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- // Boost.TypeErasure library
- //
- // Copyright 2011 Steven Watanabe
- //
- // Distributed under the Boost Software License Version 1.0. (See
- // accompanying file LICENSE_1_0.txt or copy at
- // http://www.boost.org/LICENSE_1_0.txt)
- //
- // $Id$
- #ifndef BOOST_TYPE_ERASURE_DETAIL_IS_PLACEHOLDER_HPP_INCLUDED
- #define BOOST_TYPE_ERASURE_DETAIL_IS_PLACEHOLDER_HPP_INCLUDED
- #include <boost/mpl/bool.hpp>
- namespace boost {
- namespace type_erasure {
- #ifdef BOOST_TYPE_ERASURE_DOXYGEN
- /** A metafunction that indicates whether a type is a @ref placeholder. */
- template<class T>
- struct is_placeholder {};
- #else
- template<class T, class Enable = void>
- struct is_placeholder : ::boost::mpl::false_ {};
- template<class T>
- struct is_placeholder<T, typename T::_boost_type_erasure_is_placeholder> :
- ::boost::mpl::true_ {};
- #endif
- }
- }
- #endif
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