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  1. #include <iostream>
  2. #include <memory>
  3. #include <vector>
  4. #include <functional>
  5.  
  6. using namespace std;
  7.  
  8. struct Input {
  9. 	char c; 
  10. 	string s;
  11. 	vector<int>v; 
  12. };
  13.  
  14. class Base {
  15. public:
  16. 	Base(){cout<<"Base ";}
  17. };
  18. class Foo : public Base {
  19. public: 
  20. 	Foo (int) {cout<<"Foo ";}
  21. };
  22. class Bar : public Base {
  23. public: 
  24. 	Bar (string, int) {cout<<"Bar-constructor1 ";}
  25. 	Bar (string, vector<int>) {cout<<"Bar-constructor2 ";}
  26. };
  27.  
  28. class MyFactory {
  29. public:
  30.    static unique_ptr<Base> createBase(Input& input){
  31.    	    // first that fires,  returns the element
  32.    		for (int i=0; i<test.size(); i++) {
  33.    			if (test[i](input)) { 
  34.    				cout<<"Rule "<<i<<": ";
  35.    				return create[i](input);
  36.    			}
  37.    		}
  38.    		// here,  either create a Base or, if it's abstract or wrong arguments, throw
  39.    		cout<<"No rule found: ";
  40.    		return make_unique<Base>();
  41.  
  42.    }
  43.    static void registerDerivate(function<bool(Input&)>t, function<unique_ptr<Base>(Input&)>c){
  44.    	test.push_back(t);
  45.    	create.push_back(c);
  46.    }
  47. private: 
  48. 	static vector<function<bool(Input&)>> test;
  49. 	static vector<function<unique_ptr<Base>(Input&)>> create;
  50. };
  51.  
  52. vector<function<bool(Input&)>> MyFactory::test;
  53. vector<function<unique_ptr<Base>(Input&)>> MyFactory::create;
  54.  
  55.  
  56. int main() {
  57. 	// the "smart" parametric factory is assembled
  58. 	MyFactory::registerDerivate ([](Input& input){ return input.c=='F' && input.v.size()==1; },
  59. 								[](Input& input) { return make_unique<Foo>(input.v[0]); } );
  60. 	MyFactory::registerDerivate ([](Input& input){ return input.c=='B' && input.v.size()==1; },
  61. 								[](Input& input) { return make_unique<Bar>(input.s, input.v[0]); } );
  62. 	MyFactory::registerDerivate ([](Input& input){ return input.c=='B' && input.v.size()!=1; },
  63. 								[](Input& input) { return make_unique<Bar>(input.s, input.v); } );
  64. 	// your code goes here
  65. 	Input i1{'X', "no match", {}};
  66. 	Input i2{'F', "no match", {2,3}}; 
  67. 	Input i3{'F', "match Foo", {4}}; 
  68. 	Input i4{'B', "match Bar", {5}}; 
  69. 	Input i5{'B', "match Bar other constructor", {1,2,3,4}}; 
  70. 	auto p1=MyFactory::createBase(i1); cout<<endl; 
  71. 	auto p2=MyFactory::createBase(i2); cout<<endl; 
  72. 	auto p3=MyFactory::createBase(i3); cout<<endl; 
  73. 	auto p4=MyFactory::createBase(i4); cout<<endl; 
  74. 	auto p5=MyFactory::createBase(i5); cout<<endl; 
  75.  
  76. 	return 0;
  77. }
Success #stdin #stdout 0s 5292KB
comments (?)
stdin
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Standard input is empty
stdout
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No rule found: Base 
No rule found: Base 
Rule 0: Base Foo 
Rule 1: Base Bar-constructor1 
Rule 2: Base Bar-constructor2
https://ideone.com/6NDVfX
language:
C++14 (gcc 8.3)
created:
1 year ago
visibility:
secret

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