1// Allocator that wraps operator new -*- C++ -*- 
2 
3// Copyright (C) 2001-2019 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/** @file ext/new_allocator.h 
26 * This file is a GNU extension to the Standard C++ Library. 
27 */ 
28 
29#ifndef _NEW_ALLOCATOR_H 
30#define _NEW_ALLOCATOR_H 1 
31 
32#include <bits/c++config.h> 
33#include <new> 
34#include <bits/functexcept.h> 
35#include <bits/move.h> 
36#if __cplusplus >= 201103L 
37#include <type_traits> 
38#endif 
39 
40namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 
41{ 
42_GLIBCXX_BEGIN_NAMESPACE_VERSION 
43 
44 using std::size_t; 
45 using std::ptrdiff_t; 
46 
47 /** 
48 * @brief An allocator that uses global new, as per [20.4]. 
49 * @ingroup allocators 
50 * 
51 * This is precisely the allocator defined in the C++ Standard. 
52 * - all allocation calls operator new 
53 * - all deallocation calls operator delete 
54 * 
55 * @tparam _Tp Type of allocated object. 
56 */ 
57 template<typename _Tp> 
58 class new_allocator 
59 { 
60 public: 
61 typedef size_t size_type; 
62 typedef ptrdiff_t difference_type; 
63 typedef _Tp* pointer; 
64 typedef const _Tp* const_pointer; 
65 typedef _Tp& reference; 
66 typedef const _Tp& const_reference; 
67 typedef _Tp value_type; 
68 
69 template<typename _Tp1> 
70 struct rebind 
71 { typedef new_allocator<_Tp1> other; }; 
72 
73#if __cplusplus >= 201103L 
74 // _GLIBCXX_RESOLVE_LIB_DEFECTS 
75 // 2103. propagate_on_container_move_assignment 
76 typedef std::true_type propagate_on_container_move_assignment; 
77#endif 
78 
79 _GLIBCXX20_CONSTEXPR 
80 new_allocator() _GLIBCXX_USE_NOEXCEPT { } 
81 
82 _GLIBCXX20_CONSTEXPR 
83 new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { } 
84 
85 template<typename _Tp1> 
86 _GLIBCXX20_CONSTEXPR 
87 new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { } 
88 
89 ~new_allocator() _GLIBCXX_USE_NOEXCEPT { } 
90 
91 pointer 
92 address(reference __x) const _GLIBCXX_NOEXCEPT 
93 { return std::__addressof(__x); } 
94 
95 const_pointer 
96 address(const_reference __x) const _GLIBCXX_NOEXCEPT 
97 { return std::__addressof(__x); } 
98 
99 // NB: __n is permitted to be 0. The C++ standard says nothing 
100 // about what the return value is when __n == 0. 
101 _GLIBCXX_NODISCARD pointer 
102 allocate(size_type __n, const void* = static_cast<const void*>(0)) 
103 { 
104 if (__n > this->max_size()) 
105 std::__throw_bad_alloc(); 
106 
107#if __cpp_aligned_new 
108 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 
109 { 
110 std::align_val_t __al = std::align_val_t(alignof(_Tp)); 
111 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al)); 
112 } 
113#endif 
114 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 
115 } 
116 
117 // __p is not permitted to be a null pointer. 
118 void 
119 deallocate(pointer __p, size_type) 
120 { 
121#if __cpp_aligned_new 
122 if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__) 
123 { 
124 ::operator delete(__p, std::align_val_t(alignof(_Tp))); 
125 return; 
126 } 
127#endif 
128 ::operator delete(__p); 
129 } 
130 
131 size_type 
132 max_size() const _GLIBCXX_USE_NOEXCEPT 
133 { 
134#if __PTRDIFF_MAX__ < __SIZE_MAX__ 
135 return size_t(__PTRDIFF_MAX__) / sizeof(_Tp); 
136#else 
137 return size_t(-1) / sizeof(_Tp); 
138#endif 
139 } 
140 
141#if __cplusplus >= 201103L 
142 template<typename _Up, typename... _Args> 
143 void 
144 construct(_Up* __p, _Args&&... __args) 
145 noexcept(noexcept(::new((void *)__p) 
146 _Up(std::forward<_Args>(__args)...))) 
147 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); } 
148 
149 template<typename _Up> 
150 void 
151 destroy(_Up* __p) 
152 noexcept(noexcept( __p->~_Up())) 
153 { __p->~_Up(); } 
154#else 
155 // _GLIBCXX_RESOLVE_LIB_DEFECTS 
156 // 402. wrong new expression in [some_] allocator::construct 
157 void 
158 construct(pointer __p, const _Tp& __val) 
159 { ::new((void *)__p) _Tp(__val); } 
160 
161 void 
162 destroy(pointer __p) { __p->~_Tp(); } 
163#endif 
164 
165 template<typename _Up> 
166 friend bool 
167 operator==(const new_allocator&, const new_allocator<_Up>&) 
168 _GLIBCXX_NOTHROW 
169 { return true; } 
170 
171 template<typename _Up> 
172 friend bool 
173 operator!=(const new_allocator&, const new_allocator<_Up>&) 
174 _GLIBCXX_NOTHROW 
175 { return false; } 
176 }; 
177 
178_GLIBCXX_END_NAMESPACE_VERSION 
179} // namespace 
180 
181#endif 
182