c07p357b.txt

Data Abstraction & Problem Solving with C++源码

// ********************************************************
// Implementation file QueueL.cpp for the ADT queue.
// ADT list implementation.
// ********************************************************
#include "QueueL.h"  // header file

Queue::Queue()
{
}  // end default constructor

Queue::Queue(const Queue& Q): aList(Q.aList)
{
}  // end copy constructor

Queue::~Queue()
{
}  // end destructor

bool Queue::isEmpty() const
{
   return (aList.getLength() == 0);
}  // end isEmpty

void Queue::enqueue(QueueItemType newItem) throw(QueueException)
{
   try
   {
      aList.insert(aList.getLength()+1, newItem);
   } // end try
   catch (ListException e)
   {
      throw QueueException("QueueException: cannot enqueue item");
   } // end catch
}  // end enqueue

void Queue::dequeue() throw(QueueException)
{
   if (aList.isEmpty())
      throw QueueException("QueueException: empty queue, cannot dequeue");
   else
      aList.remove(1);
}  // end dequeue

void Queue::dequeue(QueueItemType& queueFront) throw(QueueException)
{
   if (aList.isEmpty())
      throw QueueException("QueueException: empty queue, cannot dequeue");
   else
   {
      aList.retrieve(1, queueFront);
      aList.remove(1);
   } // end if
}  // end dequeue

void Queue::getFront(QueueItemType& queueFront) const 
                     throw(QueueException)
{
   if (!aList.isEmpty())
      throw QueueException("QueueException: empty queue, cannot getFront");
   else
      aList.retrieve(1, queueFront);
}  // end getFront
// End of implementation file.