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48 lines
1.6 KiB
C++
48 lines
1.6 KiB
C++
/*=============================================================================
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Copyright (c) 2011-2015 Bolero MURAKAMI
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https://github.com/bolero-MURAKAMI/Sprout
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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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#ifndef SPROUT_VARIANT_VISITOR_RESULT_HPP
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#define SPROUT_VARIANT_VISITOR_RESULT_HPP
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#include <sprout/config.hpp>
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#include <sprout/type_traits/has_xxx.hpp>
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namespace sprout {
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//
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// has_visitor_result
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//
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SPROUT_HAS_XXX_TEMPLATE_DEF_LAZY(visitor_result);
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namespace detail {
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template<typename Visitor, typename Visitable, typename = void>
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struct visitor_result_impl;
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template<typename Visitor, typename Visitable>
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struct visitor_result_impl<
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Visitor, Visitable,
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typename std::enable_if<sprout::has_visitor_result<Visitable>::value>::type
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>
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: public Visitable::template visitor_result<Visitor, Visitable>
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{};
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template<typename Visitor, typename Visitable>
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struct visitor_result_impl<
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Visitor, Visitable,
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typename std::enable_if<!sprout::has_visitor_result<Visitable>::value>::type
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> {
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public:
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typedef typename Visitor::result_type type;
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};
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} // namespace detail
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//
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// visitor_result
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//
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template<typename Visitor, typename Visitable>
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struct visitor_result
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: public sprout::detail::visitor_result_impl<Visitor, Visitable>
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{};
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} // namespace sprout
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#endif // #ifndef SPROUT_VARIANT_VISITOR_RESULT_HPP
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