allocator.h

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00001 // Allocators -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00051 #include <type_traits> // For _GLIBCXX_HAS_NESTED_TYPE
00052 #endif
00053 
00054 _GLIBCXX_BEGIN_NAMESPACE(std)
00055 
00056   /**
00057    * @defgroup allocators Allocators
00058    * @ingroup memory
00059    *
00060    * Classes encapsulating memory operations.
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    * @ingroup allocators
00085    *
00086    *  Further details:
00087    *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt04ch11.html
00088    */
00089   template<typename _Tp>
00090     class allocator: public __glibcxx_base_allocator<_Tp>
00091     {
00092    public:
00093       typedef size_t     size_type;
00094       typedef ptrdiff_t  difference_type;
00095       typedef _Tp*       pointer;
00096       typedef const _Tp* const_pointer;
00097       typedef _Tp&       reference;
00098       typedef const _Tp& const_reference;
00099       typedef _Tp        value_type;
00100 
00101       template<typename _Tp1>
00102         struct rebind
00103         { typedef allocator<_Tp1> other; };
00104 
00105       allocator() throw() { }
00106 
00107       allocator(const allocator& __a) throw()
00108       : __glibcxx_base_allocator<_Tp>(__a) { }
00109 
00110       template<typename _Tp1>
00111         allocator(const allocator<_Tp1>&) throw() { }
00112 
00113       ~allocator() throw() { }
00114 
00115       // Inherit everything else.
00116     };
00117 
00118   template<typename _T1, typename _T2>
00119     inline bool
00120     operator==(const allocator<_T1>&, const allocator<_T2>&)
00121     { return true; }
00122 
00123   template<typename _Tp>
00124     inline bool
00125     operator==(const allocator<_Tp>&, const allocator<_Tp>&)
00126     { return true; }
00127 
00128   template<typename _T1, typename _T2>
00129     inline bool
00130     operator!=(const allocator<_T1>&, const allocator<_T2>&)
00131     { return false; }
00132 
00133   template<typename _Tp>
00134     inline bool
00135     operator!=(const allocator<_Tp>&, const allocator<_Tp>&)
00136     { return false; }
00137 
00138   // Inhibit implicit instantiations for required instantiations,
00139   // which are defined via explicit instantiations elsewhere.
00140   // NB: This syntax is a GNU extension.
00141 #if _GLIBCXX_EXTERN_TEMPLATE
00142   extern template class allocator<char>;
00143   extern template class allocator<wchar_t>;
00144 #endif
00145 
00146   // Undefine.
00147 #undef __glibcxx_base_allocator
00148 
00149   // To implement Option 3 of DR 431.
00150   template<typename _Alloc, bool = __is_empty(_Alloc)>
00151     struct __alloc_swap
00152     { static void _S_do_it(_Alloc&, _Alloc&) { } };
00153 
00154   template<typename _Alloc>
00155     struct __alloc_swap<_Alloc, false>
00156     {
00157       static void
00158       _S_do_it(_Alloc& __one, _Alloc& __two)
00159       {
00160     // Precondition: swappable allocators.
00161     if (__one != __two)
00162       swap(__one, __two);
00163       }
00164     };
00165 
00166   // Optimize for stateless allocators.
00167   template<typename _Alloc, bool = __is_empty(_Alloc)>
00168     struct __alloc_neq
00169     {
00170       static bool
00171       _S_do_it(const _Alloc&, const _Alloc&)
00172       { return false; }
00173     };
00174 
00175   template<typename _Alloc>
00176     struct __alloc_neq<_Alloc, false>
00177     {
00178       static bool
00179       _S_do_it(const _Alloc& __one, const _Alloc& __two)
00180       { return __one != __two; }
00181     };
00182 
00183 #ifdef __GXX_EXPERIMENTAL_CXX0X__
00184   // A very basic implementation for now.  In general we have to wait for
00185   // the availability of the infrastructure described in N2983:  we should
00186   // try when either T has a move constructor which cannot throw or T is
00187   // CopyContructible.
00188   // NB: This code doesn't properly belong here, we should find a more
00189   // suited place common to std::vector and std::deque.
00190   template<typename _Tp,
00191        bool = __has_trivial_copy(typename _Tp::value_type)>
00192     struct __shrink_to_fit
00193     { static void _S_do_it(_Tp&) { } };
00194 
00195   template<typename _Tp>
00196     struct __shrink_to_fit<_Tp, true>
00197     {
00198       static void
00199       _S_do_it(_Tp& __v)
00200       {
00201     __try
00202       { _Tp(__v).swap(__v); }
00203     __catch(...) { }
00204       }
00205     };
00206 
00207 
00208   /// [allocator.tag]
00209   struct allocator_arg_t { };
00210 
00211   static const allocator_arg_t allocator_arg = allocator_arg_t();
00212 
00213 _GLIBCXX_HAS_NESTED_TYPE(allocator_type)
00214 
00215   template<typename _Tp, typename _Alloc,
00216        bool = __has_allocator_type<_Tp>::value>
00217     struct __uses_allocator_helper
00218     : public false_type { };
00219 
00220   template<typename _Tp, typename _Alloc>
00221     struct __uses_allocator_helper<_Tp, _Alloc, true>
00222     : public integral_constant<bool, is_convertible<_Alloc,
00223                      typename _Tp::allocator_type>::value>
00224     { };
00225 
00226   /// [allocator.uses.trait]
00227   template<typename _Tp, typename _Alloc>
00228     struct uses_allocator
00229     : public integral_constant<bool,
00230                    __uses_allocator_helper<_Tp, _Alloc>::value>
00231     { };
00232 
00233 #endif
00234 
00235 _GLIBCXX_END_NAMESPACE
00236 
00237 #endif