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https://github.com/bolero-MURAKAMI/Sprout.git
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50 lines
1.5 KiB
C++
50 lines
1.5 KiB
C++
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#ifndef SPROUT_VARIANT_AS_VARIANT_VISITOR_HPP
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#define SPROUT_VARIANT_AS_VARIANT_VISITOR_HPP
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#include <utility>
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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/utility/lvalue_forward.hpp>
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#include <sprout/utility/value_holder.hpp>
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#include <sprout/type_traits/lvalue_reference.hpp>
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#include <sprout/variant/static_variant_visitor.hpp>
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namespace sprout {
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//
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// variant_visitor_wrapper
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//
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template<typename Visitor>
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class variant_visitor_wrapper
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: public sprout::static_variant_visitor
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{
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public:
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typedef Visitor visitor_type;
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typedef sprout::value_holder<visitor_type&> holder_type;
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private:
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holder_type v_;
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public:
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SPROUT_CONSTEXPR explicit variant_visitor_wrapper(typename holder_type::param_type v)
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: v_(v)
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{}
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template<typename T>
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SPROUT_CONSTEXPR auto operator()(T&& t)
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-> decltype(std::declval<holder_type const>().get()(sprout::forward<T>(t))) const
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{
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return v_.get()(sprout::forward<T>(t));
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}
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};
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//
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// as_variant_visitor
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//
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template<typename Visitor>
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inline SPROUT_CONSTEXPR sprout::variant_visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type>
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as_variant_visitor(Visitor&& visitor) {
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typedef sprout::variant_visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type> type;
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return type(sprout::lvalue_forward<Visitor>(visitor));
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}
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} // namespace sprout
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#endif // #ifndef SPROUT_VARIANT_AS_VARIANT_VISITOR_HPP
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