1 package org.eclipse.aether.util.graph.visitor;
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 java.util.ArrayList;
23 import java.util.Arrays;
24 import java.util.List;
25
26 import org.eclipse.aether.graph.DependencyFilter;
27 import org.eclipse.aether.graph.DependencyNode;
28 import org.eclipse.aether.graph.DependencyVisitor;
29
30 /**
31 * A dependency visitor that records all paths leading to nodes matching a certain filter criteria.
32 */
33 public final class PathRecordingDependencyVisitor
34 implements DependencyVisitor
35 {
36
37 private final DependencyFilter filter;
38
39 private final List<List<DependencyNode>> paths;
40
41 private final Stack<DependencyNode> parents;
42
43 private final boolean excludeChildrenOfMatches;
44
45 /**
46 * Creates a new visitor that uses the specified filter to identify terminal nodes of interesting paths. The visitor
47 * will not search for paths going beyond an already matched node.
48 *
49 * @param filter The filter used to select terminal nodes of paths to record, may be {@code null} to match any node.
50 */
51 public PathRecordingDependencyVisitor( DependencyFilter filter )
52 {
53 this( filter, true );
54 }
55
56 /**
57 * Creates a new visitor that uses the specified filter to identify terminal nodes of interesting paths.
58 *
59 * @param filter The filter used to select terminal nodes of paths to record, may be {@code null} to match any node.
60 * @param excludeChildrenOfMatches Flag controlling whether children of matched nodes should be excluded from the
61 * traversal, thereby ignoring any potential paths to other matching nodes beneath a matching ancestor
62 * node. If {@code true}, all recorded paths will have only one matching node (namely the terminal node),
63 * if {@code false} a recorded path can consist of multiple matching nodes.
64 */
65 public PathRecordingDependencyVisitor( DependencyFilter filter, boolean excludeChildrenOfMatches )
66 {
67 this.filter = filter;
68 this.excludeChildrenOfMatches = excludeChildrenOfMatches;
69 paths = new ArrayList<>();
70 parents = new Stack<>();
71 }
72
73 /**
74 * Gets the filter being used to select terminal nodes.
75 *
76 * @return The filter being used or {@code null} if none.
77 */
78 public DependencyFilter getFilter()
79 {
80 return filter;
81 }
82
83 /**
84 * Gets the paths leading to nodes matching the filter that have been recorded during the graph visit. A path is
85 * given as a sequence of nodes, starting with the root node of the graph and ending with a node that matched the
86 * filter.
87 *
88 * @return The recorded paths, never {@code null}.
89 */
90 public List<List<DependencyNode>> getPaths()
91 {
92 return paths;
93 }
94
95 public boolean visitEnter( DependencyNode node )
96 {
97 boolean accept = filter == null || filter.accept( node, parents );
98
99 boolean hasDuplicateNodeInParent = parents.contains( node );
100 parents.push( node );
101
102 if ( accept )
103 {
104 DependencyNode[] path = new DependencyNode[parents.size()];
105 for ( int i = 0, n = parents.size(); i < n; i++ )
106 {
107 path[n - i - 1] = parents.get( i );
108 }
109 paths.add( Arrays.asList( path ) );
110
111 if ( excludeChildrenOfMatches )
112 {
113 return false;
114 }
115 }
116
117 return !hasDuplicateNodeInParent;
118 }
119
120 public boolean visitLeave( DependencyNode node )
121 {
122 parents.pop();
123
124 return true;
125 }
126
127 }