Github user okram commented on a diff in the pull request: https://github.com/apache/tinkerpop/pull/729#discussion_r142803300 --- Diff: gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/MathStep.java --- @@ -0,0 +1,171 @@ +/* + * 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.step.map; + +import net.objecthunter.exp4j.Expression; +import net.objecthunter.exp4j.ExpressionBuilder; +import org.apache.tinkerpop.gremlin.process.traversal.Pop; +import org.apache.tinkerpop.gremlin.process.traversal.Traversal; +import org.apache.tinkerpop.gremlin.process.traversal.Traverser; +import org.apache.tinkerpop.gremlin.process.traversal.step.ByModulating; +import org.apache.tinkerpop.gremlin.process.traversal.step.PathProcessor; +import org.apache.tinkerpop.gremlin.process.traversal.step.Scoping; +import org.apache.tinkerpop.gremlin.process.traversal.step.TraversalParent; +import org.apache.tinkerpop.gremlin.process.traversal.traverser.TraverserRequirement; +import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalRing; +import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalUtil; +import org.apache.tinkerpop.gremlin.structure.util.StringFactory; + +import java.util.HashSet; +import java.util.LinkedHashSet; +import java.util.List; +import java.util.Set; +import java.util.regex.Matcher; +import java.util.regex.Pattern; + +/** + * @author Marko A. Rodriguez (http://markorodriguez.com) + */ +public final class MathStep<S> extends MapStep<S, Double> implements ByModulating, TraversalParent, Scoping, PathProcessor { + + private static final String CURRENT = "_"; + private final String equation; + private final Set<String> variables; + private TraversalRing<Object, Number> traversalRing = new TraversalRing<>(); + private Set<String> keepLabels; + + public MathStep(final Traversal.Admin traversal, final String equation) { + super(traversal); + this.equation = equation; + this.variables = MathStep.getVariables(this.equation); + + } + + @Override + protected Traverser.Admin<Double> processNextStart() { + return PathProcessor.processTraverserPathLabels(super.processNextStart(), this.keepLabels); + } + + @Override + protected Double map(final Traverser.Admin<S> traverser) { + final Expression expression = new ExpressionBuilder(this.equation) --- End diff -- Not with threading. Thus, OLAP and any other execution engine that uses threads will get inconsistent results.
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