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  1. #include <iostream>
  2. #include <map>
  3. #include <utility>
  4.  
  5. class Cache
  6. {
  7. public:
  8. 	struct Value
  9. 	{
  10. 		int value = 1;
  11. 		int get() { return value; }
  12. 		void set(int newvalue) { value = newvalue; }
  13. 	};
  14.  
  15. 	Value& For(int a, int b) {
  16. 		return values[std::make_pair(a, b)];
  17. 	}
  18.  
  19. 	friend std::ostream& operator<<(std::ostream &os, const Cache &c)
  20. 	{
  21. 		for(auto &value : c.values)
  22. 			std::cout << '[' << value.first.first << ',' << value.first.second << "] = " << value.second.value << std::endl;
  23. 		return os;
  24. 	}
  25.  
  26. private:
  27. 	std::map<std::pair<int,int>, Value> values;
  28. };
  29.  
  30. class Flight 
  31. {
  32. public:
  33. 	class Proxy
  34. 	{
  35. 	private:
  36. 		Flight &f;
  37. 		int a, b;
  38.  
  39. 	public:
  40. 		Proxy(Flight &f, int a, int b) : f(f), a(a), b(b) {}
  41.  
  42. 		operator int() {
  43. 			return f.cache.For(a, b).get();
  44. 		};
  45.  
  46. 		Proxy& operator=(int value) {
  47. 			f.cache.For(a, b).set(value);
  48. 			return *this;
  49. 		}
  50. 	};
  51.  
  52. 	friend class Proxy;
  53.  
  54. 	Proxy operator()(int a, int b) {
  55. 		return Proxy{*this, a, b};
  56. 	}
  57.  
  58. 	friend std::ostream& operator<<(std::ostream &os, const Flight &f)
  59. 	{
  60. 		return os << f.cache;
  61. 	}
  62.  
  63. private:
  64. 	Cache cache;
  65. };
  66.  
  67. int main()
  68. {
  69. 	Flight s;
  70. 	int value = s(1, 2);
  71. 	s(3, 4) = value;
  72. 	std::cout << s;
  73. 	return 0;
  74. }
Success #stdin #stdout 0s 4404KB
comments (?)
stdin 
Standard input is empty
stdout 
[1,2] = 1
[3,4] = 1
https://ideone.com/cDc0YN
language:
C++ (gcc 8.3)
created:
3 years ago
visibility:
public

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