[MDEP-927] Make dependency:tree excludes prune subtrees

src/it/projects/tree-excluded/expected-included-survives.txt

@@ -0,0 +1,4 @@
+org.apache.maven.its.dependency:test:jar:1.0-SNAPSHOT
+\- org.apache.maven:maven-project:jar:2.0.6:compile
+   \- org.apache.maven:maven-artifact-manager:jar:2.0.6:compile
+      \- org.apache.maven.wagon:wagon-provider-api:jar:1.0-beta-2:compile

src/it/projects/tree-excluded/expected-v4.txt

@@ -7,7 +7,4 @@ org.apache.maven.its.dependency:test:jar:1.0-SNAPSHOT
    |  +- org.apache.maven:maven-repository-metadata:jar:2.0.6:compile
    |  \- org.apache.maven.wagon:wagon-provider-api:jar:1.0-beta-2:compile
    +- org.apache.maven:maven-plugin-registry:jar:2.0.6:compile
-   +- org.apache.maven:maven-artifact:jar:2.0.6:compile
-   \- org.codehaus.plexus:plexus-container-default:jar:1.0-alpha-9-stable-1:compile
-      +- junit:junit:jar:3.8.1:compile
-      \- classworlds:classworlds:jar:1.1:compile
+   \- org.apache.maven:maven-artifact:jar:2.0.6:compile

src/it/projects/tree-excluded/expected.txt

@@ -7,7 +7,4 @@ org.apache.maven.its.dependency:test:jar:1.0-SNAPSHOT
    |  +- org.apache.maven:maven-repository-metadata:jar:2.0.6:compile
    |  \- org.apache.maven.wagon:wagon-provider-api:jar:1.0-beta-2:compile
    +- org.apache.maven:maven-plugin-registry:jar:2.0.6:compile
-   +- org.apache.maven:maven-artifact:jar:2.0.6:compile
-   \- org.codehaus.plexus:plexus-container-default:jar:1.0-alpha-9-stable-1:compile
-      +- junit:junit:jar:3.8.1:compile
-      \- classworlds:classworlds:jar:1.1-alpha-2:compile
+   \- org.apache.maven:maven-artifact:jar:2.0.6:compile

src/it/projects/tree-excluded/invoker.properties

@@ -15,4 +15,11 @@
 # specific language governing permissions and limitations
 # under the License.
 
-invoker.goals = ${project.groupId}:${project.artifactId}:${project.version}:tree
+invoker.goals.1 = ${project.groupId}:${project.artifactId}:${project.version}:tree
+invoker.userPropertiesFile.1 = test.properties
+
+invoker.goals.2 = ${project.groupId}:${project.artifactId}:${project.version}:tree
+invoker.userPropertiesFile.2 = test-included-excluded.properties
+
+invoker.goals.3 = ${project.groupId}:${project.artifactId}:${project.version}:tree
+invoker.userPropertiesFile.3 = test-included-survives.properties

src/it/projects/tree-excluded/test-included-excluded.properties

@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+outputFile = target/included-excluded.txt
+includes = junit:junit
+excludes = org.codehaus.plexus:*

src/it/projects/tree-excluded/test-included-survives.properties

@@ -0,0 +1,20 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+outputFile = target/included-survives.txt
+includes = :wagon*
+excludes = org.codehaus.plexus:*

src/it/projects/tree-excluded/verify.groovy

@@ -25,4 +25,9 @@ def expected = mavenVersion.startsWith('4.') ? "expected-v4.txt" : "expected.txt
 assertThat(new File(basedir, "target/tree.txt"))
         .hasSameTextualContentAs(new File(basedir, expected))
 
+assertThat(new File(basedir, "target/included-excluded.txt").text).isEmpty()
+
+assertThat(new File(basedir, "target/included-survives.txt"))
+        .hasSameTextualContentAs(new File(basedir, "expected-included-survives.txt"))
+
 return true

src/main/java/org/apache/maven/plugins/dependency/tree/PruningDependencyNodeVisitor.java

@@ -0,0 +1,54 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.plugins.dependency.tree;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+import org.apache.maven.shared.dependency.graph.DependencyNode;
+import org.apache.maven.shared.dependency.graph.filter.DependencyNodeFilter;
+import org.apache.maven.shared.dependency.graph.traversal.DependencyNodeVisitor;
+
+/**
+ * A dependency node visitor that delegates accepted nodes and prunes rejected nodes and their descendants.
+ */
+final class PruningDependencyNodeVisitor implements DependencyNodeVisitor {
+    private final DependencyNodeVisitor visitor;
+
+    private final DependencyNodeFilter filter;
+
+    private final Deque<Boolean> acceptedNodes = new ArrayDeque<>();
+
+    PruningDependencyNodeVisitor(DependencyNodeVisitor visitor, DependencyNodeFilter filter) {
+        this.visitor = visitor;
+        this.filter = filter;
+    }
+
+    @Override
+    public boolean visit(DependencyNode node) {
+        boolean accepted = filter.accept(node);
+        acceptedNodes.push(accepted);
+        return accepted && visitor.visit(node);
+    }
+
+    @Override
+    public boolean endVisit(DependencyNode node) {
+        return !acceptedNodes.pop() || visitor.endVisit(node);
+    }
+}

src/main/java/org/apache/maven/plugins/dependency/tree/TreeMojo.java

@@ -24,7 +24,6 @@
 import java.io.IOException;
 import java.io.StringWriter;
 import java.io.Writer;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
 
@@ -49,7 +48,6 @@
 import org.apache.maven.shared.dependency.graph.DependencyGraphBuilderException;
 import org.apache.maven.shared.dependency.graph.DependencyNode;
 import org.apache.maven.shared.dependency.graph.filter.AncestorOrSelfDependencyNodeFilter;
-import org.apache.maven.shared.dependency.graph.filter.AndDependencyNodeFilter;
 import org.apache.maven.shared.dependency.graph.filter.ArtifactDependencyNodeFilter;
 import org.apache.maven.shared.dependency.graph.filter.DependencyNodeFilter;
 import org.apache.maven.shared.dependency.graph.traversal.CollectingDependencyNodeVisitor;
@@ -153,6 +151,8 @@ public class TreeMojo extends AbstractMojo {
      * For example, <code>org.apache.*</code> will match all artifacts whose group id starts with
      * <code>org.apache.</code>, and <code>:::*-SNAPSHOT</code> will match all snapshot artifacts.
      * </p>
+     * Paths leading to included artifacts are retained. If an artifact is also beneath a subtree matched by
+     * {@link #excludes}, the exclusion takes precedence and the artifact is not included.
      *
      * @see StrictPatternIncludesArtifactFilter
      * @since 2.0-alpha-6
@@ -174,6 +174,8 @@ public class TreeMojo extends AbstractMojo {
      * For example, <code>org.apache.*</code> will match all artifacts whose group id starts with
      * <code>org.apache.</code>, and <code>:::*-SNAPSHOT</code> will match all snapshot artifacts.
      * </p>
+     * A matching artifact and its entire dependency subtree are removed from the serialized dependency tree.
+     * Exclusions are applied before {@link #includes} and take precedence.
      *
      * @see StrictPatternExcludesArtifactFilter
      * @since 2.0-alpha-6
@@ -333,18 +335,27 @@ private String serializeDependencyTree(DependencyNode theRootNode) {
         // TODO: remove the need for this when the serializer can calculate last nodes from visitor calls only
         visitor = new BuildingDependencyNodeVisitor(visitor);
 
-        DependencyNodeFilter filter = createDependencyNodeFilter();
+        DependencyNodeFilter includesFilter = createIncludesDependencyNodeFilter();
+        DependencyNodeFilter excludesFilter = createExcludesDependencyNodeFilter();
 
-        if (filter != null) {
+        if (includesFilter != null) {
             CollectingDependencyNodeVisitor collectingVisitor = new CollectingDependencyNodeVisitor();
-            DependencyNodeVisitor firstPassVisitor = new FilteringDependencyNodeVisitor(collectingVisitor, filter);
+            DependencyNodeVisitor firstPassVisitor =
+                    new FilteringDependencyNodeVisitor(collectingVisitor, includesFilter);
+            if (excludesFilter != null) {
+                firstPassVisitor = new PruningDependencyNodeVisitor(firstPassVisitor, excludesFilter);
+            }
             theRootNode.accept(firstPassVisitor);
 
             DependencyNodeFilter secondPassFilter =
                     new AncestorOrSelfDependencyNodeFilter(collectingVisitor.getNodes());
             visitor = new FilteringDependencyNodeVisitor(visitor, secondPassFilter);
         }
 
+        if (excludesFilter != null) {
+            visitor = new PruningDependencyNodeVisitor(visitor, excludesFilter);
+        }
+
         theRootNode.accept(visitor);
 
         return writer.toString();
@@ -397,27 +408,25 @@ private GraphTokens toGraphTokens(String theTokens) {
      *
      * @return the dependency node filter, or <code>null</code> if none required
      */
-    private DependencyNodeFilter createDependencyNodeFilter() {
-        List<DependencyNodeFilter> filters = new ArrayList<>();
-
-        // filter includes
+    private DependencyNodeFilter createIncludesDependencyNodeFilter() {
         if (includes != null && !includes.isEmpty()) {
-
             getLog().debug("+ Filtering dependency tree by artifact include patterns: " + includes);
 
             ArtifactFilter artifactFilter = new StrictPatternIncludesArtifactFilter(includes);
-            filters.add(new ArtifactDependencyNodeFilter(artifactFilter));
+            return new ArtifactDependencyNodeFilter(artifactFilter);
         }
 
-        // filter excludes
-        if (excludes != null && !excludes.isEmpty()) {
+        return null;
+    }
 
+    private DependencyNodeFilter createExcludesDependencyNodeFilter() {
+        if (excludes != null && !excludes.isEmpty()) {
             getLog().debug("+ Filtering dependency tree by artifact exclude patterns: " + excludes);
 
             ArtifactFilter artifactFilter = new StrictPatternExcludesArtifactFilter(excludes);
-            filters.add(new ArtifactDependencyNodeFilter(artifactFilter));
+            return new ArtifactDependencyNodeFilter(artifactFilter);
         }
 
-        return filters.isEmpty() ? null : new AndDependencyNodeFilter(filters);
+        return null;
     }
 }

src/site/apt/examples/filtering-the-dependency-tree.apt

@@ -68,6 +68,9 @@ mvn dependency:tree -Dincludes=velocity:velocity
 mvn dependency:tree -Dexcludes=org.codehaus.plexus
 +---+
 
+  A dependency matching an exclude pattern and its entire dependency subtree are removed from the serialized tree.
+  This affects only the displayed tree; it does not change the project's dependency resolution.
+
 * Specifying multiple patterns
 
   Multiple patterns can be specified when filtering the dependency tree by separating the patterns with commas.  For
@@ -79,9 +82,13 @@ mvn dependency:tree -Dexcludes=org.apache.maven*,org.codehaus.plexus
 
 * Including and excluding dependencies from the tree
 
-  Both include and exclude patterns and be specified together to filter the dependency tree.  For example, to locate
+  Both include and exclude patterns can be specified together to filter the dependency tree.  For example, to locate
   all non-snapshot Plexus dependencies in the tree, we can execute the following:
 
 +---+
 mvn dependency:tree -Dincludes=org.codehaus.plexus -Dexcludes=:::*-SNAPSHOT
 +---+
+
+  Excludes are applied first and take precedence over includes.  Includes then select matching dependencies from the
+  remaining tree and retain the paths leading to those dependencies.  An include therefore cannot restore a dependency
+  beneath an excluded subtree.

src/test/java/org/apache/maven/plugins/dependency/tree/PruningDependencyNodeVisitorTest.java

@@ -0,0 +1,85 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.maven.plugins.dependency.tree;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.apache.maven.artifact.Artifact;
+import org.apache.maven.shared.dependency.graph.DependencyNode;
+import org.apache.maven.shared.dependency.graph.filter.DependencyNodeFilter;
+import org.apache.maven.shared.dependency.graph.internal.DefaultDependencyNode;
+import org.apache.maven.shared.dependency.graph.traversal.CollectingDependencyNodeVisitor;
+import org.apache.maven.shared.dependency.graph.traversal.DependencyNodeVisitor;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
+
+class PruningDependencyNodeVisitorTest {
+    @Test
+    void evaluatesFilterOnlyWhenStartingNodeVisit() {
+        DefaultDependencyNode root = newNode(null);
+        root.setChildren(Collections.emptyList());
+        AtomicInteger filterInvocations = new AtomicInteger();
+        AtomicInteger endVisits = new AtomicInteger();
+        DependencyNodeVisitor visitor = new DependencyNodeVisitor() {
+            @Override
+            public boolean visit(DependencyNode node) {
+                return true;
+            }
+
+            @Override
+            public boolean endVisit(DependencyNode node) {
+                endVisits.incrementAndGet();
+                return true;
+            }
+        };
+
+        root.accept(new PruningDependencyNodeVisitor(visitor, node -> filterInvocations.incrementAndGet() == 1));
+
+        assertEquals(1, filterInvocations.get());
+        assertEquals(1, endVisits.get());
+    }
+
+    @Test
+    void prunesRejectedSubtreeAndContinuesWithSiblings() {
+        DefaultDependencyNode root = newNode(null);
+        DefaultDependencyNode rejected = newNode(root);
+        DefaultDependencyNode rejectedChild = newNode(rejected);
+        DefaultDependencyNode sibling = newNode(root);
+
+        root.setChildren(Arrays.asList(rejected, sibling));
+        rejected.setChildren(Collections.singletonList(rejectedChild));
+        rejectedChild.setChildren(Collections.emptyList());
+        sibling.setChildren(Collections.emptyList());
+
+        CollectingDependencyNodeVisitor collectingVisitor = new CollectingDependencyNodeVisitor();
+        DependencyNodeFilter filter = node -> node != rejected;
+
+        root.accept(new PruningDependencyNodeVisitor(collectingVisitor, filter));
+
+        assertEquals(Arrays.asList(root, sibling), collectingVisitor.getNodes());
+    }
+
+    private DefaultDependencyNode newNode(DependencyNode parent) {
+        return new DefaultDependencyNode(parent, mock(Artifact.class), null, null, null);
+    }
+}