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The C and C++ Include Header Files
/usr/include/c++/13/bits/stl_iterator_base_funcs.h
$ cat -n /usr/include/c++/13/bits/stl_iterator_base_funcs.h 1 // Functions used by iterators -*- C++ -*- 2 3 // Copyright (C) 2001-2023 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 3, 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 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /* 26 * 27 * Copyright (c) 1994 28 * Hewlett-Packard Company 29 * 30 * Permission to use, copy, modify, distribute and sell this software 31 * and its documentation for any purpose is hereby granted without fee, 32 * provided that the above copyright notice appear in all copies and 33 * that both that copyright notice and this permission notice appear 34 * in supporting documentation. Hewlett-Packard Company makes no 35 * representations about the suitability of this software for any 36 * purpose. It is provided "as is" without express or implied warranty. 37 * 38 * 39 * Copyright (c) 1996-1998 40 * Silicon Graphics Computer Systems, Inc. 41 * 42 * Permission to use, copy, modify, distribute and sell this software 43 * and its documentation for any purpose is hereby granted without fee, 44 * provided that the above copyright notice appear in all copies and 45 * that both that copyright notice and this permission notice appear 46 * in supporting documentation. Silicon Graphics makes no 47 * representations about the suitability of this software for any 48 * purpose. It is provided "as is" without express or implied warranty. 49 */ 50 51 /** @file bits/stl_iterator_base_funcs.h 52 * This is an internal header file, included by other library headers. 53 * Do not attempt to use it directly. @headername{iterator} 54 * 55 * This file contains all of the general iterator-related utility 56 * functions, such as distance() and advance(). 57 */ 58 59 #ifndef _STL_ITERATOR_BASE_FUNCS_H 60 #define _STL_ITERATOR_BASE_FUNCS_H 1 61 62 #pragma GCC system_header 63 64 #include <bits/concept_check.h> 65 #include <debug/assertions.h> 66 #include <bits/stl_iterator_base_types.h> 67 68 namespace std _GLIBCXX_VISIBILITY(default) 69 { 70 _GLIBCXX_BEGIN_NAMESPACE_VERSION 71 72 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER 73 // Forward declaration for the overloads of __distance. 74 template <typename> struct _List_iterator; 75 template <typename> struct _List_const_iterator; 76 _GLIBCXX_END_NAMESPACE_CONTAINER 77 78 template<typename _InputIterator> 79 inline _GLIBCXX14_CONSTEXPR 80 typename iterator_traits<_InputIterator>::difference_type 81 __distance(_InputIterator __first, _InputIterator __last, 82 input_iterator_tag) 83 { 84 // concept requirements 85 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 86 87 typename iterator_traits<_InputIterator>::difference_type __n = 0; 88 while (__first != __last) 89 { 90 ++__first; 91 ++__n; 92 } 93 return __n; 94 } 95 96 template<typename _RandomAccessIterator> 97 __attribute__((__always_inline__)) 98 inline _GLIBCXX14_CONSTEXPR 99 typename iterator_traits<_RandomAccessIterator>::difference_type 100 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, 101 random_access_iterator_tag) 102 { 103 // concept requirements 104 __glibcxx_function_requires(_RandomAccessIteratorConcept< 105 _RandomAccessIterator>) 106 return __last - __first; 107 } 108 109 #if _GLIBCXX_USE_CXX11_ABI 110 // Forward declaration because of the qualified call in distance. 111 template<typename _Tp> 112 ptrdiff_t 113 __distance(_GLIBCXX_STD_C::_List_iterator<_Tp>, 114 _GLIBCXX_STD_C::_List_iterator<_Tp>, 115 input_iterator_tag); 116 117 template<typename _Tp> 118 ptrdiff_t 119 __distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp>, 120 _GLIBCXX_STD_C::_List_const_iterator<_Tp>, 121 input_iterator_tag); 122 #endif 123 124 #if __cplusplus >= 201103L 125 // Give better error if std::distance called with a non-Cpp17InputIterator. 126 template<typename _OutputIterator> 127 void 128 __distance(_OutputIterator, _OutputIterator, output_iterator_tag) = delete; 129 #endif 130 131 /** 132 * @brief A generalization of pointer arithmetic. 133 * @param __first An input iterator. 134 * @param __last An input iterator. 135 * @return The distance between them. 136 * 137 * Returns @c n such that __first + n == __last. This requires 138 * that @p __last must be reachable from @p __first. Note that @c 139 * n may be negative. 140 * 141 * For random access iterators, this uses their @c + and @c - operations 142 * and are constant time. For other %iterator classes they are linear time. 143 */ 144 template<typename _InputIterator> 145 _GLIBCXX_NODISCARD __attribute__((__always_inline__)) 146 inline _GLIBCXX17_CONSTEXPR 147 typename iterator_traits<_InputIterator>::difference_type 148 distance(_InputIterator __first, _InputIterator __last) 149 { 150 // concept requirements -- taken care of in __distance 151 return std::__distance(__first, __last, 152 std::__iterator_category(__first)); 153 } 154 155 template<typename _InputIterator, typename _Distance> 156 inline _GLIBCXX14_CONSTEXPR void 157 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) 158 { 159 // concept requirements 160 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 161 __glibcxx_assert(__n >= 0); 162 while (__n--) 163 ++__i; 164 } 165 166 template<typename _BidirectionalIterator, typename _Distance> 167 inline _GLIBCXX14_CONSTEXPR void 168 __advance(_BidirectionalIterator& __i, _Distance __n, 169 bidirectional_iterator_tag) 170 { 171 // concept requirements 172 __glibcxx_function_requires(_BidirectionalIteratorConcept< 173 _BidirectionalIterator>) 174 if (__n > 0) 175 while (__n--) 176 ++__i; 177 else 178 while (__n++) 179 --__i; 180 } 181 182 template<typename _RandomAccessIterator, typename _Distance> 183 inline _GLIBCXX14_CONSTEXPR void 184 __advance(_RandomAccessIterator& __i, _Distance __n, 185 random_access_iterator_tag) 186 { 187 // concept requirements 188 __glibcxx_function_requires(_RandomAccessIteratorConcept< 189 _RandomAccessIterator>) 190 if (__builtin_constant_p(__n) && __n == 1) 191 ++__i; 192 else if (__builtin_constant_p(__n) && __n == -1) 193 --__i; 194 else 195 __i += __n; 196 } 197 198 #if __cplusplus >= 201103L 199 // Give better error if std::advance called with a non-Cpp17InputIterator. 200 template<typename _OutputIterator, typename _Distance> 201 void 202 __advance(_OutputIterator&, _Distance, output_iterator_tag) = delete; 203 #endif 204 205 /** 206 * @brief A generalization of pointer arithmetic. 207 * @param __i An input iterator. 208 * @param __n The @a delta by which to change @p __i. 209 * @return Nothing. 210 * 211 * This increments @p i by @p n. For bidirectional and random access 212 * iterators, @p __n may be negative, in which case @p __i is decremented. 213 * 214 * For random access iterators, this uses their @c + and @c - operations 215 * and are constant time. For other %iterator classes they are linear time. 216 */ 217 template<typename _InputIterator, typename _Distance> 218 __attribute__((__always_inline__)) 219 inline _GLIBCXX17_CONSTEXPR void 220 advance(_InputIterator& __i, _Distance __n) 221 { 222 // concept requirements -- taken care of in __advance 223 typename iterator_traits<_InputIterator>::difference_type __d = __n; 224 std::__advance(__i, __d, std::__iterator_category(__i)); 225 } 226 227 #if __cplusplus >= 201103L 228 229 template<typename _InputIterator> 230 _GLIBCXX_NODISCARD [[__gnu__::__always_inline__]] 231 inline _GLIBCXX17_CONSTEXPR _InputIterator 232 next(_InputIterator __x, typename 233 iterator_traits<_InputIterator>::difference_type __n = 1) 234 { 235 // concept requirements 236 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 237 std::advance(__x, __n); 238 return __x; 239 } 240 241 template<typename _BidirectionalIterator> 242 _GLIBCXX_NODISCARD [[__gnu__::__always_inline__]] 243 inline _GLIBCXX17_CONSTEXPR _BidirectionalIterator 244 prev(_BidirectionalIterator __x, typename 245 iterator_traits<_BidirectionalIterator>::difference_type __n = 1) 246 { 247 // concept requirements 248 __glibcxx_function_requires(_BidirectionalIteratorConcept< 249 _BidirectionalIterator>) 250 std::advance(__x, -__n); 251 return __x; 252 } 253 254 #endif // C++11 255 256 _GLIBCXX_END_NAMESPACE_VERSION 257 } // namespace 258 259 #endif /* _STL_ITERATOR_BASE_FUNCS_H */
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