1// Guarded Allocation -*- C++ -*- 
2 
3// Copyright (C) 2014-2019 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