| /* |
| * 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.drill.exec.planner.physical.visitor; |
| |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.drill.exec.planner.physical.Prel; |
| import org.apache.calcite.rel.RelNode; |
| |
| import com.google.common.collect.Lists; |
| import com.google.common.collect.Sets; |
| |
| public class RelUniqifier extends BasePrelVisitor<Prel, Set<Prel>, RuntimeException>{ |
| static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(RelUniqifier.class); |
| |
| private static final RelUniqifier INSTANCE = new RelUniqifier(); |
| |
| public static Prel uniqifyGraph(Prel p) { |
| Set<Prel> data = Sets.newIdentityHashSet(); |
| return p.accept(INSTANCE, data); |
| } |
| |
| @Override |
| public Prel visitPrel(Prel prel, Set<Prel> data) throws RuntimeException { |
| List<RelNode> children = Lists.newArrayList(); |
| boolean childrenChanged = false; |
| for (Prel child : prel) { |
| Prel newChild = visitPrel(child, data); |
| if (newChild != child) { |
| childrenChanged = true; |
| } |
| children.add(newChild); |
| } |
| |
| if (data.contains(prel) || childrenChanged) { |
| return (Prel) prel.copy(prel.getTraitSet(), children); |
| } else { |
| return prel; |
| } |
| } |
| |
| } |