libstdc++
allocator.h
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00001 // Allocators -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010,
00004 // 2011 Free Software Foundation, Inc.
00005 //
00006 // This file is part of the GNU ISO C++ Library.  This library is free
00007 // software; you can redistribute it and/or modify it under the
00008 // terms of the GNU General Public License as published by the
00009 // Free Software Foundation; either version 3, or (at your option)
00010 // any later version.
00011 
00012 // This library is distributed in the hope that it will be useful,
00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015 // GNU General Public License for more details.
00016 
00017 // Under Section 7 of GPL version 3, you are granted additional
00018 // permissions described in the GCC Runtime Library Exception, version
00019 // 3.1, as published by the Free Software Foundation.
00020 
00021 // You should have received a copy of the GNU General Public License and
00022 // a copy of the GCC Runtime Library Exception along with this program;
00023 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00024 // <http://www.gnu.org/licenses/>.
00025 
00026 /*
00027  * Copyright (c) 1996-1997
00028  * Silicon Graphics Computer Systems, Inc.
00029  *
00030  * Permission to use, copy, modify, distribute and sell this software
00031  * and its documentation for any purpose is hereby granted without fee,
00032  * provided that the above copyright notice appear in all copies and
00033  * that both that copyright notice and this permission notice appear
00034  * in supporting documentation.  Silicon Graphics makes no
00035  * representations about the suitability of this software for any
00036  * purpose.  It is provided "as is" without express or implied warranty.
00037  */
00038 
00039 /** @file bits/allocator.h
00040  *  This is an internal header file, included by other library headers.
00041  *  Do not attempt to use it directly. @headername{memory}
00042  */
00043 
00044 #ifndef _ALLOCATOR_H
00045 #define _ALLOCATOR_H 1
00046 
00047 // Define the base class to std::allocator.
00048 #include <bits/c++allocator.h>
00049 
00050 namespace std _GLIBCXX_VISIBILITY(default)
00051 {
00052 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00053 
00054   /**
00055    * @defgroup allocators Allocators
00056    * @ingroup memory
00057    *
00058    * Classes encapsulating memory operations.
00059    *
00060    * @{
00061    */
00062 
00063   template<typename _Tp>
00064     class allocator;
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 
00082   /**
00083    * @brief  The @a standard allocator, as per [20.4].
00084    *
00085    *  See http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt04ch11.html
00086    *  for further details.
00087    */
00088   template<typename _Tp>
00089     class allocator: public __glibcxx_base_allocator<_Tp>
00090     {
00091    public:
00092       typedef size_t     size_type;
00093       typedef ptrdiff_t  difference_type;
00094       typedef _Tp*       pointer;
00095       typedef const _Tp* const_pointer;
00096       typedef _Tp&       reference;
00097       typedef const _Tp& const_reference;
00098       typedef _Tp        value_type;
00099 
00100       template<typename _Tp1>
00101         struct rebind
00102         { typedef allocator<_Tp1> other; };
00103 
00104       allocator() throw() { }
00105 
00106       allocator(const allocator& __a) throw()
00107       : __glibcxx_base_allocator<_Tp>(__a) { }
00108 
00109       template<typename _Tp1>
00110         allocator(const allocator<_Tp1>&) throw() { }
00111 
00112       ~allocator() throw() { }
00113 
00114       // Inherit everything else.
00115     };
00116 
00117   template<typename _T1, typename _T2>
00118     inline bool
00119     operator==(const allocator<_T1>&, const allocator<_T2>&)
00120     { return true; }
00121 
00122   template<typename _Tp>
00123     inline bool
00124     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
00125     { return true; }
00126 
00127   template<typename _T1, typename _T2>
00128     inline bool
00129     operator!=(const allocator<_T1>&, const allocator<_T2>&)
00130     { return false; }
00131 
00132   template<typename _Tp>
00133     inline bool
00134     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
00135     { return false; }
00136 
00137   /**
00138    * @}
00139    */
00140 
00141   // Inhibit implicit instantiations for required instantiations,
00142   // which are defined via explicit instantiations elsewhere.
00143 #if _GLIBCXX_EXTERN_TEMPLATE
00144   extern template class allocator<char>;
00145   extern template class allocator<wchar_t>;
00146 #endif
00147 
00148   // Undefine.
00149 #undef __glibcxx_base_allocator
00150 
00151   // To implement Option 3 of DR 431.
00152   template<typename _Alloc, bool = __is_empty(_Alloc)>
00153     struct __alloc_swap
00154     { static void _S_do_it(_Alloc&, _Alloc&) { } };
00155 
00156   template<typename _Alloc>
00157     struct __alloc_swap<_Alloc, false>
00158     {
00159       static void
00160       _S_do_it(_Alloc& __one, _Alloc& __two)
00161       {
00162     // Precondition: swappable allocators.
00163     if (__one != __two)
00164       swap(__one, __two);
00165       }
00166     };
00167 
00168   // Optimize for stateless allocators.
00169   template<typename _Alloc, bool = __is_empty(_Alloc)>
00170     struct __alloc_neq
00171     {
00172       static bool
00173       _S_do_it(const _Alloc&, const _Alloc&)
00174       { return false; }
00175     };
00176 
00177   template<typename _Alloc>
00178     struct __alloc_neq<_Alloc, false>
00179     {
00180       static bool
00181       _S_do_it(const _Alloc& __one, const _Alloc& __two)
00182       { return __one != __two; }
00183     };
00184 
00185 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00186   template<typename _Tp, bool
00187     = __or_<is_copy_constructible<typename _Tp::value_type>,
00188             is_nothrow_move_constructible<typename _Tp::value_type>>::value>
00189     struct __shrink_to_fit_aux
00190     { static bool _S_do_it(_Tp&) { return false; } };
00191 
00192   template<typename _Tp>
00193     struct __shrink_to_fit_aux<_Tp, true>
00194     {
00195       static bool
00196       _S_do_it(_Tp& __c)
00197       {
00198     __try
00199       {
00200         _Tp(__make_move_if_noexcept_iterator(__c.begin()),
00201         __make_move_if_noexcept_iterator(__c.end()),
00202         __c.get_allocator()).swap(__c);
00203         return true;
00204       }
00205     __catch(...)
00206       { return false; }
00207       }
00208     };
00209 
00210   // Declare uses_allocator so it can be specialized in <queue> etc.
00211   template<typename, typename>
00212     struct uses_allocator;
00213 #endif
00214 
00215 _GLIBCXX_END_NAMESPACE_VERSION
00216 } // namespace std
00217 
00218 #endif