1 // Guarded Allocation -*- C++ -*- 2 3 // Copyright (C) 2014-2022 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 /// @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