001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.maven.enforcer.rules.utils;
020
021import java.util.HashMap;
022import java.util.Map;
023import java.util.Stack;
024
025import org.eclipse.aether.graph.DependencyNode;
026import org.eclipse.aether.graph.DependencyVisitor;
027
028/**
029 * A {@link DependencyVisitor} building a map of parent nodes
030 */
031public class ParentsVisitor implements DependencyVisitor, ParentNodeProvider {
032
033    private final Map<DependencyNode, DependencyNode> parents = new HashMap<>();
034    private final Stack<DependencyNode> parentStack = new Stack<>();
035
036    @Override
037    public DependencyNode getParent(DependencyNode node) {
038        return parents.get(node);
039    }
040
041    @Override
042    public boolean visitEnter(DependencyNode node) {
043        parents.put(node, parentStack.isEmpty() ? null : parentStack.peek());
044        parentStack.push(node);
045        return true;
046    }
047
048    @Override
049    public boolean visitLeave(DependencyNode node) {
050        parentStack.pop();
051        return true;
052    }
053}