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/assertions.h>
67 namespace std
_GLIBCXX_VISIBILITY(default)
69 _GLIBCXX_BEGIN_NAMESPACE_VERSION
71 _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
72 // Forward declaration for the overloads of __distance.
73 template <typename
> struct _List_iterator
;
74 template <typename
> struct _List_const_iterator
;
75 _GLIBCXX_END_NAMESPACE_CONTAINER
77 template<typename _InputIterator
>
78 inline _GLIBCXX14_CONSTEXPR
79 typename iterator_traits
<_InputIterator
>::difference_type
80 __distance(_InputIterator __first
, _InputIterator __last
,
83 // concept requirements
84 __glibcxx_function_requires(_InputIteratorConcept
<_InputIterator
>)
86 typename iterator_traits
<_InputIterator
>::difference_type __n
= 0;
87 while (__first
!= __last
)
95 template<typename _RandomAccessIterator
>
96 inline _GLIBCXX14_CONSTEXPR
97 typename iterator_traits
<_RandomAccessIterator
>::difference_type
98 __distance(_RandomAccessIterator __first
, _RandomAccessIterator __last
,
99 random_access_iterator_tag
)
101 // concept requirements
102 __glibcxx_function_requires(_RandomAccessIteratorConcept
<
103 _RandomAccessIterator
>)
104 return __last
- __first
;
107 #if _GLIBCXX_USE_CXX11_ABI
108 // Forward declaration because of the qualified call in distance.
109 template<typename _Tp
>
111 __distance(_GLIBCXX_STD_C::_List_iterator
<_Tp
>,
112 _GLIBCXX_STD_C::_List_iterator
<_Tp
>,
115 template<typename _Tp
>
117 __distance(_GLIBCXX_STD_C::_List_const_iterator
<_Tp
>,
118 _GLIBCXX_STD_C::_List_const_iterator
<_Tp
>,
123 * @brief A generalization of pointer arithmetic.
124 * @param __first An input iterator.
125 * @param __last An input iterator.
126 * @return The distance between them.
128 * Returns @c n such that __first + n == __last. This requires
129 * that @p __last must be reachable from @p __first. Note that @c
132 * For random access iterators, this uses their @c + and @c - operations
133 * and are constant time. For other %iterator classes they are linear time.
135 template<typename _InputIterator
>
136 inline _GLIBCXX17_CONSTEXPR
137 typename iterator_traits
<_InputIterator
>::difference_type
138 distance(_InputIterator __first
, _InputIterator __last
)
140 // concept requirements -- taken care of in __distance
141 return std::__distance(__first
, __last
,
142 std::__iterator_category(__first
));
145 template<typename _InputIterator
, typename _Distance
>
146 inline _GLIBCXX14_CONSTEXPR
void
147 __advance(_InputIterator
& __i
, _Distance __n
, input_iterator_tag
)
149 // concept requirements
150 __glibcxx_function_requires(_InputIteratorConcept
<_InputIterator
>)
151 __glibcxx_assert(__n
>= 0);
156 template<typename _BidirectionalIterator
, typename _Distance
>
157 inline _GLIBCXX14_CONSTEXPR
void
158 __advance(_BidirectionalIterator
& __i
, _Distance __n
,
159 bidirectional_iterator_tag
)
161 // concept requirements
162 __glibcxx_function_requires(_BidirectionalIteratorConcept
<
163 _BidirectionalIterator
>)
172 template<typename _RandomAccessIterator
, typename _Distance
>
173 inline _GLIBCXX14_CONSTEXPR
void
174 __advance(_RandomAccessIterator
& __i
, _Distance __n
,
175 random_access_iterator_tag
)
177 // concept requirements
178 __glibcxx_function_requires(_RandomAccessIteratorConcept
<
179 _RandomAccessIterator
>)
180 if (__builtin_constant_p(__n
) && __n
== 1)
182 else if (__builtin_constant_p(__n
) && __n
== -1)
189 * @brief A generalization of pointer arithmetic.
190 * @param __i An input iterator.
191 * @param __n The @a delta by which to change @p __i.
194 * This increments @p i by @p n. For bidirectional and random access
195 * iterators, @p __n may be negative, in which case @p __i is decremented.
197 * For random access iterators, this uses their @c + and @c - operations
198 * and are constant time. For other %iterator classes they are linear time.
200 template<typename _InputIterator
, typename _Distance
>
201 inline _GLIBCXX17_CONSTEXPR
void
202 advance(_InputIterator
& __i
, _Distance __n
)
204 // concept requirements -- taken care of in __advance
205 typename iterator_traits
<_InputIterator
>::difference_type __d
= __n
;
206 std::__advance(__i
, __d
, std::__iterator_category(__i
));
209 #if __cplusplus >= 201103L
211 template<typename _InputIterator
>
212 inline _GLIBCXX17_CONSTEXPR _InputIterator
213 next(_InputIterator __x
, typename
214 iterator_traits
<_InputIterator
>::difference_type __n
= 1)
216 // concept requirements
217 __glibcxx_function_requires(_InputIteratorConcept
<_InputIterator
>)
218 std::advance(__x
, __n
);
222 template<typename _BidirectionalIterator
>
223 inline _GLIBCXX17_CONSTEXPR _BidirectionalIterator
224 prev(_BidirectionalIterator __x
, typename
225 iterator_traits
<_BidirectionalIterator
>::difference_type __n
= 1)
227 // concept requirements
228 __glibcxx_function_requires(_BidirectionalIteratorConcept
<
229 _BidirectionalIterator
>)
230 std::advance(__x
, -__n
);
236 _GLIBCXX_END_NAMESPACE_VERSION
239 #endif /* _STL_ITERATOR_BASE_FUNCS_H */