# 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
    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 2, 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 // You should have received a copy of the GNU General Public License along
    00018 // with this library; see the file COPYING.  If not, write to the Free
    00019 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
    00020 // USA.
    00021
    00022 // As a special exception, you may use this file as part of a free software
    00023 // library without restriction.  Specifically, if other files instantiate
    00024 // templates or use macros or inline functions from this file, or you compile
    00025 // this file and link it with other files to produce an executable, this
    00026 // file does not by itself cause the resulting executable to be covered by
    00027 // the GNU General Public License.  This exception does not however
    00028 // invalidate any other reasons why the executable file might be covered by
    00029 // the GNU General Public License.
    00030
    00031 /*
    00032  *
    00033  * Copyright (c) 1994
    00034  * Hewlett-Packard Company
    00035  *
    00036  * Permission to use, copy, modify, distribute and sell this software
    00037  * and its documentation for any purpose is hereby granted without fee,
    00038  * provided that the above copyright notice appear in all copies and
    00039  * that both that copyright notice and this permission notice appear
    00040  * in supporting documentation.  Hewlett-Packard Company makes no
    00041  * representations about the suitability of this software for any
    00042  * purpose.  It is provided "as is" without express or implied warranty.
    00043  *
    00044  *
    00045  * Copyright (c) 1996-1998
    00046  * Silicon Graphics Computer Systems, Inc.
    00047  *
    00048  * Permission to use, copy, modify, distribute and sell this software
    00049  * and its documentation for any purpose is hereby granted without fee,
    00050  * provided that the above copyright notice appear in all copies and
    00051  * that both that copyright notice and this permission notice appear
    00052  * in supporting documentation.  Silicon Graphics makes no
    00053  * representations about the suitability of this software for any
    00054  * purpose.  It is provided "as is" without express or implied warranty.
    00055  */
    00056
    00057 /** @file stl_iterator_base_types.h
    00058  *  This is an internal header file, included by other library headers.
    00059  *  You should not attempt to use it directly.
    00060  *
    00061  *  This file contains all of the general iterator-related utility types,
    00062  *  such as iterator_traits and struct iterator.
    00063  */
    00064
    00065 #ifndef _STL_ITERATOR_BASE_TYPES_H
    00066 #define _STL_ITERATOR_BASE_TYPES_H 1
    00067
    00068 #pragma GCC system_header
    00069
    00070 #include <bits/c++config.h>
    00071 #include <cstddef>
    00072
    00073 _GLIBCXX_BEGIN_NAMESPACE(std)
    00074
    00075   //@{
    00076   /**
    00077    *  @defgroup iterator_tags Iterator Tags
    00078    *  These are empty types, used to distinguish different iterators.  The
    00079    *  distinction is not made by what they contain, but simply by what they
    00080    *  are.  Different underlying algorithms can then be used based on the
    00081    *  different operations supported by different iterator types.
    00082   */
    00083   ///  Marking input iterators.
    00084   struct input_iterator_tag {};
    00085   ///  Marking output iterators.
    00086   struct output_iterator_tag {};
    00087   /// Forward iterators support a superset of input iterator operations.
    00088   struct forward_iterator_tag : public input_iterator_tag {};
    00089   /// Bidirectional iterators support a superset of forward iterator
    00090   /// operations.
    00091   struct bidirectional_iterator_tag : public forward_iterator_tag {};
    00092   /// Random-access iterators support a superset of bidirectional iterator
    00093   /// operations.
    00094   struct random_access_iterator_tag : public bidirectional_iterator_tag {};
    00095   //@}
    00096
    00097
    00098   /**
    00099    *  @brief  Common %iterator class.
    00100    *
    00101    *  This class does nothing but define nested typedefs.  %Iterator classes
    00102    *  can inherit from this class to save some work.  The typedefs are then
    00103    *  used in specializations and overloading.
    00104    *
    00105    *  In particular, there are no default implementations of requirements
    00106    *  such as @c operator++ and the like.  (How could there be?)
    00107   */
    00108   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
    00109            typename _Pointer = _Tp*, typename _Reference = _Tp&>
    00110     struct iterator
    00111     {
    00112       /// One of the @link iterator_tags tag types@endlink.
    00113       typedef _Category  iterator_category;
    00114       /// The type "pointed to" by the iterator.
    00115       typedef _Tp        value_type;
    00116       /// Distance between iterators is represented as this type.
    00117       typedef _Distance  difference_type;
    00118       /// This type represents a pointer-to-value_type.
    00119       typedef _Pointer   pointer;
    00120       /// This type represents a reference-to-value_type.
    00121       typedef _Reference reference;
    00122     };
    00123
    00124   /**
    00125    *  This class does nothing but define nested typedefs.  The general
    00126    *  version simply "forwards" the nested typedefs from the Iterator
    00127    *  argument.  Specialized versions for pointers and pointers-to-const
    00128    *  provide tighter, more correct semantics.
    00129   */
    00130   template<typename _Iterator>
    00131     struct iterator_traits
    00132     {
    00133       typedef typename _Iterator::iterator_category iterator_category;
    00134       typedef typename _Iterator::value_type        value_type;
    00135       typedef typename _Iterator::difference_type   difference_type;
    00136       typedef typename _Iterator::pointer           pointer;
    00137       typedef typename _Iterator::reference         reference;
    00138     };
    00139
    00140   template<typename _Tp>
    00141     struct iterator_traits<_Tp*>
    00142     {
    00143       typedef random_access_iterator_tag iterator_category;
    00144       typedef _Tp                         value_type;
    00145       typedef ptrdiff_t                   difference_type;
    00146       typedef _Tp*                        pointer;
    00147       typedef _Tp&                        reference;
    00148     };
    00149
    00150   template<typename _Tp>
    00151     struct iterator_traits<const _Tp*>
    00152     {
    00153       typedef random_access_iterator_tag iterator_category;
    00154       typedef _Tp                         value_type;
    00155       typedef ptrdiff_t                   difference_type;
    00156       typedef const _Tp*                  pointer;
    00157       typedef const _Tp&                  reference;
    00158     };
    00159
    00160   /**
    00161    *  This function is not a part of the C++ standard but is syntactic
    00162    *  sugar for internal library use only.
    00163   */
    00164   template<typename _Iter>
    00165     inline typename iterator_traits<_Iter>::iterator_category
    00166     __iterator_category(const _Iter&)
    00167     { return typename iterator_traits<_Iter>::iterator_category(); }
    00168
    00169 _GLIBCXX_END_NAMESPACE
    00170
    00171 #endif /* _STL_ITERATOR_BASE_TYPES_H */
    00172