1// <array> -*- C++ -*-
2
3// Copyright (C) 2007-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.
15
16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/array
26 *  This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_ARRAY
30#define _GLIBCXX_ARRAY 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <utility>
39#include <bits/functexcept.h>
40#include <bits/stl_algobase.h>
41#include <bits/range_access.h>
42#include <debug/assertions.h>
43
44namespace std _GLIBCXX_VISIBILITY(default)
45{
46_GLIBCXX_BEGIN_NAMESPACE_VERSION
47
48  template<typename _Tp, std::size_t _Nm>
49    struct __array_traits
50    {
51      typedef _Tp _Type[_Nm];
52      typedef __is_swappable<_Tp> _Is_swappable;
53      typedef __is_nothrow_swappable<_Tp> _Is_nothrow_swappable;
54
55      static constexpr _Tp&
56      _S_ref(const _Type& __t, std::size_t __n) noexcept
57      { return const_cast<_Tp&>(__t[__n]); }
58
59      static constexpr _Tp*
60      _S_ptr(const _Type& __t) noexcept
61      { return const_cast<_Tp*>(__t); }
62    };
63
64 template<typename _Tp>
65   struct __array_traits<_Tp, 0>
66   {
67     struct _Type { };
68     typedef true_type _Is_swappable;
69     typedef true_type _Is_nothrow_swappable;
70
71     static constexpr _Tp&
72     _S_ref(const _Type&, std::size_t) noexcept
73     { return *static_cast<_Tp*>(nullptr); }
74
75     static constexpr _Tp*
76     _S_ptr(const _Type&) noexcept
77     { return nullptr; }
78   };
79
80  /**
81   *  @brief A standard container for storing a fixed size sequence of elements.
82   *
83   *  @ingroup sequences
84   *
85   *  Meets the requirements of a <a href="tables.html#65">container</a>, a
86   *  <a href="tables.html#66">reversible container</a>, and a
87   *  <a href="tables.html#67">sequence</a>.
88   *
89   *  Sets support random access iterators.
90   *
91   *  @tparam  Tp  Type of element. Required to be a complete type.
92   *  @tparam  Nm  Number of elements.
93  */
94  template<typename _Tp, std::size_t _Nm>
95    struct array
96    {
97      typedef _Tp 	    			      value_type;
98      typedef value_type*			      pointer;
99      typedef const value_type*                       const_pointer;
100      typedef value_type&                   	      reference;
101      typedef const value_type&             	      const_reference;
102      typedef value_type*          		      iterator;
103      typedef const value_type*			      const_iterator;
104      typedef std::size_t                    	      size_type;
105      typedef std::ptrdiff_t                   	      difference_type;
106      typedef std::reverse_iterator<iterator>	      reverse_iterator;
107      typedef std::reverse_iterator<const_iterator>   const_reverse_iterator;
108
109      // Support for zero-sized arrays mandatory.
110      typedef __array_traits<_Tp, _Nm> _AT_Type;
111      typename _AT_Type::_Type                         _M_elems;
112
113      // No explicit construct/copy/destroy for aggregate type.
114
115      // DR 776.
116      _GLIBCXX20_CONSTEXPR void
117      fill(const value_type& __u)
118      { std::fill_n(begin(), size(), __u); }
119
120      _GLIBCXX20_CONSTEXPR void
121      swap(array& __other)
122      noexcept(_AT_Type::_Is_nothrow_swappable::value)
123      { std::swap_ranges(begin(), end(), __other.begin()); }
124
125      // Iterators.
126      _GLIBCXX17_CONSTEXPR iterator
127      begin() noexcept
128      { return iterator(data()); }
129
130      _GLIBCXX17_CONSTEXPR const_iterator
131      begin() const noexcept
132      { return const_iterator(data()); }
133
134      _GLIBCXX17_CONSTEXPR iterator
135      end() noexcept
136      { return iterator(data() + _Nm); }
137
138      _GLIBCXX17_CONSTEXPR const_iterator
139      end() const noexcept
140      { return const_iterator(data() + _Nm); }
141
142      _GLIBCXX17_CONSTEXPR reverse_iterator
143      rbegin() noexcept
144      { return reverse_iterator(end()); }
145
146      _GLIBCXX17_CONSTEXPR const_reverse_iterator
147      rbegin() const noexcept
148      { return const_reverse_iterator(end()); }
149
150      _GLIBCXX17_CONSTEXPR reverse_iterator
151      rend() noexcept
152      { return reverse_iterator(begin()); }
153
154      _GLIBCXX17_CONSTEXPR const_reverse_iterator
155      rend() const noexcept
156      { return const_reverse_iterator(begin()); }
157
158      _GLIBCXX17_CONSTEXPR const_iterator
159      cbegin() const noexcept
160      { return const_iterator(data()); }
161
162      _GLIBCXX17_CONSTEXPR const_iterator
163      cend() const noexcept
164      { return const_iterator(data() + _Nm); }
165
166      _GLIBCXX17_CONSTEXPR const_reverse_iterator
167      crbegin() const noexcept
168      { return const_reverse_iterator(end()); }
169
170      _GLIBCXX17_CONSTEXPR const_reverse_iterator
171      crend() const noexcept
172      { return const_reverse_iterator(begin()); }
173
174      // Capacity.
175      constexpr size_type
176      size() const noexcept { return _Nm; }
177
178      constexpr size_type
179      max_size() const noexcept { return _Nm; }
180
181      _GLIBCXX_NODISCARD constexpr bool
182      empty() const noexcept { return size() == 0; }
183
184      // Element access.
185      _GLIBCXX17_CONSTEXPR reference
186      operator[](size_type __n) noexcept
187      {
188	__glibcxx_requires_subscript(__n);
189	return _AT_Type::_S_ref(_M_elems, __n);
190      }
191
192      constexpr const_reference
193      operator[](size_type __n) const noexcept
194      {
195#if __cplusplus >= 201402L
196	__glibcxx_requires_subscript(__n);
197#endif
198	return _AT_Type::_S_ref(_M_elems, __n);
199      }
200
201      _GLIBCXX17_CONSTEXPR reference
202      at(size_type __n)
203      {
204	if (__n >= _Nm)
205	  std::__throw_out_of_range_fmt(__N("array::at: __n (which is %zu) "
206					    ">= _Nm (which is %zu)"),
207					__n, _Nm);
208	return _AT_Type::_S_ref(_M_elems, __n);
209      }
210
211      constexpr const_reference
212      at(size_type __n) const
213      {
214	// Result of conditional expression must be an lvalue so use
215	// boolean ? lvalue : (throw-expr, lvalue)
216	return __n < _Nm ? _AT_Type::_S_ref(_M_elems, __n)
217	  : (std::__throw_out_of_range_fmt(__N("array::at: __n (which is %zu) "
218					       ">= _Nm (which is %zu)"),
219					   __n, _Nm),
220	     _AT_Type::_S_ref(_M_elems, 0));
221      }
222
223      _GLIBCXX17_CONSTEXPR reference
224      front() noexcept
225      {
226	__glibcxx_requires_nonempty();
227	return *begin();
228      }
229
230      constexpr const_reference
231      front() const noexcept
232      {
233#if __cplusplus >= 201402L
234	__glibcxx_requires_nonempty();
235#endif
236	return _AT_Type::_S_ref(_M_elems, 0);
237      }
238
239      _GLIBCXX17_CONSTEXPR reference
240      back() noexcept
241      {
242	__glibcxx_requires_nonempty();
243	return _Nm ? *(end() - 1) : *end();
244      }
245
246      constexpr const_reference
247      back() const noexcept
248      {
249#if __cplusplus >= 201402L
250	__glibcxx_requires_nonempty();
251#endif
252	return _Nm ? _AT_Type::_S_ref(_M_elems, _Nm - 1)
253 	           : _AT_Type::_S_ref(_M_elems, 0);
254      }
255
256      _GLIBCXX17_CONSTEXPR pointer
257      data() noexcept
258      { return _AT_Type::_S_ptr(_M_elems); }
259
260      _GLIBCXX17_CONSTEXPR const_pointer
261      data() const noexcept
262      { return _AT_Type::_S_ptr(_M_elems); }
263    };
264
265#if __cpp_deduction_guides >= 201606
266  template<typename _Tp, typename... _Up>
267    array(_Tp, _Up...)
268      -> array<enable_if_t<(is_same_v<_Tp, _Up> && ...), _Tp>,
269	       1 + sizeof...(_Up)>;
270#endif
271
272  // Array comparisons.
273  template<typename _Tp, std::size_t _Nm>
274    _GLIBCXX20_CONSTEXPR
275    inline bool
276    operator==(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
277    { return std::equal(__one.begin(), __one.end(), __two.begin()); }
278
279#if __cpp_lib_three_way_comparison && __cpp_lib_concepts
280  template<typename _Tp, size_t _Nm>
281    constexpr __detail::__synth3way_t<_Tp>
282    operator<=>(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
283    {
284#ifdef __cpp_lib_is_constant_evaluated
285      if constexpr (_Nm && __is_memcmp_ordered<_Tp>::__value)
286	if (!std::is_constant_evaluated())
287	  {
288	    constexpr size_t __n = _Nm * sizeof(_Tp);
289	    return __builtin_memcmp(__a.data(), __b.data(), __n) <=> 0;
290	  }
291#endif
292
293      for (size_t __i = 0; __i < _Nm; ++__i)
294	{
295	  auto __c = __detail::__synth3way(__a[__i], __b[__i]);
296	  if (__c != 0)
297	    return __c;
298	}
299      return strong_ordering::equal;
300    }
301#else
302  template<typename _Tp, std::size_t _Nm>
303    _GLIBCXX20_CONSTEXPR
304    inline bool
305    operator!=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
306    { return !(__one == __two); }
307
308  template<typename _Tp, std::size_t _Nm>
309    _GLIBCXX20_CONSTEXPR
310    inline bool
311    operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
312    {
313      return std::lexicographical_compare(__a.begin(), __a.end(),
314					  __b.begin(), __b.end());
315    }
316
317  template<typename _Tp, std::size_t _Nm>
318    _GLIBCXX20_CONSTEXPR
319    inline bool
320    operator>(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
321    { return __two < __one; }
322
323  template<typename _Tp, std::size_t _Nm>
324    _GLIBCXX20_CONSTEXPR
325    inline bool
326    operator<=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
327    { return !(__one > __two); }
328
329  template<typename _Tp, std::size_t _Nm>
330    _GLIBCXX20_CONSTEXPR
331    inline bool
332    operator>=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
333    { return !(__one < __two); }
334#endif // three_way_comparison && concepts
335
336  // Specialized algorithms.
337  template<typename _Tp, std::size_t _Nm>
338    _GLIBCXX20_CONSTEXPR
339    inline
340#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
341    // Constrained free swap overload, see p0185r1
342    typename enable_if<
343      __array_traits<_Tp, _Nm>::_Is_swappable::value
344    >::type
345#else
346    void
347#endif
348    swap(array<_Tp, _Nm>& __one, array<_Tp, _Nm>& __two)
349    noexcept(noexcept(__one.swap(__two)))
350    { __one.swap(__two); }
351
352#if __cplusplus > 201402L || !defined(__STRICT_ANSI__) // c++1z or gnu++11
353  template<typename _Tp, std::size_t _Nm>
354    typename enable_if<
355      !__array_traits<_Tp, _Nm>::_Is_swappable::value>::type
356    swap(array<_Tp, _Nm>&, array<_Tp, _Nm>&) = delete;
357#endif
358
359  template<std::size_t _Int, typename _Tp, std::size_t _Nm>
360    constexpr _Tp&
361    get(array<_Tp, _Nm>& __arr) noexcept
362    {
363      static_assert(_Int < _Nm, "array index is within bounds");
364      return __array_traits<_Tp, _Nm>::_S_ref(__arr._M_elems, _Int);
365    }
366
367  template<std::size_t _Int, typename _Tp, std::size_t _Nm>
368    constexpr _Tp&&
369    get(array<_Tp, _Nm>&& __arr) noexcept
370    {
371      static_assert(_Int < _Nm, "array index is within bounds");
372      return std::move(std::get<_Int>(__arr));
373    }
374
375  template<std::size_t _Int, typename _Tp, std::size_t _Nm>
376    constexpr const _Tp&
377    get(const array<_Tp, _Nm>& __arr) noexcept
378    {
379      static_assert(_Int < _Nm, "array index is within bounds");
380      return __array_traits<_Tp, _Nm>::_S_ref(__arr._M_elems, _Int);
381    }
382
383  template<std::size_t _Int, typename _Tp, std::size_t _Nm>
384    constexpr const _Tp&&
385    get(const array<_Tp, _Nm>&& __arr) noexcept
386    {
387      static_assert(_Int < _Nm, "array index is within bounds");
388      return std::move(std::get<_Int>(__arr));
389    }
390
391#if __cplusplus > 201703L
392#define __cpp_lib_to_array 201907L
393
394  template<bool _Move = false, typename _Tp, size_t... _Idx>
395    constexpr array<remove_cv_t<_Tp>, sizeof...(_Idx)>
396    __to_array(_Tp (&__a)[sizeof...(_Idx)], index_sequence<_Idx...>)
397    {
398      if constexpr (_Move)
399	return {{std::move(__a[_Idx])...}};
400      else
401	return {{__a[_Idx]...}};
402    }
403
404  template<typename _Tp, size_t _Nm>
405    constexpr array<remove_cv_t<_Tp>, _Nm>
406    to_array(_Tp (&__a)[_Nm])
407    noexcept(is_nothrow_constructible_v<_Tp, _Tp&>)
408    {
409      static_assert(!is_array_v<_Tp>);
410      static_assert(is_constructible_v<_Tp, _Tp&>);
411      if constexpr (is_constructible_v<_Tp, _Tp&>)
412	return __to_array(__a, make_index_sequence<_Nm>{});
413      __builtin_unreachable(); // FIXME: see PR c++/91388
414    }
415
416  template<typename _Tp, size_t _Nm>
417    constexpr array<remove_cv_t<_Tp>, _Nm>
418    to_array(_Tp (&&__a)[_Nm])
419    noexcept(is_nothrow_move_constructible_v<_Tp>)
420    {
421      static_assert(!is_array_v<_Tp>);
422      static_assert(is_move_constructible_v<_Tp>);
423      if constexpr (is_move_constructible_v<_Tp>)
424	return __to_array<1>(__a, make_index_sequence<_Nm>{});
425      __builtin_unreachable(); // FIXME: see PR c++/91388
426    }
427#endif // C++20
428
429  // Tuple interface to class template array.
430
431  /// tuple_size
432  template<typename _Tp>
433    struct tuple_size;
434
435  /// Partial specialization for std::array
436  template<typename _Tp, std::size_t _Nm>
437    struct tuple_size<array<_Tp, _Nm>>
438    : public integral_constant<std::size_t, _Nm> { };
439
440  /// tuple_element
441  template<std::size_t _Int, typename _Tp>
442    struct tuple_element;
443
444  /// Partial specialization for std::array
445  template<std::size_t _Int, typename _Tp, std::size_t _Nm>
446    struct tuple_element<_Int, array<_Tp, _Nm>>
447    {
448      static_assert(_Int < _Nm, "index is out of bounds");
449      typedef _Tp type;
450    };
451
452  template<typename _Tp, std::size_t _Nm>
453    struct __is_tuple_like_impl<array<_Tp, _Nm>> : true_type
454    { };
455
456_GLIBCXX_END_NAMESPACE_VERSION
457} // namespace std
458
459#endif // C++11
460
461#endif // _GLIBCXX_ARRAY
462