1 package org.eclipse.aether.collection;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import org.eclipse.aether.graph.Dependency;
23
24 /**
25 * Decides whether the dependencies of a dependency node should be traversed as well.
26 * <p>
27 * <strong>Note:</strong> Implementations must be stateless.
28 * <p>
29 * <em>Warning:</em> This hook is called from a hot spot and therefore implementations should pay attention to
30 * performance. Among others, implementations should provide a semantic {@link Object#equals(Object) equals()} method.
31 *
32 * @see org.eclipse.aether.RepositorySystemSession#getDependencyTraverser()
33 * @see org.eclipse.aether.RepositorySystem#collectDependencies(org.eclipse.aether.RepositorySystemSession,
34 * CollectRequest)
35 */
36 public interface DependencyTraverser
37 {
38
39 /**
40 * Decides whether the dependencies of the specified dependency should be traversed.
41 *
42 * @param dependency The dependency to check, must not be {@code null}.
43 * @return {@code true} if the dependency graph builder should recurse into the specified dependency and process its
44 * dependencies, {@code false} otherwise.
45 */
46 boolean traverseDependency( Dependency dependency );
47
48 /**
49 * Derives a dependency traverser that will be used to decide whether the transitive dependencies of the dependency
50 * given in the collection context shall be traversed. When calculating the child traverser, implementors are
51 * strongly advised to simply return the current instance if nothing changed to help save memory.
52 *
53 * @param context The dependency collection context, must not be {@code null}.
54 * @return The dependency traverser for the target node or {@code null} if dependencies should be unconditionally
55 * traversed in the sub graph.
56 */
57 DependencyTraverser deriveChildTraverser( DependencyCollectionContext context );
58
59 }