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

   1 // Uses-allocator Construction -*- C++ -*-
   2
   3 // Copyright (C) 2010-2018 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   struct __erased_type { };
  40
  41   template<typename _Alloc, typename _Tp>
  42     using __is_erased_or_convertible
  43       = __or_<is_same<_Tp, __erased_type>, is_convertible<_Alloc, _Tp>>;
  44
  45   /// [allocator.tag]
  46   struct allocator_arg_t { explicit allocator_arg_t() = default; };
  47
  48   _GLIBCXX17_INLINE constexpr allocator_arg_t allocator_arg =
  49     allocator_arg_t();
  50
  51   template<typename _Tp, typename _Alloc, typename = __void_t<>>
  52     struct __uses_allocator_helper
  53     : false_type { };
  54
  55   template<typename _Tp, typename _Alloc>
  56     struct __uses_allocator_helper<_Tp, _Alloc,
  57                                    __void_t<typename _Tp::allocator_type>>
  58     : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type
  59     { };
  60
  61   /// [allocator.uses.trait]
  62   template<typename _Tp, typename _Alloc>
  63     struct uses_allocator
  64     : __uses_allocator_helper<_Tp, _Alloc>::type
  65     { };
  66
  67   struct __uses_alloc_base { };
  68
  69   struct __uses_alloc0 : __uses_alloc_base
  70   {
  71     struct _Sink { void operator=(const void*) { } } _M_a;
  72   };
  73
  74   template<typename _Alloc>
  75     struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; };
  76
  77   template<typename _Alloc>
  78     struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; };
  79
  80   template<bool, typename _Tp, typename _Alloc, typename... _Args>
  81     struct __uses_alloc;
  82
  83   template<typename _Tp, typename _Alloc, typename... _Args>
  84     struct __uses_alloc<true, _Tp, _Alloc, _Args...>
  85     : conditional<
  86         is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value,
  87         __uses_alloc1<_Alloc>,
  88         __uses_alloc2<_Alloc>>::type
  89     {
  90       static_assert(__or_<
  91           is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>,
  92           is_constructible<_Tp, _Args..., _Alloc>>::value, "construction with"
  93           " an allocator must be possible if uses_allocator is true");
  94     };
  95
  96   template<typename _Tp, typename _Alloc, typename... _Args>
  97     struct __uses_alloc<false, _Tp, _Alloc, _Args...>
  98     : __uses_alloc0 { };
  99
 100   template<typename _Tp, typename _Alloc, typename... _Args>
 101     using __uses_alloc_t =
 102       __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>;
 103
 104   template<typename _Tp, typename _Alloc, typename... _Args>
 105     inline __uses_alloc_t<_Tp, _Alloc, _Args...>
 106     __use_alloc(const _Alloc& __a)
 107     {
 108       __uses_alloc_t<_Tp, _Alloc, _Args...> __ret;
 109       __ret._M_a = std::__addressof(__a);
 110       return __ret;
 111     }
 112
 113   template<typename _Tp, typename _Alloc, typename... _Args>
 114     void
 115     __use_alloc(const _Alloc&&) = delete;
 116
 117 #if __cplusplus > 201402L
 118   template <typename _Tp, typename _Alloc>
 119     inline constexpr bool uses_allocator_v =
 120       uses_allocator<_Tp, _Alloc>::value;
 121 #endif // C++17
 122
 123   template<template<typename...> class _Predicate,
 124            typename _Tp, typename _Alloc, typename... _Args>
 125     struct __is_uses_allocator_predicate
 126     : conditional<uses_allocator<_Tp, _Alloc>::value,
 127       __or_<_Predicate<_Tp, allocator_arg_t, _Alloc, _Args...>,
 128             _Predicate<_Tp, _Args..., _Alloc>>,
 129       _Predicate<_Tp, _Args...>>::type { };
 130
 131   template<typename _Tp, typename _Alloc, typename... _Args>
 132     struct __is_uses_allocator_constructible
 133     : __is_uses_allocator_predicate<is_constructible, _Tp, _Alloc, _Args...>
 134     { };
 135
 136 #if __cplusplus >= 201402L
 137   template<typename _Tp, typename _Alloc, typename... _Args>
 138     _GLIBCXX17_INLINE constexpr bool __is_uses_allocator_constructible_v =
 139       __is_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
 140 #endif // C++14
 141
 142   template<typename _Tp, typename _Alloc, typename... _Args>
 143     struct __is_nothrow_uses_allocator_constructible
 144     : __is_uses_allocator_predicate<is_nothrow_constructible,
 145                                     _Tp, _Alloc, _Args...>
 146     { };
 147
 148
 149 #if __cplusplus >= 201402L
 150   template<typename _Tp, typename _Alloc, typename... _Args>
 151     _GLIBCXX17_INLINE constexpr bool
 152     __is_nothrow_uses_allocator_constructible_v =
 153       __is_nothrow_uses_allocator_constructible<_Tp, _Alloc, _Args...>::value;
 154 #endif // C++14
 155
 156   template<typename _Tp, typename... _Args>
 157     void __uses_allocator_construct_impl(__uses_alloc0 __a, _Tp* __ptr,
 158                                          _Args&&... __args)
 159     { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)...); }
 160
 161   template<typename _Tp, typename _Alloc, typename... _Args>
 162     void __uses_allocator_construct_impl(__uses_alloc1<_Alloc> __a, _Tp* __ptr,
 163                                          _Args&&... __args)
 164     {
 165       ::new ((void*)__ptr) _Tp(allocator_arg, *__a._M_a,
 166                                std::forward<_Args>(__args)...);
 167     }
 168
 169   template<typename _Tp, typename _Alloc, typename... _Args>
 170     void __uses_allocator_construct_impl(__uses_alloc2<_Alloc> __a, _Tp* __ptr,
 171                                          _Args&&... __args)
 172     { ::new ((void*)__ptr) _Tp(std::forward<_Args>(__args)..., *__a._M_a); }
 173
 174   template<typename _Tp, typename _Alloc, typename... _Args>
 175     void __uses_allocator_construct(const _Alloc& __a, _Tp* __ptr,
 176                                     _Args&&... __args)
 177     {
 178       __uses_allocator_construct_impl(__use_alloc<_Tp, _Alloc, _Args...>(__a),
 179                                       __ptr, std::forward<_Args>(__args)...);
 180     }
 181
 182 _GLIBCXX_END_NAMESPACE_VERSION
 183 } // namespace std
 184
 185 #endif
 186 #endif