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.eclipse.aether.util.graph.visitor; 020 021import org.eclipse.aether.graph.DependencyFilter; 022import org.eclipse.aether.graph.DependencyNode; 023import org.eclipse.aether.graph.DependencyVisitor; 024 025import static java.util.Objects.requireNonNull; 026 027/** 028 * A dependency visitor that delegates to another visitor if nodes match a filter. Note that in case of a mismatching 029 * node, the children of that node are still visited and presented to the filter. 030 */ 031public final class FilteringDependencyVisitor implements DependencyVisitor { 032 033 private final DependencyFilter filter; 034 035 private final DependencyVisitor visitor; 036 037 private final Stack<Boolean> accepts; 038 039 private final Stack<DependencyNode> parents; 040 041 /** 042 * Creates a new visitor that delegates traversal of nodes matching the given filter to the specified visitor. 043 * 044 * @param visitor The visitor to delegate to, must not be {@code null}. 045 * @param filter The filter to apply, may be {@code null} to not filter. 046 */ 047 public FilteringDependencyVisitor(DependencyVisitor visitor, DependencyFilter filter) { 048 this.visitor = requireNonNull(visitor, "dependency visitor delegate cannot be null"); 049 this.filter = filter; 050 this.accepts = new Stack<>(); 051 this.parents = new Stack<>(); 052 } 053 054 /** 055 * Gets the visitor to which this visitor delegates to. 056 * 057 * @return The visitor being delegated to, never {@code null}. 058 */ 059 public DependencyVisitor getVisitor() { 060 return visitor; 061 } 062 063 /** 064 * Gets the filter being applied before delegation. 065 * 066 * @return The filter being applied or {@code null} if none. 067 */ 068 public DependencyFilter getFilter() { 069 return filter; 070 } 071 072 @Override 073 public boolean visitEnter(DependencyNode node) { 074 boolean accept = filter == null || filter.accept(node, parents); 075 076 accepts.push(accept); 077 078 parents.push(node); 079 080 if (accept) { 081 return visitor.visitEnter(node); 082 } else { 083 return true; 084 } 085 } 086 087 @Override 088 public boolean visitLeave(DependencyNode node) { 089 parents.pop(); 090 091 Boolean accept = accepts.pop(); 092 093 if (accept) { 094 return visitor.visitLeave(node); 095 } else { 096 return true; 097 } 098 } 099}