Add boost::container_hash::is_tuple_like. Refs #30.

include/boost/container_hash/is_tuple_like.hpp

@@ -0,0 +1,41 @@
+#ifndef BOOST_HASH_IS_TUPLE_LIKE_HPP_INCLUDED
+#define BOOST_HASH_IS_TUPLE_LIKE_HPP_INCLUDED
+
+// Copyright 2017, 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/config.hpp>
+#include <utility>
+
+namespace boost
+{
+namespace hash_detail
+{
+
+template<class T, class E = true_type> struct is_tuple_like_: false_type
+{
+};
+
+#if !defined(BOOST_NO_CXX11_HDR_TUPLE)
+
+template<class T> struct is_tuple_like_<T, integral_constant<bool, std::tuple_size<T>::value == std::tuple_size<T>::value> >: true_type
+{
+};
+
+#endif
+
+} // namespace hash_detail
+
+namespace container_hash
+{
+
+template<class T> struct is_tuple_like: hash_detail::is_tuple_like_<T>
+{
+};
+
+} // namespace container_hash
+} // namespace boost
+
+#endif // #ifndef BOOST_HASH_IS_TUPLE_LIKE_HPP_INCLUDED