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

   1 // Allocators -*- 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 /*
  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 #define __cpp_lib_incomplete_container_elements 201505
  53 #if __cplusplus >= 201103L
  54 # define __cpp_lib_allocator_is_always_equal 201411
  55 #endif
  56
  57 namespace std _GLIBCXX_VISIBILITY(default)
  58 {
  59 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  60
  61   /**
  62    *  @addtogroup allocators
  63    *  @{
  64    */
  65
  66   /// allocator<void> specialization.
  67   template<>
  68     class allocator<void>
  69     {
  70     public:
  71       typedef size_t      size_type;
  72       typedef ptrdiff_t   difference_type;
  73       typedef void*       pointer;
  74       typedef const void* const_pointer;
  75       typedef void        value_type;
  76
  77       template<typename _Tp1>
  78         struct rebind
  79         { typedef allocator<_Tp1> other; };
  80
  81 #if __cplusplus >= 201103L
  82       // _GLIBCXX_RESOLVE_LIB_DEFECTS
  83       // 2103. std::allocator propagate_on_container_move_assignment
  84       typedef true_type propagate_on_container_move_assignment;
  85
  86       typedef true_type is_always_equal;
  87
  88       template<typename _Up, typename... _Args>
  89         void
  90         construct(_Up* __p, _Args&&... __args)
  91         { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
  92
  93       template<typename _Up>
  94         void
  95         destroy(_Up* __p) { __p->~_Up(); }
  96 #endif
  97     };
  98
  99   /**
 100    * @brief  The @a standard allocator, as per [20.4].
 101    *
 102    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
 103    *  for further details.
 104    *
 105    *  @tparam  _Tp  Type of allocated object.
 106    */
 107   template<typename _Tp>
 108     class allocator : public __allocator_base<_Tp>
 109     {
 110    public:
 111       typedef size_t     size_type;
 112       typedef ptrdiff_t  difference_type;
 113       typedef _Tp*       pointer;
 114       typedef const _Tp* const_pointer;
 115       typedef _Tp&       reference;
 116       typedef const _Tp& const_reference;
 117       typedef _Tp        value_type;
 118
 119       template<typename _Tp1>
 120         struct rebind
 121         { typedef allocator<_Tp1> other; };
 122
 123 #if __cplusplus >= 201103L
 124       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 125       // 2103. std::allocator propagate_on_container_move_assignment
 126       typedef true_type propagate_on_container_move_assignment;
 127
 128       typedef true_type is_always_equal;
 129 #endif
 130
 131       // _GLIBCXX_RESOLVE_LIB_DEFECTS
 132       // 3035. std::allocator's constructors should be constexpr
 133       _GLIBCXX20_CONSTEXPR
 134       allocator() _GLIBCXX_NOTHROW { }
 135
 136       _GLIBCXX20_CONSTEXPR
 137       allocator(const allocator& __a) _GLIBCXX_NOTHROW
 138       : __allocator_base<_Tp>(__a) { }
 139
 140 #if __cplusplus >= 201103L
 141       // Avoid implicit deprecation.
 142       allocator& operator=(const allocator&) = default;
 143 #endif
 144
 145       template<typename _Tp1>
 146         _GLIBCXX20_CONSTEXPR
 147         allocator(const allocator<_Tp1>&) _GLIBCXX_NOTHROW { }
 148
 149       ~allocator() _GLIBCXX_NOTHROW { }
 150
 151       // Inherit everything else.
 152     };
 153
 154   template<typename _T1, typename _T2>
 155     inline bool
 156     operator==(const allocator<_T1>&, const allocator<_T2>&)
 157     _GLIBCXX_NOTHROW
 158     { return true; }
 159
 160   template<typename _Tp>
 161     inline bool
 162     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
 163     _GLIBCXX_NOTHROW
 164     { return true; }
 165
 166   template<typename _T1, typename _T2>
 167     inline bool
 168     operator!=(const allocator<_T1>&, const allocator<_T2>&)
 169     _GLIBCXX_NOTHROW
 170     { return false; }
 171
 172   template<typename _Tp>
 173     inline bool
 174     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
 175     _GLIBCXX_NOTHROW
 176     { return false; }
 177
 178   // Invalid allocator<cv T> partial specializations.
 179   // allocator_traits::rebind_alloc can be used to form a valid allocator type.
 180   template<typename _Tp>
 181     class allocator<const _Tp>
 182     {
 183     public:
 184       typedef _Tp value_type;
 185       template<typename _Up> allocator(const allocator<_Up>&) { }
 186     };
 187
 188   template<typename _Tp>
 189     class allocator<volatile _Tp>
 190     {
 191     public:
 192       typedef _Tp value_type;
 193       template<typename _Up> allocator(const allocator<_Up>&) { }
 194     };
 195
 196   template<typename _Tp>
 197     class allocator<const volatile _Tp>
 198     {
 199     public:
 200       typedef _Tp value_type;
 201       template<typename _Up> allocator(const allocator<_Up>&) { }
 202     };
 203
 204   /// @} group allocator
 205
 206   // Inhibit implicit instantiations for required instantiations,
 207   // which are defined via explicit instantiations elsewhere.
 208 #if _GLIBCXX_EXTERN_TEMPLATE
 209   extern template class allocator<char>;
 210   extern template class allocator<wchar_t>;
 211 #endif
 212
 213   // Undefine.
 214 #undef __allocator_base
 215
 216   // To implement Option 3 of DR 431.
 217   template<typename _Alloc, bool = __is_empty(_Alloc)>
 218     struct __alloc_swap
 219     { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
 220
 221   template<typename _Alloc>
 222     struct __alloc_swap<_Alloc, false>
 223     {
 224       static void
 225       _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
 226       {
 227         // Precondition: swappable allocators.
 228         if (__one != __two)
 229           swap(__one, __two);
 230       }
 231     };
 232
 233   // Optimize for stateless allocators.
 234   template<typename _Alloc, bool = __is_empty(_Alloc)>
 235     struct __alloc_neq
 236     {
 237       static bool
 238       _S_do_it(const _Alloc&, const _Alloc&)
 239       { return false; }
 240     };
 241
 242   template<typename _Alloc>
 243     struct __alloc_neq<_Alloc, false>
 244     {
 245       static bool
 246       _S_do_it(const _Alloc& __one, const _Alloc& __two)
 247       { return __one != __two; }
 248     };
 249
 250 #if __cplusplus >= 201103L
 251   template<typename _Tp, bool
 252     = __or_<is_copy_constructible<typename _Tp::value_type>,
 253             is_nothrow_move_constructible<typename _Tp::value_type>>::value>
 254     struct __shrink_to_fit_aux
 255     { static bool _S_do_it(_Tp&) noexcept { return false; } };
 256
 257   template<typename _Tp>
 258     struct __shrink_to_fit_aux<_Tp, true>
 259     {
 260       static bool
 261       _S_do_it(_Tp& __c) noexcept
 262       {
 263 #if __cpp_exceptions
 264         try
 265           {
 266             _Tp(__make_move_if_noexcept_iterator(__c.begin()),
 267                 __make_move_if_noexcept_iterator(__c.end()),
 268                 __c.get_allocator()).swap(__c);
 269             return true;
 270           }
 271         catch(...)
 272           { return false; }
 273 #else
 274         return false;
 275 #endif
 276       }
 277     };
 278 #endif
 279
 280 _GLIBCXX_END_NAMESPACE_VERSION
 281 } // namespace std
 282
 283 #endif