001package 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
022import org.apache.maven.artifact.resolver.ResolutionNode;
023import org.apache.maven.artifact.versioning.ArtifactVersion;
024import org.apache.maven.artifact.versioning.OverConstrainedVersionException;
025import 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" )
036public 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}