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___ALGORITHM_ITERATOR_OPERATIONS_H 10 #define _LIBCPP___ALGORITHM_ITERATOR_OPERATIONS_H 11 12 #include <__algorithm/iter_swap.h> 13 #include <__algorithm/ranges_iterator_concept.h> 14 #include <__config> 15 #include <__iterator/advance.h> 16 #include <__iterator/distance.h> 17 #include <__iterator/incrementable_traits.h> 18 #include <__iterator/iter_move.h> 19 #include <__iterator/iter_swap.h> 20 #include <__iterator/iterator_traits.h> 21 #include <__iterator/next.h> 22 #include <__iterator/prev.h> 23 #include <__iterator/readable_traits.h> 24 #include <__type_traits/enable_if.h> 25 #include <__type_traits/is_reference.h> 26 #include <__type_traits/is_same.h> 27 #include <__type_traits/remove_cvref.h> 28 #include <__utility/declval.h> 29 #include <__utility/forward.h> 30 #include <__utility/move.h> 31 32 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 33 # pragma GCC system_header 34 #endif 35 36 _LIBCPP_PUSH_MACROS 37 #include <__undef_macros> 38 39 _LIBCPP_BEGIN_NAMESPACE_STD 40 41 template <class _AlgPolicy> 42 struct _IterOps; 43 44 #if _LIBCPP_STD_VER >= 20 45 struct _RangeAlgPolicy {}; 46 47 template <> 48 struct _IterOps<_RangeAlgPolicy> { 49 template <class _Iter> 50 using __value_type = iter_value_t<_Iter>; 51 52 template <class _Iter> 53 using __iterator_category = ranges::__iterator_concept<_Iter>; 54 55 template <class _Iter> 56 using __difference_type = iter_difference_t<_Iter>; 57 58 static constexpr auto advance = ranges::advance; 59 static constexpr auto distance = ranges::distance; 60 static constexpr auto __iter_move = ranges::iter_move; 61 static constexpr auto iter_swap = ranges::iter_swap; 62 static constexpr auto next = ranges::next; 63 static constexpr auto prev = ranges::prev; 64 static constexpr auto __advance_to = ranges::advance; 65 }; 66 67 #endif 68 69 struct _ClassicAlgPolicy {}; 70 71 template <> 72 struct _IterOps<_ClassicAlgPolicy> { 73 template <class _Iter> 74 using __value_type = typename iterator_traits<_Iter>::value_type; 75 76 template <class _Iter> 77 using __iterator_category = typename iterator_traits<_Iter>::iterator_category; 78 79 template <class _Iter> 80 using __difference_type = typename iterator_traits<_Iter>::difference_type; 81 82 // advance 83 template <class _Iter, class _Distance> 84 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 static void advance(_Iter& __iter, _Distance __count) { 85 std::advance(__iter, __count); 86 } 87 88 // distance 89 template <class _Iter> 90 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 static typename iterator_traits<_Iter>::difference_type 91 distance(_Iter __first, _Iter __last) { 92 return std::distance(__first, __last); 93 } 94 95 template <class _Iter> 96 using __deref_t = decltype(*std::declval<_Iter&>()); 97 98 template <class _Iter> 99 using __move_t = decltype(std::move(*std::declval<_Iter&>())); 100 101 template <class _Iter> 102 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 static void __validate_iter_reference() { 103 static_assert( 104 is_same<__deref_t<_Iter>, typename iterator_traits<__remove_cvref_t<_Iter> >::reference>::value, 105 "It looks like your iterator's `iterator_traits<It>::reference` does not match the return type of " 106 "dereferencing the iterator, i.e., calling `*it`. This is undefined behavior according to [input.iterators] " 107 "and can lead to dangling reference issues at runtime, so we are flagging this."); 108 } 109 110 // iter_move 111 template <class _Iter, __enable_if_t<is_reference<__deref_t<_Iter> >::value, int> = 0> 112 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 static 113 // If the result of dereferencing `_Iter` is a reference type, deduce the result of calling `std::move` on it. 114 // Note that the C++03 mode doesn't support `decltype(auto)` as the return type. 115 __move_t<_Iter> 116 __iter_move(_Iter&& __i) { 117 __validate_iter_reference<_Iter>(); 118 119 return std::move(*std::forward<_Iter>(__i)); 120 } 121 122 template <class _Iter, __enable_if_t<!is_reference<__deref_t<_Iter> >::value, int> = 0> 123 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 static 124 // If the result of dereferencing `_Iter` is a value type, deduce the return value of this function to also be a 125 // value -- otherwise, after `operator*` returns a temporary, this function would return a dangling reference to 126 // that temporary. Note that the C++03 mode doesn't support `auto` as the return type. 127 __deref_t<_Iter> 128 __iter_move(_Iter&& __i) { 129 __validate_iter_reference<_Iter>(); 130 131 return *std::forward<_Iter>(__i); 132 } 133 134 // iter_swap 135 template <class _Iter1, class _Iter2> 136 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 static void iter_swap(_Iter1&& __a, _Iter2&& __b) { 137 std::iter_swap(std::forward<_Iter1>(__a), std::forward<_Iter2>(__b)); 138 } 139 140 // next 141 template <class _Iterator> 142 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX14 _Iterator next(_Iterator, _Iterator __last) { 143 return __last; 144 } 145 146 template <class _Iter> 147 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX14 __remove_cvref_t<_Iter> 148 next(_Iter&& __it, typename iterator_traits<__remove_cvref_t<_Iter> >::difference_type __n = 1) { 149 return std::next(std::forward<_Iter>(__it), __n); 150 } 151 152 // prev 153 template <class _Iter> 154 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX14 __remove_cvref_t<_Iter> 155 prev(_Iter&& __iter, typename iterator_traits<__remove_cvref_t<_Iter> >::difference_type __n = 1) { 156 return std::prev(std::forward<_Iter>(__iter), __n); 157 } 158 159 template <class _Iter> 160 _LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX14 void __advance_to(_Iter& __first, _Iter __last) { 161 __first = __last; 162 } 163 }; 164 165 _LIBCPP_END_NAMESPACE_STD 166 167 _LIBCPP_POP_MACROS 168 169 #endif // _LIBCPP___ALGORITHM_ITERATOR_OPERATIONS_H 170