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  1. #include <iostream> 
  2. #include <vector> 
  3. using namespace std;
  4.  
  5. enum class type {
  6.   vector_type,
  7.   integer_type
  8. };
  9.  
  10. // Object can either be an Integer or Vector<Object> 
  11. class Object {
  12. public:
  13.   type type_;
  14.   union U {
  15.     vector<Object> vec_;
  16.     int num_;
  17.  
  18.     U() {}
  19.  
  20.     U(const vector<int> &vec) : vec_() {
  21.       for (size_t i = 0; i < vec.size(); i++) {
  22.         vec_.push_back(Object(i));
  23.       }
  24.     }
  25.  
  26.     U(int num) : num_(num) {}
  27.  
  28.     U& operator=(const vector<Object>& vec) {
  29.       new(&vec_) vector<Object>(vec);
  30.       return *this;
  31.     }
  32.  
  33.     ~U() {}
  34.   }u_;
  35.  
  36.   Object()
  37.     : type_(type::integer_type)
  38.   {
  39.   }
  40.  
  41.   Object(const Object& other)
  42.     : type_(other.type_)
  43.   {
  44.     if(other.type_ == type::vector_type)
  45.       u_ = other.u_.vec_;
  46.     else
  47.       u_.num_ = other.u_.num_;
  48.   }
  49.  
  50.   Object(const vector<int> &vec)
  51.     : type_(type::vector_type),
  52.       u_(vec)
  53.   {
  54.   }
  55.  
  56.   Object(int num)
  57.     : type_(type::integer_type),
  58.       u_(num)
  59.   {
  60.   }
  61.  
  62.   Object& operator=(const Object &other)
  63.   {
  64.     // Free old vector
  65.     if(type_ == type::vector_type)
  66.       u_.vec_.~vector();
  67.  
  68.     type_ = other.type_;
  69.     if(other.type_ == type::vector_type)
  70.       u_ = other.u_.vec_;
  71.     else
  72.       u_.num_ = other.u_.num_;
  73.     return *this;
  74.   }
  75.  
  76.   ~Object() {
  77.     if(type_ == type::vector_type)
  78.       u_.vec_.~vector();
  79.   }
  80. };
  81.  
  82. int main() {
  83.   // to construct somth like that: [1,2, [3, [4,5], 6], 7] 
  84.   Object o(vector<int>({ 1,2 }));
  85.  
  86.   return 0;
  87. }
Success #stdin #stdout 0s 3460KB
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https://ideone.com/4LkBWe
language:
C++14 (gcc 8.3)
created:
9 years ago
visibility:
secret

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