1 // Uses-allocator Construction -*- C++ -*- 2 3 // Copyright (C) 2010-2016 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 constexpr allocator_arg_t allocator_arg = allocator_arg_t(); 49 50 template<typename _Tp, typename _Alloc, typename = __void_t<>> 51 struct __uses_allocator_helper 52 : false_type { }; 53 54 template<typename _Tp, typename _Alloc> 55 struct __uses_allocator_helper<_Tp, _Alloc, 56 __void_t<typename _Tp::allocator_type>> 57 : __is_erased_or_convertible<_Alloc, typename _Tp::allocator_type>::type 58 { }; 59 60 /// [allocator.uses.trait] 61 template<typename _Tp, typename _Alloc> 62 struct uses_allocator 63 : __uses_allocator_helper<_Tp, _Alloc>::type 64 { }; 65 66 struct __uses_alloc_base { }; 67 68 struct __uses_alloc0 : __uses_alloc_base 69 { 70 struct _Sink { void operator=(const void*) { } } _M_a; 71 }; 72 73 template<typename _Alloc> 74 struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; }; 75 76 template<typename _Alloc> 77 struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; }; 78 79 template<bool, typename _Tp, typename _Alloc, typename... _Args> 80 struct __uses_alloc; 81 82 template<typename _Tp, typename _Alloc, typename... _Args> 83 struct __uses_alloc<true, _Tp, _Alloc, _Args...> 84 : conditional< 85 is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value, 86 __uses_alloc1<_Alloc>, 87 __uses_alloc2<_Alloc>>::type 88 { 89 static_assert(__or_< 90 is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>, 91 is_constructible<_Tp, _Args..., _Alloc>>::value, "construction with" 92 " an allocator must be possible if uses_allocator is true"); 93 }; 94 95 template<typename _Tp, typename _Alloc, typename... _Args> 96 struct __uses_alloc<false, _Tp, _Alloc, _Args...> 97 : __uses_alloc0 { }; 98 99 template<typename _Tp, typename _Alloc, typename... _Args> 100 using __uses_alloc_t = 101 __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>; 102 103 template<typename _Tp, typename _Alloc, typename... _Args> 104 inline __uses_alloc_t<_Tp, _Alloc, _Args...> 105 __use_alloc(const _Alloc& __a) 106 { 107 __uses_alloc_t<_Tp, _Alloc, _Args...> __ret; 108 __ret._M_a = std::__addressof(__a); 109 return __ret; 110 } 111 112 _GLIBCXX_END_NAMESPACE_VERSION 113 } // namespace std 114 115 #endif 116 #endif 117