _Size __b = __rotate(__a + __z, 52);
1139    _Size __c = __rotate(__a, 37);
1140    __a += __loadword<_Size>(__s + 8);
1141    __c += __rotate(__a, 7);
1142    __a += __loadword<_Size>(__s + 16);
1143    _Size __vf = __a + __z;
1144    _Size __vs = __b + __rotate(__a, 31) + __c;
1145    __a = __loadword<_Size>(__s + 16) + __loadword<_Size>(__s + __len - 32);
1146    __z += __loadword<_Size>(__s + __len - 8);
1147    __b = __rotate(__a + __z, 52);
1148    __c = __rotate(__a, 37);
1149    __a += __loadword<_Size>(__s + __len - 24);
1150    __c += __rotate(__a, 7);
1151    __a += __loadword<_Size>(__s + __len - 16);
1152    _Size __wf = __a + __z;
1153    _Size __ws = __b + __rotate(__a, 31) + __c;
1154    _Size __r = __shift_mix((__vf + __ws) * __k2 + (__wf + __vs) * __k0);
1155    return __shift_mix(__r * __k0 + __vs) * __k2;
1156  }
1157};
1158
1159// cityhash64
1160template <class _Size>
1161_Size
1162__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
1163{
1164  const char* __s = static_cast<const char*>(__key);
1165  if (__len <= 32) {
1166    if (__len <= 16) {
1167      return __hash_len_0_to_16(__s, __len);
1168    } else {
1169      return __hash_len_17_to_32(__s, __len);
1170    }
1171  } else if (__len <= 64) {
1172    return __hash_len_33_to_64(__s, __len);
1173  }
1174
1175  // For strings over 64 bytes we hash the end first, and then as we
1176  // loop we keep 56 bytes of state: v, w, x, y, and z.
1177  _Size __x = __loadword<_Size>(__s + __len - 40);
1178  _Size __y = __loadword<_Size>(__s + __len - 16) +
1179              __loadword<_Size>(__s + __len - 56);
1180  _Size __z = __hash_len_16(__loadword<_Size>(__s + __len - 48) + __len,
1181                          __loadword<_Size>(__s + __len - 24));
1182  pair<_Size, _Size> __v = __weak_hash_len_32_with_seeds(__s + __len - 64, __len, __z);
1183  pair<_Size, _Size> __w = __weak_hash_len_32_with_seeds(__s + __len - 32, __y + __k1, __x);
1184  __x = __x * __k1 + __loadword<_Size>(__s);
1185
1186  // Decrease len to the nearest multiple of 64, and operate on 64-byte chunks.
1187  __len = (__len - 1) & ~static_cast<_Size>(63);
1188  do {
1189    __x = __rotate(__x + __y + __v.first + __loadword<_Size>(__s + 8), 37) * __k1;
1190    __y = __rotate(__y + __v.second + __loadword<_Size>(__s + 48), 42) * __k1;
1191    __x ^= __w.second;
1192    __y += __v.first + __loadword<_Size>(__s + 40);
1193    __z = __rotate(__z + __w.first, 33) * __k1;
1194    __v = __weak_hash_len_32_with_seeds(__s, __v.second * __k1, __x + __w.first);
1195    __w = __weak_hash_len_32_with_seeds(__s + 32, __z + __w.second,
1196                                        __y + __loadword<_Size>(__s + 16));
1197    _VSTD::swap(__z, __x);
1198    __s += 64;
1199    __len -= 64;
1200  } while (__len != 0);
1201  return __hash_len_16(
1202      __hash_len_16(__v.first, __w.first) + __shift_mix(__y) * __k1 + __z,
1203      __hash_len_16(__v.second, __w.second) + __x);
1204}
1205
1206template <class _Tp, size_t = sizeof(_Tp) / sizeof(size_t)>
1207struct __scalar_hash;
1208
1209template <class _Tp>
1210struct __scalar_hash<_Tp, 0>
1211    : public unary_function<_Tp, size_t>
1212{
1213    _LIBCPP_INLINE_VISIBILITY
1214    size_t operator()(_Tp __v) const _NOEXCEPT
1215    {
1216        union
1217        {
1218            _Tp    __t;
1219            size_t __a;
1220        } __u;
1221        __u.__a = 0;
1222        __u.__t = __v;
1223        return __u.__a;
1224    }
1225};
1226
1227template <class _Tp>
1228struct __scalar_hash<_Tp, 1>
1229    : public unary_function<_Tp, size_t>
1230{
1231    _LIBCPP_INLINE_VISIBILITY
1232    size_t operator()(_Tp __v) const _NOEXCEPT
1233    {
1234        union
1235        {
1236            _Tp    __t;
1237            size_t __a;
1238        } __u;
1239        __u.__t = __v;
1240        return __u.__a;
1241    }
1242};
1243
1244template <class _Tp>
1245struct __scalar_hash<_Tp, 2>
1246    : public unary_function<_Tp, size_t>
1247{
1248    _LIBCPP_INLINE_VISIBILITY
1249    size_t operator()(_Tp __v) const _NOEXCEPT
1250    {
1251        union
1252        {
1253            _Tp __t;
1254            struct
1255            {
1256                size_t __a;
1257                size_t __b;
1258            } __s;
1259        } __u;
1260        __u.__t = __v;
1261        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1262    }
1263};
1264
1265template <class _Tp>
1266struct __scalar_hash<_Tp, 3>
1267    : public unary_function<_Tp, size_t>
1268{
1269    _LIBCPP_INLINE_VISIBILITY
1270    size_t operator()(_Tp __v) const _NOEXCEPT
1271    {
1272        union
1273        {
1274            _Tp __t;
1275            struct
1276            {
1277                size_t __a;
1278                size_t __b;
1279                size_t __c;
1280            } __s;
1281        } __u;
1282        __u.__t = __v;
1283        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1284    }
1285};
1286
1287template <class _Tp>
1288struct __scalar_hash<_Tp, 4>
1289    : public unary_function<_Tp, size_t>
1290{
1291    _LIBCPP_INLINE_VISIBILITY
1292    size_t operator()(_Tp __v) const _NOEXCEPT
1293    {
1294        union
1295        {
1296            _Tp __t;
1297            struct
1298            {
1299                size_t __a;
1300                size_t __b;
1301                size_t __c;
1302                size_t __d;
1303            } __s;
1304        } __u;
1305        __u.__t = __v;
1306        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1307    }
1308};
1309
1310struct _PairT {
1311  size_t first;
1312  size_t second;
1313};
1314
1315_LIBCPP_INLINE_VISIBILITY
1316inline size_t __hash_combine(size_t __lhs, size_t __rhs) _NOEXCEPT {
1317    typedef __scalar_hash<_PairT> _HashT;
1318    const _PairT __p = {__lhs, __rhs};
1319    return _HashT()(__p);
1320}
1321
1322template<class _Tp>
1323struct _LIBCPP_TEMPLATE_VIS hash<_Tp*>
1324    : public unary_function<_Tp*, size_t>
1325{
1326    _LIBCPP_INLINE_VISIBILITY
1327    size_t operator()(_Tp* __v) const _NOEXCEPT
1328    {
1329        union
1330        {
1331            _Tp* __t;
1332            size_t __a;
1333        } __u;
1334        __u.__t = __v;
1335        return __murmur2_or_cityhash<size_t>()(&__u, sizeof(__u));
1336    }
1337};
1338
1339
1340template <>
1341struct _LIBCPP_TEMPLATE_VIS hash<bool>
1342    : public unary_function<bool, size_t>
1343{
1344    _LIBCPP_INLINE_VISIBILITY
1345    size_t operator()(bool __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1346};
1347
1348template <>
1349struct _LIBCPP_TEMPLATE_VIS hash<char>
1350    : public unary_function<char, size_t>
1351{
1352    _LIBCPP_INLINE_VISIBILITY
1353    size_t operator()(char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1354};
1355
1356template <>
1357struct _LIBCPP_TEMPLATE_VIS hash<signed char>
1358    : public unary_function<signed char, size_t>
1359{
1360    _LIBCPP_INLINE_VISIBILITY
1361    size_t operator()(signed char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1362};
1363
1364template <>
1365struct _LIBCPP_TEMPLATE_VIS hash<unsigned char>
1366    : public unary_function<unsigned char, size_t>
1367{
1368    _LIBCPP_INLINE_VISIBILITY
1369    size_t operator()(unsigned char __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1370};
1371
1372#ifndef _LIBCPP_NO_HAS_CHAR8_T
1373template <>
1374struct _LIBCPP_TEMPLATE_VIS hash<char8_t>
1375    : public unary_function<char8_t, size_t>
1376{
1377    _LIBCPP_INLINE_VISIBILITY
1378    size_t operator()(char8_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1379};
1380#endif // !_LIBCPP_NO_HAS_CHAR8_T
1381
1382#ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
1383
1384template <>
1385struct _LIBCPP_TEMPLATE_VIS hash<char16_t>
1386    : public unary_function<char16_t, size_t>
1387{
1388    _LIBCPP_INLINE_VISIBILITY
1389    size_t operator()(char16_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1390};
1391
1392template <>
1393struct _LIBCPP_TEMPLATE_VIS hash<char32_t>
1394    : public unary_function<char32_t, size_t>
1395{
1396    _LIBCPP_INLINE_VISIBILITY
1397    size_t operator()(char32_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1398};
1399
1400#endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
1401
1402template <>
1403struct _LIBCPP_TEMPLATE_VIS hash<wchar_t>
1404    : public unary_function<wchar_t, size_t>
1405{
1406    _LIBCPP_INLINE_VISIBILITY
1407    size_t operator()(wchar_t __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1408};
1409
1410template <>
1411struct _LIBCPP_TEMPLATE_VIS hash<short>
1412    : public unary_function<short, size_t>
1413{
1414    _LIBCPP_INLINE_VISIBILITY
1415    size_t operator()(short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1416};
1417
1418template <>
1419struct _LIBCPP_TEMPLATE_VIS hash<unsigned short>
1420    : public unary_function<unsigned short, size_t>
1421{
1422    _LIBCPP_INLINE_VISIBILITY
1423    size_t operator()(unsigned short __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1424};
1425
1426template <>
1427struct _LIBCPP_TEMPLATE_VIS hash<int>
1428    : public unary_function<int, size_t>
1429{
1430    _LIBCPP_INLINE_VISIBILITY
1431    size_t operator()(int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1432};
1433
1434template <>
1435struct _LIBCPP_TEMPLATE_VIS hash<unsigned int>
1436    : public unary_function<unsigned int, size_t>
1437{
1438    _LIBCPP_INLINE_VISIBILITY
1439    size_t operator()(unsigned int __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1440};
1441
1442template <>
1443struct _LIBCPP_TEMPLATE_VIS hash<long>
1444    : public unary_function<long, size_t>
1445{
1446    _LIBCPP_INLINE_VISIBILITY
1447    size_t operator()(long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1448};
1449
1450template <>
1451struct _LIBCPP_TEMPLATE_VIS hash<unsigned long>
1452    : public unary_function<unsigned long, size_t>
1453{
1454    _LIBCPP_INLINE_VISIBILITY
1455    size_t operator()(unsigned long __v) const _NOEXCEPT {return static_cast<size_t>(__v);}
1456};
1457
1458template <>
1459struct _LIBCPP_TEMPLATE_VIS hash<long long>
1460    : public __scalar_hash<long long>
1461{
1462};
1463
1464template <>
1465struct _LIBCPP_TEMPLATE_VIS hash<unsigned long long>
1466    : public __scalar_hash<unsigned long long>
1467{
1468};
1469
1470#ifndef _LIBCPP_HAS_NO_INT128
1471
1472template <>
1473struct _LIBCPP_TEMPLATE_VIS hash<__int128_t>
1474    : public __scalar_hash<__int128_t>
1475{
1476};
1477
1478template <>
1479struct _LIBCPP_TEMPLATE_VIS hash<__uint128_t>
1480    : public __scalar_hash<__uint128_t>
1481{
1482};
1483
1484#endif
1485
1486template <>
1487struct _LIBCPP_TEMPLATE_VIS hash<float>
1488    : public __scalar_hash<float>
1489{
1490    _LIBCPP_INLINE_VISIBILITY
1491    size_t operator()(float __v) const _NOEXCEPT
1492    {
1493        // -0.0 and 0.0 should return same hash
1494       if (__v == 0.0f)
1495           return 0;
1496        return __scalar_hash<float>::operator()(__v);
1497    }
1498};
1499
1500template <>
1501struct _LIBCPP_TEMPLATE_VIS hash<double>
1502    : public __scalar_hash<double>
1503{
1504    _LIBCPP_INLINE_VISIBILITY
1505    size_t operator()(double __v) const _NOEXCEPT
1506    {
1507        // -0.0 and 0.0 should return same hash
1508       if (__v == 0.0)
1509           return 0;
1510        return __scalar_hash<double>::operator()(__v);
1511    }
1512};
1513
1514template <>
1515struct _LIBCPP_TEMPLATE_VIS hash<long double>
1516    : public __scalar_hash<long double>
1517{
1518    _LIBCPP_INLINE_VISIBILITY
1519    size_t operator()(long double __v) const _NOEXCEPT
1520    {
1521        // -0.0 and 0.0 should return same hash
1522        if (__v == 0.0L)
1523            return 0;
1524#if defined(__i386__) || (defined(__x86_64__) && defined(__ILP32__))
1525        // Zero out padding bits
1526        union
1527        {
1528            long double __t;
1529            struct
1530            {
1531                size_t __a;
1532                size_t __b;
1533                size_t __c;
1534                size_t __d;
1535            } __s;
1536        } __u;
1537        __u.__s.__a = 0;
1538        __u.__s.__b = 0;
1539        __u.__s.__c = 0;
1540        __u.__s.__d = 0;
1541        __u.__t = __v;
1542        return __u.__s.__a ^ __u.__s.__b ^ __u.__s.__c ^ __u.__s.__d;
1543#elif defined(__x86_64__)
1544        // Zero out padding bits
1545        union
1546        {
1547            long double __t;
1548            struct
1549            {
1550                size_t __a;
1551                size_t __b;
1552            } __s;
1553        } __u;
1554        __u.__s.__a = 0;
1555        __u.__s.__b = 0;
1556        __u.__t = __v;
1557        return __u.__s.__a ^ __u.__s.__b;
1558#else
1559        return __scalar_hash<long double>::operator()(__v);
1560#endif
1561    }
1562};
1563
1564#if _LIBCPP_STD_VER > 11
1565
1566template <class _Tp, bool = is_enum<_Tp>::value>
1567struct _LIBCPP_TEMPLATE_VIS __enum_hash
1568    : public unary_function<_Tp, size_t>
1569{
1570    _LIBCPP_INLINE_VISIBILITY
1571    size_t operator()(_Tp __v) const _NOEXCEPT
1572    {
1573        typedef typename underlying_type<_Tp>::type type;
1574        return hash<type>{}(static_cast<type>(__v));
1575    }
1576};
1577template <class _Tp>
1578struct _LIBCPP_TEMPLATE_VIS __enum_hash<_Tp, false> {
1579    __enum_hash() = delete;
1580    __enum_hash(__enum_hash const&) = delete;
1581    __enum_hash& operator=(__enum_hash const&) = delete;
1582};
1583
1584template <class _Tp>
1585struct _LIBCPP_TEMPLATE_VIS hash : public __enum_hash<_Tp>
1586{
1587};
1588#endif
1589
1590#if _LIBCPP_STD_VER > 14
1591
1592template <>
1593struct _LIBCPP_TEMPLATE_VIS hash<nullptr_t>
1594  : public unary_function<nullptr_t, size_t>
1595{
1596  _LIBCPP_INLINE_VISIBILITY
1597  size_t operator()(nullptr_t) const _NOEXCEPT {
1598    return 662607004ull;
1599  }
1600};
1601#endif
1602
1603#ifndef _LIBCPP_CXX03_LANG
1604template <class _Key, class _Hash>
1605using __check_hash_requirements _LIBCPP_NODEBUG_TYPE  = integral_constant<bool,
1606    is_copy_constructible<_Hash>::value &&
1607    is_move_constructible<_Hash>::value &&
1608    __invokable_r<size_t, _Hash, _Key const&>::value
1609>;
1610
1611template <class _Key, class _Hash = hash<_Key> >
1612using __has_enabled_hash _LIBCPP_NODEBUG_TYPE = integral_constant<bool,
1613    __check_hash_requirements<_Key, _Hash>::value &&
1614    is_default_constructible<_Hash>::value
1615>;
1616
1617#if _LIBCPP_STD_VER > 14
1618template <class _Type, class>
1619using __enable_hash_helper_imp _LIBCPP_NODEBUG_TYPE  = _Type;
1620
1621template <class _Type, class ..._Keys>
1622using __enable_hash_helper _LIBCPP_NODEBUG_TYPE  = __enable_hash_helper_imp<_Type,
1623  typename enable_if<__all<__has_enabled_hash<_Keys>::value...>::value>::type
1624>;
1625#else
1626template <class _Type, class ...>
1627using __enable_hash_helper _LIBCPP_NODEBUG_TYPE = _Type;
1628#endif
1629
1630template <class _Tp>
1631_LIBCPP_INLINE_VISIBILITY constexpr typename underlying_type<_Tp>::type
1632__to_underlying(_Tp __val) noexcept {
1633  return static_cast<typename underlying_type<_Tp>::type>(__val);
1634}
1635#endif // !_LIBCPP_CXX03_LANG
1636
1637#if _LIBCPP_STD_VER > 20
1638template <class _Tp>
1639_LIBCPP_INLINE_VISIBILITY constexpr underlying_type_t<_Tp>
1640to_underlying(_Tp __val) noexcept {
1641  return _VSTD::__to_underlying(__val);
1642}
1643#endif
1644
1645_LIBCPP_END_NAMESPACE_STD
1646
1647#endif  // _LIBCPP_UTILITY
1648