CD Ware Multimedia 1999 February/CDW0299.iso/Demos/Cafe/Source.bin/MatrixEnumeration.java

Java Source | 1998-03-18 | 4.7 KB | 221 lines

package symantec.itools.awt;


import java.util.Enumeration;
import java.text.MessageFormat;
import java.util.ResourceBundle;


//     01/30/97    RKM    Integrated fix to hasMoreElements from [e-mail] (George Rome Borden IV)
//     03/27/97    RKM    Made class public, so peole could use it
//                    Made class final
//                    Tried to make some sense of protection on methods & members
//     04/17/97    LAB Added Don Haney's ([e-mail]) fix that addressed a NullPointerException in hasMoreElements().

/**
 * This class is used to enumerate Matrix elements. Enumeration is used to
 * sequentially scan through all the elements in a Matrix one at a time.
 * @see symantec.itools.awt.Matrix
 * @see java.util.Enumeration
 *
 * @version 1.0, Nov 26, 1996
 *
 * @author    Symantec
 *
 */

public final class MatrixEnumeration
    implements Enumeration
{
    //--------------------------------------------------
    // public constructors
    //--------------------------------------------------

    /**
     * Constructs a matrix enumerator for the given Matrix.
     */
    public MatrixEnumeration(Matrix matrix)
    {
        errors = ResourceBundle.getBundle("symantec.itools.resources.ErrorsBundle");
        m = matrix;
        started = false;
    }

    //--------------------------------------------------
    // public members
    //--------------------------------------------------

    /**
     * Returns true if more elements are available to enumerate.
     * This is a standard Java Enumeration interface method.
     * @return true if more elements available, false if done enumerating
     */
    public boolean hasMoreElements()
    {
        if (m == null)
            return false;
        if (started == false && m.o != null) return true;
        if (m.nextElt != null) return true;
        return hasMoreRows();
    }

    /**
     * Returns true if more rows are available to enumerate.
     */
    public boolean hasMoreRows()
    {
        if (m.nextRow == null)
        {
            return false;
        }

        Matrix n = m.nextRow;

        //find next row
        while(n.o == null && n.nextElt == null)
        {
            if ((n = n.nextRow) == null)  return false;
        }

        return true;
    }

    /**
     * Returns the next element.
     * This is a standard Java Enumeration interface method.
     */
    public Object nextElement()
    {
        if (!started)
        {
            started = true;

            if (m.o != null)
            {
                return m.o;
            }
        }

        if (m == null)
        {
            return null;
        }

        if (m.nextElt != null)
        {
            m = m.nextElt;
        } else {

                if ((m = findNextRow()) == null)
                {
                    return null;
                }
                }

        return m.o;
    }

    /**
     * Returns the row number of the current element.
     */
    public int currRow()
    {
        return m.row;
    }

    /**
     * Returns the column number of the current element.
     */
    public int currCol()
    {
        return m.col;
    }

    /**
     * Skips enumeration ahead to the start of the next row.
     * @return the first element in the next row.
     */
    public Object nextRow()
    {
        m = findNextRow();

        return m.o;
    }

    /**
     * Skips enumeration ahead to the start of the given row.
     * @param r the row to skip ahead to. Must be greater than the current row
     * @return the first element in the given row
     * @exception IllegalArgumentException if r is less than or equal to the
     * current row
     */
    public Object advanceTo(int r)
        throws IllegalArgumentException
    {
        started = true;

        if (r < m.row || r == m.row)
        {
            Object[] args = { new Integer(r), new Integer(m.row) };
            throw new
               IllegalArgumentException(MessageFormat.format(errors.getString("MustBeGreaterThanCurrentRow"), args));
        }

        Matrix n = m;

        while (m.row < r)
        {
            m = findNextRow();

            if (m == null)
            {
                m = n;
                Object[] args = { new Integer(r) };
                throw new
                   IllegalArgumentException(MessageFormat.format(errors.getString("RowTooLarge"), args));
            }
        }

        return m.o;
    }

    //--------------------------------------------------
    // private members
    //--------------------------------------------------

    private Matrix findNextRow()
    {
        started = true;
        Matrix n = m.nextRow;

        if (n == null)
        {
            return null;
        }

        //find next row
        while(n.o == null && n.nextElt == null)
        {
            if ((n = n.nextRow) == null)
            {
                return null;
            }
        }

        n = n.o != null  ?n  :n.nextElt;
        return n;
    }

    /**
     * Error strings.
     */
    transient protected ResourceBundle errors;

    //--------------------------------------------------
    // private members
    //--------------------------------------------------

    private Matrix        m;
    private boolean    started;
}