# stl_iterator_base_funcs.h

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    00001 // Functions used by iterators -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006
    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_funcs.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
    00062  *  functions, such as distance() and advance().
    00063  */
    00064
    00065 #ifndef _ITERATOR_BASE_FUNCS_H
    00066 #define _ITERATOR_BASE_FUNCS_H 1
    00067
    00068 #pragma GCC system_header
    00069 #include <bits/concept_check.h>
    00070
    00071 _GLIBCXX_BEGIN_NAMESPACE(std)
    00072
    00073   template<typename _InputIterator>
    00074     inline typename iterator_traits<_InputIterator>::difference_type
    00075     __distance(_InputIterator __first, _InputIterator __last,
    00076                input_iterator_tag)
    00077     {
    00078       // concept requirements
    00079       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00080
    00081       typename iterator_traits<_InputIterator>::difference_type __n = 0;
    00082       while (__first != __last)
    00083     {
    00084       ++__first;
    00085       ++__n;
    00086     }
    00087       return __n;
    00088     }
    00089
    00090   template<typename _RandomAccessIterator>
    00091     inline typename iterator_traits<_RandomAccessIterator>::difference_type
    00092     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
    00093                random_access_iterator_tag)
    00094     {
    00095       // concept requirements
    00096       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00097                   _RandomAccessIterator>)
    00098       return __last - __first;
    00099     }
    00100
    00101   /**
    00102    *  @brief A generalization of pointer arithmetic.
    00103    *  @param  first  An input iterator.
    00104    *  @param  last  An input iterator.
    00105    *  @return  The distance between them.
    00106    *
    00107    *  Returns @c n such that first + n == last.  This requires that @p last
    00108    *  must be reachable from @p first.  Note that @c n may be negative.
    00109    *
    00110    *  For random access iterators, this uses their @c + and @c - operations
    00111    *  and are constant time.  For other %iterator classes they are linear time.
    00112   */
    00113   template<typename _InputIterator>
    00114     inline typename iterator_traits<_InputIterator>::difference_type
    00115     distance(_InputIterator __first, _InputIterator __last)
    00116     {
    00117       // concept requirements -- taken care of in __distance
    00118       return std::__distance(__first, __last,
    00119                  std::__iterator_category(__first));
    00120     }
    00121
    00122   template<typename _InputIterator, typename _Distance>
    00123     inline void
    00124     __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
    00125     {
    00126       // concept requirements
    00127       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00128       while (__n--)
    00129     ++__i;
    00130     }
    00131
    00132   template<typename _BidirectionalIterator, typename _Distance>
    00133     inline void
    00134     __advance(_BidirectionalIterator& __i, _Distance __n,
    00135           bidirectional_iterator_tag)
    00136     {
    00137       // concept requirements
    00138       __glibcxx_function_requires(_BidirectionalIteratorConcept<
    00139                   _BidirectionalIterator>)
    00140       if (__n > 0)
    00141         while (__n--)
    00142       ++__i;
    00143       else
    00144         while (__n++)
    00145       --__i;
    00146     }
    00147
    00148   template<typename _RandomAccessIterator, typename _Distance>
    00149     inline void
    00150     __advance(_RandomAccessIterator& __i, _Distance __n,
    00151               random_access_iterator_tag)
    00152     {
    00153       // concept requirements
    00154       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00155                   _RandomAccessIterator>)
    00156       __i += __n;
    00157     }
    00158
    00159   /**
    00160    *  @brief A generalization of pointer arithmetic.
    00161    *  @param  i  An input iterator.
    00162    *  @param  n  The "delta" by which to change @p i.
    00163    *  @return  Nothing.
    00164    *
    00165    *  This increments @p i by @p n.  For bidirectional and random access
    00166    *  iterators, @p n may be negative, in which case @p i is decremented.
    00167    *
    00168    *  For random access iterators, this uses their @c + and @c - operations
    00169    *  and are constant time.  For other %iterator classes they are linear time.
    00170   */
    00171   template<typename _InputIterator, typename _Distance>
    00172     inline void
    00173     advance(_InputIterator& __i, _Distance __n)
    00174     {
    00175       // concept requirements -- taken care of in __advance
    00176       typename iterator_traits<_InputIterator>::difference_type __d = __n;
    00177       std::__advance(__i, __d, std::__iterator_category(__i));
    00178     }
    00179
    00180 _GLIBCXX_END_NAMESPACE
    00181
    00182 #endif /* _ITERATOR_BASE_FUNCS_H */