# 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, 2007, 2008, 2009
    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_funcs.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
    00057  *  functions, such as distance() and advance().
    00058  */
    00059
    00060 #ifndef _STL_ITERATOR_BASE_FUNCS_H
    00061 #define _STL_ITERATOR_BASE_FUNCS_H 1
    00062
    00063 #pragma GCC system_header
    00064 #include <bits/concept_check.h>
    00065
    00066 _GLIBCXX_BEGIN_NAMESPACE(std)
    00067
    00068   template<typename _InputIterator>
    00069     inline typename iterator_traits<_InputIterator>::difference_type
    00070     __distance(_InputIterator __first, _InputIterator __last,
    00071                input_iterator_tag)
    00072     {
    00073       // concept requirements
    00074       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00075
    00076       typename iterator_traits<_InputIterator>::difference_type __n = 0;
    00077       while (__first != __last)
    00078     {
    00079       ++__first;
    00080       ++__n;
    00081     }
    00082       return __n;
    00083     }
    00084
    00085   template<typename _RandomAccessIterator>
    00086     inline typename iterator_traits<_RandomAccessIterator>::difference_type
    00087     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
    00088                random_access_iterator_tag)
    00089     {
    00090       // concept requirements
    00091       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00092                   _RandomAccessIterator>)
    00093       return __last - __first;
    00094     }
    00095
    00096   /**
    00097    *  @brief A generalization of pointer arithmetic.
    00098    *  @param  first  An input iterator.
    00099    *  @param  last  An input iterator.
    00100    *  @return  The distance between them.
    00101    *
    00102    *  Returns @c n such that first + n == last.  This requires that @p last
    00103    *  must be reachable from @p first.  Note that @c n may be negative.
    00104    *
    00105    *  For random access iterators, this uses their @c + and @c - operations
    00106    *  and are constant time.  For other %iterator classes they are linear time.
    00107   */
    00108   template<typename _InputIterator>
    00109     inline typename iterator_traits<_InputIterator>::difference_type
    00110     distance(_InputIterator __first, _InputIterator __last)
    00111     {
    00112       // concept requirements -- taken care of in __distance
    00113       return std::__distance(__first, __last,
    00114                  std::__iterator_category(__first));
    00115     }
    00116
    00117   template<typename _InputIterator, typename _Distance>
    00118     inline void
    00119     __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
    00120     {
    00121       // concept requirements
    00122       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00123       while (__n--)
    00124     ++__i;
    00125     }
    00126
    00127   template<typename _BidirectionalIterator, typename _Distance>
    00128     inline void
    00129     __advance(_BidirectionalIterator& __i, _Distance __n,
    00130           bidirectional_iterator_tag)
    00131     {
    00132       // concept requirements
    00133       __glibcxx_function_requires(_BidirectionalIteratorConcept<
    00134                   _BidirectionalIterator>)
    00135       if (__n > 0)
    00136         while (__n--)
    00137       ++__i;
    00138       else
    00139         while (__n++)
    00140       --__i;
    00141     }
    00142
    00143   template<typename _RandomAccessIterator, typename _Distance>
    00144     inline void
    00145     __advance(_RandomAccessIterator& __i, _Distance __n,
    00146               random_access_iterator_tag)
    00147     {
    00148       // concept requirements
    00149       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00150                   _RandomAccessIterator>)
    00151       __i += __n;
    00152     }
    00153
    00154   /**
    00155    *  @brief A generalization of pointer arithmetic.
    00156    *  @param  i  An input iterator.
    00157    *  @param  n  The "delta" by which to change @p i.
    00158    *  @return  Nothing.
    00159    *
    00160    *  This increments @p i by @p n.  For bidirectional and random access
    00161    *  iterators, @p n may be negative, in which case @p i is decremented.
    00162    *
    00163    *  For random access iterators, this uses their @c + and @c - operations
    00164    *  and are constant time.  For other %iterator classes they are linear time.
    00165   */
    00166   template<typename _InputIterator, typename _Distance>
    00167     inline void
    00168     advance(_InputIterator& __i, _Distance __n)
    00169     {
    00170       // concept requirements -- taken care of in __advance
    00171       typename iterator_traits<_InputIterator>::difference_type __d = __n;
    00172       std::__advance(__i, __d, std::__iterator_category(__i));
    00173     }
    00174
    00175 #ifdef __GXX_EXPERIMENTAL_CXX0X__
    00176   template<typename _InputIterator>
    00177     inline _InputIterator
    00178     next(_InputIterator __x, typename
    00179      iterator_traits<_InputIterator>::difference_type __n = 1)
    00180     {
    00181       std::advance(__x, __n);
    00182       return __x;
    00183     }
    00184
    00185   template<typename _BidirectionalIterator>
    00186     inline _BidirectionalIterator
    00187     prev(_BidirectionalIterator __x, typename
    00188      iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
    00189     {
    00190       std::advance(__x, -__n);
    00191       return __x;
    00192     }
    00193 #endif
    00194
    00195 _GLIBCXX_END_NAMESPACE
    00196
    00197 #endif /* _STL_ITERATOR_BASE_FUNCS_H */