libstdc++
stl_iterator_base_funcs.h
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00001 // Functions used by iterators -*- C++ -*-
00002 
00003 // Copyright (C) 2001-2015 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /*
00026  *
00027  * Copyright (c) 1994
00028  * Hewlett-Packard Company
00029  *
00030  * Permission to use, copy, modify, distribute and sell this software
00031  * and its documentation for any purpose is hereby granted without fee,
00032  * provided that the above copyright notice appear in all copies and
00033  * that both that copyright notice and this permission notice appear
00034  * in supporting documentation.  Hewlett-Packard Company makes no
00035  * representations about the suitability of this software for any
00036  * purpose.  It is provided "as is" without express or implied warranty.
00037  *
00038  *
00039  * Copyright (c) 1996-1998
00040  * Silicon Graphics Computer Systems, Inc.
00041  *
00042  * Permission to use, copy, modify, distribute and sell this software
00043  * and its documentation for any purpose is hereby granted without fee,
00044  * provided that the above copyright notice appear in all copies and
00045  * that both that copyright notice and this permission notice appear
00046  * in supporting documentation.  Silicon Graphics makes no
00047  * representations about the suitability of this software for any
00048  * purpose.  It is provided "as is" without express or implied warranty.
00049  */
00050 
00051 /** @file bits/stl_iterator_base_funcs.h
00052  *  This is an internal header file, included by other library headers.
00053  *  Do not attempt to use it directly. @headername{iterator}
00054  *
00055  *  This file contains all of the general iterator-related utility
00056  *  functions, such as distance() and advance().
00057  */
00058 
00059 #ifndef _STL_ITERATOR_BASE_FUNCS_H
00060 #define _STL_ITERATOR_BASE_FUNCS_H 1
00061 
00062 #pragma GCC system_header
00063 
00064 #include <bits/concept_check.h>
00065 #include <debug/debug.h>
00066 
00067 namespace std _GLIBCXX_VISIBILITY(default)
00068 {
00069 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00070 
00071   template<typename _InputIterator>
00072     inline typename iterator_traits<_InputIterator>::difference_type
00073     __distance(_InputIterator __first, _InputIterator __last,
00074                input_iterator_tag)
00075     {
00076       // concept requirements
00077       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
00078 
00079       typename iterator_traits<_InputIterator>::difference_type __n = 0;
00080       while (__first != __last)
00081         {
00082           ++__first;
00083           ++__n;
00084         }
00085       return __n;
00086     }
00087 
00088   template<typename _RandomAccessIterator>
00089     inline typename iterator_traits<_RandomAccessIterator>::difference_type
00090     __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
00091                random_access_iterator_tag)
00092     {
00093       // concept requirements
00094       __glibcxx_function_requires(_RandomAccessIteratorConcept<
00095                                   _RandomAccessIterator>)
00096       return __last - __first;
00097     }
00098 
00099   /**
00100    *  @brief A generalization of pointer arithmetic.
00101    *  @param  __first  An input iterator.
00102    *  @param  __last  An input iterator.
00103    *  @return  The distance between them.
00104    *
00105    *  Returns @c n such that __first + n == __last.  This requires
00106    *  that @p __last must be reachable from @p __first.  Note that @c
00107    *  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       _GLIBCXX_DEBUG_ASSERT(__n >= 0);
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 @a 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 #if __cplusplus >= 201103L
00181 
00182   template<typename _ForwardIterator>
00183     inline _ForwardIterator
00184     next(_ForwardIterator __x, typename
00185          iterator_traits<_ForwardIterator>::difference_type __n = 1)
00186     {
00187       std::advance(__x, __n);
00188       return __x;
00189     }
00190 
00191   template<typename _BidirectionalIterator>
00192     inline _BidirectionalIterator
00193     prev(_BidirectionalIterator __x, typename
00194          iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 
00195     {
00196       std::advance(__x, -__n);
00197       return __x;
00198     }
00199 
00200 #endif // C++11
00201 
00202 _GLIBCXX_END_NAMESPACE_VERSION
00203 } // namespace
00204 
00205 #endif /* _STL_ITERATOR_BASE_FUNCS_H */