1 // Functions used by iterators -*- C++ -*-
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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}
55 * This file contains all of the general iterator-related utility
56 * functions, such as distance() and advance().
59 #ifndef _STL_ITERATOR_BASE_FUNCS_H
60 #define _STL_ITERATOR_BASE_FUNCS_H 1
62 #pragma GCC system_header
64 #include <bits/concept_check.h>
65 #include <debug/debug.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
>)
127 _GLIBCXX_DEBUG_ASSERT(__n
>= 0);
132 template<typename _BidirectionalIterator
, typename _Distance
>
134 __advance(_BidirectionalIterator
& __i
, _Distance __n
,
135 bidirectional_iterator_tag
)
137 // concept requirements
138 __glibcxx_function_requires(_BidirectionalIteratorConcept
<
139 _BidirectionalIterator
>)
148 template<typename _RandomAccessIterator
, typename _Distance
>
150 __advance(_RandomAccessIterator
& __i
, _Distance __n
,
151 random_access_iterator_tag
)
153 // concept requirements
154 __glibcxx_function_requires(_RandomAccessIteratorConcept
<
155 _RandomAccessIterator
>)
160 * @brief A generalization of pointer arithmetic.
161 * @param __i An input iterator.
162 * @param __n The @a delta by which to change @p __i.
165 * This increments @p i by @p n. For bidirectional and random access
166 * iterators, @p __n may be negative, in which case @p __i is decremented.
168 * For random access iterators, this uses their @c + and @c - operations
169 * and are constant time. For other %iterator classes they are linear time.
171 template<typename _InputIterator
, typename _Distance
>
173 advance(_InputIterator
& __i
, _Distance __n
)
175 // concept requirements -- taken care of in __advance
176 typename iterator_traits
<_InputIterator
>::difference_type __d
= __n
;
177 std::__advance(__i
, __d
, std::__iterator_category(__i
));
180 #if __cplusplus >= 201103L
182 template<typename _ForwardIterator
>
183 inline _ForwardIterator
184 next(_ForwardIterator __x
, typename
185 iterator_traits
<_ForwardIterator
>::difference_type __n
= 1)
187 std::advance(__x
, __n
);
191 template<typename _BidirectionalIterator
>
192 inline _BidirectionalIterator
193 prev(_BidirectionalIterator __x
, typename
194 iterator_traits
<_BidirectionalIterator
>::difference_type __n
= 1)
196 std::advance(__x
, -__n
);
202 _GLIBCXX_END_NAMESPACE_VERSION
205 #endif /* _STL_ITERATOR_BASE_FUNCS_H */