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 */

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