libstdc++-v3/include/bits/allocated_ptr.h

   1 // Guarded Allocation -*- C++ -*-
   2
   3 // Copyright (C) 2014 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(&__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(&__a), _M_ptr(pointer_traits<pointer>::pointer_to(*__ptr))
  61       { }
  62
  63       /// Transfer ownership of the owned pointer
  64       __allocated_ptr(__allocated_ptr&& __gd) noexcept
  65       : _M_alloc(__gd._M_alloc), _M_ptr(__gd._M_ptr)
  66       { __gd._M_ptr = nullptr; }
  67
  68       /// Deallocate the owned pointer
  69       ~__allocated_ptr()
  70       {
  71         if (_M_ptr != nullptr)
  72           std::allocator_traits<_Alloc>::deallocate(*_M_alloc, _M_ptr, 1);
  73       }
  74
  75       /// Release ownership of the owned pointer
  76       __allocated_ptr&
  77       operator=(std::nullptr_t) noexcept
  78       {
  79         _M_ptr = nullptr;
  80         return *this;
  81       }
  82
  83       /// Get the address that the owned pointer refers to.
  84       value_type* get() { return _S_raw_ptr(_M_ptr); }
  85
  86     private:
  87       value_type* _S_raw_ptr(value_type* __ptr) { return __ptr; }
  88
  89       template<typename _Ptr>
  90         auto _S_raw_ptr(_Ptr __ptr) -> decltype(_S_raw_ptr(__ptr.operator->()))
  91         { return _S_raw_ptr(__ptr.operator->()); }
  92
  93       _Alloc* _M_alloc;
  94       pointer _M_ptr;
  95     };
  96
  97   /// Allocate space for a single object using __a
  98   template<typename _Alloc>
  99     __allocated_ptr<_Alloc>
 100     __allocate_guarded(_Alloc& __a)
 101     {
 102       return { __a, std::allocator_traits<_Alloc>::allocate(__a, 1) };
 103     }
 104
 105 _GLIBCXX_END_NAMESPACE_VERSION
 106 } // namespace std
 107
 108 #endif
 109 #endif