1 files changed, 27 insertions, 10 deletions
diff --git a/contrib/llvm-project/libcxx/include/__algorithm/ranges_partition_point.h b/contrib/llvm-project/libcxx/include/__algorithm/ranges_partition_point.h
index 336b29f63284..6614a0bb50fd 100644
--- a/contrib/llvm-project/libcxx/include/__algorithm/ranges_partition_point.h
+++ b/contrib/llvm-project/libcxx/include/__algorithm/ranges_partition_point.h
@@ -9,19 +9,18 @@
 #ifndef _LIBCPP___ALGORITHM_RANGES_PARTITION_POINT_H
 #define _LIBCPP___ALGORITHM_RANGES_PARTITION_POINT_H
 
-#include <__algorithm/make_projected.h>
-#include <__algorithm/partition_point.h>
+#include <__algorithm/half_positive.h>
 #include <__config>
 #include <__functional/identity.h>
 #include <__functional/invoke.h>
-#include <__functional/ranges_operations.h>
 #include <__iterator/concepts.h>
+#include <__iterator/distance.h>
 #include <__iterator/iterator_traits.h>
+#include <__iterator/next.h>
 #include <__iterator/projected.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)
@@ -37,22 +36,40 @@ namespace __partition_point {
 
 struct __fn {
 
+  // TODO(ranges): delegate to the classic algorithm.
+  template <class _Iter, class _Sent, class _Proj, class _Pred>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  static _Iter __partition_point_fn_impl(_Iter&& __first, _Sent&& __last, _Pred& __pred, _Proj& __proj) {
+    auto __len = ranges::distance(__first, __last);
+
+    while (__len != 0) {
+      auto __half_len = std::__half_positive(__len);
+      auto __mid = ranges::next(__first, __half_len);
+
+      if (std::invoke(__pred, std::invoke(__proj, *__mid))) {
+        __first = ++__mid;
+        __len -= __half_len + 1;
+
+      } else {
+        __len = __half_len;
+      }
+    }
+
+    return __first;
+  }
+
   template <forward_iterator _Iter, sentinel_for<_Iter> _Sent, class _Proj = identity,
             indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr
   _Iter operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj = {}) const {
-    // TODO: implement
-    (void)__first; (void)__last; (void)__pred; (void)__proj;
-    return {};
+    return __partition_point_fn_impl(std::move(__first), std::move(__last), __pred, __proj);
   }
 
   template <forward_range _Range, class _Proj = identity,
             indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred>
   _LIBCPP_HIDE_FROM_ABI constexpr
   borrowed_iterator_t<_Range> operator()(_Range&& __range, _Pred __pred, _Proj __proj = {}) const {
-    // TODO: implement
-    (void)__range; (void)__pred; (void)__proj;
-    return {};
+    return __partition_point_fn_impl(ranges::begin(__range), ranges::end(__range), __pred, __proj);
   }
 
 };