2015-12-08 04:51:55 +08:00
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#pragma once
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2015-08-30 07:12:46 +08:00
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namespace detail
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{
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template <typename T>
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struct VisitorBase {
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2015-10-19 01:44:00 +08:00
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virtual ~VisitorBase() = default;
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2015-08-30 07:12:46 +08:00
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virtual void visit(T&) {}
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virtual void post_visit(T&) {}
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};
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template<typename... T>
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struct RecursiveVisitorBase;
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template <typename Head, typename... Tail>
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struct RecursiveVisitorBase<Head, Tail...>
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: VisitorBase<Head>, RecursiveVisitorBase<Tail...>
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{
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using VisitorBase<Head>::visit;
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using VisitorBase<Head>::post_visit;
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using RecursiveVisitorBase<Tail...>::visit;
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using RecursiveVisitorBase<Tail...>::post_visit;
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};
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template<typename T>
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2015-10-19 01:44:00 +08:00
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struct RecursiveVisitorBase<T> : public VisitorBase<T>
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2015-08-30 07:12:46 +08:00
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{
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using VisitorBase<T>::visit;
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using VisitorBase<T>::post_visit;
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};
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}
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template <typename... T>
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2015-10-19 01:44:00 +08:00
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struct Visitor : public detail::RecursiveVisitorBase<T...>
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2015-08-30 07:12:46 +08:00
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{
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using detail::RecursiveVisitorBase<T...>::visit;
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using detail::RecursiveVisitorBase<T...>::post_visit;
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};
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