1 // Boost.TypeErasure library
3 // Copyright 2011 Steven Watanabe
5 // Distributed under the Boost Software License Version 1.0. (See
6 // accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt)
11 #ifndef BOOST_TYPE_ERASURE_DETAIL_IS_PLACEHOLDER_HPP_INCLUDED
12 #define BOOST_TYPE_ERASURE_DETAIL_IS_PLACEHOLDER_HPP_INCLUDED
14 #include <boost/mpl/bool.hpp>
15 #include <boost/type_traits/is_base_and_derived.hpp>
16 #include <boost/type_erasure/placeholder.hpp>
20 namespace type_erasure {
22 /** A metafunction that indicates whether a type is a @ref placeholder. */
24 struct is_placeholder : ::boost::is_base_and_derived<placeholder, T> {};