1 files changed, 74 insertions, 0 deletions
diff --git a/libcxx/include/__algorithm/ranges_unique.h b/libcxx/include/__algorithm/ranges_unique.h
new file mode 100644
index 000000000000..bdf755e9406e
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+++ b/libcxx/include/__algorithm/ranges_unique.h
@@ -0,0 +1,74 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_UNIQUE_H
+#define _LIBCPP___ALGORITHM_RANGES_UNIQUE_H
+
+#include <__algorithm/make_projected.h>
+#include <__algorithm/unique.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/permutable.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.h>
+#include <__ranges/subrange.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 __unique {
+
+struct __fn {
+
+  template <permutable _Iter, sentinel_for<_Iter> _Sent, class _Proj = identity,
+            indirect_equivalence_relation<projected<_Iter, _Proj>> _Comp = ranges::equal_to>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  subrange<_Iter> operator()(_Iter __first, _Sent __last, _Comp __comp = {}, _Proj __proj = {}) const {
+    // TODO: implement
+    (void)__first; (void)__last; (void)__comp; (void)__proj;
+    return {};
+  }
+
+  template <forward_range _Range, class _Proj = identity,
+            indirect_equivalence_relation<projected<iterator_t<_Range>, _Proj>> _Comp = ranges::equal_to>
+  requires permutable<iterator_t<_Range>>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  borrowed_subrange_t<_Range> operator()(_Range&& __range, _Comp __comp = {}, _Proj __proj = {}) const {
+    // TODO: implement
+    (void)__range; (void)__comp; (void)__proj;
+    return {};
+  }
+
+};
+
+} // namespace __unique
+
+inline namespace __cpo {
+  inline constexpr auto unique = __unique::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_UNIQUE_H