1 // Uses-allocator Construction -*- C++ -*- 2 3 // Copyright (C) 2010-2015 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 34 namespace std _GLIBCXX_VISIBILITY(default) 35 { 36 _GLIBCXX_BEGIN_NAMESPACE_VERSION 37 38 /// [allocator.tag] 39 struct allocator_arg_t { }; 40 41 constexpr allocator_arg_t allocator_arg = allocator_arg_t(); 42 43 template<typename _Tp, typename _Alloc, typename = __void_t<>> 44 struct __uses_allocator_helper 45 : false_type { }; 46 47 template<typename _Tp, typename _Alloc> 48 struct __uses_allocator_helper<_Tp, _Alloc, 49 __void_t<typename _Tp::allocator_type>> 50 : is_convertible<_Alloc, typename _Tp::allocator_type>::type 51 { }; 52 53 /// [allocator.uses.trait] 54 template<typename _Tp, typename _Alloc> 55 struct uses_allocator 56 : __uses_allocator_helper<_Tp, _Alloc>::type 57 { }; 58 59 struct __uses_alloc_base { }; 60 61 struct __uses_alloc0 : __uses_alloc_base 62 { 63 struct _Sink { void operator=(const void*) { } } _M_a; 64 }; 65 66 template<typename _Alloc> 67 struct __uses_alloc1 : __uses_alloc_base { const _Alloc* _M_a; }; 68 69 template<typename _Alloc> 70 struct __uses_alloc2 : __uses_alloc_base { const _Alloc* _M_a; }; 71 72 template<bool, typename _Tp, typename _Alloc, typename... _Args> 73 struct __uses_alloc; 74 75 template<typename _Tp, typename _Alloc, typename... _Args> 76 struct __uses_alloc<true, _Tp, _Alloc, _Args...> 77 : conditional< 78 is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value, 79 __uses_alloc1<_Alloc>, 80 __uses_alloc2<_Alloc>>::type 81 { }; 82 83 template<typename _Tp, typename _Alloc, typename... _Args> 84 struct __uses_alloc<false, _Tp, _Alloc, _Args...> 85 : __uses_alloc0 { }; 86 87 template<typename _Tp, typename _Alloc, typename... _Args> 88 using __uses_alloc_t = 89 __uses_alloc<uses_allocator<_Tp, _Alloc>::value, _Tp, _Alloc, _Args...>; 90 91 template<typename _Tp, typename _Alloc, typename... _Args> 92 inline __uses_alloc_t<_Tp, _Alloc, _Args...> 93 __use_alloc(const _Alloc& __a) 94 { 95 __uses_alloc_t<_Tp, _Alloc, _Args...> __ret; 96 __ret._M_a = &__a; 97 return __ret; 98 } 99 100 _GLIBCXX_END_NAMESPACE_VERSION 101 } // namespace std 102 103 #endif 104 #endif 105