gistfile1.txt

package org.apache.tinkerpop.gremlin.util;

import org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteConnection;
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.dsl.graph.GraphTraversalSource;
import org.apache.tinkerpop.gremlin.process.traversal.step.Configuring;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.FlatMapStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.map.VertexStep;
import org.apache.tinkerpop.gremlin.process.traversal.step.util.Parameters;
import org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper;
import org.apache.tinkerpop.gremlin.structure.Direction;
import org.apache.tinkerpop.gremlin.structure.Element;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph;

import java.util.Iterator;

import static org.apache.tinkerpop.gremlin.process.traversal.AnonymousTraversalSource.traversal;
import static org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.__.V;
import static org.apache.tinkerpop.gremlin.structure.T.id;

public class TinkerMultiGraph {

    public static void main(final String[] args) throws Exception {
        final TinkerGraph graph = TinkerGraph.open();
        final GraphTraversalSource g = graph.traversal();
        g.addV().property("reference", "A101").iterate();
        g.addV().property("reference", "B1001").iterate();

        final GraphTraversalSource gA = traversal().withRemote(DriverRemoteConnection.using("localhost", 8182, "g"));
        gA.V().drop().iterate();
        gA.addV().property(id, "101").iterate();
        gA.addV().property(id,"102").iterate();
        gA.addV().property(id,"103").iterate();
        gA.addE("link").from(V("101")).to(V("102")).iterate();
        gA.addE("link").from(V("101")).to(V("103")).iterate();

        final TinkerGraph graphB = TinkerGraph.open();
        final GraphTraversalSource gB = graphB.traversal();
        gB.addV().property(id, "1001").iterate();
        gB.addV().property(id,"1002").iterate();
        gB.addV().property(id,"1003").iterate();
        gB.addE("link").from(V("1001")).to(V("1002")).iterate();
        gB.addE("link").from(V("1001")).to(V("1003")).iterate();

        g.withStrategies(new MultiGraphStrategy(gA, gB)).V().out().forEachRemaining(System.out::println);

        gA.close();
    }

    public static  class MultiVertexStep<E extends Element> extends FlatMapStep<Vertex, E> implements AutoCloseable, Configuring {

        private final GraphTraversalSource gA;
        private final GraphTraversalSource gB;

        private final Direction direction;

        private final String[] edgeLabels;

        private final Class returnClass;

        public MultiVertexStep(final GraphTraversalSource gA, final GraphTraversalSource gB,
                               final Traversal.Admin traversal, final Class returnClass, final Direction direction, final String... edgeLabels) {
            super(traversal);
            this.direction = direction;
            this.edgeLabels = edgeLabels;
            this.returnClass = returnClass;
            this.gA = gA;
            this.gB = gB;
        }

        @Override
        protected Iterator flatMap(Traverser.Admin traverser) {
            final Vertex v = (Vertex) traverser.get();
            final String ref = v.value("reference");
            final GraphTraversalSource g = ref.toString().startsWith("A") ? gA : gB;
            final String id = ref.substring(1);

            if (direction == Direction.OUT) {
                if (returnClass == Vertex.class)
                    return g.V(id).out(edgeLabels);
                else
                    return g.V(id).outE(edgeLabels);
            } else if (direction == Direction.IN) {
                if (returnClass == Vertex.class)
                    return g.V(id).in(edgeLabels);
                else
                    return g.V(id).inE(edgeLabels);
            } else {
                if (returnClass == Vertex.class)
                    return g.V(id).both(edgeLabels);
                else
                    return g.V(id).bothE(edgeLabels);
            }
        }

        @Override
        public void close() throws Exception {

        }

        @Override
        public void configure(Object... keyValues) {

        }

        @Override
        public Parameters getParameters() {
            return null;
        }
    }

    public static class MultiGraphStrategy implements TraversalStrategy.DecorationStrategy {

        private final GraphTraversalSource gA;
        private final GraphTraversalSource gB;

        public MultiGraphStrategy(final GraphTraversalSource gA, final GraphTraversalSource gB) {
            this.gA = gA;
            this.gB = gB;
        }

        @Override
        public void apply(final Traversal.Admin<?, ?> traversal) {
            for (final VertexStep originalVertexStep : TraversalHelper.getStepsOfClass(VertexStep.class, traversal)) {
                final MultiVertexStep multiVertexStep = new MultiVertexStep(gA, gB, originalVertexStep.getTraversal(), originalVertexStep.getReturnClass(), originalVertexStep.getDirection(), originalVertexStep.getEdgeLabels());
                TraversalHelper.replaceStep(originalVertexStep, multiVertexStep, traversal);
            }
        }
    }
}