# 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