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

   1 // Allocator that wraps "C" malloc -*- C++ -*-
   2
   3 // Copyright (C) 2001-2015 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 <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 malloc.
  49    *  @ingroup allocators
  50    *
  51    *  This is precisely the allocator defined in the C++ Standard.
  52    *    - all allocation calls malloc
  53    *    - all deallocation calls free
  54    */
  55   template<typename _Tp>
  56     class malloc_allocator
  57     {
  58     public:
  59       typedef size_t     size_type;
  60       typedef ptrdiff_t  difference_type;
  61       typedef _Tp*       pointer;
  62       typedef const _Tp* const_pointer;
  63       typedef _Tp&       reference;
  64       typedef const _Tp& const_reference;
  65       typedef _Tp        value_type;
  66
  67       template<typename _Tp1>
  68         struct rebind
  69         { typedef malloc_allocator<_Tp1> other; };
  70
  71 #if __cplusplus >= 201103L
  72       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  73       // 2103. propagate_on_container_move_assignment
  74       typedef std::true_type propagate_on_container_move_assignment;
  75 #endif
  76
  77       malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
  78
  79       malloc_allocator(const malloc_allocator&) _GLIBCXX_USE_NOEXCEPT { }
  80
  81       template<typename _Tp1>
  82         malloc_allocator(const malloc_allocator<_Tp1>&)
  83         _GLIBCXX_USE_NOEXCEPT { }
  84
  85       ~malloc_allocator() _GLIBCXX_USE_NOEXCEPT { }
  86
  87       pointer
  88       address(reference __x) const _GLIBCXX_NOEXCEPT
  89       { return std::__addressof(__x); }
  90
  91       const_pointer
  92       address(const_reference __x) const _GLIBCXX_NOEXCEPT
  93       { return std::__addressof(__x); }
  94
  95       // NB: __n is permitted to be 0.  The C++ standard says nothing
  96       // about what the return value is when __n == 0.
  97       pointer
  98       allocate(size_type __n, const void* = 0)
  99       {
 100         if (__n > this->max_size())
 101           std::__throw_bad_alloc();
 102
 103         pointer __ret = static_cast<_Tp*>(std::malloc(__n * sizeof(_Tp)));
 104         if (!__ret)
 105           std::__throw_bad_alloc();
 106         return __ret;
 107       }
 108
 109       // __p is not permitted to be a null pointer.
 110       void
 111       deallocate(pointer __p, size_type)
 112       { std::free(static_cast<void*>(__p)); }
 113
 114       size_type
 115       max_size() const _GLIBCXX_USE_NOEXCEPT
 116       { return size_t(-1) / sizeof(_Tp); }
 117
 118 #if __cplusplus >= 201103L
 119       template<typename _Up, typename... _Args>
 120         void
 121         construct(_Up* __p, _Args&&... __args)
 122         { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
 123
 124       template<typename _Up>
 125         void
 126         destroy(_Up* __p) { __p->~_Up(); }
 127 #else
 128       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 129       // 402. wrong new expression in [some_] allocator::construct
 130       void
 131       construct(pointer __p, const _Tp& __val)
 132       { ::new((void *)__p) value_type(__val); }
 133
 134       void
 135       destroy(pointer __p) { __p->~_Tp(); }
 136 #endif
 137     };
 138
 139   template<typename _Tp>
 140     inline bool
 141     operator==(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
 142     { return true; }
 143
 144   template<typename _Tp>
 145     inline bool
 146     operator!=(const malloc_allocator<_Tp>&, const malloc_allocator<_Tp>&)
 147     { return false; }
 148
 149 _GLIBCXX_END_NAMESPACE_VERSION
 150 } // namespace
 151
 152 #endif