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  1. template<typename T, class...Fs> struct visitor_t;
  2.  
  3. template<typename T, class F1, class...Fs>
  4. struct visitor_t<T, F1, Fs...> : F1, visitor_t<T, Fs...>::type {
  5.     typedef visitor_t type;
  6.     visitor_t(F1 head, Fs...tail) : F1(head), visitor_t<T, Fs...>::type(tail...) {}
  7.  
  8.     using F1::operator();
  9.     using visitor_t<T, Fs...>::type::operator();
  10. };
  11.  
  12. template<typename T, class F> struct visitor_t<T, F> : F, boost::static_visitor<T> {
  13.     typedef visitor_t type;
  14.     visitor_t(F f) : F(f) {}
  15.     using F::operator();
  16. };
  17.  
  18. template<typename T=void, class...Fs>
  19. typename visitor_t<T, Fs...>::type make_visitor(Fs...x) { return {x...}; }
  20.  
  21. struct Person
  22. {
  23.     std::string name;
  24.     double height, weight;
  25.     friend std::ostream& operator<<(std::ostream& os, Person const& s) {
  26.         return os << "Person { name:" << s.name << ", height:" << s.height << ", weight:" << s.weight << " }";
  27.     }
  28. };
  29.  
  30.  
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https://ideone.com/fSobD8
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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