# stl_iterator_base_types.h

Go to the documentation of this file.

    00001 // Types used in iterator implementation -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
    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 _ITERATOR_BASE_TYPES_H
    00065 #define _ITERATOR_BASE_TYPES_H 1
    00066
    00067 #pragma GCC system_header
    00068
    00069 _GLIBCXX_BEGIN_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
    00086   /// operations.
    00087   struct bidirectional_iterator_tag : public forward_iterator_tag {};
    00088   /// Random-access iterators support a superset of bidirectional iterator
    00089   /// operations.
    00090   struct random_access_iterator_tag : public bidirectional_iterator_tag {};
    00091   //@}
    00092
    00093
    00094   /**
    00095    *  @brief  Common %iterator class.
    00096    *
    00097    *  This class does nothing but define nested typedefs.  %Iterator classes
    00098    *  can inherit from this class to save some work.  The typedefs are then
    00099    *  used in specializations and overloading.
    00100    *
    00101    *  In particular, there are no default implementations of requirements
    00102    *  such as @c operator++ and the like.  (How could there be?)
    00103   */
    00104   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
    00105            typename _Pointer = _Tp*, typename _Reference = _Tp&>
    00106     struct iterator
    00107     {
    00108       /// One of the @link iterator_tags tag types@endlink.
    00109       typedef _Category  iterator_category;
    00110       /// The type "pointed to" by the iterator.
    00111       typedef _Tp        value_type;
    00112       /// Distance between iterators is represented as this type.
    00113       typedef _Distance  difference_type;
    00114       /// This type represents a pointer-to-value_type.
    00115       typedef _Pointer   pointer;
    00116       /// This type represents a reference-to-value_type.
    00117       typedef _Reference reference;
    00118     };
    00119
    00120   /**
    00121    *  This class does nothing but define nested typedefs.  The general
    00122    *  version simply "forwards" the nested typedefs from the Iterator
    00123    *  argument.  Specialized versions for pointers and pointers-to-const
    00124    *  provide tighter, more correct semantics.
    00125   */
    00126   template<typename _Iterator>
    00127     struct iterator_traits
    00128     {
    00129       typedef typename _Iterator::iterator_category iterator_category;
    00130       typedef typename _Iterator::value_type        value_type;
    00131       typedef typename _Iterator::difference_type   difference_type;
    00132       typedef typename _Iterator::pointer           pointer;
    00133       typedef typename _Iterator::reference         reference;
    00134     };
    00135
    00136   template<typename _Tp>
    00137     struct iterator_traits<_Tp*>
    00138     {
    00139       typedef random_access_iterator_tag iterator_category;
    00140       typedef _Tp                         value_type;
    00141       typedef ptrdiff_t                   difference_type;
    00142       typedef _Tp*                        pointer;
    00143       typedef _Tp&                        reference;
    00144     };
    00145
    00146   template<typename _Tp>
    00147     struct iterator_traits<const _Tp*>
    00148     {
    00149       typedef random_access_iterator_tag iterator_category;
    00150       typedef _Tp                         value_type;
    00151       typedef ptrdiff_t                   difference_type;
    00152       typedef const _Tp*                  pointer;
    00153       typedef const _Tp&                  reference;
    00154     };
    00155
    00156   /**
    00157    *  @if maint
    00158    *  This function is not a part of the C++ standard but is syntactic
    00159    *  sugar for internal library use only.
    00160    *  @endif
    00161   */
    00162   template<typename _Iter>
    00163     inline typename iterator_traits<_Iter>::iterator_category
    00164     __iterator_category(const _Iter&)
    00165     { return typename iterator_traits<_Iter>::iterator_category(); }
    00166
    00167 _GLIBCXX_END_NAMESPACE
    00168
    00169 #endif /* _ITERATOR_BASE_TYPES_H */
    00170