1 files changed, 81 insertions, 0 deletions
diff --git a/libcxx/include/__algorithm/ranges_copy_if.h b/libcxx/include/__algorithm/ranges_copy_if.h
new file mode 100644
index 000000000000..492104fbbfba
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+++ b/libcxx/include/__algorithm/ranges_copy_if.h
@@ -0,0 +1,81 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_COPY_IF_H
+#define _LIBCPP___ALGORITHM_RANGES_COPY_IF_H
+
+#include <__algorithm/in_out_result.h>
+#include <__config>
+#include <__functional/identity.h>
+#include <__functional/invoke.h>
+#include <__iterator/concepts.h>
+#include <__iterator/projected.h>
+#include <__ranges/access.h>
+#include <__ranges/concepts.h>
+#include <__ranges/dangling.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 {
+
+template<class _Ip, class _Op>
+using copy_if_result = in_out_result<_Ip, _Op>;
+
+namespace __copy_if {
+struct __fn {
+
+  template <class _InIter, class _Sent, class _OutIter, class _Proj, class _Pred>
+  _LIBCPP_HIDE_FROM_ABI static constexpr
+  copy_if_result <_InIter, _OutIter>
+  __copy_if_impl(_InIter __first, _Sent __last, _OutIter __result, _Pred& __pred, _Proj& __proj) {
+    for (; __first != __last; ++__first) {
+      if (std::invoke(__pred, std::invoke(__proj, *__first))) {
+        *__result = *__first;
+        ++__result;
+      }
+    }
+    return {std::move(__first), std::move(__result)};
+  }
+
+  template <input_iterator _Iter, sentinel_for<_Iter> _Sent, weakly_incrementable _OutIter, class _Proj = identity,
+            indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
+    requires indirectly_copyable<_Iter, _OutIter>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  copy_if_result<_Iter, _OutIter>
+  operator()(_Iter __first, _Sent __last, _OutIter __result, _Pred __pred, _Proj __proj = {}) const {
+    return __copy_if_impl(std::move(__first), std::move(__last), std::move(__result), __pred, __proj);
+  }
+
+  template <input_range _Range, weakly_incrementable _OutIter, class _Proj = identity,
+            indirect_unary_predicate<projected<iterator_t<_Range>, _Proj>> _Pred>
+    requires indirectly_copyable<iterator_t<_Range>, _OutIter>
+  _LIBCPP_HIDE_FROM_ABI constexpr
+  copy_if_result<borrowed_iterator_t<_Range>, _OutIter>
+  operator()(_Range&& __r, _OutIter __result, _Pred __pred, _Proj __proj = {}) const {
+    return __copy_if_impl(ranges::begin(__r), ranges::end(__r), std::move(__result), __pred, __proj);
+  }
+};
+} // namespace __copy_if
+
+inline namespace __cpo {
+  inline constexpr auto copy_if = __copy_if::__fn{};
+} // namespace __cpo
+} // namespace ranges
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
+#endif // _LIBCPP___ALGORITHM_RANGES_COPY_IF_H