libstdc++-v3/include/experimental/array

   1 // <experimental/array> -*- C++ -*-
   2
   3 // Copyright (C) 2015-2021 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 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 #if __cplusplus >= 201402L
  36
  37 #include <array>
  38 #include <experimental/type_traits>
  39
  40 namespace std _GLIBCXX_VISIBILITY(default)
  41 {
  42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  43
  44 namespace experimental
  45 {
  46 inline namespace fundamentals_v2
  47 {
  48 #define __cpp_lib_experimental_make_array 201505
  49   /**
  50    * @defgroup make_array Array creation functions
  51    * @ingroup libfund-ts
  52    *
  53    * Array creation functions as described in N4529,
  54    * Working Draft, C++ Extensions for Library Fundamentals, Version 2
  55    *
  56    * @{
  57    */
  58
  59 template<typename _Dest, typename... _Types>
  60   struct __make_array_elem
  61   {
  62     using type = _Dest;
  63   };
  64
  65 template<typename... _Types>
  66   struct __make_array_elem<void, _Types...>
  67   : common_type<_Types...>
  68   {
  69     template <typename>
  70       struct __is_reference_wrapper : false_type
  71       {};
  72
  73     template <typename _Up>
  74       struct __is_reference_wrapper<reference_wrapper<_Up>> : true_type
  75       {};
  76
  77     static_assert(!__or_<__is_reference_wrapper<decay_t<_Types>>...>::value,
  78                   "make_array must be used with an explicit target type when"
  79                   "any of the arguments is a reference_wrapper");
  80   };
  81
  82 /// Create a std::array from a variable-length list of arguments.
  83 template <typename _Dest = void, typename... _Types>
  84   constexpr
  85   array<typename __make_array_elem<_Dest, _Types...>::type, sizeof...(_Types)>
  86   make_array(_Types&&... __t)
  87   {
  88     return {{ std::forward<_Types>(__t)... }};
  89   }
  90
  91 template <typename _Tp, size_t _Nm, size_t... _Idx>
  92   constexpr array<remove_cv_t<_Tp>, _Nm>
  93   __to_array(_Tp (&__a)[_Nm], index_sequence<_Idx...>)
  94   {
  95     return {{__a[_Idx]...}};
  96   }
  97
  98 /// Create a std::array from an array.
  99 template <typename _Tp, size_t _Nm>
 100   constexpr array<remove_cv_t<_Tp>, _Nm>
 101   to_array(_Tp (&__a)[_Nm])
 102   noexcept(is_nothrow_constructible<remove_cv_t<_Tp>, _Tp&>::value)
 103   {
 104     return experimental::__to_array(__a, make_index_sequence<_Nm>{});
 105   }
 106
 107   // @} group make_array
 108 } // namespace fundamentals_v2
 109 } // namespace experimental
 110
 111 _GLIBCXX_END_NAMESPACE_VERSION
 112 } // namespace std
 113
 114 #endif // C++14
 115
 116 #endif // _GLIBCXX_EXPERIMENTAL_ARRAY