/**
 * CharList
 *
 * A linked list of characters.  Your job is to complete the incomplete
 * methods.  Two methods (the constructor and <code>print</code>) are
 * already complete.  One (<code>set</code>) is complete except for the
 * javadoc comment.  The rest have complete javadoc comments, but only
 * stub implementations.
 * <p>
 * I have used <code>main</code> to provide a small unit test for the
 * <code>CharList</code>, <code>print</code>, and <code>set</code> methods.
 * You should expand this test as you complete the methods.
 *
 * @author Jeff Ondich (so far)
 *
 */

class CharList
{
    public CharNode     head;

    /**
     * Unit test for the <code>CharList</code> methods.
     */
    public static void main( String[] args )
    {
        CharList testList = new CharList();
        if( args.length > 0 )
            testList.set( args[0] );

        testList.printRecursive( testList.head );
        System.out.println();

        testList.printBackwards( testList.head );
        System.out.println();
    }

    /**
     * Initializes the list to empty.
     */
    public CharList()
    {
        head = null;
    }

    public void printRecursive( CharNode front )
    {
        if( front == null )
            return;

        System.out.print( front.data );
        printRecursive( front.next );
    }


    public void printBackwards( CharNode front )
    {
        if( front == null )
            return;

        printBackwards( front.next );
        System.out.print( front.data );
    }


    /**
     * Prints the contents of the list to standard output.
     */
    public void print()
    {
        CharNode current = head;
        while( current != null )
        {
            System.out.print( current.data );
            current = current.next;
        }
    }

    /**
     * ???
     *
     * @param ???
     */
    public void set( String s )
    {
        head = null;
        int length = s.length();
        for( int k=s.length()-1; k >= 0; k-- )
        {
            CharNode newNode = new CharNode( s.charAt( k ) );
            newNode.next = head;
            head = newNode;
        }
    }

    /**
     * Inserts the specified character at the specified position in the list.
     * For example, if <code>index</code> is 3, the specified character will become
     * the fourth character in the list.  If <code>index</code> is larger than the
     * current length of the list, the character is appended to the end of the list.
     * If <code>index</code> is negative, the character is inserted at the beginning
     * of this list.
     * 
     * @param  index  the position at which to insert the character
     *         ch     the character to insert
     */
    public void add( int index, char ch )
    {
    }

    /**
     * Appends the given character to the end of this list.
     *
     * @param  ch  the character to add to this list
     */
    public void add( char ch )
    {
    }

    /**
     * Appends a copy of the specified list to the end of this list.
     *
     * @param  list  the list to copy and append to the end of this list
     */
    public void add( CharList list )
    {
    }

    /**
     * Returns the number of characters in this list.
     *
     * @return  the length of this list
     */
    public int length()
    {
        return 0;
    }

    /**
     * Returns the character at the given index.
     * 
     * @param  index  the index of the character to retrieve
     * @return  the character at the given position, or the null character
     *  if the index is out of range
     */
    public char get( int index )
    {
        return '\0';
    }

    /**
     * Returns the index of the first occurrence of the specified character, or -1
     * if this list does not contain the specified character.
     *
     * @param  ch  the character to search for
     * @return  the index of the first occurrence of the specified character in this
     *  list, or -1 if the character is not found
     */
    public int indexOf( char ch )
    {
        return -1;
    }  
}