| /*============================================================================= |
| 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 |