1 // Functions used by iterators -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the 8 // terms of the GNU General Public License as published by the 9 // Free Software Foundation; either version 3, or (at your option) 10 // any later version. 11 12 // This library is distributed in the hope that it will be useful, 13 // but WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 // GNU General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 /* 27 * 28 * Copyright (c) 1994 29 * Hewlett-Packard Company 30 * 31 * Permission to use, copy, modify, distribute and sell this software 32 * and its documentation for any purpose is hereby granted without fee, 33 * provided that the above copyright notice appear in all copies and 34 * that both that copyright notice and this permission notice appear 35 * in supporting documentation. Hewlett-Packard Company makes no 36 * representations about the suitability of this software for any 37 * purpose. It is provided "as is" without express or implied warranty. 38 * 39 * 40 * Copyright (c) 1996-1998 41 * Silicon Graphics Computer Systems, Inc. 42 * 43 * Permission to use, copy, modify, distribute and sell this software 44 * and its documentation for any purpose is hereby granted without fee, 45 * provided that the above copyright notice appear in all copies and 46 * that both that copyright notice and this permission notice appear 47 * in supporting documentation. Silicon Graphics makes no 48 * representations about the suitability of this software for any 49 * purpose. It is provided "as is" without express or implied warranty. 50 */ 51 52 /** @file bits/stl_iterator_base_funcs.h 53 * This is an internal header file, included by other library headers. 54 * Do not attempt to use it directly. @headername{iterator} 55 * 56 * This file contains all of the general iterator-related utility 57 * functions, such as distance() and advance(). 58 */ 59 60 #ifndef _STL_ITERATOR_BASE_FUNCS_H 61 #define _STL_ITERATOR_BASE_FUNCS_H 1 62 63 #pragma GCC system_header 64 65 #include <bits/concept_check.h> 66 67 namespace std _GLIBCXX_VISIBILITY(default) 68 { 69 _GLIBCXX_BEGIN_NAMESPACE_VERSION 70 71 template<typename _InputIterator> 72 inline typename iterator_traits<_InputIterator>::difference_type 73 __distance(_InputIterator __first, _InputIterator __last, 74 input_iterator_tag) 75 { 76 // concept requirements 77 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 78 79 typename iterator_traits<_InputIterator>::difference_type __n = 0; 80 while (__first != __last) 81 { 82 ++__first; 83 ++__n; 84 } 85 return __n; 86 } 87 88 template<typename _RandomAccessIterator> 89 inline typename iterator_traits<_RandomAccessIterator>::difference_type 90 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, 91 random_access_iterator_tag) 92 { 93 // concept requirements 94 __glibcxx_function_requires(_RandomAccessIteratorConcept< 95 _RandomAccessIterator>) 96 return __last - __first; 97 } 98 99 /** 100 * @brief A generalization of pointer arithmetic. 101 * @param first An input iterator. 102 * @param last An input iterator. 103 * @return The distance between them. 104 * 105 * Returns @c n such that first + n == last. This requires that @p last 106 * must be reachable from @p first. Note that @c n may be negative. 107 * 108 * For random access iterators, this uses their @c + and @c - operations 109 * and are constant time. For other %iterator classes they are linear time. 110 */ 111 template<typename _InputIterator> 112 inline typename iterator_traits<_InputIterator>::difference_type 113 distance(_InputIterator __first, _InputIterator __last) 114 { 115 // concept requirements -- taken care of in __distance 116 return std::__distance(__first, __last, 117 std::__iterator_category(__first)); 118 } 119 120 template<typename _InputIterator, typename _Distance> 121 inline void 122 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 123 { 124 // concept requirements 125 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 126 while (__n--) 127 ++__i; 128 } 129 130 template<typename _BidirectionalIterator, typename _Distance> 131 inline void 132 __advance(_BidirectionalIterator& __i, _Distance __n, 133 bidirectional_iterator_tag) 134 { 135 // concept requirements 136 __glibcxx_function_requires(_BidirectionalIteratorConcept< 137 _BidirectionalIterator>) 138 if (__n > 0) 139 while (__n--) 140 ++__i; 141 else 142 while (__n++) 143 --__i; 144 } 145 146 template<typename _RandomAccessIterator, typename _Distance> 147 inline void 148 __advance(_RandomAccessIterator& __i, _Distance __n, 149 random_access_iterator_tag) 150 { 151 // concept requirements 152 __glibcxx_function_requires(_RandomAccessIteratorConcept< 153 _RandomAccessIterator>) 154 __i += __n; 155 } 156 157 /** 158 * @brief A generalization of pointer arithmetic. 159 * @param i An input iterator. 160 * @param n The @a delta by which to change @p i. 161 * @return Nothing. 162 * 163 * This increments @p i by @p n. For bidirectional and random access 164 * iterators, @p n may be negative, in which case @p i is decremented. 165 * 166 * For random access iterators, this uses their @c + and @c - operations 167 * and are constant time. For other %iterator classes they are linear time. 168 */ 169 template<typename _InputIterator, typename _Distance> 170 inline void 171 advance(_InputIterator& __i, _Distance __n) 172 { 173 // concept requirements -- taken care of in __advance 174 typename iterator_traits<_InputIterator>::difference_type __d = __n; 175 std::__advance(__i, __d, std::__iterator_category(__i)); 176 } 177 178 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 179 180 template<typename _ForwardIterator> 181 inline _ForwardIterator 182 next(_ForwardIterator __x, typename 183 iterator_traits<_ForwardIterator>::difference_type __n = 1) 184 { 185 std::advance(__x, __n); 186 return __x; 187 } 188 189 template<typename _BidirectionalIterator> 190 inline _BidirectionalIterator 191 prev(_BidirectionalIterator __x, typename 192 iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 193 { 194 std::advance(__x, -__n); 195 return __x; 196 } 197 198 #endif // __GXX_EXPERIMENTAL_CXX0X__ 199 200 _GLIBCXX_END_NAMESPACE_VERSION 201 } // namespace 202 203 #endif /* _STL_ITERATOR_BASE_FUNCS_H */ 204
