001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.eclipse.aether.util.graph.manager;
020
021import org.eclipse.aether.collection.DependencyCollectionContext;
022import org.eclipse.aether.collection.DependencyManagement;
023import org.eclipse.aether.collection.DependencyManager;
024import org.eclipse.aether.graph.Dependency;
025
026import static java.util.Objects.requireNonNull;
027
028/**
029 * A dependency manager that does not do any dependency management.
030 */
031public final class NoopDependencyManager implements DependencyManager {
032
033    /**
034     * A ready-made instance of this dependency manager which can safely be reused throughout an entire application
035     * regardless of multi-threading.
036     */
037    public static final DependencyManager INSTANCE = new NoopDependencyManager();
038
039    /**
040     * Creates a new instance of this dependency manager. Usually, {@link #INSTANCE} should be used instead.
041     */
042    public NoopDependencyManager() {}
043
044    public DependencyManager deriveChildManager(DependencyCollectionContext context) {
045        requireNonNull(context, "context cannot be null");
046        return this;
047    }
048
049    public DependencyManagement manageDependency(Dependency dependency) {
050        requireNonNull(dependency, "dependency cannot be null");
051        return null;
052    }
053
054    @Override
055    public boolean equals(Object obj) {
056        if (this == obj) {
057            return true;
058        } else if (null == obj || !getClass().equals(obj.getClass())) {
059            return false;
060        }
061        return true;
062    }
063
064    @Override
065    public int hashCode() {
066        return getClass().hashCode();
067    }
068}