contrib/gcc-8.0/libstdc++-v3/include/ext/malloc_allocator.h

   1 // Allocator that wraps "C" malloc -*- 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/malloc_allocator.h
  26  *  This file is a GNU extension to the Standard C++ Library.
  27  */
  28
  29 #ifndef _MALLOC_ALLOCATOR_H
  30 #define _MALLOC_ALLOCATOR_H 1
  31
  32 #include <cstdlib>
  33 #include <cstddef>
  34 #include <new>
  35 #include <bits/functexcept.h>
  36 #include <bits/move.h>
  37 #if __cplusplus >= 201103L
  38 #include <type_traits>
  39 #endif
  40
  41 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
  42 {
  43 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  44
  45   using std::size_t;
  46   using std::ptrdiff_t;
  47
  48   /**
  49    *  @brief  An allocator that uses malloc.
  50    *  @ingroup allocators
  51    *
  52    *  This is precisely the allocator defined in the C++ Standard.
  53    *    - all allocation calls malloc
  54    *    - all deallocation calls free
  55    */
  56   template<typename _Tp>
  57     class malloc_allocator
  58     {
  59     public:
  60       typedef size_t     size_type;
  61       typedef ptrdiff_t  difference_type;
  62       typedef _Tp*       pointer;
  63       typedef const _Tp* const_pointer;
  64       typedef _Tp&       reference;
  65       typedef const _Tp& const_reference;
  66       typedef _Tp        value_type;
  67
  68       template<typename _Tp1>
  69         struct rebind
  70         { typedef malloc_allocator<_Tp1> other; };
  71
  72 #if __cplusplus >= 201103L
  73       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  74       // 2103. propagate_on_container_move_assignment
  75       typedef std::true_type propagate_on_container_move_assignment;
  76 #endif
  77
  78       malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
  79
  80       malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { }
  81
  82       template<typename _Tp1>
  83         malloc_allocator(const malloc_allocator<_Tp1>&)
  84         _GLIBCXX_USE_NOEXCEPT { }
  85
  86       ~malloc_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         pointer __ret = 0;
 105 #if __cpp_aligned_new
 106 #if __cplusplus > 201402L && _GLIBCXX_HAVE_ALIGNED_ALLOC
 107         if (alignof(_Tp) > alignof(std::max_align_t))
 108           {
 109             __ret = static_cast<_Tp*>(::aligned_alloc(alignof(_Tp),
 110                                                       __n * sizeof(_Tp)));
 111           }
 112 #else
 113 # define _GLIBCXX_CHECK_MALLOC_RESULT
 114 #endif
 115 #endif
 116         if (!__ret)
 117           __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
 118         if (!__ret)
 119           std::__throw_bad_alloc();
 120 #ifdef _GLIBCXX_CHECK_MALLOC_RESULT
 121 #undef _GLIBCXX_CHECK_MALLOC_RESULT
 122           if (reinterpret_cast<std::size_t>(__ret) % alignof(_Tp))
 123             {
 124               // Memory returned by malloc is not suitably aligned for _Tp.
 125               deallocate(__ret, __n);
 126               std::__throw_bad_alloc();
 127             }
 128 #endif
 129         return __ret;
 130       }
 131
 132       // __p is not permitted to be a null pointer.
 133       void
 134       deallocate(pointer __p, size_type)
 135       { std::free(static_cast<void*>(__p)); }
 136
 137       size_type
 138       max_size() const _GLIBCXX_USE_NOEXCEPT
 139       { return size_t(-1) / sizeof(_Tp); }
 140
 141 #if __cplusplus >= 201103L
 142       template<typename _Up, typename... _Args>
 143         void
 144         construct(_Up* __p, _Args&&... __args)
 145         { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
 146
 147       template<typename _Up>
 148         void
 149         destroy(_Up* __p) { __p->~_Up(); }
 150 #else
 151       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 152       // 402. wrong new expression in [some_] allocator::construct
 153       void
 154       construct(pointer __p, const _Tp& __val)
 155       { ::new((void *)__p) value_type(__val); }
 156
 157       void
 158       destroy(pointer __p) { __p->~_Tp(); }
 159 #endif
 160     };
 161
 162   template<typename _Tp>
 163     inline bool
 164     operator==(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
 165     { return true; }
 166
 167   template<typename _Tp>
 168     inline bool
 169     operator!=(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
 170     { return false; }
 171
 172 _GLIBCXX_END_NAMESPACE_VERSION
 173 } // namespace
 174
 175 #endif