stl_iterator_base_types.h

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00001 // Types used in iterator implementation -*- 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  *
00028  * Copyright (c) 1994
00029  * Hewlett-Packard Company
00030  *
00031  * Permission to use, copy, modify, distribute and sell this software
00032  * and its documentation for any purpose is hereby granted without fee,
00033  * provided that the above copyright notice appear in all copies and
00034  * that both that copyright notice and this permission notice appear
00035  * in supporting documentation.  Hewlett-Packard Company makes no
00036  * representations about the suitability of this software for any
00037  * purpose.  It is provided "as is" without express or implied warranty.
00038  *
00039  *
00040  * Copyright (c) 1996-1998
00041  * Silicon Graphics Computer Systems, Inc.
00042  *
00043  * Permission to use, copy, modify, distribute and sell this software
00044  * and its documentation for any purpose is hereby granted without fee,
00045  * provided that the above copyright notice appear in all copies and
00046  * that both that copyright notice and this permission notice appear
00047  * in supporting documentation.  Silicon Graphics makes no
00048  * representations about the suitability of this software for any
00049  * purpose.  It is provided "as is" without express or implied warranty.
00050  */
00051 
00052 /** @file stl_iterator_base_types.h
00053  *  This is an internal header file, included by other library headers.
00054  *  You should not attempt to use it directly.
00055  *
00056  *  This file contains all of the general iterator-related utility types,
00057  *  such as iterator_traits and struct iterator.
00058  */
00059 
00060 #ifndef _STL_ITERATOR_BASE_TYPES_H
00061 #define _STL_ITERATOR_BASE_TYPES_H 1
00062 
00063 #pragma GCC system_header
00064 
00065 #include <bits/c++config.h>
00066 #include <cstddef>
00067 
00068 _GLIBCXX_BEGIN_NAMESPACE(std)
00069 
00070   /**
00071    *  @defgroup iterators Iterators
00072    *  These are empty types, used to distinguish different iterators.  The
00073    *  distinction is not made by what they contain, but simply by what they
00074    *  are.  Different underlying algorithms can then be used based on the
00075    *  different operations supported by different iterator types.
00076   */
00077   //@{ 
00078   ///  Marking input iterators.
00079   struct input_iterator_tag { };
00080   ///  Marking output iterators.
00081   struct output_iterator_tag { };
00082   /// Forward iterators support a superset of input iterator operations.
00083   struct forward_iterator_tag : public input_iterator_tag { };
00084   /// Bidirectional iterators support a superset of forward iterator
00085   /// operations.
00086   struct bidirectional_iterator_tag : public forward_iterator_tag { };
00087   /// Random-access iterators support a superset of bidirectional iterator
00088   /// operations.
00089   struct random_access_iterator_tag : public bidirectional_iterator_tag { };
00090 
00091 
00092   /**
00093    *  @brief  Common %iterator class.
00094    *
00095    *  This class does nothing but define nested typedefs.  %Iterator classes
00096    *  can inherit from this class to save some work.  The typedefs are then
00097    *  used in specializations and overloading.
00098    *
00099    *  In particular, there are no default implementations of requirements
00100    *  such as @c operator++ and the like.  (How could there be?)
00101   */
00102   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
00103            typename _Pointer = _Tp*, typename _Reference = _Tp&>
00104     struct iterator
00105     {
00106       /// One of the @link iterator_tags tag types@endlink.
00107       typedef _Category  iterator_category;
00108       /// The type "pointed to" by the iterator.
00109       typedef _Tp        value_type;
00110       /// Distance between iterators is represented as this type.
00111       typedef _Distance  difference_type;
00112       /// This type represents a pointer-to-value_type.
00113       typedef _Pointer   pointer;
00114       /// This type represents a reference-to-value_type.
00115       typedef _Reference reference;
00116     };
00117 
00118   /**
00119    *  This class does nothing but define nested typedefs.  The general
00120    *  version simply "forwards" the nested typedefs from the Iterator
00121    *  argument.  Specialized versions for pointers and pointers-to-const
00122    *  provide tighter, more correct semantics.
00123   */
00124   template<typename _Iterator>
00125     struct iterator_traits
00126     {
00127       typedef typename _Iterator::iterator_category iterator_category;
00128       typedef typename _Iterator::value_type        value_type;
00129       typedef typename _Iterator::difference_type   difference_type;
00130       typedef typename _Iterator::pointer           pointer;
00131       typedef typename _Iterator::reference         reference;
00132     };
00133 
00134   template<typename _Tp>
00135     struct iterator_traits<_Tp*>
00136     {
00137       typedef random_access_iterator_tag iterator_category;
00138       typedef _Tp                         value_type;
00139       typedef ptrdiff_t                   difference_type;
00140       typedef _Tp*                        pointer;
00141       typedef _Tp&                        reference;
00142     };
00143 
00144   template<typename _Tp>
00145     struct iterator_traits<const _Tp*>
00146     {
00147       typedef random_access_iterator_tag iterator_category;
00148       typedef _Tp                         value_type;
00149       typedef ptrdiff_t                   difference_type;
00150       typedef const _Tp*                  pointer;
00151       typedef const _Tp&                  reference;
00152     };
00153 
00154   /**
00155    *  This function is not a part of the C++ standard but is syntactic
00156    *  sugar for internal library use only.
00157   */
00158   template<typename _Iter>
00159     inline typename iterator_traits<_Iter>::iterator_category
00160     __iterator_category(const _Iter&)
00161     { return typename iterator_traits<_Iter>::iterator_category(); }
00162 
00163   //@}
00164 
00165 _GLIBCXX_END_NAMESPACE
00166 
00167 #endif /* _STL_ITERATOR_BASE_TYPES_H */
00168 

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