Bug 135284 [Viewers] API: need to add methods to StructuredViewer to support ViewerComparator
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/ViewerSorter.java
package org.eclipse.jface.viewers;
import java.text.Collator; 
import java.util.Comparator;
/**
 * A viewer sorter is used by a {@link StructuredViewer} to reorder the elements 
 * provided by its content provider.
 * <p>
 * The default <code>compare</code> method compares elements using two steps. 
 * The first step uses the values returned from <code>category</code>. 
 * By default, all elements are in the same category. 
 * The second level is based on a case insensitive compare of the strings obtained 
 * from the content viewer's label provider via <code>ILabelProvider.getText</code>.
 * </p>
 * <p>
 * Subclasses may implement the <code>isSorterProperty</code> method;
 * they may reimplement the <code>category</code> method to provide 
 * categorization; and they may override the <code>compare</code> methods
 * to provide a totally different way of sorting elements.
 * </p>
 * @see IStructuredContentProvider
 * @see StructuredViewer
 */
public class ViewerSorter extends ViewerComparator{
    /**
     * The collator used to sort strings.
     */
    protected Collator collator;
    /**
     * Creates a new viewer sorter, which uses the default collator
     * to sort strings.