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;
}
});
}