splavl-tree/Online-Algorithms/08/library/queue.h

#ifndef QUEUE_H_
#define QUEUE_H_

/**
 * The Queue is a pure virtual (abstract) interface of a queue.  Queue
 * implementations should inherit from and implement this interface.
 */
template <typename T>
class Queue {
  public:
    virtual ~Queue() { };              // An empty virtual destructor.
    virtual void enqueue(T item) = 0;  // Put an item on the end of the queue.
    virtual T    dequeue() = 0;        // Remove and return front item.
    virtual int  getSize() = 0;        // Returns current number of items.
    virtual bool isEmpty() = 0;        // Returns true if the queue is empty.
    virtual T    getFront() = 0;       // Returns (but does not remove) front.
};

#endif  // QUEUE_H_