001package org.eclipse.aether.util.graph.visitor;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 * 
012 *  http://www.apache.org/licenses/LICENSE-2.0
013 * 
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022import java.util.ArrayList;
023import java.util.Arrays;
024import java.util.List;
025
026import org.eclipse.aether.graph.DependencyFilter;
027import org.eclipse.aether.graph.DependencyNode;
028import org.eclipse.aether.graph.DependencyVisitor;
029
030/**
031 * A dependency visitor that records all paths leading to nodes matching a certain filter criteria.
032 */
033public final class PathRecordingDependencyVisitor
034    implements DependencyVisitor
035{
036
037    private final DependencyFilter filter;
038
039    private final List<List<DependencyNode>> paths;
040
041    private final Stack<DependencyNode> parents;
042
043    private final boolean excludeChildrenOfMatches;
044
045    /**
046     * Creates a new visitor that uses the specified filter to identify terminal nodes of interesting paths. The visitor
047     * will not search for paths going beyond an already matched node.
048     * 
049     * @param filter The filter used to select terminal nodes of paths to record, may be {@code null} to match any node.
050     */
051    public PathRecordingDependencyVisitor( DependencyFilter filter )
052    {
053        this( filter, true );
054    }
055
056    /**
057     * Creates a new visitor that uses the specified filter to identify terminal nodes of interesting paths.
058     * 
059     * @param filter The filter used to select terminal nodes of paths to record, may be {@code null} to match any node.
060     * @param excludeChildrenOfMatches Flag controlling whether children of matched nodes should be excluded from the
061     *            traversal, thereby ignoring any potential paths to other matching nodes beneath a matching ancestor
062     *            node. If {@code true}, all recorded paths will have only one matching node (namely the terminal node),
063     *            if {@code false} a recorded path can consist of multiple matching nodes.
064     */
065    public PathRecordingDependencyVisitor( DependencyFilter filter, boolean excludeChildrenOfMatches )
066    {
067        this.filter = filter;
068        this.excludeChildrenOfMatches = excludeChildrenOfMatches;
069        paths = new ArrayList<>();
070        parents = new Stack<>();
071    }
072
073    /**
074     * Gets the filter being used to select terminal nodes.
075     * 
076     * @return The filter being used or {@code null} if none.
077     */
078    public DependencyFilter getFilter()
079    {
080        return filter;
081    }
082
083    /**
084     * Gets the paths leading to nodes matching the filter that have been recorded during the graph visit. A path is
085     * given as a sequence of nodes, starting with the root node of the graph and ending with a node that matched the
086     * filter.
087     * 
088     * @return The recorded paths, never {@code null}.
089     */
090    public List<List<DependencyNode>> getPaths()
091    {
092        return paths;
093    }
094
095    public boolean visitEnter( DependencyNode node )
096    {
097        boolean accept = filter == null || filter.accept( node, parents );
098
099        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}