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perfect forwarding in apply_visitor alias

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This commit is contained in:
Artem Pavlenko 2020-07-13 10:26:59 +01:00
parent 8913b673c3
commit 9cb1b7e37f
1 changed files with 7 additions and 19 deletions
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26
include/mapnik/util/variant.hpp
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@ -34,33 +34,21 @@ using recursive_wrapper = typename mapbox::util::recursive_wrapper<T>;
template<typename... Types>
using variant = typename mapbox::util::variant<Types...>;
// unary visitor interface
// const
template <typename F, typename V>
auto VARIANT_INLINE static apply_visitor(F && f, V const& v) -> decltype(V::visit(v, std::forward<F>(f)))
auto VARIANT_INLINE apply_visitor(F&& f, V&& v)
-> decltype(v.visit(std::forward<V>(v), std::forward<F>(f)))
{
return V::visit(v, std::forward<F>(f));
}
// non-const
template <typename F, typename V>
auto VARIANT_INLINE static apply_visitor(F && f, V & v) -> decltype(V::visit(v, std::forward<F>(f)))
{
return V::visit(v, std::forward<F>(f));
return v.visit(std::forward<V>(v), std::forward<F>(f));
}
// binary visitor interface
// const
template <typename F, typename V>
auto VARIANT_INLINE static apply_visitor(F && f, V const& v0, V const& v1) -> decltype(V::binary_visit(v0, v1, std::forward<F>(f)))
auto VARIANT_INLINE apply_visitor(F&& f, V&& v0, V&& v1)
-> decltype(v0.binary_visit(std::forward<V>(v0), std::forward<V>(v1), std::forward<F>(f)))
{
return V::binary_visit(v0, v1, std::forward<F>(f));
}
// non-const
template <typename F, typename V>
auto VARIANT_INLINE static apply_visitor(F && f, V & v0, V & v1) -> decltype(V::binary_visit(v0, v1, std::forward<F>(f)))
{
return V::binary_visit(v0, v1, std::forward<F>(f));
return v0.binary_visit(std::forward<V>(v0), std::forward<V>(v1), std::forward<F>(f));
}
// getter interface