/////////////////////////////////////////////////////////////////////
//  smartPointer.cpp - demonstrates the basic ideas used with      //
//                     smart pointers                              //
//                                                                 //
//  Jim Fawcett, CSE687 - Object Oriented Design, Spring 2002      //
/////////////////////////////////////////////////////////////////////

#include <iostream>
using namespace std;

/////////////////////////////////////////////////////////////////////
//  trace display functions
//
template <class T> void trace(const char *msg, T t) {

  cout << "\n  " << msg;
  if(t)
    cout << t;
}

void trace(char underline, const char *msg) {

  cout << "\n  " << msg;
  cout << "\n " << string(strlen(msg)+2, underline).c_str();
}

void trace(const char *msg) { cout << "\n  " << msg; }

/////////////////////////////////////////////////////////////////////
//  definition of smart pointer class
//
template <class T> class smartPointer {

  public:
    smartPointer() : _tPtr(0) {}
    smartPointer(T *tPtr) : _tPtr(tPtr) { }
    ~smartPointer() { _tPtr = 0; }
    T& operator*() { return *_tPtr; }
    T* operator->() { return _tPtr; }

  private:
    T *_tPtr;
};

//

/////////////////////////////////////////////////////////////////////
//  a structure type used in a demonstration of smart pointers
//
struct aStructType { int x; double y; char z; };


//----< entry point >------------------------------------------------

void main() {

  trace('=', "Demonstration of Basic Smart Pointer Type");

  double d;
  smartPointer<double> sp1(&d);
  *sp1 = 3.1415927;
  trace("value of smartly pointed double is: ",*sp1);

  smartPointer<double> sp2 = &d;
  trace("using compiler generated copy of pointer, double value is: ",*sp2);

  aStructType aStruct = { -5, 0.33333, 'z' };
  smartPointer<aStructType> sp3(&aStruct);
  
  trace("1st field of struct has value: ", sp3->x);
  trace("2nd field of struct has value: ", sp3->y);
  trace("3rd field of struct has value: ", sp3->z);

  trace("\n\n");
}