circular-queue.h

#ifndef LAB2_CIRCULAR_QUEUE_H
#define LAB2_CIRCULAR_QUEUE_H

class CircularQueue {
public:
    // Defines the kind of data that the queue will contain.
    typedef int QueueItem;

    // Defines a constant that will be used to indicate an empty queue.
    static const QueueItem EMPTY_QUEUE;


private:
    // Befriend so tests have access to variables.
    friend class CircularQueueTest;

    // MEMBER VARIABLES
    // An array of queue items.
    QueueItem* items_;

    // Index of the first element in the circular queue.
    unsigned int head_;

    // Index of the element after the last item in the circular queue.
    unsigned int tail_;

    // Maximum number of items in the queue.
    unsigned int capacity_;

    // Current number of items in the queue.
    unsigned int size_; 


    // Copy constructor. Declared private so we don't use it incorrectly.
    CircularQueue(const CircularQueue& other) {}
    
    // Assignment operator. Declared private so we don't use it incorrectly.
    CircularQueue operator=(const CircularQueue& other) {}


public:
    // CONSTRUCTORS/DESTRUCTOR
    // Default constructor of the class CircularQueue. It uses 16 as the
    // initial capacity of the array, and allocates the required memory
    // space for the queue. The function appropriately initializes the
    // fields of the created empty queue.
    CircularQueue();

    // Parametric constructor of the class CircularQueue. It allocates
    // the required memory space for the queue of the given capacity.
    // The function appropriately initializes the fields of the created
    // empty queue.
    CircularQueue(unsigned int capacity);

    // Destructor of the class CircularQueue. It deallocates the memory
    // space allocated for the queue.
    ~CircularQueue();

    // ACCESSORS
    // Returns the number of items in the queue.
    unsigned int size() const;

    // Returns true if the queue is empty and false otherwise.
    bool empty() const;

    // Returns true if the queue is full and false otherwise.
    bool full() const;

    // Returns the value at the front of the queue without removing it
    // from the queue. If the queue is empty, it returns the EMPTY_QUEUE
    // constant instead.
    QueueItem peek() const;

    // MUTATORS
    // Takes as an argument a QueueItem value. If the queue is not at capacity,
    // it inserts the value at the rear of the queue after the last item, and
    // returns true. If the insertion fails due to lack of space, it
    // returns false.
    bool enqueue(QueueItem value);

    // Removes the item from the front of the queue and returns it. If the queue
    // is empty, it returns the EMPTY_QUEUE constant instead.
    QueueItem dequeue();

    // Prints the queue items sequentially and in order, from the front
    // to the rear of the queue.
    void print() const;
};

#endif  // LAB2_CIRCULAR_QUEUE_H