| /* |
| * 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.finalization; |
| |
| import org.apache.tinkerpop.gremlin.process.traversal.Traversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.TraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.Traverser; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.map.ScalarMapStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.ProfileSideEffectStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.util.EmptyStep; |
| import org.apache.tinkerpop.gremlin.process.traversal.strategy.AbstractTraversalStrategy; |
| import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper; |
| import org.apache.tinkerpop.gremlin.structure.util.reference.ReferenceFactory; |
| |
| import java.util.Optional; |
| |
| /** |
| * A strategy that detaches traversers with graph elements as references (i.e. without properties - just {@code id} |
| * and {@code label}. |
| * |
| * @author Stephen Mallette (http://stephen.genoprime.com) |
| */ |
| public final class ReferenceElementStrategy extends AbstractTraversalStrategy<TraversalStrategy.FinalizationStrategy> implements TraversalStrategy.FinalizationStrategy { |
| |
| private static final ReferenceElementStrategy INSTANCE = new ReferenceElementStrategy(); |
| |
| private ReferenceElementStrategy() {} |
| |
| @Override |
| public void apply(final Traversal.Admin<?, ?> traversal) { |
| if (traversal.getParent() == EmptyStep.instance()) { |
| final Optional<ProfileSideEffectStep> profileStep = TraversalHelper.getFirstStepOfAssignableClass(ProfileSideEffectStep.class, traversal); |
| final int index = profileStep.map(step -> traversal.getSteps().indexOf(step)) |
| .orElseGet(() -> traversal.getSteps().size()); |
| traversal.addStep(index, new ReferenceElementStep<>(traversal)); |
| } |
| } |
| |
| public static ReferenceElementStrategy instance() { |
| return INSTANCE; |
| } |
| |
| public static class ReferenceElementStep<S, E> extends ScalarMapStep<S, E> { |
| |
| public ReferenceElementStep(final Traversal.Admin traversal) { |
| super(traversal); |
| } |
| |
| @Override |
| protected E map(final Traverser.Admin<S> traverser) { |
| return ReferenceFactory.detach(traverser.get()); |
| } |
| } |
| } |