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(std::is_nothrow_constructible<_Up, _Args...>::value)
146 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
147
148 template<typename _Up>
149 void
150 destroy(_Up* __p)
151 noexcept(std::is_nothrow_destructible<_Up>::value)
152 { __p->~_Up(); }
153#else
154 // _GLIBCXX_RESOLVE_LIB_DEFECTS
155 // 402. wrong new expression in [some_] allocator::construct
156 void
157 construct(pointer __p, const _Tp& __val)
158 { ::new((void *)__p) _Tp(__val); }
159
160 void
161 destroy(pointer __p) { __p->~_Tp(); }
162#endif
163
164 template<typename _Up>
165 friend bool
166 operator==(const new_allocator&, const new_allocator<_Up>&)
167 _GLIBCXX_NOTHROW
168 { return true; }
169
170 template<typename _Up>
171 friend bool
172 operator!=(const new_allocator&, const new_allocator<_Up>&)
173 _GLIBCXX_NOTHROW
174 { return false; }
175 };
176
177_GLIBCXX_END_NAMESPACE_VERSION
178} // namespace
179
180#endif
181