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1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___CXX03___ALGORITHM_ITERATOR_OPERATIONS_H
10#define _LIBCPP___CXX03___ALGORITHM_ITERATOR_OPERATIONS_H
11
12#include <__cxx03/__algorithm/iter_swap.h>
13#include <__cxx03/__assert>
14#include <__cxx03/__config>
15#include <__cxx03/__iterator/advance.h>
16#include <__cxx03/__iterator/distance.h>
17#include <__cxx03/__iterator/iterator_traits.h>
18#include <__cxx03/__iterator/next.h>
19#include <__cxx03/__iterator/prev.h>
20#include <__cxx03/__type_traits/enable_if.h>
21#include <__cxx03/__type_traits/is_reference.h>
22#include <__cxx03/__type_traits/is_same.h>
23#include <__cxx03/__type_traits/remove_cvref.h>
24#include <__cxx03/__utility/declval.h>
25#include <__cxx03/__utility/forward.h>
26#include <__cxx03/__utility/move.h>
27
28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
29# pragma GCC system_header
30#endif
31
32_LIBCPP_PUSH_MACROS
33#include <__cxx03/__undef_macros>
34
35_LIBCPP_BEGIN_NAMESPACE_STD
36
37template <class _AlgPolicy>
38struct _IterOps;
39
40struct _ClassicAlgPolicy {};
41
42template <>
43struct _IterOps<_ClassicAlgPolicy> {
44 template <class _Iter>
45 using __value_type = typename iterator_traits<_Iter>::value_type;
46
47 template <class _Iter>
48 using __iterator_category = typename iterator_traits<_Iter>::iterator_category;
49
50 template <class _Iter>
51 using __difference_type = typename iterator_traits<_Iter>::difference_type;
52
53 // advance
54 template <class _Iter, class _Distance>
55 _LIBCPP_HIDE_FROM_ABI static void advance(_Iter& __iter, _Distance __count) {
56 std::advance(__iter, __count);
57 }
58
59 // distance
60 template <class _Iter>
61 _LIBCPP_HIDE_FROM_ABI static typename iterator_traits<_Iter>::difference_type distance(_Iter __first, _Iter __last) {
62 return std::distance(__first, __last);
63 }
64
65 template <class _Iter>
66 using __deref_t = decltype(*std::declval<_Iter&>());
67
68 template <class _Iter>
69 using __move_t = decltype(std::move(*std::declval<_Iter&>()));
70
71 template <class _Iter>
72 _LIBCPP_HIDE_FROM_ABI static void __validate_iter_reference() {
73 static_assert(
74 is_same<__deref_t<_Iter>, typename iterator_traits<__remove_cvref_t<_Iter> >::reference>::value,
75 "It looks like your iterator's `iterator_traits<It>::reference` does not match the return type of "
76 "dereferencing the iterator, i.e., calling `*it`. This is undefined behavior according to [input.iterators] "
77 "and can lead to dangling reference issues at runtime, so we are flagging this.");
78 }
79
80 // iter_move
81 template <class _Iter, __enable_if_t<is_reference<__deref_t<_Iter> >::value, int> = 0>
82 _LIBCPP_HIDE_FROM_ABI static
83 // If the result of dereferencing `_Iter` is a reference type, deduce the result of calling `std::move` on it.
84 // Note that the C++03 mode doesn't support `decltype(auto)` as the return type.
85 __move_t<_Iter>
86 __iter_move(_Iter&& __i) {
87 __validate_iter_reference<_Iter>();
88
89 return std::move(*std::forward<_Iter>(__i));
90 }
91
92 template <class _Iter, __enable_if_t<!is_reference<__deref_t<_Iter> >::value, int> = 0>
93 _LIBCPP_HIDE_FROM_ABI static
94 // If the result of dereferencing `_Iter` is a value type, deduce the return value of this function to also be a
95 // value -- otherwise, after `operator*` returns a temporary, this function would return a dangling reference to
96 // that temporary. Note that the C++03 mode doesn't support `auto` as the return type.
97 __deref_t<_Iter>
98 __iter_move(_Iter&& __i) {
99 __validate_iter_reference<_Iter>();
100
101 return *std::forward<_Iter>(__i);
102 }
103
104 // iter_swap
105 template <class _Iter1, class _Iter2>
106 _LIBCPP_HIDE_FROM_ABI static void iter_swap(_Iter1&& __a, _Iter2&& __b) {
107 std::iter_swap(std::forward<_Iter1>(__a), std::forward<_Iter2>(__b));
108 }
109
110 // next
111 template <class _Iterator>
112 _LIBCPP_HIDE_FROM_ABI static _Iterator next(_Iterator, _Iterator __last) {
113 return __last;
114 }
115
116 template <class _Iter>
117 _LIBCPP_HIDE_FROM_ABI static __remove_cvref_t<_Iter>
118 next(_Iter&& __it, typename iterator_traits<__remove_cvref_t<_Iter> >::difference_type __n = 1) {
119 return std::next(std::forward<_Iter>(__it), __n);
120 }
121
122 // prev
123 template <class _Iter>
124 _LIBCPP_HIDE_FROM_ABI static __remove_cvref_t<_Iter>
125 prev(_Iter&& __iter, typename iterator_traits<__remove_cvref_t<_Iter> >::difference_type __n = 1) {
126 return std::prev(std::forward<_Iter>(__iter), __n);
127 }
128
129 template <class _Iter>
130 _LIBCPP_HIDE_FROM_ABI static void __advance_to(_Iter& __first, _Iter __last) {
131 __first = __last;
132 }
133
134 // advance with sentinel, a la std::ranges::advance
135 template <class _Iter>
136 _LIBCPP_HIDE_FROM_ABI static __difference_type<_Iter>
137 __advance_to(_Iter& __iter, __difference_type<_Iter> __count, const _Iter& __sentinel) {
138 return _IterOps::__advance_to(__iter, __count, __sentinel, typename iterator_traits<_Iter>::iterator_category());
139 }
140
141private:
142 // advance with sentinel, a la std::ranges::advance -- InputIterator specialization
143 template <class _InputIter>
144 _LIBCPP_HIDE_FROM_ABI static __difference_type<_InputIter> __advance_to(
145 _InputIter& __iter, __difference_type<_InputIter> __count, const _InputIter& __sentinel, input_iterator_tag) {
146 __difference_type<_InputIter> __dist = 0;
147 for (; __dist < __count && __iter != __sentinel; ++__dist)
148 ++__iter;
149 return __count - __dist;
150 }
151
152 // advance with sentinel, a la std::ranges::advance -- BidirectionalIterator specialization
153 template <class _BiDirIter>
154 _LIBCPP_HIDE_FROM_ABI static __difference_type<_BiDirIter>
155 __advance_to(_BiDirIter& __iter,
156 __difference_type<_BiDirIter> __count,
157 const _BiDirIter& __sentinel,
158 bidirectional_iterator_tag) {
159 __difference_type<_BiDirIter> __dist = 0;
160 if (__count >= 0)
161 for (; __dist < __count && __iter != __sentinel; ++__dist)
162 ++__iter;
163 else
164 for (__count = -__count; __dist < __count && __iter != __sentinel; ++__dist)
165 --__iter;
166 return __count - __dist;
167 }
168
169 // advance with sentinel, a la std::ranges::advance -- RandomIterator specialization
170 template <class _RandIter>
171 _LIBCPP_HIDE_FROM_ABI static __difference_type<_RandIter>
172 __advance_to(_RandIter& __iter,
173 __difference_type<_RandIter> __count,
174 const _RandIter& __sentinel,
175 random_access_iterator_tag) {
176 auto __dist = _IterOps::distance(__iter, __sentinel);
177 _LIBCPP_ASSERT_VALID_INPUT_RANGE(
178 __count == 0 || (__dist < 0) == (__count < 0), "__sentinel must precede __iter when __count < 0");
179 if (__count < 0)
180 __dist = __dist > __count ? __dist : __count;
181 else
182 __dist = __dist < __count ? __dist : __count;
183 __iter += __dist;
184 return __count - __dist;
185 }
186};
187
188_LIBCPP_END_NAMESPACE_STD
189
190_LIBCPP_POP_MACROS
191
192#endif // _LIBCPP___CXX03___ALGORITHM_ITERATOR_OPERATIONS_H
193

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source code of libcxx/include/__cxx03/__algorithm/iterator_operations.h