/*============================================================================= | |
Copyright (c) 2001-2007 Joel de Guzman | |
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) | |
==============================================================================*/ | |
#ifndef PHOENIX_CORE_NOTHING_HPP | |
#define PHOENIX_CORE_NOTHING_HPP | |
#include <boost/spirit/home/phoenix/core/actor.hpp> | |
#include <boost/mpl/bool.hpp> | |
namespace boost { namespace phoenix | |
{ | |
/////////////////////////////////////////////////////////////////////////////// | |
// | |
// null_actor | |
// | |
// A actor that does nothing (a "bum", if you will :-). | |
// | |
/////////////////////////////////////////////////////////////////////////////// | |
struct null_actor | |
{ | |
typedef mpl::false_ no_nullary; | |
template <typename Env> | |
struct result | |
{ | |
typedef void type; | |
}; | |
template <typename Env> | |
void | |
eval(Env const&) const | |
{ | |
} | |
}; | |
actor<null_actor> const nothing = null_actor(); | |
}} | |
#endif |