ordering_structure.h

/**
 * @file ordering_structure.h
 * Definition of an abstract ordering structure class.
 *
 * You **should not** modify this file for the PA.
 *
 */
#ifndef _ORDERING_STRUCTURE_H_
#define _ORDERING_STRUCTURE_H_

/**
 * OrderingStructure: represents an interface for a structure that orders
 * items placed into it. Your Stack and Queue classes will implement this
 * interface.
 *
 */
template <class T>
class OrderingStructure
{
  public:
    /**
     * Destructor for the OrderingStructure. Virtual so as to allow
     * derived classes to override if necessary.
     */
    virtual ~OrderingStructure()
    {
        // nothing
    }

    /**
     * Adds the given element to the ordering structure.
     *
     * @param theItem The item to be added.
     */
    virtual void add(const T& theItem) = 0;

    /**
     * Removes an element from the ordering structure. You may assume
     * that this function is only called when the ordering structure is
     * not empty.
     *
     * @return An element from the ordering structure.
     */
    virtual T remove() = 0;

    /**
     * Looks at the next element of the ordering structure, but does
     * not remove it.
     *
     * @return The next element on the ordering structure.
     */
    virtual T peek() = 0;

    /**
     * Determines if the ordering structure is empty.
     *
     * @return Whether or not there are still elements in the ordering
     *  structure.
     */
    virtual bool isEmpty() const = 0;
};
#endif