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C:/temp/src/j2k/DataType/Queue/ArrayQueue.hpp

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#ifndef __J2K__Array_Queue_HPP__
#define __J2K__Array_Queue_HPP__

#include <j2k/Fred/Standard.hpp>

#define LIST_SIZE    100

class ArrayQueue {                      // Array based queue class
public:

  // Make list array one position
  // larger for an empty slot.
  inline ArrayQueue()                   // Default Constructor
    : size( LIST_SIZE + 1 ), front( 0 ), rear( 0 ) 
  {
      listarray = new Elem[size];
  }

  inline ArrayQueue( unsigned long sz ) // Constructor with Size
    : size( sz + 1 ), front( 0 ), rear( 0 ) 
  {
      listarray = new Elem[size];
  }

  virtual ~ArrayQueue()                 // Destructor
  {
    delete [] listarray;
  }

  void clear()                          // Clear queue
  {
    front = rear;
  }

  void enqueue( const Elem item );      // Enqueue Elem at rear
  Elem dequeue();                       // Dequeue Elem from front

  Elem firstValue() const               // Get value of front Elem
  {
    assert( !isEmpty() );
    return listarray[ (front+1) % size ];
  }

  BOOL isEmpty() const                  // TRUE if queue is empty
  {
    return front == rear;
  }

private:
  unsigned long size;                   // Maximum size of queue
  unsigned long front;                  // Index prior to front item
  unsigned long rear;                   // Index of rear item
  Elem *listarray;                      // Array holding the list Elem's
};

// Enqueue Elem at rear of queue
void ArrayQueue::enqueue( const Elem item ) 
{
  assert( ((rear+1) % size) != front ); // Queue must not be full
  rear = (rear+1) % size;               // Increment rear (in circle)
  listarray[rear] = item;
}

Elem ArrayQueue::dequeue()              // Dequeue Elem from front of queue
{
  assert( !isEmpty() );                 // There must be something to dequeue
  front = (front+1) % size;             // Increment front
  return listarray[ front ];            // Return value
}

#endif // End of ArrayQueue.hpp

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