allocator.h

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00001 // Allocators -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
00004 // 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 allocator.h
00040  *  This is an internal header file, included by other library headers.
00041  *  You should not attempt to use it directly.
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 _GLIBCXX_BEGIN_NAMESPACE(std)
00051 
00052   /**
00053    * @defgroup allocators Allocators
00054    * @ingroup memory
00055    *
00056    * Classes encapsulating memory operations.
00057    */
00058 
00059   template<typename _Tp>
00060     class allocator;
00061 
00062   /// allocator<void> specialization.
00063   template<>
00064     class allocator<void>
00065     {
00066     public:
00067       typedef size_t      size_type;
00068       typedef ptrdiff_t   difference_type;
00069       typedef void*       pointer;
00070       typedef const void* const_pointer;
00071       typedef void        value_type;
00072 
00073       template<typename _Tp1>
00074         struct rebind
00075         { typedef allocator<_Tp1> other; };
00076     };
00077 
00078   /**
00079    * @brief  The "standard" allocator, as per [20.4].
00080    * @ingroup allocators
00081    *
00082    *  Further details:
00083    *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt04ch11.html
00084    */
00085   template<typename _Tp>
00086     class allocator: public __glibcxx_base_allocator<_Tp>
00087     {
00088    public:
00089       typedef size_t     size_type;
00090       typedef ptrdiff_t  difference_type;
00091       typedef _Tp*       pointer;
00092       typedef const _Tp* const_pointer;
00093       typedef _Tp&       reference;
00094       typedef const _Tp& const_reference;
00095       typedef _Tp        value_type;
00096 
00097       template<typename _Tp1>
00098         struct rebind
00099         { typedef allocator<_Tp1> other; };
00100 
00101       allocator() throw() { }
00102 
00103       allocator(const allocator& __a) throw()
00104       : __glibcxx_base_allocator<_Tp>(__a) { }
00105 
00106       template<typename _Tp1>
00107         allocator(const allocator<_Tp1>&) throw() { }
00108 
00109       ~allocator() throw() { }
00110 
00111       // Inherit everything else.
00112     };
00113 
00114   template<typename _T1, typename _T2>
00115     inline bool
00116     operator==(const allocator<_T1>&, const allocator<_T2>&)
00117     { return true; }
00118 
00119   template<typename _Tp>
00120     inline bool
00121     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
00122     { return true; }
00123 
00124   template<typename _T1, typename _T2>
00125     inline bool
00126     operator!=(const allocator<_T1>&, const allocator<_T2>&)
00127     { return false; }
00128 
00129   template<typename _Tp>
00130     inline bool
00131     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
00132     { return false; }
00133 
00134   // Inhibit implicit instantiations for required instantiations,
00135   // which are defined via explicit instantiations elsewhere.
00136   // NB: This syntax is a GNU extension.
00137 #if _GLIBCXX_EXTERN_TEMPLATE
00138   extern template class allocator<char>;
00139   extern template class allocator<wchar_t>;
00140 #endif
00141 
00142   // Undefine.
00143 #undef __glibcxx_base_allocator
00144 
00145   // To implement Option 3 of DR 431.
00146   template<typename _Alloc, bool = __is_empty(_Alloc)>
00147     struct __alloc_swap
00148     { static void _S_do_it(_Alloc&, _Alloc&) { } };
00149 
00150   template<typename _Alloc>
00151     struct __alloc_swap<_Alloc, false>
00152     {
00153       static void
00154       _S_do_it(_Alloc& __one, _Alloc& __two)
00155       {
00156     // Precondition: swappable allocators.
00157     if (__one != __two)
00158       swap(__one, __two);
00159       }
00160     };
00161 
00162   // Optimize for stateless allocators.
00163   template<typename _Alloc, bool = __is_empty(_Alloc)>
00164     struct __alloc_neq
00165     {
00166       static bool
00167       _S_do_it(const _Alloc&, const _Alloc&)
00168       { return false; }
00169     };
00170 
00171   template<typename _Alloc>
00172     struct __alloc_neq<_Alloc, false>
00173     {
00174       static bool
00175       _S_do_it(const _Alloc& __one, const _Alloc& __two)
00176       { return __one != __two; }
00177     };
00178 
00179 _GLIBCXX_END_NAMESPACE
00180 
00181 #endif

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