1// Guarded Allocation -*- C++ -*-
2
3// Copyright (C) 2014-2024 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
40namespace std _GLIBCXX_VISIBILITY(default)
41{
42_GLIBCXX_BEGIN_NAMESPACE_VERSION
43/// @cond undocumented
44
45 /// Non-standard RAII type for managing pointers obtained from allocators.
46 template<typename _Alloc>
47 struct __allocated_ptr
48 {
49 using pointer = typename allocator_traits<_Alloc>::pointer;
50 using value_type = typename allocator_traits<_Alloc>::value_type;
51
52 /// Take ownership of __ptr
53 __allocated_ptr(_Alloc& __a, pointer __ptr) noexcept
54 : _M_alloc(std::__addressof(__a)), _M_ptr(__ptr)
55 { }
56
57 /// Convert __ptr to allocator's pointer type and take ownership of it
58 template<typename _Ptr,
59 typename _Req = _Require<is_same<_Ptr, value_type*>>>
60 __allocated_ptr(_Alloc& __a, _Ptr __ptr)
61 : _M_alloc(std::__addressof(__a)),
62 _M_ptr(pointer_traits<pointer>::pointer_to(*__ptr))
63 { }
64
65 /// Transfer ownership of the owned pointer
66 __allocated_ptr(__allocated_ptr&& __gd) noexcept
67 : _M_alloc(__gd._M_alloc), _M_ptr(__gd._M_ptr)
68 { __gd._M_ptr = nullptr; }
69
70 /// Deallocate the owned pointer
71 ~__allocated_ptr()
72 {
73 if (_M_ptr != nullptr)
74 std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
75 }
76
77 /// Release ownership of the owned pointer
78 __allocated_ptr&
79 operator=(std::nullptr_t) noexcept
80 {
81 _M_ptr = nullptr;
82 return *this;
83 }
84
85 /// Get the address that the owned pointer refers to.
86 value_type* get() { return std::__to_address(_M_ptr); }
87
88 private:
89 _Alloc* _M_alloc;
90 pointer _M_ptr;
91 };
92
93 /// Allocate space for a single object using __a
94 template<typename _Alloc>
95 __allocated_ptr<_Alloc>
96 __allocate_guarded(_Alloc& __a)
97 {
98 return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) };
99 }
100
101/// @endcond
102_GLIBCXX_END_NAMESPACE_VERSION
103} // namespace std
104
105#endif
106#endif
107