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
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 _STL_ITERATOR_BASE_FUNCS_H
00066 #define _STL_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 /* _STL_ITERATOR_BASE_FUNCS_H */

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