| /******************************************************************************* |
| * Copyright (c) 2008 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.databinding.viewers; |
| |
| /** |
| * Instances of this class can be used to improve accuracy and performance of an |
| * {@link ObservableListTreeContentProvider} or an |
| * {@link ObservableSetTreeContentProvider}. This class is intended to be |
| * subclassed by clients. |
| * |
| * @since 3.4 |
| * |
| */ |
| public abstract class TreeStructureAdvisor { |
| |
| /** |
| * Returns the parent for the given element, or <code>null</code> |
| * indicating that the parent can't be computed. In this case the |
| * tree-structured viewer can't expand a given node correctly if requested. |
| * The default implementation returns null; clients should override. |
| * |
| * @param element |
| * the element |
| * @return the parent element, or <code>null</code> if it has none or if |
| * the parent cannot be computed |
| */ |
| public Object getParent(Object element) { |
| return null; |
| } |
| |
| /** |
| * Returns whether the given element has children, or <code>null</code> if |
| * the actual children collection should be consulted. The default |
| * implementation returns null; clients should override. |
| * <p> |
| * Intended as an optimization for when the viewer does not need the actual |
| * children. Clients may be able to implement this more efficiently than |
| * <code>getChildren</code>. |
| * </p> |
| * |
| * @param element |
| * the element |
| * @return <code>Boolean.TRUE</code> if the given element has children, |
| * <code>Boolean.FALSE</code> if it has no children, or |
| * <code>null</code> if the children collection should be |
| * consulted. |
| */ |
| public Boolean hasChildren(Object element) { |
| return null; |
| } |
| |
| } |