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86 lines
1.8 KiB
C++
86 lines
1.8 KiB
C++
#ifndef VARIANT_CAST_HPP
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#define VARIANT_CAST_HPP
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#include <type_traits>
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namespace mapbox {
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namespace util {
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namespace detail {
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template <class T>
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class static_caster
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{
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public:
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template <class V>
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T& operator()(V& v) const
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{
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return static_cast<T&>(v);
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}
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};
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template <class T>
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class dynamic_caster
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{
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public:
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using result_type = T&;
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template <class V>
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T& operator()(V& v, typename std::enable_if<!std::is_polymorphic<V>::value>::type* = nullptr) const
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{
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throw std::bad_cast();
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}
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template <class V>
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T& operator()(V& v, typename std::enable_if<std::is_polymorphic<V>::value>::type* = nullptr) const
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{
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return dynamic_cast<T&>(v);
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}
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};
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template <class T>
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class dynamic_caster<T*>
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{
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public:
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using result_type = T*;
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template <class V>
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T* operator()(V& v, typename std::enable_if<!std::is_polymorphic<V>::value>::type* = nullptr) const
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{
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return nullptr;
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}
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template <class V>
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T* operator()(V& v, typename std::enable_if<std::is_polymorphic<V>::value>::type* = nullptr) const
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{
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return dynamic_cast<T*>(&v);
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}
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};
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}
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template <class T, class V>
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typename detail::dynamic_caster<T>::result_type
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dynamic_variant_cast(V& v)
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{
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return mapbox::util::apply_visitor(detail::dynamic_caster<T>(), v);
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}
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template <class T, class V>
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typename detail::dynamic_caster<const T>::result_type
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dynamic_variant_cast(const V& v)
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{
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return mapbox::util::apply_visitor(detail::dynamic_caster<const T>(), v);
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}
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template <class T, class V>
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T& static_variant_cast(V& v)
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{
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return mapbox::util::apply_visitor(detail::static_caster<T>(), v);
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}
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template <class T, class V>
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const T& static_variant_cast(const V& v)
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{
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return mapbox::util::apply_visitor(detail::static_caster<const T>(), v);
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}
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}
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}
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#endif // VARIANT_CAST_HPP
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