# stl_iterator_base_funcs.h

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    00001 // Functions used by iterators -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
    00004 //
    00005 // This file is part of the GNU ISO C++ Library.  This library is free
    00006 // software; you can redistribute it and/or modify it under the
    00007 // terms of the GNU General Public License as published by the
    00008 // Free Software Foundation; either version 2, or (at your option)
    00009 // any later version.
    00010
    00011 // This library is distributed in the hope that it will be useful,
    00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
    00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    00014 // GNU General Public License for more details.
    00015
    00016 // You should have received a copy of the GNU General Public License along
    00017 // with this library; see the file COPYING.  If not, write to the Free
    00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    00019 // USA.
    00020
    00021 // As a special exception, you may use this file as part of a free software
    00022 // library without restriction.  Specifically, if other files instantiate
    00023 // templates or use macros or inline functions from this file, or you compile
    00024 // this file and link it with other files to produce an executable, this
    00025 // file does not by itself cause the resulting executable to be covered by
    00026 // the GNU General Public License.  This exception does not however
    00027 // invalidate any other reasons why the executable file might be covered by
    00028 // the GNU General Public License.
    00029
    00030 /*
    00031  *
    00032  * Copyright (c) 1994
    00033  * Hewlett-Packard Company
    00034  *
    00035  * Permission to use, copy, modify, distribute and sell this software
    00036  * and its documentation for any purpose is hereby granted without fee,
    00037  * provided that the above copyright notice appear in all copies and
    00038  * that both that copyright notice and this permission notice appear
    00039  * in supporting documentation.  Hewlett-Packard Company makes no
    00040  * representations about the suitability of this software for any
    00041  * purpose.  It is provided "as is" without express or implied warranty.
    00042  *
    00043  *
    00044  * Copyright (c) 1996-1998
    00045  * Silicon Graphics Computer Systems, Inc.
    00046  *
    00047  * Permission to use, copy, modify, distribute and sell this software
    00048  * and its documentation for any purpose is hereby granted without fee,
    00049  * provided that the above copyright notice appear in all copies and
    00050  * that both that copyright notice and this permission notice appear
    00051  * in supporting documentation.  Silicon Graphics makes no
    00052  * representations about the suitability of this software for any
    00053  * purpose.  It is provided "as is" without express or implied warranty.
    00054  */
    00055
    00056 /** @file stl_iterator_base_funcs.h
    00057  *  This is an internal header file, included by other library headers.
    00058  *  You should not attempt to use it directly.
    00059  *
    00060  *  This file contains all of the general iterator-related utility
    00061  *  functions, such as distance() and advance().
    00062  */
    00063
    00064 #ifndef _ITERATOR_BASE_FUNCS_H
    00065 #define _ITERATOR_BASE_FUNCS_H 1
    00066
    00067 #pragma GCC system_header
    00068 #include <bits/concept_check.h>
    00069
    00070 namespace std
    00071 {
    00072   template<typename _InputIterator>
    00073     inline typename iterator_traits<_InputIterator>::difference_type
    00074     __distance(_InputIterator __first, _InputIterator __last,
    00075                input_iterator_tag)
    00076     {
    00077       // concept requirements
    00078       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00079
    00080       typename iterator_traits<_InputIterator>::difference_type __n = 0;
    00081       while (__first != __last)
    00082     {
    00083       ++__first;
    00084       ++__n;
    00085     }
    00086       return __n;
    00087     }
    00088
    00089   template<typename _RandomAccessIterator>
    00090     inline typename iterator_traits<_RandomAccessIterator>::difference_type
    00091     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
    00092                random_access_iterator_tag)
    00093     {
    00094       // concept requirements
    00095       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00096                   _RandomAccessIterator>)
    00097       return __last - __first;
    00098     }
    00099
    00100   /**
    00101    *  @brief A generalization of pointer arithmetic.
    00102    *  @param  first  An input iterator.
    00103    *  @param  last  An input iterator.
    00104    *  @return  The distance between them.
    00105    *
    00106    *  Returns @c n such that first + n == last.  This requires that @p last
    00107    *  must be reachable from @p first.  Note that @c n may be negative.
    00108    *
    00109    *  For random access iterators, this uses their @c + and @c - operations
    00110    *  and are constant time.  For other %iterator classes they are linear time.
    00111   */
    00112   template<typename _InputIterator>
    00113     inline typename iterator_traits<_InputIterator>::difference_type
    00114     distance(_InputIterator __first, _InputIterator __last)
    00115     {
    00116       // concept requirements -- taken care of in __distance
    00117       return std::__distance(__first, __last,
    00118                  std::__iterator_category(__first));
    00119     }
    00120
    00121   template<typename _InputIterator, typename _Distance>
    00122     inline void
    00123     __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
    00124     {
    00125       // concept requirements
    00126       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00127       while (__n--)
    00128     ++__i;
    00129     }
    00130
    00131   template<typename _BidirectionalIterator, typename _Distance>
    00132     inline void
    00133     __advance(_BidirectionalIterator& __i, _Distance __n,
    00134               bidirectional_iterator_tag)
    00135     {
    00136       // concept requirements
    00137       __glibcxx_function_requires(_BidirectionalIteratorConcept<
    00138                   _BidirectionalIterator>)
    00139       if (__n > 0)
    00140         while (__n--)
    00141       ++__i;
    00142       else
    00143         while (__n++)
    00144       --__i;
    00145     }
    00146
    00147   template<typename _RandomAccessIterator, typename _Distance>
    00148     inline void
    00149     __advance(_RandomAccessIterator& __i, _Distance __n,
    00150               random_access_iterator_tag)
    00151     {
    00152       // concept requirements
    00153       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00154                   _RandomAccessIterator>)
    00155       __i += __n;
    00156     }
    00157
    00158   /**
    00159    *  @brief A generalization of pointer arithmetic.
    00160    *  @param  i  An input iterator.
    00161    *  @param  n  The "delta" by which to change @p i.
    00162    *  @return  Nothing.
    00163    *
    00164    *  This increments @p i by @p n.  For bidirectional and random access
    00165    *  iterators, @p n may be negative, in which case @p i is decremented.
    00166    *
    00167    *  For random access iterators, this uses their @c + and @c - operations
    00168    *  and are constant time.  For other %iterator classes they are linear time.
    00169   */
    00170   template<typename _InputIterator, typename _Distance>
    00171     inline void
    00172     advance(_InputIterator& __i, _Distance __n)
    00173     {
    00174       // concept requirements -- taken care of in __advance
    00175       std::__advance(__i, __n, std::__iterator_category(__i));
    00176     }
    00177 } // namespace std
    00178
    00179 #endif /* _ITERATOR_BASE_FUNCS_H */