1// Functions used by iterators -*- C++ -*- 2 3// Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 2, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// You should have received a copy of the GNU General Public License along 17// with this library; see the file COPYING. If not, write to the Free 18// Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 19// USA. 20 21// As a special exception, you may use this file as part of a free software 22// library without restriction. Specifically, if other files instantiate 23// templates or use macros or inline functions from this file, or you compile 24// this file and link it with other files to produce an executable, this 25// file does not by itself cause the resulting executable to be covered by 26// the GNU General Public License. This exception does not however 27// invalidate any other reasons why the executable file might be covered by 28// the GNU General Public License. 29 30/* 31 * 32 * Copyright (c) 1994 33 * Hewlett-Packard Company 34 * 35 * Permission to use, copy, modify, distribute and sell this software 36 * and its documentation for any purpose is hereby granted without fee, 37 * provided that the above copyright notice appear in all copies and 38 * that both that copyright notice and this permission notice appear 39 * in supporting documentation. Hewlett-Packard Company makes no 40 * representations about the suitability of this software for any 41 * purpose. It is provided "as is" without express or implied warranty. 42 * 43 * 44 * Copyright (c) 1996-1998 45 * Silicon Graphics Computer Systems, Inc. 46 * 47 * Permission to use, copy, modify, distribute and sell this software 48 * and its documentation for any purpose is hereby granted without fee, 49 * provided that the above copyright notice appear in all copies and 50 * that both that copyright notice and this permission notice appear 51 * in supporting documentation. Silicon Graphics makes no 52 * representations about the suitability of this software for any 53 * purpose. It is provided "as is" without express or implied warranty. 54 */ 55 56/** @file stl_iterator_base_funcs.h 57 * This is an internal header file, included by other library headers. 58 * You should not attempt to use it directly. 59 * 60 * This file contains all of the general iterator-related utility 61 * functions, such as distance() and advance(). 62 */ 63 64#ifndef _ITERATOR_BASE_FUNCS_H 65#define _ITERATOR_BASE_FUNCS_H 1 66 67#pragma GCC system_header 68#include <bits/concept_check.h> 69 70namespace std 71{ 72 template<typename _InputIterator> 73 inline typename iterator_traits<_InputIterator>::difference_type 74 __distance(_InputIterator __first, _InputIterator __last, 75 input_iterator_tag) 76 { 77 // concept requirements 78 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 79 80 typename iterator_traits<_InputIterator>::difference_type __n = 0; 81 while (__first != __last) 82 { 83 ++__first; 84 ++__n; 85 } 86 return __n; 87 } 88 89 template<typename _RandomAccessIterator> 90 inline typename iterator_traits<_RandomAccessIterator>::difference_type 91 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, 92 random_access_iterator_tag) 93 { 94 // concept requirements 95 __glibcxx_function_requires(_RandomAccessIteratorConcept< 96 _RandomAccessIterator>) 97 return __last - __first; 98 } 99 100 /** 101 * @brief A generalization of pointer arithmetic. 102 * @param first An input iterator. 103 * @param last An input iterator. 104 * @return The distance between them. 105 * 106 * Returns @c n such that first + n == last. This requires that @p last 107 * must be reachable from @p first. Note that @c n may be negative. 108 * 109 * For random access iterators, this uses their @c + and @c - operations 110 * and are constant time. For other %iterator classes they are linear time. 111 */ 112 template<typename _InputIterator> 113 inline typename iterator_traits<_InputIterator>::difference_type 114 distance(_InputIterator __first, _InputIterator __last) 115 { 116 // concept requirements -- taken care of in __distance 117 return std::__distance(__first, __last, 118 std::__iterator_category(__first)); 119 } 120 121 template<typename _InputIterator, typename _Distance> 122 inline void 123 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 124 { 125 // concept requirements 126 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 127 while (__n--) 128 ++__i; 129 } 130 131 template<typename _BidirectionalIterator, typename _Distance> 132 inline void 133 __advance(_BidirectionalIterator& __i, _Distance __n, 134 bidirectional_iterator_tag) 135 { 136 // concept requirements 137 __glibcxx_function_requires(_BidirectionalIteratorConcept< 138 _BidirectionalIterator>) 139 if (__n > 0) 140 while (__n--) 141 ++__i; 142 else 143 while (__n++) 144 --__i; 145 } 146 147 template<typename _RandomAccessIterator, typename _Distance> 148 inline void 149 __advance(_RandomAccessIterator& __i, _Distance __n, 150 random_access_iterator_tag) 151 { 152 // concept requirements 153 __glibcxx_function_requires(_RandomAccessIteratorConcept< 154 _RandomAccessIterator>) 155 __i += __n; 156 } 157 158 /** 159 * @brief A generalization of pointer arithmetic. 160 * @param i An input iterator. 161 * @param n The "delta" by which to change @p i. 162 * @return Nothing. 163 * 164 * This increments @p i by @p n. For bidirectional and random access 165 * iterators, @p n may be negative, in which case @p i is decremented. 166 * 167 * For random access iterators, this uses their @c + and @c - operations 168 * and are constant time. For other %iterator classes they are linear time. 169 */ 170 template<typename _InputIterator, typename _Distance> 171 inline void 172 advance(_InputIterator& __i, _Distance __n) 173 { 174 // concept requirements -- taken care of in __advance 175 std::__advance(__i, __n, std::__iterator_category(__i)); 176 } 177} // namespace std 178 179#endif /* _ITERATOR_BASE_FUNCS_H */ 180