Method breadthFirst

src/main/java/fieldbox/boxes/Box.java:321–356

returns breadth first Stream given a direction function. It is an error to call this when this box is not connected to anything (which is a common error --- calling this method at construction time).

(Function<Box, Collection<Box>> map)

	/**
	 * returns breadth first Stream given a direction function. It is an error to call this when this box is not connected to anything (which is a common error --- calling this method at
	 * construction time).
	 */
	@HiddenInAutocomplete
	public Stream<Box> breadthFirst(Function<Box, Collection<Box>> map) {

		if (this.all.size() == 0)
			Log.log("box.warning", () -> " breadthFirst called on a box not connected to the box graph");

		return new Lazy<Box>() {
			LinkedHashSet<Box> ret = null;
			Set<Box> thisLevel = null;

			protected Iterator<Box> initialize() {

				ret = new LinkedHashSet<>();
				ret.add(Box.this);
				thisLevel = ret;
				return ret.iterator();
			}

			@Override
			protected Iterator<Box> pull() {
				if (thisLevel.size() == 0) return null;

				Set<Box> nextLevel = new LinkedHashSet<>();
				for (Box b : thisLevel)
					if (!b.disconnected)
						nextLevel.addAll(map.apply(b));
				nextLevel.removeAll(ret);
				ret.addAll(nextLevel);
				thisLevel = nextLevel;

				return thisLevel.iterator();

			}
		}.reset()
			.stream().filter(x -> !x.disconnected);
	}