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

   1 // Allocators -*- C++ -*-
   2
   3 // Copyright (C) 2001-2014 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 /*
  26  * Copyright (c) 1996-1997
  27  * Silicon Graphics Computer Systems, Inc.
  28  *
  29  * Permission to use, copy, modify, distribute and sell this software
  30  * and its documentation for any purpose is hereby granted without fee,
  31  * provided that the above copyright notice appear in all copies and
  32  * that both that copyright notice and this permission notice appear
  33  * in supporting documentation.  Silicon Graphics makes no
  34  * representations about the suitability of this software for any
  35  * purpose.  It is provided "as is" without express or implied warranty.
  36  */
  37
  38 /** @file bits/allocator.h
  39  *  This is an internal header file, included by other library headers.
  40  *  Do not attempt to use it directly. @headername{memory}
  41  */
  42
  43 #ifndef _ALLOCATOR_H
  44 #define _ALLOCATOR_H 1
  45
  46 #include <bits/c++allocator.h> // Define the base class to std::allocator.
  47 #include <bits/memoryfwd.h>
  48 #if __cplusplus >= 201103L
  49 #include <type_traits>
  50 #endif
  51
  52 namespace std _GLIBCXX_VISIBILITY(default)
  53 {
  54 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  55
  56   /**
  57    *  @addtogroup allocators
  58    *  @{
  59    */
  60
  61   /// allocator<void> specialization.
  62   template<>
  63     class allocator<void>
  64     {
  65     public:
  66       typedef size_t      size_type;
  67       typedef ptrdiff_t   difference_type;
  68       typedef void*       pointer;
  69       typedef const void* const_pointer;
  70       typedef void        value_type;
  71
  72       template<typename _Tp1>
  73         struct rebind
  74         { typedef allocator<_Tp1> other; };
  75
  76 #if __cplusplus >= 201103L
  77       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  78       // 2103. std::allocator propagate_on_container_move_assignment
  79       typedef true_type propagate_on_container_move_assignment;
  80 #endif
  81     };
  82
  83   /**
  84    * @brief  The @a standard allocator, as per [20.4].
  85    *
  86    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
  87    *  for further details.
  88    *
  89    *  @tparam  _Tp  Type of allocated object.
  90    */
  91   template<typename _Tp>
  92     class allocator: public __allocator_base<_Tp>
  93     {
  94    public:
  95       typedef size_t     size_type;
  96       typedef ptrdiff_t  difference_type;
  97       typedef _Tp*       pointer;
  98       typedef const _Tp* const_pointer;
  99       typedef _Tp&       reference;
 100       typedef const _Tp& const_reference;
 101       typedef _Tp        value_type;
 102
 103       template<typename _Tp1>
 104         struct rebind
 105         { typedef allocator<_Tp1> other; };
 106
 107 #if __cplusplus >= 201103L
 108       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 109       // 2103. std::allocator propagate_on_container_move_assignment
 110       typedef true_type propagate_on_container_move_assignment;
 111 #endif
 112
 113       allocator() throw() { }
 114
 115       allocator(const allocator& __a) throw()
 116       : __allocator_base<_Tp>(__a) { }
 117
 118       template<typename _Tp1>
 119         allocator(const allocator<_Tp1>&) throw() { }
 120
 121       ~allocator() throw() { }
 122
 123       // Inherit everything else.
 124     };
 125
 126   template<typename _T1, typename _T2>
 127     inline bool
 128     operator==(const allocator<_T1>&, const allocator<_T2>&)
 129     _GLIBCXX_USE_NOEXCEPT
 130     { return true; }
 131
 132   template<typename _Tp>
 133     inline bool
 134     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
 135     _GLIBCXX_USE_NOEXCEPT
 136     { return true; }
 137
 138   template<typename _T1, typename _T2>
 139     inline bool
 140     operator!=(const allocator<_T1>&, const allocator<_T2>&)
 141     _GLIBCXX_USE_NOEXCEPT
 142     { return false; }
 143
 144   template<typename _Tp>
 145     inline bool
 146     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
 147     _GLIBCXX_USE_NOEXCEPT
 148     { return false; }
 149
 150   /// @} group allocator
 151
 152   // Inhibit implicit instantiations for required instantiations,
 153   // which are defined via explicit instantiations elsewhere.
 154 #if _GLIBCXX_EXTERN_TEMPLATE
 155   extern template class allocator<char>;
 156   extern template class allocator<wchar_t>;
 157 #endif
 158
 159   // Undefine.
 160 #undef __allocator_base
 161
 162   // To implement Option 3 of DR 431.
 163   template<typename _Alloc, bool = __is_empty(_Alloc)>
 164     struct __alloc_swap
 165     { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
 166
 167   template<typename _Alloc>
 168     struct __alloc_swap<_Alloc, false>
 169     {
 170       static void
 171       _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
 172       {
 173         // Precondition: swappable allocators.
 174         if (__one != __two)
 175           swap(__one, __two);
 176       }
 177     };
 178
 179   // Optimize for stateless allocators.
 180   template<typename _Alloc, bool = __is_empty(_Alloc)>
 181     struct __alloc_neq
 182     {
 183       static bool
 184       _S_do_it(const _Alloc&, const _Alloc&)
 185       { return false; }
 186     };
 187
 188   template<typename _Alloc>
 189     struct __alloc_neq<_Alloc, false>
 190     {
 191       static bool
 192       _S_do_it(const _Alloc& __one, const _Alloc& __two)
 193       { return __one != __two; }
 194     };
 195
 196 #if __cplusplus >= 201103L
 197   template<typename _Tp, bool
 198     = __or_<is_copy_constructible<typename _Tp::value_type>,
 199             is_nothrow_move_constructible<typename _Tp::value_type>>::value>
 200     struct __shrink_to_fit_aux
 201     { static bool _S_do_it(_Tp&) noexcept { return false; } };
 202
 203   template<typename _Tp>
 204     struct __shrink_to_fit_aux<_Tp, true>
 205     {
 206       static bool
 207       _S_do_it(_Tp& __c) noexcept
 208       {
 209         __try
 210           {
 211             _Tp(__make_move_if_noexcept_iterator(__c.begin()),
 212                 __make_move_if_noexcept_iterator(__c.end()),
 213                 __c.get_allocator()).swap(__c);
 214             return true;
 215           }
 216         __catch(...)
 217           { return false; }
 218       }
 219     };
 220 #endif
 221
 222 _GLIBCXX_END_NAMESPACE_VERSION
 223 } // namespace std
 224
 225 #endif