libstdc++
allocated_ptr.h
Go to the documentation of this file.
1 // Guarded Allocation -*- C++ -*-
2 
3 // Copyright (C) 2014-2020 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 bits/allocated_ptr.h
26  * This is an internal header file, included by other library headers.
27  * Do not attempt to use it directly. @headername{memory}
28  */
29 
30 #ifndef _ALLOCATED_PTR_H
31 #define _ALLOCATED_PTR_H 1
32 
33 #if __cplusplus < 201103L
34 # include <bits/c++0xwarning.h>
35 #else
36 # include <type_traits>
37 # include <bits/ptr_traits.h>
38 # include <bits/alloc_traits.h>
39 
40 namespace std _GLIBCXX_VISIBILITY(default)
41 {
42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
43 
44  /// Non-standard RAII type for managing pointers obtained from allocators.
45  template<typename _Alloc>
47  {
48  using pointer = typename allocator_traits<_Alloc>::pointer;
49  using value_type = typename allocator_traits<_Alloc>::value_type;
50 
51  /// Take ownership of __ptr
52  __allocated_ptr(_Alloc& __a, pointer __ptr) noexcept
53  : _M_alloc(std::__addressof(__a)), _M_ptr(__ptr)
54  { }
55 
56  /// Convert __ptr to allocator's pointer type and take ownership of it
57  template<typename _Ptr,
58  typename _Req = _Require<is_same<_Ptr, value_type*>>>
59  __allocated_ptr(_Alloc& __a, _Ptr __ptr)
60  : _M_alloc(std::__addressof(__a)),
61  _M_ptr(pointer_traits<pointer>::pointer_to(*__ptr))
62  { }
63 
64  /// Transfer ownership of the owned pointer
66  : _M_alloc(__gd._M_alloc), _M_ptr(__gd._M_ptr)
67  { __gd._M_ptr = nullptr; }
68 
69  /// Deallocate the owned pointer
71  {
72  if (_M_ptr != nullptr)
73  std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
74  }
75 
76  /// Release ownership of the owned pointer
78  operator=(std::nullptr_t) noexcept
79  {
80  _M_ptr = nullptr;
81  return *this;
82  }
83 
84  /// Get the address that the owned pointer refers to.
85  value_type* get() { return std::__to_address(_M_ptr); }
86 
87  private:
88  _Alloc* _M_alloc;
89  pointer _M_ptr;
90  };
91 
92  /// Allocate space for a single object using __a
93  template<typename _Alloc>
94  __allocated_ptr<_Alloc>
95  __allocate_guarded(_Alloc& __a)
96  {
97  return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) };
98  }
99 
100 _GLIBCXX_END_NAMESPACE_VERSION
101 } // namespace std
102 
103 #endif
104 #endif
constexpr _Tp * __addressof(_Tp &__r) noexcept
Same as C++11 std::addressof.
Definition: move.h:49
ISO C++ entities toplevel namespace is std.
__allocated_ptr< _Alloc > __allocate_guarded(_Alloc &__a)
Allocate space for a single object using __a.
Definition: allocated_ptr.h:95
__detected_or_t< value_type *, __pointer, _Alloc > pointer
The allocator's pointer type.
static constexpr pointer allocate(_Alloc &__a, size_type __n)
Allocate memory.
_Alloc::value_type value_type
The allocated type.
static constexpr void deallocate(_Alloc &__a, pointer __p, size_type __n)
Deallocate memory.
Non-standard RAII type for managing pointers obtained from allocators.
Definition: allocated_ptr.h:47
__allocated_ptr(__allocated_ptr &&__gd) noexcept
Transfer ownership of the owned pointer.
Definition: allocated_ptr.h:65
value_type * get()
Get the address that the owned pointer refers to.
Definition: allocated_ptr.h:85
__allocated_ptr(_Alloc &__a, _Ptr __ptr)
Convert __ptr to allocator's pointer type and take ownership of it.
Definition: allocated_ptr.h:59
__allocated_ptr(_Alloc &__a, pointer __ptr) noexcept
Take ownership of __ptr.
Definition: allocated_ptr.h:52
~__allocated_ptr()
Deallocate the owned pointer.
Definition: allocated_ptr.h:70
__allocated_ptr & operator=(std::nullptr_t) noexcept
Release ownership of the owned pointer.
Definition: allocated_ptr.h:78
Uniform interface to all pointer-like types.
Definition: ptr_traits.h:84