| /* |
| * 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.sparql.process.traversal.strategy; |
| |
| import org.apache.tinkerpop.gremlin.process.remote.traversal.strategy.decoration.RemoteStrategy; |
| 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.GraphTraversalSource; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.sideEffect.InjectStep; |
| 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.sparql.SparqlToGremlinCompiler; |
| import org.apache.tinkerpop.gremlin.sparql.process.traversal.dsl.sparql.SparqlTraversalSource; |
| import org.apache.tinkerpop.gremlin.structure.Graph; |
| import org.apache.tinkerpop.gremlin.structure.Vertex; |
| |
| import java.util.Collections; |
| import java.util.Set; |
| |
| /** |
| * This {@link TraversalStrategy} is used in conjunction with the {@link SparqlTraversalSource} which has a single |
| * {@code sparql()} start step. That step adds a {@link InjectStep} to the traversal with the SPARQL query within |
| * it as a string value. This strategy finds that step and compiles it to a Gremlin traversal which then replaces |
| * the {@link InjectStep}. |
| * |
| * For remote bytecode execution, note that the {@code sparql-gremlin} dependencies need to be on the server. The |
| * way remoting works - see {@code RemoteStep} - prevents modified bytecode from being submitted to the server, so |
| * technically, this strategy can't be applied first on the client. |
| * |
| * @author Stephen Mallette (http://stephen.genoprime.com) |
| */ |
| public class SparqlStrategy extends AbstractTraversalStrategy<TraversalStrategy.DecorationStrategy> |
| implements TraversalStrategy.DecorationStrategy { |
| private static final SparqlStrategy INSTANCE = new SparqlStrategy(); |
| |
| private static final Set<Class<? extends DecorationStrategy>> PRIORS = Collections.singleton(RemoteStrategy.class); |
| |
| private SparqlStrategy() {} |
| |
| public static SparqlStrategy instance() { |
| return INSTANCE; |
| } |
| |
| @Override |
| public Set<Class<? extends DecorationStrategy>> applyPrior() { |
| return PRIORS; |
| } |
| |
| @Override |
| public void apply(final Traversal.Admin<?, ?> traversal) { |
| if (!(traversal.getParent() instanceof EmptyStep)) |
| return; |
| |
| // assumes that the traversal starts with the single inject step that holds the sparql query |
| if (traversal.getStartStep() instanceof InjectStep) { |
| final InjectStep stepWithSparql = (InjectStep) traversal.getStartStep(); |
| final Object[] injections = stepWithSparql.getInjections(); |
| |
| // further assumes that there is just one argument to that injection which is a string (i.e. sparql query) |
| if (injections.length == 1 && injections[0] instanceof String) { |
| final String sparql = (String) injections[0]; |
| |
| // try to grab the TraversalSource from the Traversal, but if it's not there then try to the Graph |
| // instance and spawn one off from there. |
| final Traversal<Vertex, ?> sparqlTraversal = SparqlToGremlinCompiler.compile( |
| (GraphTraversalSource) traversal.getTraversalSource().orElseGet(() -> traversal.getGraph().map(Graph::traversal).get()), sparql); |
| TraversalHelper.insertTraversal(stepWithSparql, sparqlTraversal.asAdmin(), traversal); |
| traversal.removeStep(stepWithSparql); |
| } |
| } |
| } |
| } |