libstdc++
array
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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 
44 namespace 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;
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...)
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>
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
constexpr bool equal(_IIter1 __first1, _IIter1 __last1, _IIter2 __first2, _IIter2 __last2, _BinaryPredicate __binary_pred)
Tests a range for element-wise equality.
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
A standard container for storing a fixed size sequence of elements.
Definition: array:95
constexpr _ForwardIterator2 swap_ranges(_ForwardIterator1 __first1, _ForwardIterator1 __last1, _ForwardIterator2 __first2)
Swap the elements of two sequences.
Definition: stl_algobase.h:201
tuple_size
Definition: array:433
integral_constant< bool, true > true_type
The type used as a compile-time boolean with true value.
Definition: type_traits:75
tuple_element
Definition: array:442
make_integer_sequence< size_t, _Num > make_index_sequence
Alias template make_index_sequence.
Definition: utility:343
constexpr bool lexicographical_compare(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2, _Compare __comp)
Performs dictionary comparison on ranges.
constexpr _OI fill_n(_OI __first, _Size __n, const _Tp &__value)
Fills the range [first,first+n) with copies of value.
integral_constant
Definition: type_traits:57