# 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, 2010
    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    *  Abstractions for uniform iterating through various underlying types.
    00073   */
    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   //@{
    00084   ///  Marking input iterators.
    00085   struct input_iterator_tag { };
    00086
    00087   ///  Marking output iterators.
    00088   struct output_iterator_tag { };
    00089
    00090   /// Forward iterators support a superset of input iterator operations.
    00091   struct forward_iterator_tag : public input_iterator_tag { };
    00092
    00093   /// Bidirectional iterators support a superset of forward iterator
    00094   /// operations.
    00095   struct bidirectional_iterator_tag : public forward_iterator_tag { };
    00096
    00097   /// Random-access iterators support a superset of bidirectional
    00098   /// iterator operations.
    00099   struct random_access_iterator_tag : public bidirectional_iterator_tag { };
    00100   //@}
    00101
    00102   /**
    00103    *  @brief  Common %iterator class.
    00104    *
    00105    *  This class does nothing but define nested typedefs.  %Iterator classes
    00106    *  can inherit from this class to save some work.  The typedefs are then
    00107    *  used in specializations and overloading.
    00108    *
    00109    *  In particular, there are no default implementations of requirements
    00110    *  such as @c operator++ and the like.  (How could there be?)
    00111   */
    00112   template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
    00113            typename _Pointer = _Tp*, typename _Reference = _Tp&>
    00114     struct iterator
    00115     {
    00116       /// One of the @link iterator_tags tag types@endlink.
    00117       typedef _Category  iterator_category;
    00118       /// The type "pointed to" by the iterator.
    00119       typedef _Tp        value_type;
    00120       /// Distance between iterators is represented as this type.
    00121       typedef _Distance  difference_type;
    00122       /// This type represents a pointer-to-value_type.
    00123       typedef _Pointer   pointer;
    00124       /// This type represents a reference-to-value_type.
    00125       typedef _Reference reference;
    00126     };
    00127
    00128   /**
    00129    *  @brief  Traits class for iterators.
    00130    *
    00131    *  This class does nothing but define nested typedefs.  The general
    00132    *  version simply @a forwards the nested typedefs from the Iterator
    00133    *  argument.  Specialized versions for pointers and pointers-to-const
    00134    *  provide tighter, more correct semantics.
    00135   */
    00136   template<typename _Iterator>
    00137     struct iterator_traits
    00138     {
    00139       typedef typename _Iterator::iterator_category iterator_category;
    00140       typedef typename _Iterator::value_type        value_type;
    00141       typedef typename _Iterator::difference_type   difference_type;
    00142       typedef typename _Iterator::pointer           pointer;
    00143       typedef typename _Iterator::reference         reference;
    00144     };
    00145
    00146   /// Partial specialization for pointer types.
    00147   template<typename _Tp>
    00148     struct iterator_traits<_Tp*>
    00149     {
    00150       typedef random_access_iterator_tag iterator_category;
    00151       typedef _Tp                         value_type;
    00152       typedef ptrdiff_t                   difference_type;
    00153       typedef _Tp*                        pointer;
    00154       typedef _Tp&                        reference;
    00155     };
    00156
    00157   /// Partial specialization for const pointer types.
    00158   template<typename _Tp>
    00159     struct iterator_traits<const _Tp*>
    00160     {
    00161       typedef random_access_iterator_tag iterator_category;
    00162       typedef _Tp                         value_type;
    00163       typedef ptrdiff_t                   difference_type;
    00164       typedef const _Tp*                  pointer;
    00165       typedef const _Tp&                  reference;
    00166     };
    00167
    00168   /**
    00169    *  This function is not a part of the C++ standard but is syntactic
    00170    *  sugar for internal library use only.
    00171   */
    00172   template<typename _Iter>
    00173     inline typename iterator_traits<_Iter>::iterator_category
    00174     __iterator_category(const _Iter&)
    00175     { return typename iterator_traits<_Iter>::iterator_category(); }
    00176
    00177   //@}
    00178
    00179 _GLIBCXX_END_NAMESPACE
    00180
    00181 #endif /* _STL_ITERATOR_BASE_TYPES_H */
    00182