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_RANGES_ADJACENT_FIND_H
10 #define _LIBCPP___ALGORITHM_RANGES_ADJACENT_FIND_H
11 
12 #include <__config>
13 #include <__functional/identity.h>
14 #include <__functional/invoke.h>
15 #include <__functional/ranges_operations.h>
16 #include <__iterator/concepts.h>
17 #include <__iterator/projected.h>
18 #include <__ranges/access.h>
19 #include <__ranges/concepts.h>
20 #include <__ranges/dangling.h>
21 #include <__utility/move.h>
22 
23 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
24 #  pragma GCC system_header
25 #endif
26 
27 #if _LIBCPP_STD_VER >= 20
28 
29 _LIBCPP_BEGIN_NAMESPACE_STD
30 
31 namespace ranges {
32 namespace __adjacent_find {
33 struct __fn {
34   template <class _Iter, class _Sent, class _Proj, class _Pred>
35   _LIBCPP_HIDE_FROM_ABI constexpr static _Iter
36   __adjacent_find_impl(_Iter __first, _Sent __last, _Pred& __pred, _Proj& __proj) {
37     if (__first == __last)
38       return __first;
39 
40     auto __i = __first;
41     while (++__i != __last) {
42       if (std::invoke(__pred, std::invoke(__proj, *__first), std::invoke(__proj, *__i)))
43         return __first;
44       __first = __i;
45     }
46     return __i;
47   }
48 
49   template <forward_iterator _Iter,
50             sentinel_for<_Iter> _Sent,
51             class _Proj                                                                       = identity,
52             indirect_binary_predicate<projected<_Iter, _Proj>, projected<_Iter, _Proj>> _Pred = ranges::equal_to>
53   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _Iter
54   operator()(_Iter __first, _Sent __last, _Pred __pred = {}, _Proj __proj = {}) const {
55     return __adjacent_find_impl(std::move(__first), std::move(__last), __pred, __proj);
56   }
57 
58   template <forward_range _Range,
59             class _Proj = identity,
60             indirect_binary_predicate<projected<iterator_t<_Range>, _Proj>, projected<iterator_t<_Range>, _Proj>>
61                 _Pred = ranges::equal_to>
62   _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr borrowed_iterator_t<_Range>
63   operator()(_Range&& __range, _Pred __pred = {}, _Proj __proj = {}) const {
64     return __adjacent_find_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
65   }
66 };
67 } // namespace __adjacent_find
68 
69 inline namespace __cpo {
70 inline constexpr auto adjacent_find = __adjacent_find::__fn{};
71 } // namespace __cpo
72 } // namespace ranges
73 
74 _LIBCPP_END_NAMESPACE_STD
75 
76 #endif // _LIBCPP_STD_VER >= 20
77 
78 #endif // _LIBCPP___ALGORITHM_RANGES_ADJACENT_FIND_H
79