libstdc++-v3/include/bits/uses_allocator_args.h

   1 // Utility functions for uses-allocator construction -*- C++ -*-
   2
   3 // Copyright (C) 2019-2023 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/bits/uses_allocator_args.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{memory}
  28  */
  29
  30 #ifndef _USES_ALLOCATOR_ARGS
  31 #define _USES_ALLOCATOR_ARGS 1
  32
  33 #pragma GCC system_header
  34
  35 #include <bits/version.h>
  36
  37 #ifdef __glibcxx_make_obj_using_allocator // C++ >= 20 && concepts
  38 #include <new>                  // for placement operator new
  39 #include <tuple>                // for tuple, make_tuple, make_from_tuple
  40 #include <bits/stl_construct.h> // construct_at
  41 #include <bits/stl_pair.h>      // pair
  42
  43 namespace std _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46
  47   template<typename _Tp>
  48     concept _Std_pair = __is_pair<remove_cv_t<_Tp>>;
  49
  50 /** @addtogroup allocators
  51  *  @{
  52  */
  53   template<typename _Tp, typename _Alloc, typename... _Args>
  54     constexpr auto
  55     uses_allocator_construction_args(const _Alloc& __a,
  56                                      _Args&&... __args) noexcept
  57     requires (! _Std_pair<_Tp>)
  58     {
  59       if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
  60         {
  61           if constexpr (is_constructible_v<_Tp, allocator_arg_t,
  62                                            const _Alloc&, _Args...>)
  63             {
  64               return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
  65                   allocator_arg, __a, std::forward<_Args>(__args)...);
  66             }
  67           else
  68             {
  69               static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
  70                   "construction with an allocator must be possible"
  71                   " if uses_allocator is true");
  72
  73               return tuple<_Args&&..., const _Alloc&>(
  74                   std::forward<_Args>(__args)..., __a);
  75             }
  76         }
  77       else
  78         {
  79           static_assert(is_constructible_v<_Tp, _Args...>);
  80
  81           return tuple<_Args&&...>(std::forward<_Args>(__args)...);
  82         }
  83     }
  84
  85   template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
  86     constexpr auto
  87     uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
  88                                      _Tuple1&& __x, _Tuple2&& __y) noexcept;
  89
  90   template<_Std_pair _Tp, typename _Alloc>
  91     constexpr auto
  92     uses_allocator_construction_args(const _Alloc&) noexcept;
  93
  94   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
  95     constexpr auto
  96     uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
  97
  98   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
  99     constexpr auto
 100     uses_allocator_construction_args(const _Alloc&,
 101                                      const pair<_Up, _Vp>&) noexcept;
 102
 103   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 104     constexpr auto
 105     uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
 106
 107 #if __cplusplus > 202002L
 108   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 109     constexpr auto
 110     uses_allocator_construction_args(const _Alloc&,
 111                                      pair<_Up, _Vp>&) noexcept;
 112
 113   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 114     constexpr auto
 115     uses_allocator_construction_args(const _Alloc&, const pair<_Up, _Vp>&&) noexcept;
 116 #endif // C++23
 117
 118   template<_Std_pair _Tp, typename _Alloc, typename _Tuple1, typename _Tuple2>
 119     constexpr auto
 120     uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
 121                                      _Tuple1&& __x, _Tuple2&& __y) noexcept
 122     {
 123       using _Tp1 = typename _Tp::first_type;
 124       using _Tp2 = typename _Tp::second_type;
 125
 126       return std::make_tuple(piecewise_construct,
 127           std::apply([&__a](auto&&... __args1) {
 128               return std::uses_allocator_construction_args<_Tp1>(
 129                   __a, std::forward<decltype(__args1)>(__args1)...);
 130           }, std::forward<_Tuple1>(__x)),
 131           std::apply([&__a](auto&&... __args2) {
 132               return std::uses_allocator_construction_args<_Tp2>(
 133                   __a, std::forward<decltype(__args2)>(__args2)...);
 134           }, std::forward<_Tuple2>(__y)));
 135     }
 136
 137   template<_Std_pair _Tp, typename _Alloc>
 138     constexpr auto
 139     uses_allocator_construction_args(const _Alloc& __a) noexcept
 140     {
 141       using _Tp1 = typename _Tp::first_type;
 142       using _Tp2 = typename _Tp::second_type;
 143
 144       return std::make_tuple(piecewise_construct,
 145           std::uses_allocator_construction_args<_Tp1>(__a),
 146           std::uses_allocator_construction_args<_Tp2>(__a));
 147     }
 148
 149   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 150     constexpr auto
 151     uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
 152       noexcept
 153     {
 154       using _Tp1 = typename _Tp::first_type;
 155       using _Tp2 = typename _Tp::second_type;
 156
 157       return std::make_tuple(piecewise_construct,
 158           std::uses_allocator_construction_args<_Tp1>(__a,
 159             std::forward<_Up>(__u)),
 160           std::uses_allocator_construction_args<_Tp2>(__a,
 161             std::forward<_Vp>(__v)));
 162     }
 163
 164   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 165     constexpr auto
 166     uses_allocator_construction_args(const _Alloc& __a,
 167                                      const pair<_Up, _Vp>& __pr) noexcept
 168     {
 169       using _Tp1 = typename _Tp::first_type;
 170       using _Tp2 = typename _Tp::second_type;
 171
 172       return std::make_tuple(piecewise_construct,
 173           std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
 174           std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
 175     }
 176
 177   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 178     constexpr auto
 179     uses_allocator_construction_args(const _Alloc& __a,
 180                                      pair<_Up, _Vp>&& __pr) noexcept
 181     {
 182       using _Tp1 = typename _Tp::first_type;
 183       using _Tp2 = typename _Tp::second_type;
 184
 185       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 186       // 3527. uses_allocator_construction_args handles rvalue pairs
 187       // of rvalue references incorrectly
 188       return std::make_tuple(piecewise_construct,
 189           std::uses_allocator_construction_args<_Tp1>(__a,
 190             std::get<0>(std::move(__pr))),
 191           std::uses_allocator_construction_args<_Tp2>(__a,
 192             std::get<1>(std::move(__pr))));
 193     }
 194
 195 #if __cplusplus > 202002L
 196   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 197     constexpr auto
 198     uses_allocator_construction_args(const _Alloc& __a,
 199                                      pair<_Up, _Vp>& __pr) noexcept
 200     {
 201       using _Tp1 = typename _Tp::first_type;
 202       using _Tp2 = typename _Tp::second_type;
 203
 204       return std::make_tuple(piecewise_construct,
 205           std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
 206           std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
 207     }
 208
 209   template<_Std_pair _Tp, typename _Alloc, typename _Up, typename _Vp>
 210     constexpr auto
 211     uses_allocator_construction_args(const _Alloc& __a,
 212                                      const pair<_Up, _Vp>&& __pr) noexcept
 213     {
 214       using _Tp1 = typename _Tp::first_type;
 215       using _Tp2 = typename _Tp::second_type;
 216
 217       return std::make_tuple(piecewise_construct,
 218           std::uses_allocator_construction_args<_Tp1>(__a,
 219             std::get<0>(std::move(__pr))),
 220           std::uses_allocator_construction_args<_Tp2>(__a,
 221             std::get<1>(std::move(__pr))));
 222     }
 223 #endif // C++23
 224
 225   template<typename _Tp, typename _Alloc, typename... _Args>
 226     constexpr _Tp
 227     make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
 228     {
 229       return std::make_from_tuple<_Tp>(
 230           std::uses_allocator_construction_args<_Tp>(__a,
 231             std::forward<_Args>(__args)...));
 232     }
 233
 234   template<typename _Tp, typename _Alloc, typename... _Args>
 235     constexpr _Tp*
 236     uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
 237                                             _Args&&... __args)
 238     {
 239       return std::apply([&](auto&&... __xs) {
 240         return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
 241       }, std::uses_allocator_construction_args<_Tp>(__a,
 242         std::forward<_Args>(__args)...));
 243     }
 244 /// @}
 245 _GLIBCXX_END_NAMESPACE_VERSION
 246 } // namespace std
 247 #endif // __glibcxx_make_obj_using_allocator
 248 #endif // _USES_ALLOCATOR_ARGS