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add as_variant_visitor

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bolero-MURAKAMI 2012-12-20 01:06:50 +09:00
parent fce61f0def
commit dd2b9511eb
2 changed files with 50 additions and 0 deletions
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1
sprout/variant.hpp
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@ -8,6 +8,7 @@
#include <sprout/variant/get.hpp> #include <sprout/variant/get.hpp>
#include <sprout/variant/static_visitor.hpp> #include <sprout/variant/static_visitor.hpp>
#include <sprout/variant/static_variant_visitor.hpp> #include <sprout/variant/static_variant_visitor.hpp>
#include <sprout/variant/as_variant_visitor.hpp>
#include <sprout/variant/visitor_result.hpp> #include <sprout/variant/visitor_result.hpp>
#include <sprout/variant/apply_visitor.hpp> #include <sprout/variant/apply_visitor.hpp>

49
sprout/variant/as_variant_visitor.hpp Normal file
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@ -0,0 +1,49 @@
#ifndef SPROUT_VARIANT_AS_VARIANT_VISITOR_HPP
#define SPROUT_VARIANT_AS_VARIANT_VISITOR_HPP
#include <utility>
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/utility/forward.hpp>
#include <sprout/utility/lvalue_forward.hpp>
#include <sprout/utility/value_holder.hpp>
#include <sprout/type_traits/lvalue_reference.hpp>
#include <sprout/variant/static_variant_visitor.hpp>
namespace sprout {
//
// variant_visitor_wrapper
//
template<typename Visitor>
class variant_visitor_wrapper
: public sprout::static_variant_visitor
{
public:
typedef Visitor visitor_type;
typedef sprout::value_holder<visitor_type&> holder_type;
private:
holder_type v_;
public:
SPROUT_CONSTEXPR explicit variant_visitor_wrapper(typename holder_type::param_type v)
: v_(v)
{}
template<typename T>
SPROUT_CONSTEXPR auto operator()(T&& t)
-> decltype(std::declval<holder_type const>().get()(sprout::forward<T>(t))) const
{
return v_.get()(sprout::forward<T>(t));
}
};
//
// as_variant_visitor
//
template<typename Visitor>
inline SPROUT_CONSTEXPR sprout::variant_visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type>
as_variant_visitor(Visitor&& visitor) {
typedef sprout::variant_visitor_wrapper<typename std::remove_reference<typename sprout::lvalue_reference<Visitor>::type>::type> type;
return type(sprout::lvalue_forward<Visitor>(visitor));
}
} // namespace sprout
#endif // #ifndef SPROUT_VARIANT_AS_VARIANT_VISITOR_HPP