libstdc++
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00001 // Functions used by iterators -*- C++ -*- 00002 00003 // Copyright (C) 2001-2016 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /* 00026 * 00027 * Copyright (c) 1994 00028 * Hewlett-Packard Company 00029 * 00030 * Permission to use, copy, modify, distribute and sell this software 00031 * and its documentation for any purpose is hereby granted without fee, 00032 * provided that the above copyright notice appear in all copies and 00033 * that both that copyright notice and this permission notice appear 00034 * in supporting documentation. Hewlett-Packard Company makes no 00035 * representations about the suitability of this software for any 00036 * purpose. It is provided "as is" without express or implied warranty. 00037 * 00038 * 00039 * Copyright (c) 1996-1998 00040 * Silicon Graphics Computer Systems, Inc. 00041 * 00042 * Permission to use, copy, modify, distribute and sell this software 00043 * and its documentation for any purpose is hereby granted without fee, 00044 * provided that the above copyright notice appear in all copies and 00045 * that both that copyright notice and this permission notice appear 00046 * in supporting documentation. Silicon Graphics makes no 00047 * representations about the suitability of this software for any 00048 * purpose. It is provided "as is" without express or implied warranty. 00049 */ 00050 00051 /** @file bits/stl_iterator_base_funcs.h 00052 * This is an internal header file, included by other library headers. 00053 * Do not attempt to use it directly. @headername{iterator} 00054 * 00055 * This file contains all of the general iterator-related utility 00056 * functions, such as distance() and advance(). 00057 */ 00058 00059 #ifndef _STL_ITERATOR_BASE_FUNCS_H 00060 #define _STL_ITERATOR_BASE_FUNCS_H 1 00061 00062 #pragma GCC system_header 00063 00064 #include <bits/concept_check.h> 00065 #include <debug/assertions.h> 00066 00067 namespace std _GLIBCXX_VISIBILITY(default) 00068 { 00069 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER 00070 // Forward declaration for the overloads of __distance. 00071 template <typename> struct _List_iterator; 00072 template <typename> struct _List_const_iterator; 00073 _GLIBCXX_END_NAMESPACE_CONTAINER 00074 00075 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00076 00077 template<typename _InputIterator> 00078 inline typename iterator_traits<_InputIterator>::difference_type 00079 __distance(_InputIterator __first, _InputIterator __last, 00080 input_iterator_tag) 00081 { 00082 // concept requirements 00083 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00084 00085 typename iterator_traits<_InputIterator>::difference_type __n = 0; 00086 while (__first != __last) 00087 { 00088 ++__first; 00089 ++__n; 00090 } 00091 return __n; 00092 } 00093 00094 template<typename _RandomAccessIterator> 00095 inline typename iterator_traits<_RandomAccessIterator>::difference_type 00096 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, 00097 random_access_iterator_tag) 00098 { 00099 // concept requirements 00100 __glibcxx_function_requires(_RandomAccessIteratorConcept< 00101 _RandomAccessIterator>) 00102 return __last - __first; 00103 } 00104 00105 #if _GLIBCXX_USE_CXX11_ABI 00106 // Forward declaration because of the qualified call in distance. 00107 template<typename _Tp> 00108 ptrdiff_t 00109 __distance(_GLIBCXX_STD_C::_List_iterator<_Tp>, 00110 _GLIBCXX_STD_C::_List_iterator<_Tp>, 00111 input_iterator_tag); 00112 00113 template<typename _Tp> 00114 ptrdiff_t 00115 __distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp>, 00116 _GLIBCXX_STD_C::_List_const_iterator<_Tp>, 00117 input_iterator_tag); 00118 #endif 00119 00120 /** 00121 * @brief A generalization of pointer arithmetic. 00122 * @param __first An input iterator. 00123 * @param __last An input iterator. 00124 * @return The distance between them. 00125 * 00126 * Returns @c n such that __first + n == __last. This requires 00127 * that @p __last must be reachable from @p __first. Note that @c 00128 * n may be negative. 00129 * 00130 * For random access iterators, this uses their @c + and @c - operations 00131 * and are constant time. For other %iterator classes they are linear time. 00132 */ 00133 template<typename _InputIterator> 00134 inline typename iterator_traits<_InputIterator>::difference_type 00135 distance(_InputIterator __first, _InputIterator __last) 00136 { 00137 // concept requirements -- taken care of in __distance 00138 return std::__distance(__first, __last, 00139 std::__iterator_category(__first)); 00140 } 00141 00142 template<typename _InputIterator, typename _Distance> 00143 inline void 00144 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 00145 { 00146 // concept requirements 00147 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00148 __glibcxx_assert(__n >= 0); 00149 while (__n--) 00150 ++__i; 00151 } 00152 00153 template<typename _BidirectionalIterator, typename _Distance> 00154 inline void 00155 __advance(_BidirectionalIterator& __i, _Distance __n, 00156 bidirectional_iterator_tag) 00157 { 00158 // concept requirements 00159 __glibcxx_function_requires(_BidirectionalIteratorConcept< 00160 _BidirectionalIterator>) 00161 if (__n > 0) 00162 while (__n--) 00163 ++__i; 00164 else 00165 while (__n++) 00166 --__i; 00167 } 00168 00169 template<typename _RandomAccessIterator, typename _Distance> 00170 inline void 00171 __advance(_RandomAccessIterator& __i, _Distance __n, 00172 random_access_iterator_tag) 00173 { 00174 // concept requirements 00175 __glibcxx_function_requires(_RandomAccessIteratorConcept< 00176 _RandomAccessIterator>) 00177 __i += __n; 00178 } 00179 00180 /** 00181 * @brief A generalization of pointer arithmetic. 00182 * @param __i An input iterator. 00183 * @param __n The @a delta by which to change @p __i. 00184 * @return Nothing. 00185 * 00186 * This increments @p i by @p n. For bidirectional and random access 00187 * iterators, @p __n may be negative, in which case @p __i is decremented. 00188 * 00189 * For random access iterators, this uses their @c + and @c - operations 00190 * and are constant time. For other %iterator classes they are linear time. 00191 */ 00192 template<typename _InputIterator, typename _Distance> 00193 inline void 00194 advance(_InputIterator& __i, _Distance __n) 00195 { 00196 // concept requirements -- taken care of in __advance 00197 typename iterator_traits<_InputIterator>::difference_type __d = __n; 00198 std::__advance(__i, __d, std::__iterator_category(__i)); 00199 } 00200 00201 #if __cplusplus >= 201103L 00202 00203 template<typename _ForwardIterator> 00204 inline _ForwardIterator 00205 next(_ForwardIterator __x, typename 00206 iterator_traits<_ForwardIterator>::difference_type __n = 1) 00207 { 00208 // concept requirements 00209 __glibcxx_function_requires(_ForwardIteratorConcept< 00210 _ForwardIterator>) 00211 std::advance(__x, __n); 00212 return __x; 00213 } 00214 00215 template<typename _BidirectionalIterator> 00216 inline _BidirectionalIterator 00217 prev(_BidirectionalIterator __x, typename 00218 iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 00219 { 00220 // concept requirements 00221 __glibcxx_function_requires(_BidirectionalIteratorConcept< 00222 _BidirectionalIterator>) 00223 std::advance(__x, -__n); 00224 return __x; 00225 } 00226 00227 #endif // C++11 00228 00229 _GLIBCXX_END_NAMESPACE_VERSION 00230 } // namespace 00231 00232 #endif /* _STL_ITERATOR_BASE_FUNCS_H */