libstdc++
allocator.h
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00001 // Allocators -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2018 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /*
00026  * Copyright (c) 1996-1997
00027  * Silicon Graphics Computer Systems, Inc.
00028  *
00029  * Permission to use, copy, modify, distribute and sell this software
00030  * and its documentation for any purpose is hereby granted without fee,
00031  * provided that the above copyright notice appear in all copies and
00032  * that both that copyright notice and this permission notice appear
00033  * in supporting documentation.  Silicon Graphics makes no
00034  * representations about the suitability of this software for any
00035  * purpose.  It is provided "as is" without express or implied warranty.
00036  */
00037 
00038 /** @file bits/allocator.h
00039  *  This is an internal header file, included by other library headers.
00040  *  Do not attempt to use it directly. @headername{memory}
00041  */
00042 
00043 #ifndef _ALLOCATOR_H
00044 #define _ALLOCATOR_H 1
00045 
00046 #include <bits/c++allocator.h> // Define the base class to std::allocator.
00047 #include <bits/memoryfwd.h>
00048 #if __cplusplus >= 201103L
00049 #include <type_traits>
00050 #endif
00051 
00052 #define __cpp_lib_incomplete_container_elements 201505
00053 #if __cplusplus >= 201103L
00054 # define __cpp_lib_allocator_is_always_equal 201411
00055 #endif
00056 
00057 namespace std _GLIBCXX_VISIBILITY(default)
00058 {
00059 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00060 
00061   /**
00062    *  @addtogroup allocators
00063    *  @{
00064    */
00065 
00066   /// allocator<void> specialization.
00067   template<>
00068     class allocator<void>
00069     {
00070     public:
00071       typedef size_t      size_type;
00072       typedef ptrdiff_t   difference_type;
00073       typedef void*       pointer;
00074       typedef const void* const_pointer;
00075       typedef void        value_type;
00076 
00077       template<typename _Tp1>
00078         struct rebind
00079         { typedef allocator<_Tp1> other; };
00080 
00081 #if __cplusplus >= 201103L
00082       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00083       // 2103. std::allocator propagate_on_container_move_assignment
00084       typedef true_type propagate_on_container_move_assignment;
00085 
00086       typedef true_type is_always_equal;
00087 
00088       template<typename _Up, typename... _Args>
00089         void
00090         construct(_Up* __p, _Args&&... __args)
00091         { ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
00092 
00093       template<typename _Up>
00094         void
00095         destroy(_Up* __p) { __p->~_Up(); }
00096 #endif
00097     };
00098 
00099   /**
00100    * @brief  The @a standard allocator, as per [20.4].
00101    *
00102    *  See https://gcc.gnu.org/onlinedocs/libstdc++/manual/memory.html#std.util.memory.allocator
00103    *  for further details.
00104    *
00105    *  @tparam  _Tp  Type of allocated object.
00106    */
00107   template<typename _Tp>
00108     class allocator : public __allocator_base<_Tp>
00109     {
00110    public:
00111       typedef size_t     size_type;
00112       typedef ptrdiff_t  difference_type;
00113       typedef _Tp*       pointer;
00114       typedef const _Tp* const_pointer;
00115       typedef _Tp&       reference;
00116       typedef const _Tp& const_reference;
00117       typedef _Tp        value_type;
00118 
00119       template<typename _Tp1>
00120         struct rebind
00121         { typedef allocator<_Tp1> other; };
00122 
00123 #if __cplusplus >= 201103L
00124       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00125       // 2103. std::allocator propagate_on_container_move_assignment
00126       typedef true_type propagate_on_container_move_assignment;
00127 
00128       typedef true_type is_always_equal;
00129 #endif
00130 
00131       allocator() throw() { }
00132 
00133       allocator(const allocator& __a) throw()
00134       : __allocator_base<_Tp>(__a) { }
00135 
00136       template<typename _Tp1>
00137         allocator(const allocator<_Tp1>&) throw() { }
00138 
00139       ~allocator() throw() { }
00140 
00141       // Inherit everything else.
00142     };
00143 
00144   template<typename _T1, typename _T2>
00145     inline bool
00146     operator==(const allocator<_T1>&, const allocator<_T2>&)
00147     _GLIBCXX_USE_NOEXCEPT
00148     { return true; }
00149 
00150   template<typename _Tp>
00151     inline bool
00152     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
00153     _GLIBCXX_USE_NOEXCEPT
00154     { return true; }
00155 
00156   template<typename _T1, typename _T2>
00157     inline bool
00158     operator!=(const allocator<_T1>&, const allocator<_T2>&)
00159     _GLIBCXX_USE_NOEXCEPT
00160     { return false; }
00161 
00162   template<typename _Tp>
00163     inline bool
00164     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
00165     _GLIBCXX_USE_NOEXCEPT
00166     { return false; }
00167 
00168   // Invalid allocator<cv T> partial specializations.
00169   // allocator_traits::rebind_alloc can be used to form a valid allocator type.
00170   template<typename _Tp>
00171     class allocator<const _Tp>
00172     {
00173     public:
00174       typedef _Tp value_type;
00175       template<typename _Up> allocator(const allocator<_Up>&) { }
00176     };
00177 
00178   template<typename _Tp>
00179     class allocator<volatile _Tp>
00180     {
00181     public:
00182       typedef _Tp value_type;
00183       template<typename _Up> allocator(const allocator<_Up>&) { }
00184     };
00185 
00186   template<typename _Tp>
00187     class allocator<const volatile _Tp>
00188     {
00189     public:
00190       typedef _Tp value_type;
00191       template<typename _Up> allocator(const allocator<_Up>&) { }
00192     };
00193 
00194   /// @} group allocator
00195 
00196   // Inhibit implicit instantiations for required instantiations,
00197   // which are defined via explicit instantiations elsewhere.
00198 #if _GLIBCXX_EXTERN_TEMPLATE
00199   extern template class allocator<char>;
00200   extern template class allocator<wchar_t>;
00201 #endif
00202 
00203   // Undefine.
00204 #undef __allocator_base
00205 
00206   // To implement Option 3 of DR 431.
00207   template<typename _Alloc, bool = __is_empty(_Alloc)>
00208     struct __alloc_swap
00209     { static void _S_do_it(_Alloc&, _Alloc&) _GLIBCXX_NOEXCEPT { } };
00210 
00211   template<typename _Alloc>
00212     struct __alloc_swap<_Alloc, false>
00213     {
00214       static void
00215       _S_do_it(_Alloc& __one, _Alloc& __two) _GLIBCXX_NOEXCEPT
00216       {
00217         // Precondition: swappable allocators.
00218         if (__one != __two)
00219           swap(__one, __two);
00220       }
00221     };
00222 
00223   // Optimize for stateless allocators.
00224   template<typename _Alloc, bool = __is_empty(_Alloc)>
00225     struct __alloc_neq
00226     {
00227       static bool
00228       _S_do_it(const _Alloc&, const _Alloc&)
00229       { return false; }
00230     };
00231 
00232   template<typename _Alloc>
00233     struct __alloc_neq<_Alloc, false>
00234     {
00235       static bool
00236       _S_do_it(const _Alloc& __one, const _Alloc& __two)
00237       { return __one != __two; }
00238     };
00239 
00240 #if __cplusplus >= 201103L
00241   template<typename _Tp, bool
00242     = __or_<is_copy_constructible<typename _Tp::value_type>,
00243             is_nothrow_move_constructible<typename _Tp::value_type>>::value>
00244     struct __shrink_to_fit_aux
00245     { static bool _S_do_it(_Tp&) noexcept { return false; } };
00246 
00247   template<typename _Tp>
00248     struct __shrink_to_fit_aux<_Tp, true>
00249     {
00250       static bool
00251       _S_do_it(_Tp& __c) noexcept
00252       {
00253 #if __cpp_exceptions
00254         try
00255           {
00256             _Tp(__make_move_if_noexcept_iterator(__c.begin()),
00257                 __make_move_if_noexcept_iterator(__c.end()),
00258                 __c.get_allocator()).swap(__c);
00259             return true;
00260           }
00261         catch(...)
00262           { return false; }
00263 #else
00264         return false;
00265 #endif
00266       }
00267     };
00268 #endif
00269 
00270 _GLIBCXX_END_NAMESPACE_VERSION
00271 } // namespace std
00272 
00273 #endif