libstdc++
experimental/array
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1 // <experimental/array> -*- C++ -*-
2 
3 // Copyright (C) 2015-2025 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 experimental/array
26  * This is a TS C++ Library header.
27  * @ingroup libfund-ts
28  */
29 
30 #ifndef _GLIBCXX_EXPERIMENTAL_ARRAY
31 #define _GLIBCXX_EXPERIMENTAL_ARRAY 1
32 
33 #ifdef _GLIBCXX_SYSHDR
34 #pragma GCC system_header
35 #endif
36 
37 #include <bits/requires_hosted.h> // experimental is currently omitted
38 
39 #if __cplusplus >= 201402L
40 
41 #include <array>
42 #include <experimental/type_traits>
43 
44 namespace std _GLIBCXX_VISIBILITY(default)
45 {
46 _GLIBCXX_BEGIN_NAMESPACE_VERSION
47 
48 namespace experimental
49 {
50 inline namespace fundamentals_v2
51 {
52 #define __cpp_lib_experimental_make_array 201505
53  /**
54  * @defgroup make_array Array creation functions
55  * @ingroup libfund-ts
56  *
57  * Array creation functions as described in N4529,
58  * Working Draft, C++ Extensions for Library Fundamentals, Version 2
59  *
60  * @{
61  */
62 
63 template<typename _Dest, typename... _Types>
64  struct __make_array_elem
65  {
66  using type = _Dest;
67  };
68 
69 template<typename... _Types>
70  struct __make_array_elem<void, _Types...>
71  : common_type<_Types...>
72  {
73  template <typename>
74  struct __is_reference_wrapper : false_type
75  {};
76 
77  template <typename _Up>
78  struct __is_reference_wrapper<reference_wrapper<_Up>> : true_type
79  {};
80 
81  static_assert(!__or_<__is_reference_wrapper<decay_t<_Types>>...>::value,
82  "make_array must be used with an explicit target type when"
83  "any of the arguments is a reference_wrapper");
84  };
85 
86 /// Create a std::array from a variable-length list of arguments.
87 template <typename _Dest = void, typename... _Types>
88  constexpr
89  array<typename __make_array_elem<_Dest, _Types...>::type, sizeof...(_Types)>
90  make_array(_Types&&... __t)
91  {
92  return {{ std::forward<_Types>(__t)... }};
93  }
94 
95 template <typename _Tp, size_t _Nm, size_t... _Idx>
96  constexpr array<remove_cv_t<_Tp>, _Nm>
97  __to_array(_Tp (&__a)[_Nm], index_sequence<_Idx...>)
98  {
99  return {{__a[_Idx]...}};
100  }
101 
102 /// Create a std::array from an array.
103 template <typename _Tp, size_t _Nm>
104  constexpr array<remove_cv_t<_Tp>, _Nm>
105  to_array(_Tp (&__a)[_Nm])
106  noexcept(is_nothrow_constructible<remove_cv_t<_Tp>, _Tp&>::value)
107  {
108  return experimental::__to_array(__a, make_index_sequence<_Nm>{});
109  }
110 
111  /// @} group make_array
112 } // namespace fundamentals_v2
113 } // namespace experimental
114 
115 _GLIBCXX_END_NAMESPACE_VERSION
116 } // namespace std
117 
118 #endif // C++14
119 
120 #endif // _GLIBCXX_EXPERIMENTAL_ARRAY