/*=============================================================================
    Copyright (c) 2001-2014 Joel de Guzman
    http://spirit.sourceforge.net/

    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)
=============================================================================*/
#if !defined(BOOST_SPIRIT_X3_VARIANT_HAS_SUBSTITUTE_APR_18_2014_925AM)
#define BOOST_SPIRIT_X3_VARIANT_HAS_SUBSTITUTE_APR_18_2014_925AM

#include <boost/spirit/home/x3/support/traits/is_substitute.hpp>
#include <boost/mpl/find.hpp>

namespace boost {
namespace spirit {
namespace x3 {
namespace traits {
template <typename Variant, typename T>
struct variant_has_substitute_impl
{
    // Find a type from the Variant that can be a substitute for T.
    // return true_ if one is found, else false_

    typedef Variant variant_type;
    typedef typename variant_type::types types;
    typedef typename mpl::end<types>::type end;

    typedef typename mpl::find<types, T>::type iter_1;

    typedef typename
    mpl::eval_if<
    is_same<iter_1, end>,
            mpl::find_if<types, traits::is_substitute<T, mpl::_1>>,
            mpl::identity<iter_1>
            >::type
            iter;

    typedef mpl::not_<is_same<iter, end>> type;
};

template <typename Variant, typename T>
struct variant_has_substitute
    : variant_has_substitute_impl<Variant, T>::type {};

template <typename T>
struct variant_has_substitute<unused_type, T> : mpl::true_ {};

template <typename T>
struct variant_has_substitute<unused_type const, T> : mpl::true_ {};

}
}
}
}

#endif
