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       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      117397 :       __allocated_ptr(_Alloc& __a, pointer __ptr) noexcept
      54      117397 :       : _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      117397 :       ~__allocated_ptr()
      72             :       {
      73      117397 :         if (_M_ptr != nullptr)
      74           0 :           std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
      75      117397 :       }
      76             : 
      77             :       /// Release ownership of the owned pointer
      78             :       __allocated_ptr&
      79      117397 :       operator=(std::nullptr_t) noexcept
      80             :       {
      81      117397 :         _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