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  1. #include <iostream>
  2. #include <type_traits>
  3. using namespace std;
  4.  
  5. template <typename ... Types> struct GenKey;
  6. template <typename R, typename ... Types> struct GenKey <R, Types...> : public GenKey<Types...>{
  7. 	template <typename P> 
  8. 	constexpr bool operator()(const P&p) const { return is_same<R,P>::value || GenKey<Types...>::operator()(p); }
  9. };
  10. template <typename R> struct GenKey <R>{
  11. 	template <typename P> 
  12. 	constexpr bool operator()(const P&) const { return is_same<R,P>::value; }
  13. };
  14. template <> struct GenKey <>{
  15. 	template <typename P> 
  16. 	constexpr bool operator()(const P&) const { return false; }
  17. };
  18.  
  19. class Server  {
  20. 	public:
  21. struct common{};
  22. struct canEdit{};
  23. struct canKill{};
  24. 	public:
  25. 	Server(){}
  26. 	void exec(const auto& key) {
  27. 		if (key(common())) {
  28. 			execCommon();
  29. 		}
  30. 		if (key(canEdit())) {
  31. 			execCanEdit();
  32. 		}
  33. 		if (key(canKill())) {
  34. 			execCanKill();
  35. 		}
  36. 	}
  37. 	private: 
  38. 	void execCommon() {
  39. 		cout << "common exec" << endl;
  40. 	}
  41. 	void execCanEdit() {
  42. 		cout << "edit exec" << endl;
  43. 	}
  44. 	void execCanKill() {
  45. 		cout << "kill exec" << endl;
  46. 	}
  47. };
  48.  
  49. int main() {
  50. 	Server server;
  51. 	cout << "key0" << endl;
  52. 	server.exec(GenKey<>());
  53. 	cout << "key1" << endl;
  54. 	server.exec(GenKey<Server::common,Server::canEdit>());
  55. 	return 0;
  56. }
Success #stdin #stdout 0s 15240KB
comments (?)
stdin 
Standard input is empty
stdout 
key0
key1
common exec
edit exec
https://ideone.com/9pQayU
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
secret

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