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  1. #include <iostream>
  2. #include <cstddef>
  3. #include <type_traits>
  4. #include <memory>
  5. #include <vector>
  6. using namespace std;
  7.  
  8. namespace details {
  9.   template<class T>
  10.   struct plain_ptr_t;
  11.  
  12.   //specialzation for T*
  13.   template<class T>
  14.   struct plain_ptr_t<T*> {
  15.     T* operator()(T* t)const{return t;}
  16.   };
  17.  
  18.   //specialzation for std::unique_ptr
  19.   template<class T, class D>
  20.   struct plain_ptr_t<std::unique_ptr<T,D>> {
  21.     T* operator()(std::unique_ptr<T>const& t)const{return t.get();}
  22.   };
  23.  
  24.   //specialzation for std::shared_ptr
  25.   template<class T>
  26.   struct plain_ptr_t<std::shared_ptr<T>> {
  27.     T* operator()(std::shared_ptr<T>const& t)const{return t.get();}
  28.   };
  29. }
  30.  
  31. struct plain_ptr {
  32.   template<class T>
  33.   typename std::result_of< details::plain_ptr_t<T>( T const& ) >::type
  34.   operator()( T const& t ) const {
  35.     return details::plain_ptr_t<T>{}( t );
  36.   }
  37. };
  38.  
  39.  
  40.     template<typename T>
  41.     class VectorT : std::vector<T> {
  42.         using vec = std::vector<T>;
  43.  
  44.     public:
  45.         using vec::at;
  46.         using vec::emplace_back;
  47.         using vec::push_back;
  48.  
  49.         typename std::result_of< plain_ptr(typename vec::value_type const&)>::type
  50.     	operator[](const size_t _Pos) const {
  51.     	  return plain_ptr{}(at(_Pos));
  52.     	}
  53.     };
  54.  
  55.  
  56.  
  57. int main() {
  58.  
  59. 	VectorT<std::unique_ptr<int>> uptr_v; 
  60. 	uptr_v.emplace_back(std::make_unique<int>(1));
  61. 	int* p1 = uptr_v[0]; 
  62. 	std::cout << *p1;
  63.  
  64. 	VectorT<int*> v;
  65. 	v.emplace_back(p1);
  66. 	int *p2 = v[0];
  67. 	std::cout << *p2;
  68.  
  69. 	// your code goes here
  70. 	return 0;
  71. }
Success #stdin #stdout 0s 3468KB
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https://ideone.com/EQq4wd
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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