Add support for described classes to hash.hpp

include/boost/container_hash/hash.hpp

@@ -26,7 +26,15 @@
 #include <boost/type_traits/make_unsigned.hpp>
 #include <boost/type_traits/enable_if.hpp>
 #include <boost/type_traits/conjunction.hpp>
+#include <boost/type_traits/is_union.hpp>
+#include <boost/describe/bases.hpp>
+#include <boost/describe/members.hpp>
 #include <boost/cstdint.hpp>
+
+#if defined(BOOST_DESCRIBE_CXX14)
+# include <boost/mp11/algorithm.hpp>
+#endif
+
 #include <string>
 #include <iterator>
 #include <complex>
@@ -384,6 +392,49 @@ namespace boost
         return boost::hash_unordered_range( v.begin(), v.end() );
     }
 
+#endif
+
+    // described classes
+
+#if defined(BOOST_DESCRIBE_CXX14)
+
+#if defined(_MSC_VER) && _MSC_VER == 1900
+# pragma warning(push)
+# pragma warning(disable: 4100) // unreferenced formal parameter
+#endif
+
+    template <typename T>
+    typename boost::enable_if_<container_hash::is_described_class<T>::value, std::size_t>::type
+        hash_value( T const& v )
+    {
+        static_assert( !boost::is_union<T>::value, "described unions are not supported" );
+
+        std::size_t r = 0;
+
+        using Bd = describe::describe_bases<T, describe::mod_any_access>;
+
+        mp11::mp_for_each<Bd>([&](auto D){
+
+            using B = typename decltype(D)::type;
+            boost::hash_combine( r, (B const&)v );
+
+        });
+
+        using Md = describe::describe_members<T, describe::mod_any_access>;
+
+        mp11::mp_for_each<Md>([&](auto D){
+
+            boost::hash_combine( r, v.*D.pointer );
+
+        });
+
+        return r;
+    }
+
+#if defined(_MSC_VER) && _MSC_VER == 1900
+# pragma warning(pop)
+#endif
+
 #endif
 
     // std::unique_ptr, std::shared_ptr