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       1                 :            : // Guarded Allocation -*- C++ -*-
       2                 :            : 
       3                 :            : // Copyright (C) 2014-2019 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                 :         18 :       __allocated_ptr(_Alloc& __a, pointer __ptr) noexcept
      53                 :         18 :       : _M_alloc(std::__addressof(__a)), _M_ptr(__ptr)
      54                 :         18 :       { }
      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                 :         18 :       ~__allocated_ptr()
      71                 :            :       {
      72         [ -  + ]:         18 :         if (_M_ptr != nullptr)
      73                 :          0 :           std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
      74                 :         18 :       }
      75                 :            : 
      76                 :            :       /// Release ownership of the owned pointer
      77                 :            :       __allocated_ptr&
      78                 :         18 :       operator=(std::nullptr_t) noexcept
      79                 :            :       {
      80                 :         18 :         _M_ptr = nullptr;
      81                 :         18 :         return *this;
      82                 :            :       }
      83                 :            : 
      84                 :            :       /// Get the address that the owned pointer refers to.
      85                 :            :       value_type* get() { return std::__to_address(_M_ptr); }
      86                 :            : 
      87                 :            :     private:
      88                 :            :       _Alloc* _M_alloc;
      89                 :            :       pointer _M_ptr;
      90                 :            :     };
      91                 :            : 
      92                 :            :   /// Allocate space for a single object using __a
      93                 :            :   template<typename _Alloc>
      94                 :            :     __allocated_ptr<_Alloc>
      95                 :            :     __allocate_guarded(_Alloc& __a)
      96                 :            :     {
      97                 :            :       return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) };
      98                 :            :     }
      99                 :            : 
     100                 :            : _GLIBCXX_END_NAMESPACE_VERSION
     101                 :            : } // namespace std
     102                 :            : 
     103                 :            : #endif
     104                 :            : #endif