001    package org.apache.maven.repository.legacy.resolver.conflict;
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    
022    import org.apache.maven.artifact.resolver.ResolutionNode;
023    import org.apache.maven.artifact.versioning.ArtifactVersion;
024    import org.apache.maven.artifact.versioning.OverConstrainedVersionException;
025    import org.codehaus.plexus.component.annotations.Component;
026    
027    /**
028     * Resolves conflicting artifacts by always selecting the <em>oldest</em> declaration. Oldest is defined as the
029     * declaration whose version is less according to <code>ArtifactVersion.compareTo</code>.
030     *
031     * @author <a href="mailto:markhobson@gmail.com">Mark Hobson</a>
032     * @see ArtifactVersion#compareTo
033     * @since 3.0
034     */
035    @Component( role = ConflictResolver.class, hint = "oldest" )
036    public class OldestConflictResolver
037        implements ConflictResolver
038    {
039        // ConflictResolver methods -----------------------------------------------
040    
041        /*
042        * @see org.apache.maven.artifact.resolver.conflict.ConflictResolver#resolveConflict(org.apache.maven.artifact.resolver.ResolutionNode,
043        *      org.apache.maven.artifact.resolver.ResolutionNode)
044        */
045    
046        public ResolutionNode resolveConflict( ResolutionNode node1, ResolutionNode node2 )
047        {
048            try
049            {
050                ArtifactVersion version1 = node1.getArtifact().getSelectedVersion();
051                ArtifactVersion version2 = node2.getArtifact().getSelectedVersion();
052    
053                return version1.compareTo( version2 ) <= 0 ? node1 : node2;
054            }
055            catch ( OverConstrainedVersionException exception )
056            {
057                // TODO: log message or throw exception?
058    
059                return null;
060            }
061        }
062    }