xref: /llvm-project-15.0.7/libcxx/include/array (revision 2e6eccfe) 
1// -*- C++ -*-
2//===----------------------------------------------------------------------===//
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_ARRAY
11#define _LIBCPP_ARRAY
12
13/*
14    array synopsis
15
16namespace std
17{
18template <class T, size_t N >
19struct array
20{
21    // types:
22    typedef T & reference;
23    typedef const T & const_reference;
24    typedef implementation defined iterator;
25    typedef implementation defined const_iterator;
26    typedef size_t size_type;
27    typedef ptrdiff_t difference_type;
28    typedef T value_type;
29    typedef T* pointer;
30    typedef const T* const_pointer;
31    typedef std::reverse_iterator<iterator> reverse_iterator;
32    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
33
34    // No explicit construct/copy/destroy for aggregate type
35    void fill(const T& u);                                      // constexpr in C++20
36    void swap(array& a) noexcept(is_nothrow_swappable_v<T>);    // constexpr in C++20
37
38    // iterators:
39    iterator begin() noexcept;                                  // constexpr in C++17
40    const_iterator begin() const noexcept;                      // constexpr in C++17
41    iterator end() noexcept;                                    // constexpr in C++17
42    const_iterator end() const noexcept;                        // constexpr in C++17
43
44    reverse_iterator rbegin() noexcept;                         // constexpr in C++17
45    const_reverse_iterator rbegin() const noexcept;             // constexpr in C++17
46    reverse_iterator rend() noexcept;                           // constexpr in C++17
47    const_reverse_iterator rend() const noexcept;               // constexpr in C++17
48
49    const_iterator cbegin() const noexcept;                     // constexpr in C++17
50    const_iterator cend() const noexcept;                       // constexpr in C++17
51    const_reverse_iterator crbegin() const noexcept;            // constexpr in C++17
52    const_reverse_iterator crend() const noexcept;              // constexpr in C++17
53
54    // capacity:
55    constexpr size_type size() const noexcept;
56    constexpr size_type max_size() const noexcept;
57    constexpr bool empty() const noexcept;
58
59    // element access:
60    reference operator[](size_type n);                          // constexpr in C++17
61    const_reference operator[](size_type n) const;              // constexpr in C++14
62    reference at(size_type n);                                  // constexpr in C++17
63    const_reference at(size_type n) const;                      // constexpr in C++14
64
65    reference front();                                          // constexpr in C++17
66    const_reference front() const;                              // constexpr in C++14
67    reference back();                                           // constexpr in C++17
68    const_reference back() const;                               // constexpr in C++14
69
70    T* data() noexcept;                                         // constexpr in C++17
71    const T* data() const noexcept;                             // constexpr in C++17
72};
73
74template <class T, class... U>
75  array(T, U...) -> array<T, 1 + sizeof...(U)>;                 // C++17
76
77template <class T, size_t N>
78  bool operator==(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
79template <class T, size_t N>
80  bool operator!=(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
81template <class T, size_t N>
82  bool operator<(const array<T,N>& x, const array<T,N>& y);     // constexpr in C++20
83template <class T, size_t N>
84  bool operator>(const array<T,N>& x, const array<T,N>& y);     // constexpr in C++20
85template <class T, size_t N>
86  bool operator<=(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
87template <class T, size_t N>
88  bool operator>=(const array<T,N>& x, const array<T,N>& y);    // constexpr in C++20
89
90template <class T, size_t N >
91  void swap(array<T,N>& x, array<T,N>& y) noexcept(noexcept(x.swap(y))); // constexpr in C++20
92
93template <class T, size_t N>
94  constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);  // C++20
95template <class T, size_t N>
96  constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]); // C++20
97
98template <class T> struct tuple_size;
99template <size_t I, class T> struct tuple_element;
100template <class T, size_t N> struct tuple_size<array<T, N>>;
101template <size_t I, class T, size_t N> struct tuple_element<I, array<T, N>>;
102template <size_t I, class T, size_t N> T& get(array<T, N>&) noexcept;               // constexpr in C++14
103template <size_t I, class T, size_t N> const T& get(const array<T, N>&) noexcept;   // constexpr in C++14
104template <size_t I, class T, size_t N> T&& get(array<T, N>&&) noexcept;             // constexpr in C++14
105template <size_t I, class T, size_t N> const T&& get(const array<T, N>&&) noexcept; // constexpr in C++14
106
107}  // std
108
109*/
110
111#include <__algorithm/equal.h>
112#include <__algorithm/fill_n.h>
113#include <__algorithm/lexicographical_compare.h>
114#include <__algorithm/swap_ranges.h>
115#include <__assert> // all public C++ headers provide the assertion handler
116#include <__config>
117#include <__iterator/reverse_iterator.h>
118#include <__tuple>
119#include <__utility/integer_sequence.h>
120#include <__utility/move.h>
121#include <__utility/unreachable.h>
122#include <compare>
123#include <stdexcept>
124#include <type_traits>
125#include <version>
126
127#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
128#  pragma GCC system_header
129#endif
130
131_LIBCPP_BEGIN_NAMESPACE_STD
132
133template <class _Tp, size_t _Size>
134struct _LIBCPP_TEMPLATE_VIS array
135{
136    // types:
137    typedef array __self;
138    typedef _Tp                                   value_type;
139    typedef value_type&                           reference;
140    typedef const value_type&                     const_reference;
141    typedef value_type*                           iterator;
142    typedef const value_type*                     const_iterator;
143    typedef value_type*                           pointer;
144    typedef const value_type*                     const_pointer;
145    typedef size_t                                size_type;
146    typedef ptrdiff_t                             difference_type;
147    typedef _VSTD::reverse_iterator<iterator>       reverse_iterator;
148    typedef _VSTD::reverse_iterator<const_iterator> const_reverse_iterator;
149
150    _Tp __elems_[_Size];
151
152    // No explicit construct/copy/destroy for aggregate type
153    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
154    void fill(const value_type& __u) {
155        _VSTD::fill_n(data(), _Size, __u);
156    }
157
158    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
159    void swap(array& __a) _NOEXCEPT_(__is_nothrow_swappable<_Tp>::value) {
160        _VSTD::swap_ranges(data(), data() + _Size, __a.data());
161    }
162
163    // iterators:
164    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
165    iterator begin() _NOEXCEPT {return iterator(data());}
166    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
167    const_iterator begin() const _NOEXCEPT {return const_iterator(data());}
168    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
169    iterator end() _NOEXCEPT {return iterator(data() + _Size);}
170    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
171    const_iterator end() const _NOEXCEPT {return const_iterator(data() + _Size);}
172
173    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
174    reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
175    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
176    const_reverse_iterator rbegin() const _NOEXCEPT {return const_reverse_iterator(end());}
177    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
178    reverse_iterator rend() _NOEXCEPT {return reverse_iterator(begin());}
179    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
180    const_reverse_iterator rend() const _NOEXCEPT {return const_reverse_iterator(begin());}
181
182    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
183    const_iterator cbegin() const _NOEXCEPT {return begin();}
184    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
185    const_iterator cend() const _NOEXCEPT {return end();}
186    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
187    const_reverse_iterator crbegin() const _NOEXCEPT {return rbegin();}
188    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
189    const_reverse_iterator crend() const _NOEXCEPT {return rend();}
190
191    // capacity:
192    _LIBCPP_INLINE_VISIBILITY
193    _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT {return _Size;}
194    _LIBCPP_INLINE_VISIBILITY
195    _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT {return _Size;}
196    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
197    _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return _Size == 0;}
198
199    // element access:
200    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
201    reference operator[](size_type __n) _NOEXCEPT {
202        _LIBCPP_ASSERT(__n < _Size, "out-of-bounds access in std::array<T, N>");
203        return __elems_[__n];
204    }
205    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
206    const_reference operator[](size_type __n) const _NOEXCEPT {
207        _LIBCPP_ASSERT(__n < _Size, "out-of-bounds access in std::array<T, N>");
208        return __elems_[__n];
209    }
210
211    _LIBCPP_CONSTEXPR_AFTER_CXX14 reference at(size_type __n)
212    {
213        if (__n >= _Size)
214            __throw_out_of_range("array::at");
215        return __elems_[__n];
216    }
217
218    _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference at(size_type __n) const
219    {
220        if (__n >= _Size)
221            __throw_out_of_range("array::at");
222        return __elems_[__n];
223    }
224
225    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference front()             _NOEXCEPT {return (*this)[0];}
226    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference front() const _NOEXCEPT {return (*this)[0];}
227    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 reference back()              _NOEXCEPT {return (*this)[_Size - 1];}
228    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11 const_reference back() const  _NOEXCEPT {return (*this)[_Size - 1];}
229
230    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
231    value_type* data() _NOEXCEPT {return __elems_;}
232    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
233    const value_type* data() const _NOEXCEPT {return __elems_;}
234};
235
236template <class _Tp>
237struct _LIBCPP_TEMPLATE_VIS array<_Tp, 0>
238{
239    // types:
240    typedef array __self;
241    typedef _Tp                                   value_type;
242    typedef value_type&                           reference;
243    typedef const value_type&                     const_reference;
244    typedef value_type*                           iterator;
245    typedef const value_type*                     const_iterator;
246    typedef value_type*                           pointer;
247    typedef const value_type*                     const_pointer;
248    typedef size_t                                size_type;
249    typedef ptrdiff_t                             difference_type;
250    typedef _VSTD::reverse_iterator<iterator>       reverse_iterator;
251    typedef _VSTD::reverse_iterator<const_iterator> const_reverse_iterator;
252
253    typedef typename conditional<is_const<_Tp>::value, const char,
254                                char>::type _CharType;
255
256    struct  _ArrayInStructT { _Tp __data_[1]; };
257    _ALIGNAS_TYPE(_ArrayInStructT) _CharType __elems_[sizeof(_ArrayInStructT)];
258
259    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
260    value_type* data() _NOEXCEPT {return nullptr;}
261    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
262    const value_type* data() const _NOEXCEPT {return nullptr;}
263
264    // No explicit construct/copy/destroy for aggregate type
265    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
266    void fill(const value_type&) {
267      static_assert(!is_const<_Tp>::value,
268                    "cannot fill zero-sized array of type 'const T'");
269    }
270
271    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
272    void swap(array&) _NOEXCEPT {
273      static_assert(!is_const<_Tp>::value,
274                    "cannot swap zero-sized array of type 'const T'");
275    }
276
277    // iterators:
278    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
279    iterator begin() _NOEXCEPT {return iterator(data());}
280    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
281    const_iterator begin() const _NOEXCEPT {return const_iterator(data());}
282    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
283    iterator end() _NOEXCEPT {return iterator(data());}
284    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
285    const_iterator end() const _NOEXCEPT {return const_iterator(data());}
286
287    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
288    reverse_iterator rbegin() _NOEXCEPT {return reverse_iterator(end());}
289    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
290    const_reverse_iterator rbegin() const _NOEXCEPT {return const_reverse_iterator(end());}
291    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
292    reverse_iterator rend() _NOEXCEPT {return reverse_iterator(begin());}
293    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
294    const_reverse_iterator rend() const _NOEXCEPT {return const_reverse_iterator(begin());}
295
296    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
297    const_iterator cbegin() const _NOEXCEPT {return begin();}
298    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
299    const_iterator cend() const _NOEXCEPT {return end();}
300    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
301    const_reverse_iterator crbegin() const _NOEXCEPT {return rbegin();}
302    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
303    const_reverse_iterator crend() const _NOEXCEPT {return rend();}
304
305    // capacity:
306    _LIBCPP_INLINE_VISIBILITY
307    _LIBCPP_CONSTEXPR size_type size() const _NOEXCEPT {return 0; }
308    _LIBCPP_INLINE_VISIBILITY
309    _LIBCPP_CONSTEXPR size_type max_size() const _NOEXCEPT {return 0;}
310    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
311    _LIBCPP_CONSTEXPR bool empty() const _NOEXCEPT {return true;}
312
313    // element access:
314    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
315    reference operator[](size_type) _NOEXCEPT {
316      _LIBCPP_ASSERT(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
317      __libcpp_unreachable();
318    }
319
320    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
321    const_reference operator[](size_type) const _NOEXCEPT {
322      _LIBCPP_ASSERT(false, "cannot call array<T, 0>::operator[] on a zero-sized array");
323      __libcpp_unreachable();
324    }
325
326    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
327    reference at(size_type) {
328      __throw_out_of_range("array<T, 0>::at");
329      __libcpp_unreachable();
330    }
331
332    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
333    const_reference at(size_type) const {
334      __throw_out_of_range("array<T, 0>::at");
335      __libcpp_unreachable();
336    }
337
338    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
339    reference front() _NOEXCEPT {
340      _LIBCPP_ASSERT(false, "cannot call array<T, 0>::front() on a zero-sized array");
341      __libcpp_unreachable();
342    }
343
344    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
345    const_reference front() const _NOEXCEPT {
346      _LIBCPP_ASSERT(false, "cannot call array<T, 0>::front() on a zero-sized array");
347      __libcpp_unreachable();
348    }
349
350    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
351    reference back() _NOEXCEPT {
352      _LIBCPP_ASSERT(false, "cannot call array<T, 0>::back() on a zero-sized array");
353      __libcpp_unreachable();
354    }
355
356    _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
357    const_reference back() const _NOEXCEPT {
358      _LIBCPP_ASSERT(false, "cannot call array<T, 0>::back() on a zero-sized array");
359      __libcpp_unreachable();
360    }
361};
362
363
364#if _LIBCPP_STD_VER > 14
365template<class _Tp, class... _Args,
366         class = enable_if_t<__all<_IsSame<_Tp, _Args>::value...>::value>
367         >
368array(_Tp, _Args...)
369  -> array<_Tp, 1 + sizeof...(_Args)>;
370#endif
371
372template <class _Tp, size_t _Size>
373inline _LIBCPP_INLINE_VISIBILITY
374_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
375operator==(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
376{
377    return _VSTD::equal(__x.begin(), __x.end(), __y.begin());
378}
379
380template <class _Tp, size_t _Size>
381inline _LIBCPP_INLINE_VISIBILITY
382_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
383operator!=(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
384{
385    return !(__x == __y);
386}
387
388template <class _Tp, size_t _Size>
389inline _LIBCPP_INLINE_VISIBILITY
390_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
391operator<(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
392{
393    return _VSTD::lexicographical_compare(__x.begin(), __x.end(),
394                                          __y.begin(), __y.end());
395}
396
397template <class _Tp, size_t _Size>
398inline _LIBCPP_INLINE_VISIBILITY
399_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
400operator>(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
401{
402    return __y < __x;
403}
404
405template <class _Tp, size_t _Size>
406inline _LIBCPP_INLINE_VISIBILITY
407_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
408operator<=(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
409{
410    return !(__y < __x);
411}
412
413template <class _Tp, size_t _Size>
414inline _LIBCPP_INLINE_VISIBILITY
415_LIBCPP_CONSTEXPR_AFTER_CXX17 bool
416operator>=(const array<_Tp, _Size>& __x, const array<_Tp, _Size>& __y)
417{
418    return !(__x < __y);
419}
420
421template <class _Tp, size_t _Size>
422inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
423typename enable_if
424<
425    _Size == 0 ||
426    __is_swappable<_Tp>::value,
427    void
428>::type
429swap(array<_Tp, _Size>& __x, array<_Tp, _Size>& __y)
430                                  _NOEXCEPT_(noexcept(__x.swap(__y)))
431{
432    __x.swap(__y);
433}
434
435template <class _Tp, size_t _Size>
436struct _LIBCPP_TEMPLATE_VIS tuple_size<array<_Tp, _Size> >
437    : public integral_constant<size_t, _Size> {};
438
439template <size_t _Ip, class _Tp, size_t _Size>
440struct _LIBCPP_TEMPLATE_VIS tuple_element<_Ip, array<_Tp, _Size> >
441{
442    static_assert(_Ip < _Size, "Index out of bounds in std::tuple_element<> (std::array)");
443    typedef _Tp type;
444};
445
446template <size_t _Ip, class _Tp, size_t _Size>
447inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
448_Tp&
449get(array<_Tp, _Size>& __a) _NOEXCEPT
450{
451    static_assert(_Ip < _Size, "Index out of bounds in std::get<> (std::array)");
452    return __a.__elems_[_Ip];
453}
454
455template <size_t _Ip, class _Tp, size_t _Size>
456inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
457const _Tp&
458get(const array<_Tp, _Size>& __a) _NOEXCEPT
459{
460    static_assert(_Ip < _Size, "Index out of bounds in std::get<> (const std::array)");
461    return __a.__elems_[_Ip];
462}
463
464template <size_t _Ip, class _Tp, size_t _Size>
465inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
466_Tp&&
467get(array<_Tp, _Size>&& __a) _NOEXCEPT
468{
469    static_assert(_Ip < _Size, "Index out of bounds in std::get<> (std::array &&)");
470    return _VSTD::move(__a.__elems_[_Ip]);
471}
472
473template <size_t _Ip, class _Tp, size_t _Size>
474inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX11
475const _Tp&&
476get(const array<_Tp, _Size>&& __a) _NOEXCEPT
477{
478    static_assert(_Ip < _Size, "Index out of bounds in std::get<> (const std::array &&)");
479    return _VSTD::move(__a.__elems_[_Ip]);
480}
481
482#if _LIBCPP_STD_VER > 17
483
484template <typename _Tp, size_t _Size, size_t... _Index>
485_LIBCPP_INLINE_VISIBILITY constexpr array<remove_cv_t<_Tp>, _Size>
486__to_array_lvalue_impl(_Tp (&__arr)[_Size], index_sequence<_Index...>) {
487  return {{__arr[_Index]...}};
488}
489
490template <typename _Tp, size_t _Size, size_t... _Index>
491_LIBCPP_INLINE_VISIBILITY constexpr array<remove_cv_t<_Tp>, _Size>
492__to_array_rvalue_impl(_Tp(&&__arr)[_Size], index_sequence<_Index...>) {
493  return {{_VSTD::move(__arr[_Index])...}};
494}
495
496template <typename _Tp, size_t _Size>
497_LIBCPP_INLINE_VISIBILITY constexpr array<remove_cv_t<_Tp>, _Size>
498to_array(_Tp (&__arr)[_Size]) noexcept(is_nothrow_constructible_v<_Tp, _Tp&>) {
499  static_assert(
500      !is_array_v<_Tp>,
501      "[array.creation]/1: to_array does not accept multidimensional arrays.");
502  static_assert(
503      is_constructible_v<_Tp, _Tp&>,
504      "[array.creation]/1: to_array requires copy constructible elements.");
505  return _VSTD::__to_array_lvalue_impl(__arr, make_index_sequence<_Size>());
506}
507
508template <typename _Tp, size_t _Size>
509_LIBCPP_INLINE_VISIBILITY constexpr array<remove_cv_t<_Tp>, _Size>
510to_array(_Tp(&&__arr)[_Size]) noexcept(is_nothrow_move_constructible_v<_Tp>) {
511  static_assert(
512      !is_array_v<_Tp>,
513      "[array.creation]/4: to_array does not accept multidimensional arrays.");
514  static_assert(
515      is_move_constructible_v<_Tp>,
516      "[array.creation]/4: to_array requires move constructible elements.");
517  return _VSTD::__to_array_rvalue_impl(_VSTD::move(__arr),
518                                       make_index_sequence<_Size>());
519}
520
521#endif // _LIBCPP_STD_VER > 17
522
523_LIBCPP_END_NAMESPACE_STD
524
525#endif // _LIBCPP_ARRAY
526