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