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  1. #include <unordered_map>
  2. #include <string>
  3. #include <utility>
  4. #include <typeinfo>
  5. #include <stdexcept>
  6. #include <iostream>
  7.  
  8. struct BeliefCondFunc
  9. {
  10.     using cb_type = bool(*)();
  11.     using map_val = std::pair<cb_type, std::type_info const*>;
  12.     static std::unordered_map<std::string, map_val> const FuncMap;
  13.  
  14.     static bool Greater(int A, int B)
  15.     {
  16.         return A > B;
  17.     }
  18.  
  19.     static bool Between(float A, float B, float C)
  20.     {
  21.         return A > B && A < C;
  22.     }
  23.  
  24.     template<typename ...Args>
  25.     static map_val make_map_val(bool (*func)(Args...)) {
  26.  
  27.     	return std::make_pair(reinterpret_cast<cb_type>(func), 
  28.     	                      &typeid(decltype(func)));
  29.     }
  30.  
  31.     template<typename ...Args>
  32.     static bool call(std::string const& key, Args&&... args){
  33.       using prototype = bool(*)(Args...);
  34.  
  35.       auto& func_n_typeid = FuncMap.at(key);
  36.  
  37.       if (typeid(prototype) != *func_n_typeid.second )
  38.         throw std::domain_error("Prototype mismatch");
  39.  
  40.       return reinterpret_cast<prototype>(func_n_typeid.first)(std::forward<Args>(args)...);
  41.     };
  42. };
  43.  
  44. std::unordered_map<std::string, BeliefCondFunc::map_val> const BeliefCondFunc::FuncMap {
  45.   {"Greater", make_map_val(&BeliefCondFunc::Greater) },
  46.   {"Between", make_map_val(&BeliefCondFunc::Between) }
  47. };
  48.  
  49. int main() {
  50. 	BeliefCondFunc::call("Greater", 1, 2);
  51.  
  52. 	try {
  53. 		BeliefCondFunc::call("Lesser", 1, 2);
  54. 	} catch (std::out_of_range&) {
  55. 		std::cout << "No such function\n";
  56. 	}
  57.  
  58. 	try {
  59. 		BeliefCondFunc::call("Between", 1, 2);
  60. 	} catch (std::domain_error&) {
  61. 		std::cout << "Wrong number of arguments\n";
  62. 	}
  63.  
  64. 	return 0;
  65. }
Success #stdin #stdout 0s 3472KB
comments (?)
stdin 
Standard input is empty
stdout 
No such function
Wrong number of arguments
https://ideone.com/MEa25q
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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