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

   1 // Uses-allocator Construction -*- C++ -*-
   2
   3 // Copyright (C) 2010-2019 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 #ifndef _USES_ALLOCATOR_H
  26 #define _USES_ALLOCATOR_H 1
  27
  28 #if __cplusplus < 201103L
  29 # include <bits/c++0x_warning.h>
  30 #else
  31
  32 #include <type_traits>
  33 #include <bits/move.h>
  34
  35 namespace std _GLIBCXX_VISIBILITY(default)
  36 {
  37 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  38
  39   // This is used for std::experimental::erased_type from Library Fundamentals.
  40   struct __erased_type { };
  41
  42   // This also supports the "type-erased allocator" protocol from the
  43   // Library Fundamentals TS, where allocator_type is erased_type.
  44   // The second condition will always be false for types not using the TS.
  45   template<typename _Alloc, typename _Tp>
  46     using __is_erased_or_convertible
  47       = __or_<is_convertible<_Alloc, _Tp>, is_same<_Tp, __erased_type>>;
  48
  49   /// [allocator.tag]
  50   struct allocator_arg_t { explicit allocator_arg_t() = default; };
  51
  52   _GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg =
  53     allocator_arg_t();
  54
  55   template<typename _Tp, typename _Alloc, typename = __void_t<>>
  56     struct __uses_allocator_helper
  57     : false_type { };
  58
  59   template<typename _Tp, typename _Alloc>
  60     struct __uses_allocator_helper<_Tp, _Alloc,
  61                                    __void_t<typename _Tp::allocator_type>>
  62     : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type
  63     { };
  64
  65   /// [allocator.uses.trait]
  66   template<typename _Tp, typename _Alloc>
  67     struct uses_allocator
  68     : __uses_allocator_helper<_Tp, _Alloc>::type
  69     { };
  70
  71   struct __uses_alloc_base { };
  72
  73   struct __uses_alloc0 : __uses_alloc_base
  74   {
  75     struct _Sink { void operator=(const void*) { } } _M_a;
  76   };
  77
  78   template<typename _Alloc>
  79     struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
  80
  81   template<typename _Alloc>
  82     struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
  83
  84   template<bool, typename _Tp, typename _Alloc, typename... _Args>
  85     struct __uses_alloc;
  86
  87   template<typename _Tp, typename _Alloc, typename... _Args>
  88     struct __uses_alloc<true, _Tp, _Alloc, _Args...>
  89     : conditional<
  90         is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>::value,
  91         __uses_alloc1<_Alloc>,
  92         __uses_alloc2<_Alloc>>::type
  93     {
  94       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  95       // 2586. Wrong value category used in scoped_allocator_adaptor::construct
  96       static_assert(__or_<
  97           is_constructible<_Tp, allocator_arg_t, const _Alloc&, _Args...>,
  98           is_constructible<_Tp, _Args..., const _Alloc&>>::value,
  99           "construction with an allocator must be possible"
 100           " if uses_allocator is true");
 101     };
 102
 103   template<typename _Tp, typename _Alloc, typename... _Args>
 104     struct __uses_alloc<false, _Tp, _Alloc, _Args...>
 105     : __uses_alloc0 { };
 106
 107   template<typename _Tp, typename _Alloc, typename... _Args>
 108     using __uses_alloc_t =
 109       __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>;
 110
 111   template<typename _Tp, typename _Alloc, typename... _Args>
 112     inline __uses_alloc_t<_Tp, _Alloc, _Args...>
 113     __use_alloc(const _Alloc& __a)
 114     {
 115       __uses_alloc_t<_Tp, _Alloc, _Args...> __ret;
 116       __ret._M_a = std::__addressof(__a);
 117       return __ret;
 118     }
 119
 120   template<typename _Tp, typename _Alloc, typename... _Args>
 121     void
 122     __use_alloc(const _Alloc&&) = delete;
 123
 124 #if __cplusplus > 201402L
 125   template <typename _Tp, typename _Alloc>
 126     inline constexpr bool uses_allocator_v =
 127       uses_allocator<_Tp, _Alloc>::value;
 128 #endif // C++17
 129
 130   template<template<typename...> class _Predicate,
 131            typename _Tp, typename _Alloc, typename... _Args>
 132     struct __is_uses_allocator_predicate
 133     : conditional<uses_allocator<_Tp, _Alloc>::value,
 134       __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>,
 135             _Predicate<_Tp, _Args..., _Alloc>>,
 136       _Predicate<_Tp, _Args...>>::type { };
 137
 138   template<typename _Tp, typename _Alloc, typename... _Args>
 139     struct __is_uses_allocator_constructible
 140     : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...>
 141     { };
 142
 143 #if __cplusplus >= 201402L
 144   template<typename _Tp, typename _Alloc, typename... _Args>
 145     _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v =
 146       __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
 147 #endif // C++14
 148
 149   template<typename _Tp, typename _Alloc, typename... _Args>
 150     struct __is_nothrow_uses_allocator_constructible
 151     : __is_uses_allocator_predicate<is_nothrow_constructible,
 152                                     _Tp, _Alloc, _Args...>
 153     { };
 154
 155
 156 #if __cplusplus >= 201402L
 157   template<typename _Tp, typename _Alloc, typename... _Args>
 158     _GLIBCXX17_INLINE constexpr bool
 159     __is_nothrow_uses_allocator_constructible_v =
 160       __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
 161 #endif // C++14
 162
 163   template<typename _Tp, typename... _Args>
 164     void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
 165                                          _Args&&... __args)
 166     { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); }
 167
 168   template<typename _Tp, typename _Alloc, typename... _Args>
 169     void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr,
 170                                          _Args&&... __args)
 171     {
 172       ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a,
 173                                std::forward<_Args>(__args)...);
 174     }
 175
 176   template<typename _Tp, typename _Alloc, typename... _Args>
 177     void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr,
 178                                          _Args&&... __args)
 179     { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); }
 180
 181   template<typename _Tp, typename _Alloc, typename... _Args>
 182     void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr,
 183                                     _Args&&... __args)
 184     {
 185       std::__uses_allocator_construct_impl(
 186           std::__use_alloc<_Tp, _Alloc, _Args...>(__a), __ptr,
 187           std::forward<_Args>(__args)...);
 188     }
 189
 190 _GLIBCXX_END_NAMESPACE_VERSION
 191 } // namespace std
 192
 193 #endif
 194 #endif