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 java.util.Collection;
023
024import org.eclipse.aether.RepositoryException;
025import org.eclipse.aether.util.graph.transformer.ConflictResolver.ConflictContext;
026import org.eclipse.aether.util.graph.transformer.ConflictResolver.ConflictItem;
027import org.eclipse.aether.util.graph.transformer.ConflictResolver.OptionalitySelector;
028
029/**
030 * An optionality selector for use with {@link ConflictResolver}. In general, this selector only marks a dependency as
031 * optional if all its occurrences are optional. If however a direct dependency is involved, its optional flag is
032 * selected.
033 */
034public final class SimpleOptionalitySelector
035    extends OptionalitySelector
036{
037
038    /**
039     * Creates a new instance of this optionality selector.
040     */
041    public SimpleOptionalitySelector()
042    {
043    }
044
045    @Override
046    public void selectOptionality( ConflictContext context )
047        throws RepositoryException
048    {
049        boolean optional = chooseEffectiveOptionality( context.getItems() );
050        context.setOptional( optional );
051    }
052
053    private boolean chooseEffectiveOptionality( Collection<ConflictItem> items )
054    {
055        boolean optional = true;
056        for ( ConflictItem item : items )
057        {
058            if ( item.getDepth() <= 1 )
059            {
060                return item.getDependency().isOptional();
061            }
062            if ( ( item.getOptionalities() & ConflictItem.OPTIONAL_FALSE ) != 0 )
063            {
064                optional = false;
065            }
066        }
067        return optional;
068    }
069
070}