#include "Queue.h"
#include <cstdlib>

Queue& Queue::insert(const ElemType& el)
{
 Node* pNode = new Node(el);
 
 if (isEmpty())
    front = back = pNode;
 else
   {
    back->next = pNode;
    back = pNode;
   }

 return *this;
}

ElemType Queue::remove()
{
 if (isEmpty())
   {
    cerr << "Cannot remove an element from an empty queue" << endl;
    exit(1);
   }

 Node* pNode = front;
 front = front->next;
 ElemType retElem(pNode->elem);
 delete pNode;
 return retElem;
}

// Commented out to highlight the error in calling
// the class with a dynamic data member via a pass
// by reference parameter and using the default copy
// constuctor.  In production code, this mention needs
// to exist. 
//Queue::Queue (const Queue& q)
//{
 //front = back = NULL;
 //Node* pNode = q.front;

 //while (pNode != NULL)
   //{
    //insert(pNode->elem);
    //pNode = pNode->next;
   //}
//}

Queue::~Queue()
{
 cout << "In ~Queue() for: " << *this << endl;
 while (! isEmpty() )
    remove();
}

Queue& Queue::operator= (const Queue& rhs)
{
 if (this == &rhs)
   return *this;

 // deallocated the current Queue
 while (! isEmpty() )
    remove();

 front = back = NULL;
 Node* pNode = rhs.front;

 while (pNode != NULL)
   {
    insert(pNode->elem);
    pNode = pNode->next;
   }

 return *this; 
}

ostream& operator<< (ostream& ostr, Queue &rhs)
{
 bool firstLoop = true;

 Node* pNode = rhs.front;

 while (pNode != NULL)
   {
    if (firstLoop)
       firstLoop = false;
    else
       ostr << "->";

    ostr << pNode->elem;
    pNode = pNode->next;
   }
 ostr << ".";
 return ostr;
}