public void apply()

in gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/optimization/MatchPredicateStrategy.java [62:91]


    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;
            }
        });
    }