| /* |
| * 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.util; |
| |
| import org.apache.tinkerpop.gremlin.process.computer.GraphComputer; |
| import org.apache.tinkerpop.gremlin.process.computer.traversal.TraversalVertexProgram; |
| import org.apache.tinkerpop.gremlin.process.traversal.Step; |
| import org.apache.tinkerpop.gremlin.process.traversal.Traversal; |
| import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent; |
| |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| /** |
| * A TraversalMatrix provides random, non-linear access to the steps of a traversal by their step id. |
| * This is useful in situations where traversers becomes detached from their traversal (and step) and later need to be re-attached. |
| * A classic use case is {@link TraversalVertexProgram} on {@link GraphComputer}. |
| * |
| * @author Marko A. Rodriguez (http://markorodriguez.com) |
| */ |
| public final class TraversalMatrix<S, E> { |
| |
| private final Map<String, Step<?, ?>> matrix = new HashMap<>(); |
| private final Traversal.Admin<S, E> traversal; |
| |
| public TraversalMatrix(final Traversal.Admin<S, E> traversal) { |
| this.harvestSteps(this.traversal = traversal); |
| } |
| |
| public <A, B, C extends Step<A, B>> C getStepById(final String stepId) { |
| return (C) this.matrix.get(stepId); |
| } |
| |
| public Traversal.Admin<S, E> getTraversal() { |
| return this.traversal; |
| } |
| |
| private final void harvestSteps(final Traversal.Admin<?, ?> traversal) { |
| for (final Step<?, ?> step : traversal.getSteps()) { |
| this.matrix.put(step.getId(), step); |
| if (step instanceof TraversalParent) { |
| for (final Traversal.Admin<?, ?> globalChild : ((TraversalParent) step).getGlobalChildren()) { |
| this.harvestSteps(globalChild); |
| } |
| for (final Traversal.Admin<?, ?> localChild : ((TraversalParent) step).getLocalChildren()) { |
| this.harvestSteps(localChild); |
| } |
| } |
| } |
| } |
| } |