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.IdentityHashMap;
25 import java.util.List;
26 import java.util.Map;
27
28 import org.eclipse.aether.graph.DependencyFilter;
29 import org.eclipse.aether.graph.DependencyNode;
30 import org.eclipse.aether.graph.DependencyVisitor;
31
32 /**
33 * A dependency visitor that records all paths leading to nodes matching a certain filter criteria.
34 */
35 public final class PathRecordingDependencyVisitor
36 implements DependencyVisitor
37 {
38
39 private final DependencyFilter filter;
40
41 private final List<List<DependencyNode>> paths;
42
43 private final Stack<DependencyNode> parents;
44
45 private final Map<DependencyNode, Object> visited;
46
47 private final boolean excludeChildrenOfMatches;
48
49 /**
50 * Creates a new visitor that uses the specified filter to identify terminal nodes of interesting paths. The visitor
51 * will not search for paths going beyond an already matched node.
52 *
53 * @param filter The filter used to select terminal nodes of paths to record, may be {@code null} to match any node.
54 */
55 public PathRecordingDependencyVisitor( DependencyFilter filter )
56 {
57 this( filter, true );
58 }
59
60 /**
61 * Creates a new visitor that uses the specified filter to identify terminal nodes of interesting paths.
62 *
63 * @param filter The filter used to select terminal nodes of paths to record, may be {@code null} to match any node.
64 * @param excludeChildrenOfMatches Flag controlling whether children of matched nodes should be excluded from the
65 * traversal, thereby ignoring any potential paths to other matching nodes beneath a matching ancestor
66 * node. If {@code true}, all recorded paths will have only one matching node (namely the terminal node),
67 * if {@code false} a recorded path can consist of multiple matching nodes.
68 */
69 public PathRecordingDependencyVisitor( DependencyFilter filter, boolean excludeChildrenOfMatches )
70 {
71 this.filter = filter;
72 this.excludeChildrenOfMatches = excludeChildrenOfMatches;
73 paths = new ArrayList<List<DependencyNode>>();
74 parents = new Stack<DependencyNode>();
75 visited = new IdentityHashMap<DependencyNode, Object>( 128 );
76 }
77
78 /**
79 * Gets the filter being used to select terminal nodes.
80 *
81 * @return The filter being used or {@code null} if none.
82 */
83 public DependencyFilter getFilter()
84 {
85 return filter;
86 }
87
88 /**
89 * Gets the paths leading to nodes matching the filter that have been recorded during the graph visit. A path is
90 * given as a sequence of nodes, starting with the root node of the graph and ending with a node that matched the
91 * filter.
92 *
93 * @return The recorded paths, never {@code null}.
94 */
95 public List<List<DependencyNode>> getPaths()
96 {
97 return paths;
98 }
99
100 public boolean visitEnter( DependencyNode node )
101 {
102 boolean accept = filter == null || filter.accept( node, parents );
103
104 parents.push( node );
105
106 if ( accept )
107 {
108 DependencyNode[] path = new DependencyNode[parents.size()];
109 for ( int i = 0, n = parents.size(); i < n; i++ )
110 {
111 path[n - i - 1] = parents.get( i );
112 }
113 paths.add( Arrays.asList( path ) );
114
115 if ( excludeChildrenOfMatches )
116 {
117 return false;
118 }
119 }
120
121 if ( visited.put( node, Boolean.TRUE ) != null )
122 {
123 return false;
124 }
125
126 return true;
127 }
128
129 public boolean visitLeave( DependencyNode node )
130 {
131 parents.pop();
132 visited.remove( node );
133
134 return true;
135 }
136
137 }