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.collection;
020
021import org.eclipse.aether.RepositoryException;
022import org.eclipse.aether.graph.DependencyNode;
023
024/**
025 * Transforms a given dependency graph.
026 * <p>
027 * <strong>Note:</strong> Implementations must be stateless.
028 * <p>
029 * <em>Warning:</em> Dependency graphs may generally contain cycles. As such a graph transformer that cannot assume for
030 * sure that cycles have already been eliminated must gracefully handle cyclic graphs, e.g. guard against infinite
031 * recursion.
032 *
033 * @see org.eclipse.aether.RepositorySystemSession#getDependencyGraphTransformer()
034 */
035public interface DependencyGraphTransformer {
036
037    /**
038     * Transforms the dependency graph denoted by the specified root node. The transformer may directly change the
039     * provided input graph or create a new graph, the former is recommended for performance reasons.
040     *
041     * @param node The root node of the (possibly cyclic!) graph to transform, must not be {@code null}.
042     * @param context The graph transformation context, must not be {@code null}.
043     * @return The result graph of the transformation, never {@code null}.
044     * @throws RepositoryException If the transformation failed.
045     */
046    DependencyNode transformGraph(DependencyNode node, DependencyGraphTransformationContext context)
047            throws RepositoryException;
048}