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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
- #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_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<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 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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