/* Filename:  arrqueue.cpp

   Programmer:  Br. David Carlson

   Date:  May 14, 1999

   Revised:  July 21, 2000 to use modern headers.

   This file implements the functions of the ArrQueClass found in
   arrqueue.h.
*/

#include "arrqueue.h"


/* Given:  Index     An integer index with value from 0 to MaxQueue - 1.
   Task:   To advance Index by 1, with wrap-around.
   Return: Index     Updated index value.
*/
inline void ArrQueClass::Advance(int & Index)
   {
   Index++;
   if (Index == QueueMax)
      Index = 0;
   }


/* Given:  Nothing.
   Task:   To construct a new object of this class.
   Return: Nothing other than the implicit object that's been constructed.
*/
ArrQueClass::ArrQueClass(void)
   {
   Front = 0;
   Rear = QueueMax - 1;
   Count = 0;
   }


/* Given:  Nothing (other than the implicit ArrQueClass object).
   Task:   To check whether this object is empty.
   Return: true if it is empty, false otherwise.
*/
bool ArrQueClass::Empty(void) const
   {
   if (Count == 0)
      return true;
   else
      return false;
   }


/* Given:  Item   A data item.
   Task:   To insert item into the queue (implicit object) at the rear.
   Return: Nothing directly, but the implicit object is modified.
*/
void ArrQueClass::Insert(const ItemType & Item)
   {
   if (Count == QueueMax)
      {
      cerr << "ERROR: Cannot insert -- queue is full" << endl;
      exit(1);
      }
   else
      {
      Advance(Rear);
      Info[Rear] = Item;
      Count++;
      }
   }


/* Given:  Nothing.
   Task:   To remove the front item from the queue (the implicit object).
   Return: Item   The item removed from the queue.
*/
void ArrQueClass::Remove(ItemType & Item)
   {
   if (Count == 0)
      {
      cerr << "ERROR: Cannot remove -- queue is empty" << endl;
      exit(1);
      }
   else
      {
      Item = Info[Front];
      Advance(Front);
      Count--;
      }
   }