1 // Functions used by iterators -*- C++ -*-
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52 /** @file bits/stl_iterator_base_funcs.h
53 * This is an internal header file, included by other library headers.
54 * Do not attempt to use it directly. @headername{iterator}
56 * This file contains all of the general iterator-related utility
57 * functions, such as distance() and advance().
60 #ifndef _STL_ITERATOR_BASE_FUNCS_H
61 #define _STL_ITERATOR_BASE_FUNCS_H 1
63 #pragma GCC system_header
65 #include <bits/concept_check.h>
67 namespace std _GLIBCXX_VISIBILITY(default)
69 _GLIBCXX_BEGIN_NAMESPACE_VERSION
71 template<typename _InputIterator>
72 inline typename iterator_traits<_InputIterator>::difference_type
73 __distance(_InputIterator __first, _InputIterator __last,
76 // concept requirements
77 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
79 typename iterator_traits<_InputIterator>::difference_type __n = 0;
80 while (__first != __last)
88 template<typename _RandomAccessIterator>
89 inline typename iterator_traits<_RandomAccessIterator>::difference_type
90 __distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
91 random_access_iterator_tag)
93 // concept requirements
94 __glibcxx_function_requires(_RandomAccessIteratorConcept<
95 _RandomAccessIterator>)
96 return __last - __first;
100 * @brief A generalization of pointer arithmetic.
101 * @param __first An input iterator.
102 * @param __last An input iterator.
103 * @return The distance between them.
105 * Returns @c n such that __first + n == __last. This requires
106 * that @p __last must be reachable from @p __first. Note that @c
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.
112 template<typename _InputIterator>
113 inline typename iterator_traits<_InputIterator>::difference_type
114 distance(_InputIterator __first, _InputIterator __last)
116 // concept requirements -- taken care of in __distance
117 return std::__distance(__first, __last,
118 std::__iterator_category(__first));
121 template<typename _InputIterator, typename _Distance>
123 __advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
125 // concept requirements
126 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
131 template<typename _BidirectionalIterator, typename _Distance>
133 __advance(_BidirectionalIterator& __i, _Distance __n,
134 bidirectional_iterator_tag)
136 // concept requirements
137 __glibcxx_function_requires(_BidirectionalIteratorConcept<
138 _BidirectionalIterator>)
147 template<typename _RandomAccessIterator, typename _Distance>
149 __advance(_RandomAccessIterator& __i, _Distance __n,
150 random_access_iterator_tag)
152 // concept requirements
153 __glibcxx_function_requires(_RandomAccessIteratorConcept<
154 _RandomAccessIterator>)
159 * @brief A generalization of pointer arithmetic.
160 * @param __i An input iterator.
161 * @param __n The @a delta by which to change @p __i.
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.
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.
170 template<typename _InputIterator, typename _Distance>
172 advance(_InputIterator& __i, _Distance __n)
174 // concept requirements -- taken care of in __advance
175 typename iterator_traits<_InputIterator>::difference_type __d = __n;
176 std::__advance(__i, __d, std::__iterator_category(__i));
179 #ifdef __GXX_EXPERIMENTAL_CXX0X__
181 template<typename _ForwardIterator>
182 inline _ForwardIterator
183 next(_ForwardIterator __x, typename
184 iterator_traits<_ForwardIterator>::difference_type __n = 1)
186 std::advance(__x, __n);
190 template<typename _BidirectionalIterator>
191 inline _BidirectionalIterator
192 prev(_BidirectionalIterator __x, typename
193 iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
195 std::advance(__x, -__n);
199 #endif // __GXX_EXPERIMENTAL_CXX0X__
201 _GLIBCXX_END_NAMESPACE_VERSION
204 #endif /* _STL_ITERATOR_BASE_FUNCS_H */