treepathviewersorter.java

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/*******************************************************************************
 * Copyright (c) 2006 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 ******************************************************************************/

package org.eclipse.jface.viewers;

import java.util.Arrays;
import java.util.Comparator;

/**
 * A viewer sorter that is provded extra context in the form of the path of the
 * parent element of the elements being sorted.
 * 
 * @since 3.2
 */
public class TreePathViewerSorter extends ViewerSorter {

	/**
	 * Provide a category for the given element that will have the given parent
	 * path when it is added to the viewer. The provided path is
	 * relative to the viewer input. The parent path will
	 * be <code>null</code> when the elements are root elements.
	 * <p>
	 * By default, the this method calls
	 * {@link ViewerSorter#category(Object)}. Subclasses may override.
	 * 
	 * @param parentPath
	 *            the parent path for the element
	 * @param element
	 *            the element
	 * @return the category of the element
	 */
	public int category(TreePath parentPath, Object element) {
		return category(element);
	}
	
	/**
	 * Compare the givcen elements that will have the given parent
	 * path when they are added to the viewer. The provided path is
	 * relative to the viewer input. The parent path will
	 * be <code>null</code> when the elements are root elements.
	 * <p>
	 * By default, the this method calls
	 * {@link ViewerSorter#sort(Viewer, Object[])}. Subclasses may override.
	 * @param viewer the viewer
	 * @param parentPath the parent path for the two elements
     * @param e1 the first element
     * @param e2 the second element
     * @return a negative number if the first element is less  than the 
     *  second element; the value <code>0</code> if the first element is
     *  equal to the second element; and a positive
	 */
	public int compare(Viewer viewer, TreePath parentPath, Object e1, Object e2) {
		return compare(viewer, e1, e2);
	}
	
	/**
     * Returns whether this viewer sorter would be affected 
     * by a change to the given property of the given element.
     * The provided path is
	 * relative to the viewer input. The parent path will
	 * be <code>null</code> when the elements are root elements.
     * <p>
     * The default implementation of this method calls
     * {@link ViewerSorter#isSorterProperty(Object, String)}.
     * Subclasses may reimplement.
	 * @param parentPath the parent path of the element
     * @param element the element
     * @param property the property
     * @return <code>true</code> if the sorting would be affected,
     *    and <code>false</code> if it would be unaffected
	 */
    public boolean isSorterProperty(TreePath parentPath, Object element, String property) {
        return isSorterProperty(element, property);
    }
    
    /**
     * Sorts the given elements in-place, modifying the given array.
     * The provided path is
	 * relative to the viewer input. The parent path will
	 * be <code>null</code> when the elements are root elements.
     * <p>
     * The default implementation of this method uses the 
     * java.util.Arrays#sort algorithm on the given array, 
     * calling {@link #compare(Viewer, TreePath, Object, Object)} to compare elements.
     * </p>
     * <p>
     * Subclasses may reimplement this method to provide a more optimized implementation.
     * </p>
     *
     * @param viewer the viewer
     * @param parentPath the parent path of the given elements
     * @param elements the elements to sort
     */
    public void sort(final Viewer viewer, final TreePath parentPath, Object[] elements) {
        Arrays.sort(elements, new Comparator() {
            public int compare(Object a, Object b) {
                return TreePathViewerSorter.this.compare(viewer, parentPath, a, b);
            }
        });
    }
}