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  1. #include <set>
  2. #include <memory>
  3.  
  4. int main() {
  5. 	//attempt 1
  6. 	struct Comp1{
  7. 		bool operator()(const std::unique_ptr<int> &lhs, const std::unique_ptr<int> &rhs) const{
  8. 			return *lhs < *rhs;
  9. 		};
  10. 		bool operator()(int lhs, const std::unique_ptr<int> &rhs) const{
  11. 			return lhs < *rhs;
  12. 		};
  13. 		bool operator()(const std::unique_ptr<int> &lhs, int rhs) const{
  14. 			return *lhs < rhs;
  15. 		};
  16. 		typedef void is_transparent;
  17. 	};
  18. 	std::set<std::unique_ptr<int>,	Comp1> s1;
  19. 	s1.count(42); //this should check if a unique_ptr<int> with value 42 exists
  20. 	              //in s1 without constructing it
  21.  
  22. 	//attempt 2
  23. 	struct Wrapper{
  24. 		Wrapper(const int &i) : i(&i){}
  25. 		Wrapper(const std::unique_ptr<int> &ip) : i(ip.get()){}
  26. 		const int *i;
  27. 	};
  28. 	struct Comp2{
  29. 		bool operator()(Wrapper lhs, Wrapper rhs) const{
  30. 			return *lhs.i < *rhs.i;
  31. 		};
  32. 		typedef void is_transparent;
  33. 	};
  34. 	std::set<std::unique_ptr<int>,	Comp2> s2;
  35. 	s2.count(42); //this should check if a unique_ptr<int> with value 42 exists
  36. 	              //in s2 without constructing it
  37. }
Success #stdin #stdout 0s 3464KB
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https://ideone.com/0JJG7o
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
public

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