001package org.eclipse.aether.util.graph.transformer;
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.RepositoryException;
023import org.eclipse.aether.collection.DependencyGraphTransformationContext;
024import org.eclipse.aether.collection.DependencyGraphTransformer;
025import org.eclipse.aether.graph.DependencyNode;
026
027/**
028 * A dependency graph transformer that chains other transformers.
029 */
030public final class ChainedDependencyGraphTransformer
031    implements DependencyGraphTransformer
032{
033
034    private final DependencyGraphTransformer[] transformers;
035
036    /**
037     * Creates a new transformer that chains the specified transformers.
038     * 
039     * @param transformers The transformers to chain, may be {@code null} or empty.
040     */
041    public ChainedDependencyGraphTransformer( DependencyGraphTransformer... transformers )
042    {
043        if ( transformers == null )
044        {
045            this.transformers = new DependencyGraphTransformer[0];
046        }
047        else
048        {
049            this.transformers = transformers;
050        }
051    }
052
053    /**
054     * Creates a new transformer that chains the specified transformers or simply returns one of them if the other one
055     * is {@code null}.
056     * 
057     * @param transformer1 The first transformer of the chain, may be {@code null}.
058     * @param transformer2 The second transformer of the chain, may be {@code null}.
059     * @return The chained transformer or {@code null} if both input transformers are {@code null}.
060     */
061    public static DependencyGraphTransformer newInstance( DependencyGraphTransformer transformer1,
062                                                          DependencyGraphTransformer transformer2 )
063    {
064        if ( transformer1 == null )
065        {
066            return transformer2;
067        }
068        else if ( transformer2 == null )
069        {
070            return transformer1;
071        }
072        return new ChainedDependencyGraphTransformer( transformer1, transformer2 );
073    }
074
075    public DependencyNode transformGraph( DependencyNode node, DependencyGraphTransformationContext context )
076        throws RepositoryException
077    {
078        for ( DependencyGraphTransformer transformer : transformers )
079        {
080            node = transformer.transformGraph( node, context );
081        }
082        return node;
083    }
084
085}