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

   1 // Allocator that wraps operator new -*- C++ -*-
   2
   3 // Copyright (C) 2001-2016 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 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       new_allocator() _GLIBCXX_USE_NOEXCEPT { }
  80
  81       new_allocator(const new_allocator&) _GLIBCXX_USE_NOEXCEPT { }
  82
  83       template<typename _Tp1>
  84         new_allocator(const new_allocator<_Tp1>&) _GLIBCXX_USE_NOEXCEPT { }
  85
  86       ~new_allocator() _GLIBCXX_USE_NOEXCEPT { }
  87
  88       pointer
  89       address(reference __x) const _GLIBCXX_NOEXCEPT
  90       { return std::__addressof(__x); }
  91
  92       const_pointer
  93       address(const_reference __x) const _GLIBCXX_NOEXCEPT
  94       { return std::__addressof(__x); }
  95
  96       // NB: __n is permitted to be 0.  The C++ standard says nothing
  97       // about what the return value is when __n == 0.
  98       pointer
  99       allocate(size_type __n, const void* = 0)
 100       {
 101         if (__n > this->max_size())
 102           std::__throw_bad_alloc();
 103
 104         return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp)));
 105       }
 106
 107       // __p is not permitted to be a null pointer.
 108       void
 109       deallocate(pointer __p, size_type)
 110       { ::operator delete(__p); }
 111
 112       size_type
 113       max_size() const _GLIBCXX_USE_NOEXCEPT
 114       { return size_t(-1) / sizeof(_Tp); }
 115
 116 #if __cplusplus >= 201103L
 117       template<typename _Up, typename... _Args>
 118         void
 119         construct(_Up* __p, _Args&&... __args)
 120         { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
 121
 122       template<typename _Up>
 123         void
 124         destroy(_Up* __p) { __p->~_Up(); }
 125 #else
 126       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 127       // 402. wrong new expression in [some_] allocator::construct
 128       void
 129       construct(pointer __p, const _Tp& __val)
 130       { ::new((void *)__p) _Tp(__val); }
 131
 132       void
 133       destroy(pointer __p) { __p->~_Tp(); }
 134 #endif
 135     };
 136
 137   template<typename _Tp>
 138     inline bool
 139     operator==(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
 140     { return true; }
 141
 142   template<typename _Tp>
 143     inline bool
 144     operator!=(const new_allocator<_Tp>&, const new_allocator<_Tp>&)
 145     { return false; }
 146
 147 _GLIBCXX_END_NAMESPACE_VERSION
 148 } // namespace
 149
 150 #endif