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  1. #include <iostream>
  2. #include <vector>
  3.  
  4.  
  5. class RefCounter
  6. {
  7. private:
  8.     int count = 0;
  9.  
  10. public:
  11.     void AddRef()
  12.     {
  13.  
  14.         count++;
  15.     }
  16.  
  17.     int Release()
  18.     {
  19.         return --count;
  20.     }
  21.     int getCount()
  22.     {
  23.  
  24.         return count;
  25.     }
  26. };
  27.  
  28. template<typename T> class sharedPTR
  29. {
  30. private:
  31.     T* myData;
  32.     RefCounter* myRef;
  33.  
  34. public:
  35.     sharedPTR() :
  36.             myData(0), myRef(0)
  37.     {
  38.  
  39.         myRef = new RefCounter();
  40.         myRef->AddRef();
  41.     }
  42.  
  43.     sharedPTR(T* pValue) :
  44.             myData(pValue), myRef(0)
  45.     {
  46.  
  47.         myRef = new RefCounter();
  48.         myRef->AddRef();
  49.  
  50.     }
  51.  
  52.     ~sharedPTR()
  53.     {
  54.         if (myRef && myRef->Release() == 0)
  55.         {
  56.             delete myData;
  57.             delete myRef;
  58.         }
  59.     }
  60.  
  61. sharedPTR(const sharedPTR<T>& ref) : myData(nullptr), myRef(nullptr)
  62. {
  63.     if (ref.myRef &&  ref.myRef->getCount() < 3) {
  64.         myData = ref.myData;
  65.         myRef = ref.myRef;
  66.         myRef->AddRef();
  67.     }
  68. }
  69.  
  70. sharedPTR<T>& operator = (const sharedPTR<T>& ref)
  71. {
  72.     if (this == &ref) {
  73.         return *this;
  74.     }
  75.     if (myRef && myRef->Release() == 0)
  76.     {
  77.         delete myData;
  78.         delete myRef;
  79.     }
  80.     myData = nullptr;
  81.     myRef = nullptr;
  82.     if (ref.myRef && ref.myRef->getCount() < 3) {
  83.         myData = ref.myData;
  84.         myRef = ref.myRef;
  85.         myRef->AddRef();
  86.     }
  87.     return *this;
  88. }
  89.  
  90.     T& getData()
  91.     {
  92.         return *myData;
  93.     }
  94.  
  95.     T* getPointer()
  96.     {
  97.         return myData;
  98.     }
  99. };
  100.  
  101. class Cat
  102. {
  103. public:
  104.     Cat(unsigned int w_score, const std::string& w_name) :
  105.         score(w_score),
  106.         name(w_name)
  107.     {}
  108.     std::string getName()
  109.     {
  110.         return name;
  111.     }
  112.  
  113.     unsigned int score;
  114. private:
  115.     std::string name;
  116. };
  117.  
  118. int main(void)
  119. {
  120.     sharedPTR<Cat> newCat(new Cat(0, "Ferrari"));
  121.  
  122.     // should print "Ferrari"
  123.     std::cout << newCat.getPointer()->getName() << std::endl;
  124.  
  125.     // should also print "Ferrari"
  126.     std::cout << newCat.getData().getName() << std::endl;
  127.  
  128.     newCat.getData().score = 50;
  129.  
  130.     // should printf "50", as it was just assigned before
  131.     std::cout << newCat.getPointer()->score << std::endl;
  132.  
  133.     // make some copies
  134.     sharedPTR<Cat> copyOfnewCat = newCat;
  135.     sharedPTR<Cat> copyOfnewCat2 = newCat;
  136.  
  137.     // this copy should fail
  138.     sharedPTR<Cat> copyOfnewCat3 = newCat;
  139.  
  140.     // should be nullptr
  141.     std::cout << copyOfnewCat3.getPointer() << std::endl;
  142.  
  143.     // should be something other than 0 and equal
  144.     std::cout << "copy2 pointer: " << copyOfnewCat2.getPointer() << " copy1 pointer: " << copyOfnewCat.getPointer() << std::endl;
  145.     copyOfnewCat2.getData().score = 40;
  146.  
  147.     // should be 40 now 
  148.     std::cout << newCat.getPointer()->score << std::endl;
  149.     sharedPTR<Cat> copyOfnewCat4(newCat);
  150.  
  151.     // should be nullptr
  152.     std::cout << copyOfnewCat4.getPointer() << std::endl;
  153. }
Success #stdin #stdout 0s 16064KB
comments (?)
stdin 
Standard input is empty
stdout 
Ferrari
Ferrari
50
0
copy2 pointer: 0x2af4ede9dc20 copy1 pointer: 0x2af4ede9dc20
40
0
https://ideone.com/plgTMe
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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