linear.java

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// An interface for LIFO/FIFO structures.
// (c) 1998,2001 duane a. bailey

package structure;

/**
 * An interface describing the behavior of linear data structures, structures that 
 * that have completely determined  add and remove methods.  
 * Linear structures are often used to store the the state of a recursively
 * solved problem and stacks and queues are classic examples of such structures.
 * The structure package provides several implementations of the Linear interface, 
 * each of which has its particular strengths and weaknesses.
 *
 * @version $Id: Linear.java,v 4.0 2000/12/27 21:21:47 bailey Exp bailey $
 * @author, 2001 duane a. bailey
 * @see structure.Stack
 * @see structure.Queue
 */
public interface Linear extends Structure
{
    /**
     * Add a value to the structure.  The type of structure determines
     * the location of the value added.
     *
     * @pre value is non-null
     * @post the value is added to the collection,
     *       the consistent replacement policy is not specified
     * 
     * @param value The value to be added to the structure.
     */
    public void add(Object value);

    /**
     * Preview the object to be removed.
     *
     * @pre structure is not empty
     * @post returns reference to next object to be removed
     *
     * @return A reference to the next object to be removed.
     */
    public Object get();

    /**
     * Remove a value from the structure.  The particular value
     * to be removed is determined by the structure.
     *
     * @pre structure is not empty
     * @post removes an object from store
     * 
     * @return Value removed from structure.
     */
    public Object remove();

    /**
     * Returns the number of elements in the linear structure.
     *
     * @post returns the number of elements in the structure
     * @return number of elements in structure.
     */
    public int size();

    /**
     * Returns true iff the structure is empty.
     *
     * @post returns true if and only if the linear structure is empty
     * 
     * @return True iff the linear structure is empty.
     */
    public boolean empty();
}