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/*=============================================================================
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
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/spirit/home/x3/support/traits/is_substitute.hpp>
namespace boost { namespace spirit { namespace x3 { namespace traits
{
template <typename Variant, typename Attribute>
struct variant_has_substitute_impl
{
// Find a type from the variant that can be a substitute for Attribute.
// 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_if<types, is_same<mpl::_1, Attribute>>::type
iter_1;
typedef typename
mpl::eval_if<
is_same<iter_1, end>,
mpl::find_if<types, traits::is_substitute<mpl::_1, Attribute>>,
mpl::identity<iter_1>
>::type
iter;
typedef mpl::not_<is_same<iter, end>> type;
};
template <typename Variant, typename Attribute>
struct variant_has_substitute
: variant_has_substitute_impl<Variant, Attribute>::type {};
template <typename Attribute>
struct variant_has_substitute<unused_type, Attribute> : mpl::true_ {};
template <typename Attribute>
struct variant_has_substitute<unused_type const, Attribute> : mpl::true_ {};
}}}}
#endif
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