00001 // Functions used by iterators -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002 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 __GLIBCPP_INTERNAL_ITERATOR_BASE_FUNCS_H 00065 #define __GLIBCPP_INTERNAL_ITERATOR_BASE_FUNCS_H 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 __glibcpp_function_requires(_InputIteratorConcept<_InputIterator>) 00079 00080 typename iterator_traits<_InputIterator>::difference_type __n = 0; 00081 while (__first != __last) { 00082 ++__first; ++__n; 00083 } 00084 return __n; 00085 } 00086 00087 template<typename _RandomAccessIterator> 00088 inline typename iterator_traits<_RandomAccessIterator>::difference_type 00089 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, 00090 random_access_iterator_tag) 00091 { 00092 // concept requirements 00093 __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>) 00094 return __last - __first; 00095 } 00096 00097 /** 00098 * @brief A generalization of pointer arithmetic. 00099 * @param first An input iterator. 00100 * @param last An input iterator. 00101 * @return The distance between them. 00102 * 00103 * Returns @c n such that first + n == last. This requires that @p last 00104 * must be reachable from @p first. Note that @c n may be negative. 00105 * 00106 * For random access iterators, this uses their @c + and @c - operations 00107 * and are constant time. For other %iterator classes they are linear time. 00108 */ 00109 template<typename _InputIterator> 00110 inline typename iterator_traits<_InputIterator>::difference_type 00111 distance(_InputIterator __first, _InputIterator __last) 00112 { 00113 // concept requirements -- taken care of in __distance 00114 return __distance(__first, __last, __iterator_category(__first)); 00115 } 00116 00117 template<typename _InputIter, typename _Distance> 00118 inline void 00119 __advance(_InputIter& __i, _Distance __n, input_iterator_tag) 00120 { 00121 // concept requirements 00122 __glibcpp_function_requires(_InputIteratorConcept<_InputIter>) 00123 while (__n--) ++__i; 00124 } 00125 00126 template<typename _BidirectionalIterator, typename _Distance> 00127 inline void 00128 __advance(_BidirectionalIterator& __i, _Distance __n, 00129 bidirectional_iterator_tag) 00130 { 00131 // concept requirements 00132 __glibcpp_function_requires(_BidirectionalIteratorConcept<_BidirectionalIterator>) 00133 00134 if (__n > 0) 00135 while (__n--) ++__i; 00136 else 00137 while (__n++) --__i; 00138 } 00139 00140 template<typename _RandomAccessIterator, typename _Distance> 00141 inline void 00142 __advance(_RandomAccessIterator& __i, _Distance __n, 00143 random_access_iterator_tag) 00144 { 00145 // concept requirements 00146 __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>) 00147 __i += __n; 00148 } 00149 00150 /** 00151 * @brief A generalization of pointer arithmetic. 00152 * @param i An input iterator. 00153 * @param n The "delta" by which to change @p i. 00154 * @return Nothing. 00155 * 00156 * This increments @p i by @p n. For bidirectional and random access 00157 * iterators, @p n may be negative, in which case @p i is decremented. 00158 * 00159 * For random access iterators, this uses their @c + and @c - operations 00160 * and are constant time. For other %iterator classes they are linear time. 00161 */ 00162 template<typename _InputIterator, typename _Distance> 00163 inline void 00164 advance(_InputIterator& __i, _Distance __n) 00165 { 00166 // concept requirements -- taken care of in __advance 00167 __advance(__i, __n, __iterator_category(__i)); 00168 } 00169 } // namespace std 00170 00171 #endif /* __GLIBCPP_INTERNAL_ITERATOR_BASE_FUNCS_H */