import java.util.Iterator;

// Interface: CS210ListADT
//
// License Information:
//   This class is free software; you can redistribute it and/or modify
//   it under the terms of the GNU General Public License as published by
//   the Free Software Foundation.
//
//   This class is distributed in the hope that it will be useful,
//   but WITHOUT ANY WARRANTY; without even the implied warranty of
//   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//   GNU General Public License for more details.

/**
 *  The <code>CS210ListADT</code> interface specifies the methods that
 *  a list should have, as identified by the students in CS210 on
 *  10 October, 2008.
 *  Modified Oct. 11, 2009 - Nathan Sprague
 *  @author Pam Cutter
 *  @version October 14, 2008
 */
public interface CS210ListADT<T> extends Iterable<T>
{
    /** Tests whether this is an empty list.
     *      @return <code>true</code> if the list is empty;
     *              <code>false</code> otherwise
     */
    boolean isEmpty();

    /** Returns the number of elements in the list.
     */
    int size();

    /** Gets the data value at the beginning of the list.<br>
    *    Precondition: list is not empty
     */
    T first();

    /** Gets the data value at the end of the list.<br>
    *    Precondition: list is not empty
     */
    T last();

    /** Tests whether the specified object is in the list or not.
     *      @return <code>true</code> if <code>obj</code> is in the list;
     *              <code>false</code> otherwise
     */
    boolean contains(T obj);
    
    /** Deletes the data value at the beginning of the list.<br>
     *    Precondition: list is not empty
     */
    T removeFirst();

    /** Deletes the data value at the end of the list.
     *    Precondition: list is not empty
     */
    T removeLast();

    /** Deletes the given object from the list (if it is in the list).
     *  If there is more than one occurrence of <code>obj</code> in
     *  the list, the first is removed.
     *      @param obj  the object to find and delete from the list
     *      @return <code>true</code> if the object was in the list and
     *              removed; <code>false</code> otherwise
     */
     boolean remove(T obj);
    
     /** Removes all data values from the list.
     */
    void clear();


    /** Returns an iterator that can step through this list.
     */
    Iterator<T> iterator();
      
    /** Deletes all occurrences of objects in the specified
     * list from this list.
     *    @param fromList list of elements to be removed
     */
    void removeAll(CS210ListADT<? extends T> fromList);
    
    /** Creates a string representation of the elements in the list.
     *      @return the string representation
     */   
    String toString();
}