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.transformer;
020
021import java.util.Collection;
022
023import org.eclipse.aether.RepositoryException;
024import org.eclipse.aether.util.graph.transformer.ConflictResolver.ConflictContext;
025import org.eclipse.aether.util.graph.transformer.ConflictResolver.ConflictItem;
026import org.eclipse.aether.util.graph.transformer.ConflictResolver.OptionalitySelector;
027
028/**
029 * An optionality selector for use with {@link ConflictResolver}. In general, this selector only marks a dependency as
030 * optional if all its occurrences are optional. If however a direct dependency is involved, its optional flag is
031 * selected.
032 */
033public final class SimpleOptionalitySelector extends OptionalitySelector {
034
035    /**
036     * Creates a new instance of this optionality selector.
037     */
038    public SimpleOptionalitySelector() {}
039
040    @Override
041    public void selectOptionality(ConflictContext context) throws RepositoryException {
042        boolean optional = chooseEffectiveOptionality(context.getItems());
043        context.setOptional(optional);
044    }
045
046    private boolean chooseEffectiveOptionality(Collection<ConflictItem> items) {
047        boolean optional = true;
048        for (ConflictItem item : items) {
049            if (item.getDepth() <= 1) {
050                return item.getDependency().isOptional();
051            }
052            if ((item.getOptionalities() & ConflictItem.OPTIONAL_FALSE) != 0) {
053                optional = false;
054            }
055        }
056        return optional;
057    }
058}