Added thirdparty: boost library

thirdparty/include/boost/hana/detail/variadic/reverse_apply/flat.hpp

@@ -0,0 +1,41 @@
+/*!
+@file
+Defines `boost::hana::detail::variadic::reverse_apply_flat`.
+
+Copyright Louis Dionne 2013-2022
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_DETAIL_VARIADIC_REVERSE_APPLY_FLAT_HPP
+#define BOOST_HANA_DETAIL_VARIADIC_REVERSE_APPLY_FLAT_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/detail/variadic/at.hpp>
+
+#include <utility>
+
+
+namespace boost { namespace hana { namespace detail { namespace variadic {
+    template <int ...i, typename F, typename ...X>
+    constexpr decltype(auto)
+    reverse_apply_flat_helper(std::integer_sequence<int, i...>, F&& f, X&& ...x)
+    {
+        return static_cast<F&&>(f)(
+            detail::variadic::at<sizeof...(x) - i - 1>(
+                static_cast<X&&>(x)...
+            )...
+        );
+    }
+
+    template <typename F, typename ...X>
+    constexpr decltype(auto) reverse_apply_flat(F&& f, X&& ...x) {
+        return reverse_apply_flat_helper(
+            std::make_integer_sequence<int, sizeof...(x)>{},
+            static_cast<F&&>(f),
+            static_cast<X&&>(x)...
+        );
+    }
+}} }} // end namespace boost::hana
+
+#endif // !BOOST_HANA_DETAIL_VARIADIC_REVERSE_APPLY_FLAT_HPP