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_NTH_ELEMENT_H 10 #define _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H 11 12 #include <__algorithm/iterator_operations.h> 13 #include <__algorithm/make_projected.h> 14 #include <__algorithm/nth_element.h> 15 #include <__config> 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> 29 30 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 31 # pragma GCC system_header 32 #endif 33 34 #if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 35 36 _LIBCPP_BEGIN_NAMESPACE_STD 37 38 namespace ranges { 39 namespace __nth_element { 40 41 struct __fn { 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); 46 47 auto&& __projected_comp = std::__make_projected(__comp, __proj); 48 std::__nth_element_impl<_RangeAlgPolicy>(std::move(__first), std::move(__nth), __last_iter, __projected_comp); 49 50 return __last_iter; 51 } 52 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); 58 } 59 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); 66 } 67 }; 68 69 } // namespace __nth_element 70 71 inline namespace __cpo { 72 inline constexpr auto nth_element = __nth_element::__fn{}; 73 } // namespace __cpo 74 } // namespace ranges 75 76 _LIBCPP_END_NAMESPACE_STD 77 78 #endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES) 79 80 #endif // _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H 81