mirror of
https://github.com/bolero-MURAKAMI/Sprout
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55 lines
1.6 KiB
C++
55 lines
1.6 KiB
C++
#ifndef SPROUT_VARIANT_APPLY_VISITOR_HPP
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#define SPROUT_VARIANT_APPLY_VISITOR_HPP
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#include <type_traits>
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#include <sprout/config.hpp>
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#include <sprout/utility/forward.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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//
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// apply_visitor
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//
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template<typename Visitor, typename Visitable>
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inline SPROUT_CONSTEXPR typename sprout::visitor_result<
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typename std::remove_reference<Visitor>::type,
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typename std::remove_reference<Visitable>::type
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>::type
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apply_visitor(Visitor&& visitor, Visitable&& visitable) {
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return sprout::forward<Visitable>(visitable).apply_visitor(sprout::forward<Visitor>(visitor));
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_VARIANT_APPLY_VISITOR_HPP
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