1// Guarded Allocation -*- C++ -*-
2
3// Copyright (C) 2014-2021 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
44 /// Non-standard RAII type for managing pointers obtained from allocators.
45 template<typename _Alloc>
46 struct __allocated_ptr
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
65 __allocated_ptr(__allocated_ptr&& __gd) noexcept
66 : _M_alloc(__gd._M_alloc), _M_ptr(__gd._M_ptr)
67 { __gd._M_ptr = nullptr; }
68
69 /// Deallocate the owned pointer
70 ~__allocated_ptr()
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
77 __allocated_ptr&
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
105