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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_FIND_SUBSTITUTE_APR_18_2014_930AM)
- #define BOOST_SPIRIT_X3_VARIANT_FIND_SUBSTITUTE_APR_18_2014_930AM
- #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 Attribute>
- struct variant_find_substitute
- {
- // Get the type from the variant that can be a substitute for Attribute.
- // If none is found, just return Attribute
- typedef Variant variant_type;
- typedef typename variant_type::types types;
- typedef typename mpl::end<types>::type end;
- typedef typename mpl::find<types, 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 typename
- mpl::eval_if<
- is_same<iter, end>,
- mpl::identity<Attribute>,
- mpl::deref<iter>
- >::type
- type;
- };
-
- template <typename Variant>
- struct variant_find_substitute<Variant, Variant>
- : mpl::identity<Variant> {};
- }}}}
- #endif
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