libstdc++
experimental/array
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1 // <experimental/array> -*- C++ -*-
2 
3 // Copyright (C) 2015-2024 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 #pragma GCC system_header
34 
35 #include <bits/requires_hosted.h> // experimental is currently omitted
36 
37 #if __cplusplus >= 201402L
38 
39 #include <array>
40 #include <experimental/type_traits>
41 
42 namespace std _GLIBCXX_VISIBILITY(default)
43 {
44 _GLIBCXX_BEGIN_NAMESPACE_VERSION
45 
46 namespace experimental
47 {
48 inline namespace fundamentals_v2
49 {
50 #define __cpp_lib_experimental_make_array 201505
51  /**
52  * @defgroup make_array Array creation functions
53  * @ingroup libfund-ts
54  *
55  * Array creation functions as described in N4529,
56  * Working Draft, C++ Extensions for Library Fundamentals, Version 2
57  *
58  * @{
59  */
60 
61 template<typename _Dest, typename... _Types>
62  struct __make_array_elem
63  {
64  using type = _Dest;
65  };
66 
67 template<typename... _Types>
68  struct __make_array_elem<void, _Types...>
69  : common_type<_Types...>
70  {
71  template <typename>
72  struct __is_reference_wrapper : false_type
73  {};
74 
75  template <typename _Up>
76  struct __is_reference_wrapper<reference_wrapper<_Up>> : true_type
77  {};
78 
79  static_assert(!__or_<__is_reference_wrapper<decay_t<_Types>>...>::value,
80  "make_array must be used with an explicit target type when"
81  "any of the arguments is a reference_wrapper");
82  };
83 
84 /// Create a std::array from a variable-length list of arguments.
85 template <typename _Dest = void, typename... _Types>
86  constexpr
87  array<typename __make_array_elem<_Dest, _Types...>::type, sizeof...(_Types)>
88  make_array(_Types&&... __t)
89  {
90  return {{ std::forward<_Types>(__t)... }};
91  }
92 
93 template <typename _Tp, size_t _Nm, size_t... _Idx>
94  constexpr array<remove_cv_t<_Tp>, _Nm>
95  __to_array(_Tp (&__a)[_Nm], index_sequence<_Idx...>)
96  {
97  return {{__a[_Idx]...}};
98  }
99 
100 /// Create a std::array from an array.
101 template <typename _Tp, size_t _Nm>
102  constexpr array<remove_cv_t<_Tp>, _Nm>
103  to_array(_Tp (&__a)[_Nm])
104  noexcept(is_nothrow_constructible<remove_cv_t<_Tp>, _Tp&>::value)
105  {
106  return experimental::__to_array(__a, make_index_sequence<_Nm>{});
107  }
108 
109  /// @} group make_array
110 } // namespace fundamentals_v2
111 } // namespace experimental
112 
113 _GLIBCXX_END_NAMESPACE_VERSION
114 } // namespace std
115 
116 #endif // C++14
117 
118 #endif // _GLIBCXX_EXPERIMENTAL_ARRAY