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  1. #include <iostream>
  2. #include <iomanip>
  3. #include <memory>
  4. using namespace std;
  5.  
  6. template<typename FROM, typename TO>
  7. class Adapter
  8. {
  9. public:
  10.     /**
  11.      * Adapts something from one type to a type. 
  12.      * @param f
  13.      * @return
  14.      */
  15.     virtual TO adapt(FROM f) = 0;
  16.  
  17.     /**
  18.      * Chains adapters. 
  19.      * 
  20.      * @param <NEXT>
  21.      * @param next 
  22.      * @return a new adapter that takes the output of this adapter and 
  23.      * adapts to something of type NEXT.
  24.      */
  25.     template<typename NEXT>
  26.     std::unique_ptr<Adapter<FROM, NEXT>> chain(Adapter<TO, NEXT> *next)
  27.     {
  28.     	class ChainedAdapter : public Adapter<FROM, NEXT>
  29.     	{
  30.     	private:
  31. 	        Adapter<FROM, TO> *x; 
  32.     	    Adapter<TO, NEXT> *next;
  33.     	public:
  34.         	ChainedAdapter(Adapter<FROM, TO> *x, Adapter<TO, NEXT> *next)
  35.             	: x(x), next(next) {}
  36.  
  37. 	        NEXT adapt(FROM f) override {
  38.     	        return next->adapt(x->adapt(f));
  39.         	}
  40. 	    };
  41.  
  42. 		//return std::make_unique<ChainedAdapter>(this, next);
  43. 		return std::unique_ptr<ChainedAdapter>(new ChainedAdapter(this, next));
  44.     }
  45. };
  46.  
  47. class CharIntAdapter : public Adapter<char, int>
  48. {
  49. public:
  50. 	int adapt(char f) override {
  51. 		int ret = static_cast<int>(f);
  52. 		cout << "char('" << f << "') -> int(" << ret << ")" << endl;
  53. 		return ret;
  54. 	}
  55. };
  56.  
  57. class IntBoolAdapter : public Adapter<int, bool>
  58. {
  59. public:
  60. 	bool adapt(int f) override {
  61. 		bool ret = f != 0;
  62. 		cout << "int(" << f << ") -> bool(" << boolalpha << ret << ")" << endl;
  63. 		return ret;
  64. 	}
  65. };
  66.  
  67. int main() {
  68. 	CharIntAdapter cia;
  69. 	cout << cia.adapt('a') << endl;
  70.  
  71. 	cout << endl;
  72.  
  73.     IntBoolAdapter iba;
  74. 	cout << boolalpha << cia.chain(&iba)->adapt('a') << endl;
  75.  
  76. 	return 0;
  77. }
Success #stdin #stdout 0.01s 5496KB
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Standard input is empty
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char('a') -> int(97)
97

char('a') -> int(97)
int(97) -> bool(true)
true
https://ideone.com/z1gpIJ
language:
C++ 4.3.2 (gcc-4.3.2)
created:
3 years ago
visibility:
public

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