#include <iostream>
#include <iomanip>
#include <string>
#include <memory>
#include <vector>
using namespace std;

class Demo
{
public:
   Demo()
   {
      cout << "default Demo ctor: " << this << endl;
   }
   Demo(const Demo&)
   {
      cout << "copy Demo ctor: " << this << endl;
   }
   ~Demo()
   {
      cout << "Demo dtor: " << this << endl;
   }
};

ostream& operator<<(ostream& out, const Demo&)
{
   out << "Demo object";
   return out;
}

template <typename T>
ostream& operator<<(ostream& out, const shared_ptr<T>& obj);

int main()
{
   shared_ptr<string> sp1;
   shared_ptr<string> sp2(nullptr);
   shared_ptr<string> sp3(new string("carrot"));
   shared_ptr<string> sp4(make_shared<string>("potato"));
   shared_ptr<string> sp5(sp3);

   cout << "sp1: " << sp1 << endl;
   cout << "sp2: " << sp2 << endl;
   cout << "sp3: " << sp3 << endl;
   cout << "sp4: " << sp4 << endl;
   cout << "sp5: " << sp5 << endl << endl;

   cout << "sp1 = sp4;" << endl;
   sp1 = sp4;
   cout << "sp1: " << sp1 << endl;
   cout << "sp4: " << sp4 << endl << endl;

   cout << "sp2 = sp3;" << endl;
   sp2 = sp3;
   cout << "sp2: " << sp2 << endl;
   cout << "sp3: " << sp3 << endl << endl;

   cout << "sp1.reset();" << endl;
   sp1.reset();
   cout << "sp1: " << sp1 << endl << endl;

   shared_ptr<Demo> sp6(nullptr);    // create an "empty" shared pointer
   shared_ptr<Demo> sp7(new Demo);            // calls Demo default ctor
   shared_ptr<Demo> sp8(new Demo(*sp7));         // calls Demo copy ctor
   shared_ptr<Demo> sp9(make_shared<Demo>()); // calls Demo default ctor
   shared_ptr<Demo> sp10(sp7);             // calls shared_ptr copy ctor
   cout << "sp6: " << sp6 << endl;
   cout << "sp7: " << sp7 << endl;
   cout << "sp8: " << sp8 << endl;
   cout << "sp9: " << sp9 << endl;
   cout << "sp10:" << sp10 << endl << endl;

   cout << "sp6 = move(sp7);" << endl;
   sp6 = move(sp7);
   cout << "sp6: " << sp6 << endl;
   cout << "sp7: " << sp7 << endl << endl;

   cout << "sp6.reset();" << endl;
   sp6.reset();
   cout << "sp6: " << sp6 << endl;
   cout << "sp10: " << sp10 << endl << endl;

   cout << "sp10.reset();" << endl;
   sp10.reset();
   cout << "sp6: " << sp6 << endl;
   cout << "sp7: " << sp7 << endl;
   cout << "sp8: " << sp8 << endl;
   cout << "sp9: " << sp9 << endl;
   cout << "sp10:" << sp10 << endl << endl;

   cout << "That's all folks" << endl;
}

template <typename T>
ostream& operator<<(ostream& out, const shared_ptr<T>& obj)
{
   if (obj.get())
   out << setw(10) << obj.get() << "  " << setw(8) << *obj << "  " << obj.use_count();
   else
   out << setw(10) << obj.get();
   return out;
}