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       1             : // Guarded Allocation -*- C++ -*-
       2             : 
       3             : // Copyright (C) 2014-2016 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           0 :       __allocated_ptr(_Alloc& __a, pointer __ptr) noexcept
      53           0 :       : _M_alloc(std::__addressof(__a)), _M_ptr(__ptr)
      54           0 :       { }
      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           0 :       ~__allocated_ptr()
      71             :       {
      72           0 :         if (_M_ptr != nullptr)
      73           0 :           std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
      74           0 :       }
      75             : 
      76             :       /// Release ownership of the owned pointer
      77             :       __allocated_ptr&
      78           0 :       operator=(std::nullptr_t) noexcept
      79             :       {
      80           0 :         _M_ptr = nullptr;
      81           0 :         return *this;
      82             :       }
      83             : 
      84             :       /// Get the address that the owned pointer refers to.
      85           0 :       value_type* get() { return _S_raw_ptr(_M_ptr); }
      86             : 
      87             :     private:
      88           0 :       value_type* _S_raw_ptr(value_type* __ptr) { return __ptr; }
      89             : 
      90             :       template<typename _Ptr>
      91             :         auto _S_raw_ptr(_Ptr __ptr) -> decltype(_S_raw_ptr(__ptr.operator->()))
      92             :         { return _S_raw_ptr(__ptr.operator->()); }
      93             : 
      94             :       _Alloc* _M_alloc;
      95             :       pointer _M_ptr;
      96             :     };
      97             : 
      98             :   /// Allocate space for a single object using __a
      99             :   template<typename _Alloc>
     100             :     __allocated_ptr<_Alloc>
     101           0 :     __allocate_guarded(_Alloc& __a)
     102             :     {
     103           0 :       return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) };
     104             :     }
     105             : 
     106             : _GLIBCXX_END_NAMESPACE_VERSION
     107             : } // namespace std
     108             : 
     109             : #endif
     110             : #endif