phoenix/core/is_actor.hpp

0001 /*==============================================================================
0002     Copyright (c) 2005-2010 Joel de Guzman
0003
0004     Distributed under the Boost Software License, Version 1.0. (See accompanying
0005     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0006 ==============================================================================*/
0007 #ifndef BOOST_PHOENIX_CORE_IS_ACTOR_HPP
0008 #define BOOST_PHOENIX_CORE_IS_ACTOR_HPP
0009
0010 #include <boost/mpl/bool.hpp>
0011
0012 // Note to Thomas and any future maintainer: please make this as
0013 // lightweight as possible (as it is right now).
0014
0015 namespace boost { namespace phoenix
0016 {
0017 ///////////////////////////////////////////////////////////////////////////////
0018 //
0019 //  is_actor<T>
0020 //
0021 //      Tests if T is an actor. Evaluates to mpl::true_ or mpl::false_
0022 //
0023 ///////////////////////////////////////////////////////////////////////////////
0024
0025     template <typename Expr>
0026     struct actor;
0027
0028     template <typename T, typename Enable = void>
0029     struct is_actor
0030         : mpl::false_
0031     {};
0032
0033     template <typename T>
0034     struct is_actor<T const>
0035         : is_actor<T>
0036     {};
0037
0038     template <typename T>
0039     struct is_actor<T &>
0040         : is_actor<T>
0041     {};
0042
0043     template <typename Expr>
0044     struct is_actor<actor<Expr> >
0045         : mpl::true_
0046     {};
0047 }}
0048
0049 #endif