1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.eclipse.aether.util.graph.manager;
20
21 import java.util.ArrayList;
22 import java.util.Collection;
23
24 import org.eclipse.aether.collection.DependencyCollectionContext;
25 import org.eclipse.aether.collection.DependencyManager;
26 import org.eclipse.aether.graph.Exclusion;
27 import org.eclipse.aether.scope.ScopeManager;
28 import org.eclipse.aether.scope.SystemDependencyScope;
29
30 /**
31 * A dependency manager that mimics the way Maven 2.x works for backward compatibility.
32 *
33 * <h2>Overview</h2>
34 * <p>
35 * This manager was used throughout all Maven 3.x versions for backward compatibility reasons.
36 * It provides the exact same dependency management behavior as Maven 2.x, which differs
37 * significantly from modern dependency management approaches.
38 * </p>
39 *
40 * <h2>Key Characteristics</h2>
41 * <ul>
42 * <li><strong>Exclusion Handling:</strong> Ignores exclusions introduced by direct dependencies</li>
43 * <li><strong>Management Scope:</strong> Only obeys root management, ignoring intermediate management</li>
44 * <li><strong>Depth Behavior:</strong> {@code deriveUntil=2}, {@code applyFrom=2} with special "hop" at {@code depth=1}</li>
45 * <li><strong>Level 1 Skip:</strong> Ignores context from depth=1 for Maven 2.x compatibility</li>
46 * </ul>
47 *
48 * <h2>When to Use</h2>
49 * <p>
50 * Use this manager when you need exact Maven 2.x compatibility behavior or when working
51 * with legacy projects that depend on Maven 2.x dependency resolution semantics.
52 * </p>
53 *
54 * <h2>Comparison with Other Managers</h2>
55 * <p>
56 * Unlike {@link TransitiveDependencyManager} and {@link DefaultDependencyManager}, this manager
57 * deliberately ignores certain dependency management rules to maintain backward compatibility.
58 * See {@code MavenITmng4720DependencyManagementExclusionMergeTest} for behavioral differences.
59 * </p>
60 *
61 * @see TransitiveDependencyManager
62 * @see DefaultDependencyManager
63 */
64 public final class ClassicDependencyManager extends AbstractDependencyManager {
65 /**
66 * Creates a new dependency manager without any management information.
67 */
68 public ClassicDependencyManager() {
69 this(null);
70 }
71
72 /**
73 * Creates a new dependency manager without any management information.
74 * <p>
75 * This constructor initializes the manager with Maven 2.x compatible behavior:
76 * <ul>
77 * <li>deriveUntil = 2 (collect rules only from root level)</li>
78 * <li>applyFrom = 2 (apply rules starting from depth 2)</li>
79 * <li>Special depth=1 handling for backward compatibility</li>
80 * </ul>
81 *
82 * @param scopeManager application-specific scope manager for handling system dependencies,
83 * may be null to use legacy system dependency scope handling
84 * @since 2.0.12
85 */
86 public ClassicDependencyManager(ScopeManager scopeManager) {
87 super(2, 2, scopeManager);
88 }
89
90 @SuppressWarnings("checkstyle:ParameterNumber")
91 private ClassicDependencyManager(
92 ArrayList<AbstractDependencyManager> path,
93 int depth,
94 int deriveUntil,
95 int applyFrom,
96 MMap<Key, String> managedVersions,
97 MMap<Key, String> managedScopes,
98 MMap<Key, Boolean> managedOptionals,
99 MMap<Key, String> managedLocalPaths,
100 MMap<Key, Holder<Collection<Exclusion>>> managedExclusions,
101 SystemDependencyScope systemDependencyScope) {
102 super(
103 path,
104 depth,
105 deriveUntil,
106 applyFrom,
107 managedVersions,
108 managedScopes,
109 managedOptionals,
110 managedLocalPaths,
111 managedExclusions,
112 systemDependencyScope);
113 }
114
115 /**
116 * Derives a child manager with Maven 2.x compatibility behavior.
117 * <p>
118 * <strong>Critical Maven 2.x Compatibility:</strong> This method implements a special
119 * "hop" at depth=1 that skips dependency management collection at that level. This
120 * behavior is essential for Maven 2.x compatibility and is verified by integration tests.
121 * </p>
122 * <p>
123 * <strong>Why the depth=1 skip is necessary:</strong> Maven 2.x did not collect dependency
124 * management from first-level dependencies, only from the root. Removing this skip would
125 * break backward compatibility with Maven 2.x projects.
126 * </p>
127 *
128 * @param context the dependency collection context
129 * @return a new child manager or the current instance with passed-through management
130 * @see <a href="https://github.com/apache/maven-integration-testing/blob/master/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng4720DependencyManagementExclusionMergeTest.java">MNG-4720 Integration Test</a>
131 */
132 @Override
133 public DependencyManager deriveChildManager(DependencyCollectionContext context) {
134 // MNG-4720: Maven2 backward compatibility
135 // Removing this IF makes one IT fail here (read comment above):
136 // https://github.com/apache/maven-integration-testing/blob/b4e8fd52b99a058336f9c7c5ec44fdbc1427759c/core-it-suite/src/test/java/org/apache/maven/it/MavenITmng4720DependencyManagementExclusionMergeTest.java#L67
137 // Skipping level=1 (maven2 compatibility); see MavenITmng4720DependencyManagementExclusionMergeTest
138 if (depth == 1) {
139 return newInstance(managedVersions, managedScopes, managedOptionals, managedLocalPaths, managedExclusions);
140 }
141 return super.deriveChildManager(context);
142 }
143
144 @Override
145 protected DependencyManager newInstance(
146 MMap<Key, String> managedVersions,
147 MMap<Key, String> managedScopes,
148 MMap<Key, Boolean> managedOptionals,
149 MMap<Key, String> managedLocalPaths,
150 MMap<Key, Holder<Collection<Exclusion>>> managedExclusions) {
151 ArrayList<AbstractDependencyManager> path = new ArrayList<>(this.path);
152 path.add(this);
153 return new ClassicDependencyManager(
154 path,
155 depth + 1,
156 deriveUntil,
157 applyFrom,
158 managedVersions,
159 managedScopes,
160 managedOptionals,
161 managedLocalPaths,
162 managedExclusions,
163 systemDependencyScope);
164 }
165 }