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 static java.util.Objects.requireNonNull; 023 024import org.eclipse.aether.graph.DependencyFilter; 025import org.eclipse.aether.graph.DependencyNode; 026import org.eclipse.aether.graph.DependencyVisitor; 027 028/** 029 * A dependency visitor that delegates to another visitor if nodes match a filter. Note that in case of a mismatching 030 * node, the children of that node are still visisted and presented to the filter. 031 */ 032public final class FilteringDependencyVisitor 033 implements DependencyVisitor 034{ 035 036 private final DependencyFilter filter; 037 038 private final DependencyVisitor visitor; 039 040 private final Stack<Boolean> accepts; 041 042 private final Stack<DependencyNode> parents; 043 044 /** 045 * Creates a new visitor that delegates traversal of nodes matching the given filter to the specified visitor. 046 * 047 * @param visitor The visitor to delegate to, must not be {@code null}. 048 * @param filter The filter to apply, may be {@code null} to not filter. 049 */ 050 public FilteringDependencyVisitor( DependencyVisitor visitor, DependencyFilter filter ) 051 { 052 this.visitor = requireNonNull( visitor, "dependency visitor delegate cannot be null" ); 053 this.filter = filter; 054 this.accepts = new Stack<Boolean>(); 055 this.parents = new Stack<DependencyNode>(); 056 } 057 058 /** 059 * Gets the visitor to which this visitor delegates to. 060 * 061 * @return The visitor being delegated to, never {@code null}. 062 */ 063 public DependencyVisitor getVisitor() 064 { 065 return visitor; 066 } 067 068 /** 069 * Gets the filter being applied before delegation. 070 * 071 * @return The filter being applied or {@code null} if none. 072 */ 073 public DependencyFilter getFilter() 074 { 075 return filter; 076 } 077 078 public boolean visitEnter( DependencyNode node ) 079 { 080 boolean accept = filter == null || filter.accept( node, parents ); 081 082 accepts.push( accept ); 083 084 parents.push( node ); 085 086 if ( accept ) 087 { 088 return visitor.visitEnter( node ); 089 } 090 else 091 { 092 return true; 093 } 094 } 095 096 public boolean visitLeave( DependencyNode node ) 097 { 098 parents.pop(); 099 100 Boolean accept = accepts.pop(); 101 102 if ( accept ) 103 { 104 return visitor.visitLeave( node ); 105 } 106 else 107 { 108 return true; 109 } 110 } 111 112}