//================================================================
// This module provides class PQueue, a kind of priority
// queues.  The constructor creates an empty queue.  Objects of
// class PQueue have the following capabilities.
//
// q.insert(p,e)  Insert Event object e (given by a pointer to the object)
//                into priority queue q, with priority p.  The priority 
//                has type double.
//
// q.remove(p,e)  Remove the event object from priority queue q 
//                that has the smallest priority.  Store its priority
//                into variable p, and store a pointer to the event object
//                into variable e.  An attempt to remove an object
//                from an empty queue is an error, and causes the
//                program to stop.
//
// q.isEmpty()    Return true if q is empty, false if not.
//
// q.print()      Print all of the objects in priority queue q,
//                in nondecreasing order of priority.
//================================================================

#ifndef PQUEUE_H
#define PQUEUE_H

#include "event.h"

class PQueue
{
public:
  PQueue();
  void insert(double priority, Event* obj);
  void remove(double& priority, Event*& obj);
  bool isEmpty() const;
  void print() const;

private:
  struct PQCell;
  PQCell* ptr;
  void insert(PQCell*& p, double priority, Event* obj);
};

#endif