libstdc++

new_allocator.h
Go to the documentation of this file.
1 // Allocator that wraps operator new -*- C++ -*-
2
3 // Copyright (C) 2001-2013 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 /** @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
40 namespace __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 new_allocator() _GLIBCXX_USE_NOEXCEPT { }
80
81 new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
82
83 template<typename _Tp1>
84 new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
85
86 ~new_allocator() _GLIBCXX_USE_NOEXCEPT { }
87
88 pointer
89 address(reference __x) const _GLIBCXX_NOEXCEPT
90 { return std::__addressof(__x); }
91
92 const_pointer
93 address(const_reference __x) const _GLIBCXX_NOEXCEPT
94 { return std::__addressof(__x); }
95
96 // NB: __n is permitted to be 0. The C++ standard says nothing
97 // about what the return value is when __n == 0.
98 pointer
99 allocate(size_type __n, const void* = 0)
100 {
101 if (__n > this->max_size())
102 std::__throw_bad_alloc();
103
104 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
105 }
106
107 // __p is not permitted to be a null pointer.
108 void
109 deallocate(pointer __p, size_type)
110 { ::operator delete(__p); }
111
112 size_type
113 max_size() const _GLIBCXX_USE_NOEXCEPT
114 { return size_t(-1) / sizeof(_Tp); }
115
116 #if __cplusplus >= 201103L
117 template<typename _Up, typename... _Args>
118 void
119 construct(_Up* __p, _Args&&... __args)
120 { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
121
122 template<typename _Up>
123 void
124 destroy(_Up* __p) { __p->~_Up(); }
125 #else
126 // _GLIBCXX_RESOLVE_LIB_DEFECTS
127 // 402. wrong new expression in [some_] allocator::construct
128 void
129 construct(pointer __p, const _Tp& __val)
130 { ::new((void *)__p) _Tp(__val); }
131
132 void
133 destroy(pointer __p) { __p->~_Tp(); }
134 #endif
135 };
136
137 template<typename _Tp>
138 inline bool
139 operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
140 { return true; }
141
142 template<typename _Tp>
143 inline bool
144 operator!=(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
145 { return false; }
146
147 _GLIBCXX_END_NAMESPACE_VERSION
148 } // namespace
149
150 #endif