1 /*******************************************************************************
2  * Copyright (c) 2011 Wind River Systems and others.
3  *
4  * This program and the accompanying materials
5  * are made available under the terms of the Eclipse Public License 2.0
6  * which accompanies this distribution, and is available at
7  * https://www.eclipse.org/legal/epl-2.0/
8  *
9  * SPDX-License-Identifier: EPL-2.0
10  *
11  * Contributors:
12  *     Wind River Systems - initial API and implementation
13  *******************************************************************************/
14 package org.eclipse.debug.internal.ui.viewers.model.provisional;
15 
16 import org.eclipse.jface.viewers.ViewerFilter;
17 
18 /**
19  * Viewer filter for the Tree Model Viewer which allows more efficient filtering
20  * in the lazy viewer.
21  * <p>
22  * The standard {@link ViewerFilter} class must be applied to all elements in the
23  * tree, thus forcing the lazy viewer to retrieve all children of all elements and
24  * defeating the lazy loading behavior.  This class adds an {@link #isApplicable(ITreeModelViewer, Object)}
25  * method, which can be used by the filter to discern which parent elements the
26  * filter should apply to.
27  * </p>
28  *
29  * @since 3.8
30  */
31 abstract public class TreeModelViewerFilter extends ViewerFilter {
32 
33 	/**
34 	 * Determines whether the filter applies to the given parent element.
35 	 * @return Returns true if the viewer should use the given filter on the
36 	 * given element.
37 	 * @param viewer The viewer that is using this filter to select elements.
38 	 * @param parentElement Parent element to check filter for.
39 	 */
isApplicable(ITreeModelViewer viewer, Object parentElement)40 	abstract public boolean isApplicable(ITreeModelViewer viewer, Object parentElement);
41 }
42