| /* |
| * 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.tinkerpop.gremlin.process.traversal.strategy.optimization; |
| |
| import org.apache.tinkerpop.gremlin.process.traversal.Step; |
| import org.apache.tinkerpop.gremlin.process.traversal.Traversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.DefaultGraphTraversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.filter.DedupGlobalStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.filter.WherePredicateStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.filter.WhereTraversalStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.MatchStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.SelectOneStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.SelectStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper; |
| |
| import java.util.Arrays; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.Set; |
| |
| /** |
| * {@code MatchWhereStrategy} will fold any post-{@code where()} step that maintains a traversal constraint into |
| * {@code match()}. {@link MatchStep} is intelligent with traversal constraint applications and thus, can more |
| * efficiently use the constraint of {@link WhereTraversalStep} or {@link WherePredicateStep}. |
| * |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| * @example <pre> |
| * __.match(a,b).where(c) // is replaced by __.match(a,b,c) |
| * __.match(a,b).select().where(c) // is replaced by __.match(a,b,c).select() |
| * </pre> |
| */ |
| public final class MatchPredicateStrategy extends AbstractTraversalStrategy<TraversalStrategy.OptimizationStrategy> implements TraversalStrategy.OptimizationStrategy { |
| |
| private static final MatchPredicateStrategy INSTANCE = new MatchPredicateStrategy(); |
| private static final Set<Class<? extends OptimizationStrategy>> PRIORS = Collections.singleton(IdentityRemovalStrategy.class); |
| private static final Set<Class<? extends OptimizationStrategy>> POSTS = Collections.singleton(FilterRankingStrategy.class); |
| |
| private MatchPredicateStrategy() { |
| } |
| |
| @Override |
| public void apply(final Traversal.Admin<?, ?> traversal) { |
| if (!TraversalHelper.hasStepOfClass(MatchStep.class, traversal)) |
| return; |
| |
| TraversalHelper.getStepsOfClass(MatchStep.class, traversal).forEach(matchStep -> { |
| // match().select().where() --> match(where()).select() |
| // match().select().dedup() --> match(dedup()).select() |
| Step<?, ?> nextStep = matchStep.getNextStep(); |
| while (nextStep instanceof WherePredicateStep || |
| nextStep instanceof WhereTraversalStep || |
| (nextStep instanceof DedupGlobalStep && !((DedupGlobalStep) nextStep).getScopeKeys().isEmpty() && ((DedupGlobalStep) nextStep).getLocalChildren().isEmpty()) || |
| (nextStep instanceof SelectStep && ((SelectStep) nextStep).getLocalChildren().isEmpty()) || |
| (nextStep instanceof SelectOneStep && ((SelectOneStep) nextStep).getLocalChildren().isEmpty())) { |
| if (nextStep instanceof WherePredicateStep || nextStep instanceof WhereTraversalStep) { |
| traversal.removeStep(nextStep); |
| matchStep.addGlobalChild(traversal instanceof GraphTraversal ? |
| new DefaultGraphTraversal<>().addStep(nextStep) : |
| new DefaultTraversal<>().addStep(nextStep)); |
| nextStep = matchStep.getNextStep(); |
| } else if (nextStep instanceof DedupGlobalStep && !((DedupGlobalStep) nextStep).getScopeKeys().isEmpty() && ((DedupGlobalStep) nextStep).getLocalChildren().isEmpty() && !TraversalHelper.onGraphComputer(traversal)) { |
| traversal.removeStep(nextStep); |
| matchStep.setDedupLabels(((DedupGlobalStep<?>) nextStep).getScopeKeys()); |
| nextStep = matchStep.getNextStep(); |
| } else if (nextStep.getLabels().isEmpty()) { |
| nextStep = nextStep.getNextStep(); |
| } else |
| break; |
| } |
| }); |
| } |
| |
| public static MatchPredicateStrategy instance() { |
| return INSTANCE; |
| } |
| |
| @Override |
| public Set<Class<? extends OptimizationStrategy>> applyPrior() { |
| return PRIORS; |
| } |
| |
| @Override |
| public Set<Class<? extends OptimizationStrategy>> applyPost() { |
| return POSTS; |
| } |
| } |