[libc++][ranges] Implement `ranges::nth_element`.
Differential Revision: https://reviews.llvm.org/D128149
NOKEYCHECK=True
GitOrigin-RevId: 23c7328bad927c2ec4d1ecf37fc07b4475f68a76
diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index 09ce7bf..a5191f5 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -103,6 +103,7 @@
__algorithm/ranges_move.h
__algorithm/ranges_move_backward.h
__algorithm/ranges_none_of.h
+ __algorithm/ranges_nth_element.h
__algorithm/ranges_remove.h
__algorithm/ranges_remove_if.h
__algorithm/ranges_replace.h
diff --git a/include/__algorithm/nth_element.h b/include/__algorithm/nth_element.h
index a2ef638..c7cdef5 100644
--- a/include/__algorithm/nth_element.h
+++ b/include/__algorithm/nth_element.h
@@ -16,6 +16,7 @@
#include <__debug>
#include <__debug_utils/randomize_range.h>
#include <__iterator/iterator_traits.h>
+#include <__utility/move.h>
#include <__utility/swap.h>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -220,25 +221,35 @@
}
template <class _RandomAccessIterator, class _Compare>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last, _Compare __comp)
-{
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+void __nth_element_impl(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last,
+ _Compare& __comp) {
+ if (__nth == __last)
+ return;
+
std::__debug_randomize_range(__first, __last);
- typedef typename __comp_ref_type<_Compare>::type _Comp_ref;
- _VSTD::__nth_element<_Comp_ref>(__first, __nth, __last, __comp);
+
+ using _Comp_ref = typename __comp_ref_type<_Compare>::type;
+ std::__nth_element<_Comp_ref>(__first, __nth, __last, __comp);
+
std::__debug_randomize_range(__first, __nth);
if (__nth != __last) {
std::__debug_randomize_range(++__nth, __last);
}
}
+template <class _RandomAccessIterator, class _Compare>
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+void nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last,
+ _Compare __comp) {
+ std::__nth_element_impl(std::move(__first), std::move(__nth), std::move(__last), __comp);
+}
+
template <class _RandomAccessIterator>
-inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
-void
-nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last)
-{
- _VSTD::nth_element(__first, __nth, __last, __less<typename iterator_traits<_RandomAccessIterator>::value_type>());
+inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_AFTER_CXX17
+void nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth, _RandomAccessIterator __last) {
+ std::nth_element(std::move(__first), std::move(__nth), std::move(__last), __less<typename
+ iterator_traits<_RandomAccessIterator>::value_type>());
}
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/__algorithm/ranges_nth_element.h b/include/__algorithm/ranges_nth_element.h
new file mode 100644
index 0000000..2a929ea
--- /dev/null
+++ b/include/__algorithm/ranges_nth_element.h
@@ -0,0 +1,79 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H
+#define _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H
+
+#include <__algorithm/make_projected.h>
+#include <__algorithm/nth_element.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__functional/ranges_operations.h>
+#include <__iterator/concepts.h>
+#include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
+#include <__iterator/projected.h>
+#include <__iterator/sortable.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+namespace ranges {
+namespace __nth_element {
+
+struct __fn {
+ template <class _Iter, class _Sent, class _Comp, class _Proj>
+ _LIBCPP_HIDE_FROM_ABI constexpr static
+ _Iter __nth_element_fn_impl(_Iter __first, _Iter __nth, _Sent __last, _Comp& __comp, _Proj& __proj) {
+ auto __last_iter = ranges::next(__first, __last);
+
+ auto&& __projected_comp = ranges::__make_projected_comp(__comp, __proj);
+ std::__nth_element_impl(std::move(__first), std::move(__nth), __last_iter, __projected_comp);
+
+ return __last_iter;
+ }
+
+ template <random_access_iterator _Iter, sentinel_for<_Iter> _Sent, class _Comp = ranges::less, class _Proj = identity>
+ requires sortable<_Iter, _Comp, _Proj>
+ _LIBCPP_HIDE_FROM_ABI constexpr
+ _Iter operator()(_Iter __first, _Iter __nth, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
+ return __nth_element_fn_impl(std::move(__first), std::move(__nth), std::move(__last), __comp, __proj);
+ }
+
+ template <random_access_range _Range, class _Comp = ranges::less, class _Proj = identity>
+ requires sortable<iterator_t<_Range>, _Comp, _Proj>
+ _LIBCPP_HIDE_FROM_ABI constexpr
+ borrowed_iterator_t<_Range> operator()(_Range&& __r, iterator_t<_Range> __nth, _Comp __comp = {},
+ _Proj __proj = {}) const {
+ return __nth_element_fn_impl(ranges::begin(__r), std::move(__nth), ranges::end(__r), __comp, __proj);
+ }
+};
+
+} // namespace __nth_element
+
+inline namespace __cpo {
+ inline constexpr auto nth_element = __nth_element::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_NTH_ELEMENT_H
diff --git a/include/algorithm b/include/algorithm
index fef1ad3..1b1dc16 100644
--- a/include/algorithm
+++ b/include/algorithm
@@ -379,6 +379,17 @@
constexpr borrowed_iterator_t<R>
ranges::is_sorted_until(R&& r, Comp comp = {}, Proj proj = {}); // since C++20
+ template<random_access_iterator I, sentinel_for<I> S, class Comp = ranges::less,
+ class Proj = identity>
+ requires sortable<I, Comp, Proj>
+ constexpr I
+ ranges::nth_element(I first, I nth, S last, Comp comp = {}, Proj proj = {}); // since C++20
+
+ template<random_access_range R, class Comp = ranges::less, class Proj = identity>
+ requires sortable<iterator_t<R>, Comp, Proj>
+ constexpr borrowed_iterator_t<R>
+ ranges::nth_element(R&& r, iterator_t<R> nth, Comp comp = {}, Proj proj = {}); // since C++20
+
template<forward_iterator I, sentinel_for<I> S, class T, class Proj = identity,
indirect_strict_weak_order<const T*, projected<I, Proj>> Comp = ranges::less>
constexpr I upper_bound(I first, S last, const T& value, Comp comp = {}, Proj proj = {}); // since C++20
@@ -1313,6 +1324,7 @@
#include <__algorithm/ranges_move.h>
#include <__algorithm/ranges_move_backward.h>
#include <__algorithm/ranges_none_of.h>
+#include <__algorithm/ranges_nth_element.h>
#include <__algorithm/ranges_remove.h>
#include <__algorithm/ranges_remove_if.h>
#include <__algorithm/ranges_replace.h>
diff --git a/include/module.modulemap.in b/include/module.modulemap.in
index 98bb00b..0447cf0 100644
--- a/include/module.modulemap.in
+++ b/include/module.modulemap.in
@@ -342,6 +342,7 @@
module ranges_move { private header "__algorithm/ranges_move.h" }
module ranges_move_backward { private header "__algorithm/ranges_move_backward.h" }
module ranges_none_of { private header "__algorithm/ranges_none_of.h" }
+ module ranges_nth_element { private header "__algorithm/ranges_nth_element.h" }
module ranges_remove { private header "__algorithm/ranges_remove.h" }
module ranges_remove_if { private header "__algorithm/ranges_remove_if.h" }
module ranges_replace { private header "__algorithm/ranges_replace.h" }