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 00106 * that @p __last must be reachable from @p __first. Note that @c 00107 * n may be negative. 00108 * 00109 * For random access iterators, this uses their @c + and @c - operations 00110 * and are constant time. For other %iterator classes they are linear time. 00111 */ 00112 template<typename _InputIterator> 00113 inline typename iterator_traits<_InputIterator>::difference_type 00114 distance(_InputIterator __first, _InputIterator __last) 00115 { 00116 // concept requirements -- taken care of in __distance 00117 return std::__distance(__first, __last, 00118 std::__iterator_category(__first)); 00119 } 00120 00121 template<typename _InputIterator, typename _Distance> 00122 inline void 00123 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 00124 { 00125 // concept requirements 00126 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00127 while (__n--) 00128 ++__i; 00129 } 00130 00131 template<typename _BidirectionalIterator, typename _Distance> 00132 inline void 00133 __advance(_BidirectionalIterator& __i, _Distance __n, 00134 bidirectional_iterator_tag) 00135 { 00136 // concept requirements 00137 __glibcxx_function_requires(_BidirectionalIteratorConcept< 00138 _BidirectionalIterator>) 00139 if (__n > 0) 00140 while (__n--) 00141 ++__i; 00142 else 00143 while (__n++) 00144 --__i; 00145 } 00146 00147 template<typename _RandomAccessIterator, typename _Distance> 00148 inline void 00149 __advance(_RandomAccessIterator& __i, _Distance __n, 00150 random_access_iterator_tag) 00151 { 00152 // concept requirements 00153 __glibcxx_function_requires(_RandomAccessIteratorConcept< 00154 _RandomAccessIterator>) 00155 __i += __n; 00156 } 00157 00158 /** 00159 * @brief A generalization of pointer arithmetic. 00160 * @param __i An input iterator. 00161 * @param __n The @a delta by which to change @p __i. 00162 * @return Nothing. 00163 * 00164 * This increments @p i by @p n. For bidirectional and random access 00165 * iterators, @p __n may be negative, in which case @p __i is decremented. 00166 * 00167 * For random access iterators, this uses their @c + and @c - operations 00168 * and are constant time. For other %iterator classes they are linear time. 00169 */ 00170 template<typename _InputIterator, typename _Distance> 00171 inline void 00172 advance(_InputIterator& __i, _Distance __n) 00173 { 00174 // concept requirements -- taken care of in __advance 00175 typename iterator_traits<_InputIterator>::difference_type __d = __n; 00176 std::__advance(__i, __d, std::__iterator_category(__i)); 00177 } 00178 00179 #ifdef __GXX_EXPERIMENTAL_CXX0X__ 00180 00181 template<typename _ForwardIterator> 00182 inline _ForwardIterator 00183 next(_ForwardIterator __x, typename 00184 iterator_traits<_ForwardIterator>::difference_type __n = 1) 00185 { 00186 std::advance(__x, __n); 00187 return __x; 00188 } 00189 00190 template<typename _BidirectionalIterator> 00191 inline _BidirectionalIterator 00192 prev(_BidirectionalIterator __x, typename 00193 iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 00194 { 00195 std::advance(__x, -__n); 00196 return __x; 00197 } 00198 00199 #endif // __GXX_EXPERIMENTAL_CXX0X__ 00200 00201 _GLIBCXX_END_NAMESPACE_VERSION 00202 } // namespace 00203 00204 #endif /* _STL_ITERATOR_BASE_FUNCS_H */