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/// @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