/*******************************************************************************
 * 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
 ******************************************************************************/
module org.eclipse.jface.databinding.viewers.TreeStructureAdvisor;

import java.lang.all;

/**
 * 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 1.2
 * 
 */
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;
    }

}