Add is_described_class<T>

include/boost/container_hash/is_described_class.hpp

@@ -0,0 +1,35 @@
+// Copyright 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#ifndef BOOST_HASH_IS_DESCRIBED_CLASS_HPP_INCLUDED
+#define BOOST_HASH_IS_DESCRIBED_CLASS_HPP_INCLUDED
+
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/describe/bases.hpp>
+#include <boost/describe/members.hpp>
+
+namespace boost
+{
+namespace container_hash
+{
+
+#if defined(BOOST_DESCRIBE_CXX11)
+
+template<class T> struct is_described_class: boost::integral_constant<bool,
+    describe::has_describe_bases<T>::value && describe::has_describe_members<T>::value>
+{
+};
+
+#else
+
+template<class T> struct is_described_class: boost::false_type
+{
+};
+
+#endif
+
+} // namespace container_hash
+} // namespace boost
+
+#endif // #ifndef BOOST_HASH_IS_DESCRIBED_CLASS_HPP_INCLUDED