libstdc++-v3/include/ext/new_allocator.h

   1 // Allocator that wraps operator new -*- C++ -*-
   2
   3 // Copyright (C) 2001-2018 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 ext/new_allocator.h
  26  *  This file is a GNU extension to the Standard C++ Library.
  27  */
  28
  29 #ifndef _NEW_ALLOCATOR_H
  30 #define _NEW_ALLOCATOR_H 1
  31
  32 #include <bits/c++config.h>
  33 #include <new>
  34 #include <bits/functexcept.h>
  35 #include <bits/move.h>
  36 #if __cplusplus >= 201103L
  37 #include <type_traits>
  38 #endif
  39
  40 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  41 {
  42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  43
  44   using std::size_t;
  45   using std::ptrdiff_t;
  46
  47   /**
  48    *  @brief  An allocator that uses global new, as per [20.4].
  49    *  @ingroup allocators
  50    *
  51    *  This is precisely the allocator defined in the C++ Standard.
  52    *    - all allocation calls operator new
  53    *    - all deallocation calls operator delete
  54    *
  55    *  @tparam  _Tp  Type of allocated object.
  56    */
  57   template<typename _Tp>
  58     class new_allocator
  59     {
  60     public:
  61       typedef size_t     size_type;
  62       typedef ptrdiff_t  difference_type;
  63       typedef _Tp*       pointer;
  64       typedef const _Tp* const_pointer;
  65       typedef _Tp&       reference;
  66       typedef const _Tp& const_reference;
  67       typedef _Tp        value_type;
  68
  69       template<typename _Tp1>
  70         struct rebind
  71         { typedef new_allocator<_Tp1> other; };
  72
  73 #if __cplusplus >= 201103L
  74       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  75       // 2103. propagate_on_container_move_assignment
  76       typedef std::true_type propagate_on_container_move_assignment;
  77 #endif
  78
  79       _GLIBCXX20_CONSTEXPR
  80       new_allocator() _GLIBCXX_USE_NOEXCEPT { }
  81
  82       _GLIBCXX20_CONSTEXPR
  83       new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
  84
  85       template<typename _Tp1>
  86         _GLIBCXX20_CONSTEXPR
  87         new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
  88
  89       ~new_allocator() _GLIBCXX_USE_NOEXCEPT { }
  90
  91       pointer
  92       address(reference __x) const _GLIBCXX_NOEXCEPT
  93       { return std::__addressof(__x); }
  94
  95       const_pointer
  96       address(const_reference __x) const _GLIBCXX_NOEXCEPT
  97       { return std::__addressof(__x); }
  98
  99       // NB: __n is permitted to be 0.  The C++ standard says nothing
 100       // about what the return value is when __n == 0.
 101       pointer
 102       allocate(size_type __n, const void* = static_cast<const void*>(0))
 103       {
 104         if (__n > this->max_size())
 105           std::__throw_bad_alloc();
 106
 107 #if __cpp_aligned_new
 108         if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
 109           {
 110             std::align_val_t __al = std::align_val_t(alignof(_Tp));
 111             return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al));
 112           }
 113 #endif
 114         return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
 115       }
 116
 117       // __p is not permitted to be a null pointer.
 118       void
 119       deallocate(pointer __p, size_type)
 120       {
 121 #if __cpp_aligned_new
 122         if (alignof(_Tp) > __STDCPP_DEFAULT_NEW_ALIGNMENT__)
 123           {
 124             ::operator delete(__p, std::align_val_t(alignof(_Tp)));
 125             return;
 126           }
 127 #endif
 128         ::operator delete(__p);
 129       }
 130
 131       size_type
 132       max_size() const _GLIBCXX_USE_NOEXCEPT
 133       { return size_t(-1) / sizeof(_Tp); }
 134
 135 #if __cplusplus >= 201103L
 136       template<typename _Up, typename... _Args>
 137         void
 138         construct(_Up* __p, _Args&&... __args)
 139         { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
 140
 141       template<typename _Up>
 142         void
 143         destroy(_Up* __p) { __p->~_Up(); }
 144 #else
 145       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 146       // 402. wrong new expression in [some_] allocator::construct
 147       void
 148       construct(pointer __p, const _Tp& __val)
 149       { ::new((void *)__p) _Tp(__val); }
 150
 151       void
 152       destroy(pointer __p) { __p->~_Tp(); }
 153 #endif
 154     };
 155
 156   template<typename _Tp>
 157     inline bool
 158     operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
 159     { return true; }
 160
 161   template<typename _Tp>
 162     inline bool
 163     operator!=(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
 164     { return false; }
 165
 166 _GLIBCXX_END_NAMESPACE_VERSION
 167 } // namespace
 168
 169 #endif