Provide TreeTraverser.fromFunction(Function)

Instead of implementing TreeTraverser.children(T) in anonymous classes each time a function that retrieves children from each node could be handy also.

What about this static method at TreeTraverser

static <T> TreeTraverser<T> fromFunction(final Function<? super T, ? extends Iterable<? extends T>> descendants) {
  return new TreeTraverser (...);
}

and a possible implementation as proposal.

/**
 * @see Traversers#fromFunction(Function)
 */
static final class TreeTraverserFromFunction<T> extends TreeTraverser<T> {

  private final Function<? super T, ? extends Iterable<? extends T>> descendants;

  TreeTraverserFromFunction(final Function<? super T, ? extends Iterable<? extends T>> children) {
    descendants = checkNotNull(children);
  }

  @Override
  public Iterable<T> children(final T root) {
    @SuppressWarnings("unchecked")
    final Iterable<T> checkedIterable = (Iterable<T>) descendants.apply(root);
    return checkedIterable;
  }

  @Override
  public String toString() {
    return "TreeTraverser.fromFunction(" + descendants + ")";
  }

}

[ronshapiro]

I believe this is taken care of by common.graph.Traverser.forTree(SuccessorsFunction) once it’s implemented (which should be very soon)

[kevinb9n]

Yeah, we still need to do it for BinaryTreeTraverser too.

On Sat, Sep 24, 2016 at 11:43 AM, Jonathan Bluett-Duncan < [e-mail]> wrote:

I see this has been completed now (at least to some extent).

Does any more work need to be done on this (like doing a lambda version of BinaryTreeTraverser)? Or can this issue be closed now?

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