libstdc++
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00001 // Functions used by iterators -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the 00008 // terms of the GNU General Public License as published by the 00009 // Free Software Foundation; either version 3, or (at your option) 00010 // any later version. 00011 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 // GNU General Public License for more details. 00016 00017 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 /* 00027 * 00028 * Copyright (c) 1994 00029 * Hewlett-Packard Company 00030 * 00031 * Permission to use, copy, modify, distribute and sell this software 00032 * and its documentation for any purpose is hereby granted without fee, 00033 * provided that the above copyright notice appear in all copies and 00034 * that both that copyright notice and this permission notice appear 00035 * in supporting documentation. Hewlett-Packard Company makes no 00036 * representations about the suitability of this software for any 00037 * purpose. It is provided "as is" without express or implied warranty. 00038 * 00039 * 00040 * Copyright (c) 1996-1998 00041 * Silicon Graphics Computer Systems, Inc. 00042 * 00043 * Permission to use, copy, modify, distribute and sell this software 00044 * and its documentation for any purpose is hereby granted without fee, 00045 * provided that the above copyright notice appear in all copies and 00046 * that both that copyright notice and this permission notice appear 00047 * in supporting documentation. Silicon Graphics makes no 00048 * representations about the suitability of this software for any 00049 * purpose. It is provided "as is" without express or implied warranty. 00050 */ 00051 00052 /** @file bits/stl_iterator_base_funcs.h 00053 * This is an internal header file, included by other library headers. 00054 * Do not attempt to use it directly. @headername{iterator} 00055 * 00056 * This file contains all of the general iterator-related utility 00057 * functions, such as distance() and advance(). 00058 */ 00059 00060 #ifndef _STL_ITERATOR_BASE_FUNCS_H 00061 #define _STL_ITERATOR_BASE_FUNCS_H 1 00062 00063 #pragma GCC system_header 00064 00065 #include <bits/concept_check.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 that @p last 00106 * must be reachable from @p first. Note that @c n may be negative. 00107 * 00108 * For random access iterators, this uses their @c + and @c - operations 00109 * and are constant time. For other %iterator classes they are linear time. 00110 */ 00111 template<typename _InputIterator> 00112 inline typename iterator_traits<_InputIterator>::difference_type 00113 distance(_InputIterator __first, _InputIterator __last) 00114 { 00115 // concept requirements -- taken care of in __distance 00116 return std::__distance(__first, __last, 00117 std::__iterator_category(__first)); 00118 } 00119 00120 template<typename _InputIterator, typename _Distance> 00121 inline void 00122 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 00123 { 00124 // concept requirements 00125 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00126 while (__n--) 00127 ++__i; 00128 } 00129 00130 template<typename _BidirectionalIterator, typename _Distance> 00131 inline void 00132 __advance(_BidirectionalIterator& __i, _Distance __n, 00133 bidirectional_iterator_tag) 00134 { 00135 // concept requirements 00136 __glibcxx_function_requires(_BidirectionalIteratorConcept< 00137 _BidirectionalIterator>) 00138 if (__n > 0) 00139 while (__n--) 00140 ++__i; 00141 else 00142 while (__n++) 00143 --__i; 00144 } 00145 00146 template<typename _RandomAccessIterator, typename _Distance> 00147 inline void 00148 __advance(_RandomAccessIterator& __i, _Distance __n, 00149 random_access_iterator_tag) 00150 { 00151 // concept requirements 00152 __glibcxx_function_requires(_RandomAccessIteratorConcept< 00153 _RandomAccessIterator>) 00154 __i += __n; 00155 } 00156 00157 /** 00158 * @brief A generalization of pointer arithmetic. 00159 * @param i An input iterator. 00160 * @param n The @a delta by which to change @p i. 00161 * @return Nothing. 00162 * 00163 * This increments @p i by @p n. For bidirectional and random access 00164 * iterators, @p n may be negative, in which case @p i is decremented. 00165 * 00166 * For random access iterators, this uses their @c + and @c - operations 00167 * and are constant time. For other %iterator classes they are linear time. 00168 */ 00169 template<typename _InputIterator, typename _Distance> 00170 inline void 00171 advance(_InputIterator& __i, _Distance __n) 00172 { 00173 // concept requirements -- taken care of in __advance 00174 typename iterator_traits<_InputIterator>::difference_type __d = __n; 00175 std::__advance(__i, __d, std::__iterator_category(__i)); 00176 } 00177 00178 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 00179 00180 template<typename _ForwardIterator> 00181 inline _ForwardIterator 00182 next(_ForwardIterator __x, typename 00183 iterator_traits<_ForwardIterator>::difference_type __n = 1) 00184 { 00185 std::advance(__x, __n); 00186 return __x; 00187 } 00188 00189 template<typename _BidirectionalIterator> 00190 inline _BidirectionalIterator 00191 prev(_BidirectionalIterator __x, typename 00192 iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 00193 { 00194 std::advance(__x, -__n); 00195 return __x; 00196 } 00197 00198 #endif // __GXX_EXPERIMENTAL_CXX0X__ 00199 00200 _GLIBCXX_END_NAMESPACE_VERSION 00201 } // namespace 00202 00203 #endif /* _STL_ITERATOR_BASE_FUNCS_H */