public final T traverse(RelNode n) throws Exception {
  List<T> inputStreams = new ArrayList<>();
  for (RelNode input : n.getInputs()) {
    inputStreams.add(traverse(input));
  }

  if (n instanceof Aggregate) {
    return visitAggregate((Aggregate) n, inputStreams);
  } else if (n instanceof Calc) {
    return visitCalc((Calc) n, inputStreams);
  } else if (n instanceof Collect) {
    return visitCollect((Collect) n, inputStreams);
  } else if (n instanceof Correlate) {
    return visitCorrelate((Correlate) n, inputStreams);
  } else if (n instanceof Delta) {
    return visitDelta((Delta) n, inputStreams);
  } else if (n instanceof Exchange) {
    return visitExchange((Exchange) n, inputStreams);
  } else if (n instanceof Project) {
    return visitProject((Project) n, inputStreams);
  } else if (n instanceof Filter) {
    return visitFilter((Filter) n, inputStreams);
  } else if (n instanceof Sample) {
    return visitSample((Sample) n, inputStreams);
  } else if (n instanceof Sort) {
    return visitSort((Sort) n, inputStreams);
  } else if (n instanceof TableModify) {
    return visitTableModify((TableModify) n, inputStreams);
  } else if (n instanceof TableScan) {
    return visitTableScan((TableScan) n, inputStreams);
  } else if (n instanceof Uncollect) {
    return visitUncollect((Uncollect) n, inputStreams);
  } else if (n instanceof Window) {
    return visitWindow((Window) n, inputStreams);
  } else if (n instanceof Join) {
    return visitJoin((Join) n, inputStreams);
  } else {
    return defaultValue(n, inputStreams);
  }
}
 

public RelNode convert(RelNode rel) {
  final Collect collect = (Collect) rel;
  final RelTraitSet traitSet =
      collect.getTraitSet().replace(EnumerableConvention.INSTANCE);
  final RelNode input = collect.getInput();
  return new EnumerableCollect(
      rel.getCluster(),
      traitSet,
      convert(input,
          input.getTraitSet().replace(EnumerableConvention.INSTANCE)),
      collect.getFieldName());
}
 

public void rewriteRel(Collect rel) {
    rewriteGeneric(rel);
}
 

public T visitCollect(Collect collect, List<T> inputStreams) throws Exception {
  return defaultValue(collect, inputStreams);
}
 

EnumerableCollectRule() {
  super(Collect.class, Convention.NONE, EnumerableConvention.INSTANCE,
      "EnumerableCollectRule");
}
 

public void rewriteRel(Collect rel) {
  rewriteGeneric(rel);
}
 

public void visit(Collect collect) {
  node = new CollectNode(this, collect);
}
 

public CollectNode(Compiler compiler, Collect rel) {
  super(compiler, rel);
}