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.transformer;
020
021import org.eclipse.aether.RepositoryException;
022import org.eclipse.aether.collection.DependencyGraphTransformationContext;
023import org.eclipse.aether.collection.DependencyGraphTransformer;
024import org.eclipse.aether.graph.DependencyNode;
025
026import static java.util.Objects.requireNonNull;
027
028/**
029 * A dependency graph transformer that does not perform any changes on its input.
030 */
031public final class NoopDependencyGraphTransformer implements DependencyGraphTransformer {
032
033    /**
034     * A ready-made instance of this dependency graph transformer which can safely be reused throughout an entire
035     * application regardless of multi-threading.
036     */
037    public static final DependencyGraphTransformer INSTANCE = new NoopDependencyGraphTransformer();
038
039    /**
040     * Creates a new instance of this graph transformer. Usually, {@link #INSTANCE} should be used instead.
041     */
042    public NoopDependencyGraphTransformer() {}
043
044    public DependencyNode transformGraph(DependencyNode node, DependencyGraphTransformationContext context)
045            throws RepositoryException {
046        requireNonNull(node, "node cannot be null");
047        requireNonNull(context, "context cannot be null");
048        return node;
049    }
050}