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  1. #include <iostream>
  2.  
  3.  
  4. // The essence
  5.  
  6. namespace essence {
  7. template<class Ptr, size_t Id>
  8. Ptr result;
  9.  
  10. template<class Ptr, Ptr TargetPointer, size_t InstantiationId>
  11. struct steal {
  12.     struct exec_on_instantiation {
  13.         exec_on_instantiation() { 
  14.             result<Ptr, InstantiationId> = TargetPointer;
  15.         }
  16.     };
  17.     static exec_on_instantiation essence;
  18. };
  19. template <typename Ptr, Ptr TargetPointer, size_t InstantiationId>
  20. typename steal<
  21.     Ptr, 
  22.     TargetPointer, 
  23.     InstantiationId
  24. >::exec_on_instantiation steal<
  25.     Ptr, 
  26.     TargetPointer, 
  27.     InstantiationId
  28. >::essence;
  29. }  // namespace essence
  30.  
  31.  
  32. // Demo
  33.  
  34. using std::string;
  35. using std::cout;
  36. using std::endl;
  37.  
  38. class Victim {
  39.     void f() { cout << "PoC - member function f" << endl; }
  40.     void h() { cout << "PoC - member function h" << endl; }
  41.     string str = "PoC - member data";
  42.     static void g() { cout << "PoC - static member function" << endl; }
  43.     static string static_str;
  44. };
  45. string Victim::static_str = "PoC - static member data";
  46.  
  47. template struct essence::steal<decltype(&Victim::f), &Victim::f, 1>;
  48. template struct essence::steal<decltype(&Victim::h), &Victim::h, 2>;
  49. template struct essence::steal<decltype(&Victim::str), &Victim::str, 3>;
  50. template struct essence::steal<decltype(&Victim::g), &Victim::g, 4>;
  51. template struct essence::steal<
  52.     decltype(&Victim::static_str), 
  53.     &Victim::static_str, 
  54.     5
  55. >;
  56.  
  57. int main() {
  58.     auto ptr1 = essence::result<void (Victim::*)(), 1>;
  59.     auto ptr2 = essence::result<void (Victim::*)(), 2>;
  60.     auto ptr3 = essence::result<string (Victim::*), 3>;
  61.     auto ptr4 = essence::result<void(*)(), 4>;
  62.     auto ptr5 = essence::result<string*, 5>;
  63.  
  64.     Victim a;
  65.  
  66.     (a.*ptr1)();
  67.     (a.*ptr2)();
  68.     a.*ptr3 += " (modified)", cout << a.*ptr3 << endl;
  69.     ptr4();
  70.     *ptr5 += " (modified)", cout << *ptr5 << endl;
  71. }
Success #stdin #stdout 0s 4380KB
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PoC - member function f
PoC - member function h
PoC - member data (modified)
PoC - static member function
PoC - static member data (modified)
https://ideone.com/Gnjvn2
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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