#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;
}

Queue::~Queue()
{
 while (! isEmpty() )
    remove();
}

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;
}