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