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.version;
020
021import java.util.Iterator;
022
023import org.eclipse.aether.collection.DependencyCollectionContext;
024import org.eclipse.aether.collection.VersionFilter;
025import org.eclipse.aether.version.Version;
026
027/**
028 * A version filter that excludes any version except the lowest one.
029 *
030 * @since 2.0.0
031 */
032public final class LowestVersionFilter implements VersionFilter {
033
034    /**
035     * Creates a new instance of this version filter.
036     */
037    public LowestVersionFilter() {}
038
039    @Override
040    public void filterVersions(VersionFilterContext context) {
041        Iterator<Version> it = context.iterator();
042        if (it.hasNext()) {
043            it.next();
044            while (it.hasNext()) {
045                it.next();
046                it.remove();
047            }
048        }
049    }
050
051    @Override
052    public VersionFilter deriveChildFilter(DependencyCollectionContext context) {
053        return this;
054    }
055
056    @Override
057    public boolean equals(Object obj) {
058        if (this == obj) {
059            return true;
060        } else if (null == obj || !getClass().equals(obj.getClass())) {
061            return false;
062        }
063        return true;
064    }
065
066    @Override
067    public int hashCode() {
068        return getClass().hashCode();
069    }
070}