| /*============================================================================== |
| Copyright (c) 2005-2010 Joel de Guzman |
| Copyright (c) 2015 John Fletcher |
| |
| 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 BOOST_PHOENIX_CORE_IS_VALUE_HPP |
| #define BOOST_PHOENIX_CORE_IS_VALUE_HPP |
| |
| #include <boost/mpl/bool.hpp> |
| |
| // Copied from is_actor.hpp |
| |
| // Note to Thomas and any future maintainer: please make this as |
| // lightweight as possible (as it is right now). |
| |
| namespace boost { namespace phoenix |
| { |
| /////////////////////////////////////////////////////////////////////////////// |
| // |
| // is_value<T> |
| // |
| // Tests if T is a value. Evaluates to mpl::true_ or mpl::false_ |
| // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| namespace expression { |
| template <typename T> |
| struct value; |
| } |
| |
| template <typename T, typename Enable = void> |
| struct is_value |
| : mpl::false_ |
| {}; |
| |
| template <typename T> |
| struct is_value<T const> |
| : is_value<T> |
| {}; |
| |
| template <typename T> |
| struct is_value<T &> |
| : is_value<T> |
| {}; |
| |
| // This does not seem to work. |
| // There is an alternative in value.hpp which does work. |
| template <typename T> |
| struct is_value< expression::value<T> > |
| : mpl::true_ |
| {}; |
| |
| template <typename T> |
| bool is_val(T const & /* t */) |
| { |
| return is_value<T>::value; |
| } |
| |
| }} |
| |
| #endif |