1 // <extptr_allocator.h> -*- C++ -*- 2 3 // Copyright (C) 2008-2013 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 /** 26 * @file ext/extptr_allocator.h 27 * This file is a GNU extension to the Standard C++ Library. 28 * 29 * @author Bob Walters 30 * 31 * An example allocator which uses an alternative pointer type from 32 * bits/pointer.h. Supports test cases which confirm container support 33 * for alternative pointers. 34 */ 35 36 #ifndef _EXTPTR_ALLOCATOR_H 37 #define _EXTPTR_ALLOCATOR_H 1 38 39 #include <memory> 40 #include <ext/numeric_traits.h> 41 #include <ext/pointer.h> 42 43 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 44 { 45 _GLIBCXX_BEGIN_NAMESPACE_VERSION 46 47 /** 48 * @brief An example allocator which uses a non-standard pointer type. 49 * @ingroup allocators 50 * 51 * This allocator specifies that containers use a 'relative pointer' as it's 52 * pointer type. (See ext/pointer.h) Memory allocation in this example 53 * is still performed using std::allocator. 54 */ 55 template<typename _Tp> 56 class _ExtPtr_allocator 57 { 58 public: 59 typedef std::size_t size_type; 60 typedef std::ptrdiff_t difference_type; 61 62 // Note the non-standard pointer types. 63 typedef _Pointer_adapter<_Relative_pointer_impl<_Tp> > pointer; 64 typedef _Pointer_adapter<_Relative_pointer_impl<const _Tp> > 65 const_pointer; 66 67 typedef _Tp& reference; 68 typedef const _Tp& const_reference; 69 typedef _Tp value_type; 70 71 template<typename _Up> 72 struct rebind 73 { typedef _ExtPtr_allocator<_Up> other; }; 74 75 _ExtPtr_allocator() _GLIBCXX_USE_NOEXCEPT 76 : _M_real_alloc() { } 77 78 _ExtPtr_allocator(const _ExtPtr_allocator& __rarg) _GLIBCXX_USE_NOEXCEPT 79 : _M_real_alloc(__rarg._M_real_alloc) { } 80 81 template<typename _Up> 82 _ExtPtr_allocator(const _ExtPtr_allocator<_Up>& __rarg) 83 _GLIBCXX_USE_NOEXCEPT 84 : _M_real_alloc(__rarg._M_getUnderlyingImp()) { } 85 86 ~_ExtPtr_allocator() _GLIBCXX_USE_NOEXCEPT 87 { } 88 89 pointer address(reference __x) const _GLIBCXX_NOEXCEPT 90 { return std::__addressof(__x); } 91 92 const_pointer address(const_reference __x) const _GLIBCXX_NOEXCEPT 93 { return std::__addressof(__x); } 94 95 pointer allocate(size_type __n, void* __hint = 0) 96 { return _M_real_alloc.allocate(__n,__hint); } 97 98 void deallocate(pointer __p, size_type __n) 99 { _M_real_alloc.deallocate(__p.get(), __n); } 100 101 size_type max_size() const _GLIBCXX_USE_NOEXCEPT 102 { return __numeric_traits<size_type>::__max / sizeof(_Tp); } 103 104 #if __cplusplus >= 201103L 105 template<typename _Up, typename... _Args> 106 void 107 construct(_Up* __p, _Args&&... __args) 108 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 109 110 template<typename... _Args> 111 void 112 construct(pointer __p, _Args&&... __args) 113 { construct(__p.get(), std::forward<_Args>(__args)...); } 114 115 template<typename _Up> 116 void 117 destroy(_Up* __p) 118 { __p->~_Up(); } 119 120 void destroy(pointer __p) 121 { destroy(__p.get()); } 122 123 #else 124 125 void construct(pointer __p, const _Tp& __val) 126 { ::new(__p.get()) _Tp(__val); } 127 128 void destroy(pointer __p) 129 { __p->~_Tp(); } 130 #endif 131 132 template<typename _Up> 133 inline bool 134 operator==(const _ExtPtr_allocator<_Up>& __rarg) 135 { return _M_real_alloc == __rarg._M_getUnderlyingImp(); } 136 137 inline bool 138 operator==(const _ExtPtr_allocator& __rarg) 139 { return _M_real_alloc == __rarg._M_real_alloc; } 140 141 template<typename _Up> 142 inline bool 143 operator!=(const _ExtPtr_allocator<_Up>& __rarg) 144 { return _M_real_alloc != __rarg._M_getUnderlyingImp(); } 145 146 inline bool 147 operator!=(const _ExtPtr_allocator& __rarg) 148 { return _M_real_alloc != __rarg._M_real_alloc; } 149 150 template<typename _Up> 151 inline friend void 152 swap(_ExtPtr_allocator<_Up>&, _ExtPtr_allocator<_Up>&); 153 154 // A method specific to this implementation. 155 const std::allocator<_Tp>& 156 _M_getUnderlyingImp() const 157 { return _M_real_alloc; } 158 159 private: 160 std::allocator<_Tp> _M_real_alloc; 161 }; 162 163 // _ExtPtr_allocator<void> specialization. 164 template<> 165 class _ExtPtr_allocator<void> 166 { 167 public: 168 typedef std::size_t size_type; 169 typedef std::ptrdiff_t difference_type; 170 typedef void value_type; 171 172 // Note the non-standard pointer types 173 typedef _Pointer_adapter<_Relative_pointer_impl<void> > pointer; 174 typedef _Pointer_adapter<_Relative_pointer_impl<const void> > 175 const_pointer; 176 177 template<typename _Up> 178 struct rebind 179 { typedef _ExtPtr_allocator<_Up> other; }; 180 181 private: 182 std::allocator<void> _M_real_alloc; 183 }; 184 185 template<typename _Tp> 186 inline void 187 swap(_ExtPtr_allocator<_Tp>& __larg, _ExtPtr_allocator<_Tp>& __rarg) 188 { 189 std::allocator<_Tp> __tmp( __rarg._M_real_alloc ); 190 __rarg._M_real_alloc = __larg._M_real_alloc; 191 __larg._M_real_alloc = __tmp; 192 } 193 194 _GLIBCXX_END_NAMESPACE_VERSION 195 } // namespace 196 197 #endif /* _EXTPTR_ALLOCATOR_H */ 198
