/*=============================================================================
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Copyright (c) 2001-2014 Joel de Guzman
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http://spirit.sourceforge.net/
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#if !defined(BOOST_SPIRIT_X3_VARIANT_FIND_SUBSTITUTE_APR_18_2014_930AM)
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#define BOOST_SPIRIT_X3_VARIANT_FIND_SUBSTITUTE_APR_18_2014_930AM
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#include <boost/spirit/home/x3/support/traits/is_substitute.hpp>
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#include <boost/mpl/find.hpp>
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namespace boost { namespace spirit { namespace x3 { namespace traits
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{
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template <typename Variant, typename Attribute>
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struct variant_find_substitute
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{
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// Get the type from the variant that can be a substitute for Attribute.
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// If none is found, just return Attribute
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typedef Variant variant_type;
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typedef typename variant_type::types types;
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typedef typename mpl::end<types>::type end;
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typedef typename mpl::find<types, Attribute>::type iter_1;
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typedef typename
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mpl::eval_if<
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is_same<iter_1, end>,
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mpl::find_if<types, traits::is_substitute<mpl::_1, Attribute> >,
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mpl::identity<iter_1>
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>::type
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iter;
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typedef typename
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mpl::eval_if<
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is_same<iter, end>,
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mpl::identity<Attribute>,
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mpl::deref<iter>
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>::type
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type;
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};
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template <typename Variant>
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struct variant_find_substitute<Variant, Variant>
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: mpl::identity<Variant> {};
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}}}}
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#endif
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