1 // Functions used by iterators -*- C++ -*- 2 3 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 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 stl_iterator_base_funcs.h 53 * This is an internal header file, included by other library headers. 54 * You should not attempt to use it directly. 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 #include <bits/concept_check.h> 65 66 _GLIBCXX_BEGIN_NAMESPACE(std) 67 68 template<typename _InputIterator> 69 inline typename iterator_traits<_InputIterator>::difference_type 70 __distance(_InputIterator __first, _InputIterator __last, 71 input_iterator_tag) 72 { 73 // concept requirements 74 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 75 76 typename iterator_traits<_InputIterator>::difference_type __n = 0; 77 while (__first != __last) 78 { 79 ++__first; 80 ++__n; 81 } 82 return __n; 83 } 84 85 template<typename _RandomAccessIterator> 86 inline typename iterator_traits<_RandomAccessIterator>::difference_type 87 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, 88 random_access_iterator_tag) 89 { 90 // concept requirements 91 __glibcxx_function_requires(_RandomAccessIteratorConcept< 92 _RandomAccessIterator>) 93 return __last - __first; 94 } 95 96 /** 97 * @brief A generalization of pointer arithmetic. 98 * @param first An input iterator. 99 * @param last An input iterator. 100 * @return The distance between them. 101 * 102 * Returns @c n such that first + n == last. This requires that @p last 103 * must be reachable from @p first. Note that @c n may be negative. 104 * 105 * For random access iterators, this uses their @c + and @c - operations 106 * and are constant time. For other %iterator classes they are linear time. 107 */ 108 template<typename _InputIterator> 109 inline typename iterator_traits<_InputIterator>::difference_type 110 distance(_InputIterator __first, _InputIterator __last) 111 { 112 // concept requirements -- taken care of in __distance 113 return std::__distance(__first, __last, 114 std::__iterator_category(__first)); 115 } 116 117 template<typename _InputIterator, typename _Distance> 118 inline void 119 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 120 { 121 // concept requirements 122 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 123 while (__n--) 124 ++__i; 125 } 126 127 template<typename _BidirectionalIterator, typename _Distance> 128 inline void 129 __advance(_BidirectionalIterator& __i, _Distance __n, 130 bidirectional_iterator_tag) 131 { 132 // concept requirements 133 __glibcxx_function_requires(_BidirectionalIteratorConcept< 134 _BidirectionalIterator>) 135 if (__n > 0) 136 while (__n--) 137 ++__i; 138 else 139 while (__n++) 140 --__i; 141 } 142 143 template<typename _RandomAccessIterator, typename _Distance> 144 inline void 145 __advance(_RandomAccessIterator& __i, _Distance __n, 146 random_access_iterator_tag) 147 { 148 // concept requirements 149 __glibcxx_function_requires(_RandomAccessIteratorConcept< 150 _RandomAccessIterator>) 151 __i += __n; 152 } 153 154 /** 155 * @brief A generalization of pointer arithmetic. 156 * @param i An input iterator. 157 * @param n The "delta" by which to change @p i. 158 * @return Nothing. 159 * 160 * This increments @p i by @p n. For bidirectional and random access 161 * iterators, @p n may be negative, in which case @p i is decremented. 162 * 163 * For random access iterators, this uses their @c + and @c - operations 164 * and are constant time. For other %iterator classes they are linear time. 165 */ 166 template<typename _InputIterator, typename _Distance> 167 inline void 168 advance(_InputIterator& __i, _Distance __n) 169 { 170 // concept requirements -- taken care of in __advance 171 typename iterator_traits<_InputIterator>::difference_type __d = __n; 172 std::__advance(__i, __d, std::__iterator_category(__i)); 173 } 174 175 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 176 template<typename _InputIterator> 177 inline _InputIterator 178 next(_InputIterator __x, typename 179 iterator_traits<_InputIterator>::difference_type __n = 1) 180 { 181 std::advance(__x, __n); 182 return __x; 183 } 184 185 template<typename _BidirectionalIterator> 186 inline _BidirectionalIterator 187 prev(_BidirectionalIterator __x, typename 188 iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 189 { 190 std::advance(__x, -__n); 191 return __x; 192 } 193 #endif 194 195 _GLIBCXX_END_NAMESPACE 196 197 #endif /* _STL_ITERATOR_BASE_FUNCS_H */ 198
