001package org.eclipse.aether.util.graph.manager;
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.DependencyManagement;
024import org.eclipse.aether.collection.DependencyManager;
025import org.eclipse.aether.graph.Dependency;
026
027import static java.util.Objects.requireNonNull;
028
029/**
030 * A dependency manager that does not do any dependency management.
031 */
032public final class NoopDependencyManager
033    implements DependencyManager
034{
035
036    /**
037     * A ready-made instance of this dependency manager which can safely be reused throughout an entire application
038     * regardless of multi-threading.
039     */
040    public static final DependencyManager INSTANCE = new NoopDependencyManager();
041
042    /**
043     * Creates a new instance of this dependency manager. Usually, {@link #INSTANCE} should be used instead.
044     */
045    public NoopDependencyManager()
046    {
047    }
048
049    public DependencyManager deriveChildManager( DependencyCollectionContext context )
050    {
051        requireNonNull( context, "context cannot be null" );
052        return this;
053    }
054
055    public DependencyManagement manageDependency( Dependency dependency )
056    {
057        requireNonNull( dependency, "dependency cannot be null" );
058        return null;
059    }
060
061    @Override
062    public boolean equals( Object obj )
063    {
064        if ( this == obj )
065        {
066            return true;
067        }
068        else if ( null == obj || !getClass().equals( obj.getClass() ) )
069        {
070            return false;
071        }
072        return true;
073    }
074
075    @Override
076    public int hashCode()
077    {
078        return getClass().hashCode();
079    }
080
081}