@Override
public void apply(final Traversal<?, ?> traversal, final TraversalEngine engine) {
TraversalHelper.getStepsOfClass(LocalRangeStep.class, traversal)
.forEach(
localRangeStep -> {
Step previousStep = localRangeStep.getPreviousStep();
while (!previousStep.equals(EmptyStep.instance())
&& !(previousStep instanceof PropertiesStep)
&& !(previousStep instanceof VertexStep)) {
previousStep = previousStep.getPreviousStep();
// TODO: check for not filtering/sideEffect steps and throw an exception?
}
if (previousStep instanceof VertexStep) {
VertexStep vertexStep = (VertexStep) previousStep;
if (vertexStep.getReturnClass().equals(Edge.class)) {
localRangeStep.setDirection(vertexStep.getDirection());
} else {
throw new IllegalStateException(
"LocalRangeStep must follow a VertexStep that produces edges, not vertices");
}
} else if (previousStep instanceof PropertiesStep) {
// do nothing, all is good
} else {
throw new IllegalStateException(
"LocalRangeStep must follow a VertexStep or PropertiesStep");
}
});
}
