1 // Guarded Allocation -*- C++ -*- 2 3 // Copyright (C) 2014-2017 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 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 _S_raw_ptr(_M_ptr); } 86 87 private: 88 static value_type* _S_raw_ptr(value_type* __ptr) { return __ptr; } 89 90 template<typename _Ptr> 91 static auto 92 _S_raw_ptr(_Ptr __ptr) -> decltype(_S_raw_ptr(__ptr.operator->())) 93 { return _S_raw_ptr(__ptr.operator->()); } 94 95 _Alloc* _M_alloc; 96 pointer _M_ptr; 97 }; 98 99 /// Allocate space for a single object using __a 100 template<typename _Alloc> 101 __allocated_ptr<_Alloc> 102 __allocate_guarded(_Alloc& __a) 103 { 104 return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) }; 105 } 106 107 _GLIBCXX_END_NAMESPACE_VERSION 108 } // namespace std 109 110 #endif 111 #endif 112