any/detail/placeholder.hpp

0001 // Copyright Antony Polukhin, 2021-2023.
0002 //
0003 // Distributed under the Boost Software License, Version 1.0. (See
0004 // accompanying file LICENSE_1_0.txt or copy at
0005 // http://www.boost.org/LICENSE_1_0.txt)
0006
0007 #ifndef BOOST_ANY_ANYS_DETAIL_PLACEHOLDER_HPP
0008 #define BOOST_ANY_ANYS_DETAIL_PLACEHOLDER_HPP
0009
0010 #include <boost/config.hpp>
0011 #ifdef BOOST_HAS_PRAGMA_ONCE
0012 # pragma once
0013 #endif
0014
0015 #include <boost/type_index.hpp>
0016
0017 /// @cond
0018 namespace boost {
0019 namespace anys {
0020 namespace detail {
0021
0022 class BOOST_SYMBOL_VISIBLE placeholder {
0023 public:
0024     virtual ~placeholder() {}
0025     virtual const boost::typeindex::type_info& type() const noexcept = 0;
0026 };
0027
0028 } // namespace detail
0029 } // namespace anys
0030 } // namespace boost
0031 /// @endcond
0032
0033 #endif  // #ifndef BOOST_ANY_ANYS_DETAIL_PLACEHOLDER_HPP