001package org.eclipse.aether.util.graph.traverser;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 * 
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 * 
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import org.eclipse.aether.collection.DependencyCollectionContext;
023import org.eclipse.aether.collection.DependencyTraverser;
024import org.eclipse.aether.graph.Dependency;
025
026import static java.util.Objects.requireNonNull;
027
028/**
029 * A dependency traverser which always or never traverses children.
030 */
031public final class StaticDependencyTraverser
032    implements DependencyTraverser
033{
034
035    private final boolean traverse;
036
037    /**
038     * Creates a new traverser with the specified traversal behavior.
039     * 
040     * @param traverse {@code true} to traverse all dependencies, {@code false} to never traverse.
041     */
042    public StaticDependencyTraverser( boolean traverse )
043    {
044        this.traverse = traverse;
045    }
046
047    public boolean traverseDependency( Dependency dependency )
048    {
049        requireNonNull( dependency, "dependency cannot be null" );
050        return traverse;
051    }
052
053    public DependencyTraverser deriveChildTraverser( DependencyCollectionContext context )
054    {
055        requireNonNull( context, "context cannot be null" );
056        return this;
057    }
058
059    @Override
060    public boolean equals( Object obj )
061    {
062        if ( this == obj )
063        {
064            return true;
065        }
066        else if ( null == obj || !getClass().equals( obj.getClass() ) )
067        {
068            return false;
069        }
070
071        StaticDependencyTraverser that = (StaticDependencyTraverser) obj;
072        return traverse == that.traverse;
073    }
074
075    @Override
076    public int hashCode()
077    {
078        int hash = getClass().hashCode();
079        hash = hash * 31 + ( traverse ? 1 : 0 );
080        return hash;
081    }
082
083}