1 //===----------------------------------------------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H
10 #define _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H
12 #include <__algorithm/iterator_operations.h>
13 #include <__algorithm/make_projected.h>
14 #include <__algorithm/nth_element.h>
16 #include <__functional/identity.h>
17 #include <__functional/invoke.h>
18 #include <__functional/ranges_operations.h>
19 #include <__iterator/concepts.h>
20 #include <__iterator/iterator_traits.h>
21 #include <__iterator/next.h>
22 #include <__iterator/projected.h>
23 #include <__iterator/sortable.h>
24 #include <__ranges/access.h>
25 #include <__ranges/concepts.h>
26 #include <__ranges/dangling.h>
27 #include <__utility/forward.h>
28 #include <__utility/move.h>
30 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
31 # pragma GCC system_header
34 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
36 _LIBCPP_BEGIN_NAMESPACE_STD
39 namespace __nth_element {
42 template <class _Iter, class _Sent, class _Comp, class _Proj>
43 _LIBCPP_HIDE_FROM_ABI constexpr static
44 _Iter __nth_element_fn_impl(_Iter __first, _Iter __nth, _Sent __last, _Comp& __comp, _Proj& __proj) {
45 auto __last_iter = ranges::next(__first, __last);
47 auto&& __projected_comp = ranges::__make_projected_comp(__comp, __proj);
48 std::__nth_element_impl<_RangeAlgPolicy>(std::move(__first), std::move(__nth), __last_iter, __projected_comp);
53 template <random_access_iterator _Iter, sentinel_for<_Iter> _Sent, class _Comp = ranges::less, class _Proj = identity>
54 requires sortable<_Iter, _Comp, _Proj>
55 _LIBCPP_HIDE_FROM_ABI constexpr
56 _Iter operator()(_Iter __first, _Iter __nth, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
57 return __nth_element_fn_impl(std::move(__first), std::move(__nth), std::move(__last), __comp, __proj);
60 template <random_access_range _Range, class _Comp = ranges::less, class _Proj = identity>
61 requires sortable<iterator_t<_Range>, _Comp, _Proj>
62 _LIBCPP_HIDE_FROM_ABI constexpr
63 borrowed_iterator_t<_Range> operator()(_Range&& __r, iterator_t<_Range> __nth, _Comp __comp = {},
64 _Proj __proj = {}) const {
65 return __nth_element_fn_impl(ranges::begin(__r), std::move(__nth), ranges::end(__r), __comp, __proj);
69 } // namespace __nth_element
71 inline namespace __cpo {
72 inline constexpr auto nth_element = __nth_element::__fn{};
76 _LIBCPP_END_NAMESPACE_STD
78 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
80 #endif // _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H