/*******************************************************************************
 * Copyright (c) 2010, 2011 Sonatype, Inc.
 * 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:
 *    Sonatype, Inc. - initial API and implementation
 *******************************************************************************/
package org.eclipse.aether.graph;

/**
 * A visitor for nodes of the dependency graph.
 * 
 * @see DependencyNode#accept(DependencyVisitor)
 */
public interface DependencyVisitor
{

    /**
     * Notifies the visitor of a node visit before its children have been processed.
     * 
     * @param node The dependency node being visited, must not be {@code null}.
     * @return {@code true} to visit child nodes of the specified node as well, {@code false} to skip children.
     */
    boolean visitEnter( DependencyNode node );

    /**
     * Notifies the visitor of a node visit after its children have been processed. Note that this method is always
     * invoked regardless whether any children have actually been visited.
     * 
     * @param node The dependency node being visited, must not be {@code null}.
     * @return {@code true} to visit siblings nodes of the specified node as well, {@code false} to skip siblings.
     */
    boolean visitLeave( DependencyNode node );

}