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commented
10 years ago Original comment posted by ray.a.conner on 2014-03-05 at 03:28 AM
I just wanted to say I finally migrated my graph library to use TreeTraverser with Louis's suggestion of using TreeTraverser<Walk<T>> for maintaining paths during the traversal. It works without any unexpected problems, and was a bit cleaner than what I had been doing previously; so thanks. The only dissonance remaining is that is that I'm using something named TreeTraverser for general graph traversals, but I can live with that.
Original issue created by jvdneste on 2009-05-25 at 02:34 PM
As a suggestion; I find it quite useful!
/* * returns a depth-first iterator for a tree of T * @param f a function that returns the children of node of the tree * @param root The root element of the tree * @return / public static <T> Iterable<T> walk(final T root, final Function<? super T, ? extends Iterable<? extends T>> getChildren) { final Function<T, Iterable<? extends T>> walkFunc = new Function<T, Iterable<? extends T>>() { public Iterable<? extends T> apply(final T from) { return walk(from, getChildren, this); } }; return walk(root, getChildren, walkFunc); }
private static <T> Iterable<T> walk(final T root, final Function<? super T, ? extends Iterable<? extends T>> getChildren, final Function<T, Iterable<? extends T>> walkFunction) { return Iterables.concat( Collections.singleton(root), Iterables.concat( Iterables.transform( getChildren.apply(root), walkFunction))); }
And a shortcut in case the nodes implement Iterable:
@SuppressWarnings("unchecked") public static <T extends Iterable<T>> Iterable<T> walk(final T root) { return walk(root, Functions.identity(), WalkIterableFunction.INSTANCE); }
@SuppressWarnings("unchecked") private static enum WalkIterableFunction implements Function { INSTANCE;
public Object apply(final Object from) { return walk(from, Functions.identity(), this); } };