stl_iterator_base_types.h

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00001 // Types used in iterator implementation -*- C++ -*-
00002 
00003 // Copyright (C) 2001, 2002 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 2, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // You should have received a copy of the GNU General Public License along
00017 // with this library; see the file COPYING.  If not, write to the Free
00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
00019 // USA.
00020 
00021 // As a special exception, you may use this file as part of a free software
00022 // library without restriction.  Specifically, if other files instantiate
00023 // templates or use macros or inline functions from this file, or you compile
00024 // this file and link it with other files to produce an executable, this
00025 // file does not by itself cause the resulting executable to be covered by
00026 // the GNU General Public License.  This exception does not however
00027 // invalidate any other reasons why the executable file might be covered by
00028 // the GNU General Public License.
00029 
00030 /*
00031  *
00032  * Copyright (c) 1994
00033  * Hewlett-Packard Company
00034  *
00035  * Permission to use, copy, modify, distribute and sell this software
00036  * and its documentation for any purpose is hereby granted without fee,
00037  * provided that the above copyright notice appear in all copies and
00038  * that both that copyright notice and this permission notice appear
00039  * in supporting documentation.  Hewlett-Packard Company makes no
00040  * representations about the suitability of this software for any
00041  * purpose.  It is provided "as is" without express or implied warranty.
00042  *
00043  *
00044  * Copyright (c) 1996-1998
00045  * Silicon Graphics Computer Systems, Inc.
00046  *
00047  * Permission to use, copy, modify, distribute and sell this software
00048  * and its documentation for any purpose is hereby granted without fee,
00049  * provided that the above copyright notice appear in all copies and
00050  * that both that copyright notice and this permission notice appear
00051  * in supporting documentation.  Silicon Graphics makes no
00052  * representations about the suitability of this software for any
00053  * purpose.  It is provided "as is" without express or implied warranty.
00054  */
00055 
00056 /** @file stl_iterator_base_types.h
00057  *  This is an internal header file, included by other library headers.
00058  *  You should not attempt to use it directly.
00059  *
00060  *  This file contains all of the general iterator-related utility types,
00061  *  such as iterator_traits and struct iterator.
00062  */
00063 
00064 #ifndef __GLIBCPP_INTERNAL_ITERATOR_BASE_TYPES_H
00065 #define __GLIBCPP_INTERNAL_ITERATOR_BASE_TYPES_H
00066 
00067 #pragma GCC system_header
00068 
00069 namespace std
00070 {
00071   //@{
00072   /**
00073    *  @defgroup iterator_tags Iterator Tags
00074    *  These are empty types, used to distinguish different iterators.  The
00075    *  distinction is not made by what they contain, but simply by what they
00076    *  are.  Different underlying algorithms can then be used based on the
00077    *  different operations supporetd by different iterator types.
00078   */
00079   ///  Marking input iterators.
00080   struct input_iterator_tag {};
00081   ///  Marking output iterators.
00082   struct output_iterator_tag {};
00083   /// Forward iterators support a superset of input iterator operations.
00084   struct forward_iterator_tag : public input_iterator_tag {};
00085   /// Bidirectional iterators support a superset of forward iterator operations.
00086   struct bidirectional_iterator_tag : public forward_iterator_tag {};
00087   /// Random-access iterators support a superset of bidirectional iterator operations.
00088   struct random_access_iterator_tag : public bidirectional_iterator_tag {};
00089   //@}
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       typedef typename _Iterator::iterator_category iterator_category;
00127       typedef typename _Iterator::value_type        value_type;
00128       typedef typename _Iterator::difference_type   difference_type;
00129       typedef typename _Iterator::pointer           pointer;
00130       typedef typename _Iterator::reference         reference;
00131     };
00132 
00133   template<typename _Tp>
00134     struct iterator_traits<_Tp*> {
00135       typedef random_access_iterator_tag iterator_category;
00136       typedef _Tp                         value_type;
00137       typedef ptrdiff_t                   difference_type;
00138       typedef _Tp*                        pointer;
00139       typedef _Tp&                        reference;
00140     };
00141 
00142   template<typename _Tp>
00143     struct iterator_traits<const _Tp*> {
00144       typedef random_access_iterator_tag iterator_category;
00145       typedef _Tp                         value_type;
00146       typedef ptrdiff_t                   difference_type;
00147       typedef const _Tp*                  pointer;
00148       typedef const _Tp&                  reference;
00149     };
00150 
00151   /**
00152    *  @if maint
00153    *  This function is not a part of the C++ standard but is syntactic
00154    *  sugar for internal library use only.
00155    *  @endif
00156   */
00157   template<typename _Iter>
00158     inline typename iterator_traits<_Iter>::iterator_category
00159     __iterator_category(const _Iter&)
00160     { return typename iterator_traits<_Iter>::iterator_category(); }
00161 
00162 } // namespace std
00163 
00164 #endif /* __GLIBCPP_INTERNAL_ITERATOR_BASE_TYPES_H */
00165 

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