org.apache.tinkerpop.gremlin.process.traversal.step.map.SelectStep Java Examples

private static <S> GraphTraversal<S, Map<String, Vertex>> selectVars(GraphTraversal<S, Vertex> traversal, Set<Variable> vars) {
    if (vars.isEmpty()) {
        // Produce an empty result
        return traversal.constant(ImmutableMap.of());
    } else if (vars.size() == 1) {
        String label = vars.iterator().next().symbol();
        return traversal.select(label, label);
    } else {
        String[] labelArray = vars.stream().map(Variable::symbol).toArray(String[]::new);
        return traversal.asAdmin().addStep(new SelectStep<>(traversal.asAdmin(), null, labelArray));
    }
}
 

@Override
public void apply(final Traversal.Admin<?, ?> traversal) {
    if (!TraversalHelper.hasStepOfClass(MatchStep.class, traversal))
        return;

    TraversalHelper.getStepsOfClass(MatchStep.class, traversal).forEach(matchStep -> {
        // match().select().where() --> match(where()).select()
        // match().select().dedup() --> match(dedup()).select()
        Step<?, ?> nextStep = matchStep.getNextStep();
        while (nextStep instanceof WherePredicateStep ||
                nextStep instanceof WhereTraversalStep ||
                (nextStep instanceof DedupGlobalStep && !((DedupGlobalStep) nextStep).getScopeKeys().isEmpty() && ((DedupGlobalStep) nextStep).getLocalChildren().isEmpty()) ||
                (nextStep instanceof SelectStep && ((SelectStep) nextStep).getLocalChildren().isEmpty()) ||
                (nextStep instanceof SelectOneStep && ((SelectOneStep) nextStep).getLocalChildren().isEmpty())) {
            if (nextStep instanceof WherePredicateStep || nextStep instanceof WhereTraversalStep) {
                traversal.removeStep(nextStep);
                matchStep.addGlobalChild(traversal instanceof GraphTraversal ?
                        new DefaultGraphTraversal<>().addStep(nextStep) :
                        new DefaultTraversal<>().addStep(nextStep));
                nextStep = matchStep.getNextStep();
            } else if (nextStep instanceof DedupGlobalStep && !((DedupGlobalStep) nextStep).getScopeKeys().isEmpty() && ((DedupGlobalStep) nextStep).getLocalChildren().isEmpty() && !TraversalHelper.onGraphComputer(traversal)) {
                traversal.removeStep(nextStep);
                matchStep.setDedupLabels(((DedupGlobalStep<?>) nextStep).getScopeKeys());
                nextStep = matchStep.getNextStep();
            } else if (nextStep.getLabels().isEmpty()) {
                nextStep = nextStep.getNextStep();
            } else
                break;
        }
    });
}
 

@Test
public void testSelectFollowedByValues() {
    Vertex a1 = this.sqlgGraph.addVertex(T.label, "A", "name", "a1");
    Vertex a2 = this.sqlgGraph.addVertex(T.label, "A", "name", "a2");
    Vertex b1 = this.sqlgGraph.addVertex(T.label, "B", "name", "b1");
    Vertex b2 = this.sqlgGraph.addVertex(T.label, "B", "name", "b2");
    Vertex c1 = this.sqlgGraph.addVertex(T.label, "C", "xxxx", "c1", "yyyy", "y1", "zzzz", "z1");
    Vertex c2 = this.sqlgGraph.addVertex(T.label, "C", "xxxx", "c2", "yyyy", "y2", "zzzz", "z2");
    Vertex d1 = this.sqlgGraph.addVertex(T.label, "D", "name", "d1");
    Vertex d2 = this.sqlgGraph.addVertex(T.label, "D", "name", "d2");
    a1.addEdge("ab", b1);
    a2.addEdge("ab", b2);
    b1.addEdge("bc", c1);
    b2.addEdge("bc", c2);
    c1.addEdge("cd", d1);
    c2.addEdge("cd", d2);
    this.sqlgGraph.tx().commit();
    DefaultGraphTraversal<Vertex, String> traversal = (DefaultGraphTraversal<Vertex, String>)this.sqlgGraph.traversal().V()
            .hasLabel("C")
            .has("yyyy", "y1")
            .as("c")
            .in("bc")
            .in("ab")
            .has("name", "a1")
            .as("a")
            .<Vertex>select("a", "c")
            .select("c")
            .<String>values("xxxx");
    printTraversalForm(traversal);
    Assert.assertEquals(6, traversal.getSteps().size());
    Assert.assertTrue(traversal.getSteps().get(0) instanceof SqlgGraphStep);
    Assert.assertTrue(traversal.getSteps().get(1) instanceof IdentityStep);
    Assert.assertTrue(traversal.getSteps().get(2) instanceof IdentityStep);
    Assert.assertTrue(traversal.getSteps().get(3) instanceof SelectStep);
    Assert.assertTrue(traversal.getSteps().get(4) instanceof SelectOneStep);
    Assert.assertTrue(traversal.getSteps().get(5) instanceof PropertiesStep);
    List<String> names = traversal.toList();
    Assert.assertEquals(1, names.size());
    Assert.assertEquals("c1", names.get(0));
    checkRestrictedProperties(SqlgGraphStep.class, traversal, 0,  "xxxx");
}
 

/**
 * Map the {@link Traverser} to a {@link Map} projection of sideEffect values, map values, and/or path values.
 *
 * @param pop             if there are multiple objects referenced in the path, the {@link Pop} to use.
 * @param selectKey1      the first key to project
 * @param selectKey2      the second key to project
 * @param otherSelectKeys the third+ keys to project
 * @param <E2>            the type of the objects projected
 * @return the traversal with an appended {@link SelectStep}.
 * @see <a href="http://tinkerpop.apache.org/docs/${project.version}/reference/#select-step" target="_blank">Reference Documentation - Select Step</a>
 * @since 3.0.0-incubating
 */
public default <E2> GraphTraversal<S, Map<String, E2>> select(final Pop pop, final String selectKey1, final String selectKey2, String... otherSelectKeys) {
    final String[] selectKeys = new String[otherSelectKeys.length + 2];
    selectKeys[0] = selectKey1;
    selectKeys[1] = selectKey2;
    System.arraycopy(otherSelectKeys, 0, selectKeys, 2, otherSelectKeys.length);
    this.asAdmin().getBytecode().addStep(Symbols.select, pop, selectKey1, selectKey2, otherSelectKeys);
    return this.asAdmin().addStep(new SelectStep<>(this.asAdmin(), pop, selectKeys));
}
 

/**
 * Map the {@link Traverser} to a {@link Map} projection of sideEffect values, map values, and/or path values.
 *
 * @param selectKey1      the first key to project
 * @param selectKey2      the second key to project
 * @param otherSelectKeys the third+ keys to project
 * @param <E2>            the type of the objects projected
 * @return the traversal with an appended {@link SelectStep}.
 * @see <a href="http://tinkerpop.apache.org/docs/${project.version}/reference/#select-step" target="_blank">Reference Documentation - Select Step</a>
 * @since 3.0.0-incubating
 */
public default <E2> GraphTraversal<S, Map<String, E2>> select(final String selectKey1, final String selectKey2, String... otherSelectKeys) {
    final String[] selectKeys = new String[otherSelectKeys.length + 2];
    selectKeys[0] = selectKey1;
    selectKeys[1] = selectKey2;
    System.arraycopy(otherSelectKeys, 0, selectKeys, 2, otherSelectKeys.length);
    this.asAdmin().getBytecode().addStep(Symbols.select, selectKey1, selectKey2, otherSelectKeys);
    return this.asAdmin().addStep(new SelectStep<>(this.asAdmin(), Pop.last, selectKeys));
}