com.tinkerpop.gremlin.tinkergraph.process.graph.strategy.TinkerGraphStepStrategy Maven / Gradle / Ivy

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package com.tinkerpop.gremlin.tinkergraph.process.graph.strategy;

import com.tinkerpop.gremlin.process.Step;
import com.tinkerpop.gremlin.process.Traversal;
import com.tinkerpop.gremlin.process.TraversalStrategy;
import com.tinkerpop.gremlin.process.graph.step.filter.HasStep;
import com.tinkerpop.gremlin.process.graph.step.filter.IntervalStep;
import com.tinkerpop.gremlin.process.graph.step.sideEffect.IdentityStep;
import com.tinkerpop.gremlin.process.util.EmptyStep;
import com.tinkerpop.gremlin.process.util.TraversalHelper;
import com.tinkerpop.gremlin.tinkergraph.process.graph.step.sideEffect.TinkerGraphStep;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
public class TinkerGraphStepStrategy implements TraversalStrategy.NoDependencies {

    private static final TinkerGraphStepStrategy INSTANCE = new TinkerGraphStepStrategy();

    private TinkerGraphStepStrategy() {
    }

    @Override
    public void apply(final Traversal traversal) {

        if (TraversalHelper.getStart(traversal) instanceof TinkerGraphStep) {
            final TinkerGraphStep tinkerGraphStep = (TinkerGraphStep) traversal.getSteps().get(0);
            Step currentStep = tinkerGraphStep.getNextStep();
            while (true) {
                if (currentStep == EmptyStep.instance() || TraversalHelper.isLabeled(currentStep)) break;

                if (currentStep instanceof HasStep) {
                    tinkerGraphStep.hasContainers.addAll(((HasStep) currentStep).getHasContainers());
                    TraversalHelper.removeStep(currentStep, traversal);
                } else if (currentStep instanceof IntervalStep) {
                    tinkerGraphStep.hasContainers.addAll(((IntervalStep) currentStep).getHasContainers());
                    TraversalHelper.removeStep(currentStep, traversal);
                } else if (currentStep instanceof IdentityStep) {
                    // do nothing
                } else {
                    break;
                }
                currentStep = currentStep.getNextStep();
            }
        }
    }

    public static TinkerGraphStepStrategy instance() {
        return INSTANCE;
    }
}