| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package org.apache.pig.pen.util; |
| |
| import java.util.Collection; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.pig.newplan.DepthFirstWalker; |
| import org.apache.pig.newplan.Operator; |
| import org.apache.pig.newplan.OperatorPlan; |
| import org.apache.pig.newplan.PlanVisitor; |
| import org.apache.pig.newplan.PlanWalker; |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| import org.apache.pig.impl.util.Utils; |
| |
| public class PreOrderDepthFirstWalker extends PlanWalker { |
| |
| private boolean branchFlag = false; |
| |
| /** |
| * @param plan |
| * Plan for this walker to traverse. |
| */ |
| public PreOrderDepthFirstWalker(OperatorPlan plan) { |
| super(plan); |
| } |
| |
| public void setBranchFlag() { |
| branchFlag = true; |
| } |
| |
| public boolean getBranchFlag() { |
| return branchFlag; |
| } |
| |
| /** |
| * Begin traversing the graph. |
| * |
| * @param visitor |
| * Visitor this walker is being used by. |
| * @throws VisitorException |
| * if an error is encountered while walking. |
| */ |
| public void walk(PlanVisitor visitor) throws FrontendException { |
| List<Operator> leaves = plan.getSinks(); |
| Set<Operator> seen = new HashSet<Operator>(); |
| |
| depthFirst(null, leaves, seen, visitor); |
| } |
| |
| public PlanWalker spawnChildWalker(OperatorPlan plan) { |
| return new DepthFirstWalker(plan); |
| } |
| |
| private void depthFirst(Operator node, Collection<Operator> predecessors, Set<Operator> seen, |
| PlanVisitor visitor) throws FrontendException { |
| if (predecessors == null) |
| return; |
| |
| boolean thisBranchFlag = branchFlag; |
| for (Operator pred : predecessors) { |
| if (seen.add(pred)) { |
| branchFlag = thisBranchFlag; |
| pred.accept(visitor); |
| Collection<Operator> newPredecessors = Utils.mergeCollection(plan.getPredecessors(pred), plan.getSoftLinkPredecessors(pred)); |
| depthFirst(pred, newPredecessors, seen, visitor); |
| } |
| } |
| } |
| } |