Bugfix for base boundaries and fix for stackoverflow

When dist happens to be on exact base boundaries, the wrong decision was being made. For example when the distance between a and b is exactly 1, it will not correctly insert the second node. Leading to wrong size() computation and wrong neighbor retrieval.

And, nodes toString, equals and hashCode yield StackOverflowError because they used parent and children.

de.zabuza.closy/src/de/zabuza/closy/internal/CoverTree.java

@@ -242,7 +242,7 @@ public Collection<E> getKNearestNeighbors(final E point, final int k) {
 				// Create a set of nearest neighbor candidates
 				final double greatestMinDist = Objects.requireNonNull(minDistances.peek());
 				for (final Node<E> nextCandidate : nextCandidates) {
-					if (nextCandidate.getDistance() < greatestMinDist + Math.pow(base, level)) {
+					if (nextCandidate.getDistance() <= greatestMinDist + Math.pow(base, level)) {
 						candidates.add(nextCandidate);
 					}
 				}
@@ -292,7 +292,7 @@ public Optional<E> getNearestNeighbor(final E point) {
 
 				// Create a set of nearest neighbor candidates
 				for (final Node<E> nextCandidate : nextCandidates) {
-					if (nextCandidate.getDistance() < minDist + Math.pow(base, level)) {
+					if (nextCandidate.getDistance() <= minDist + Math.pow(base, level)) {
 						candidates.add(nextCandidate);
 					}
 				}
@@ -338,7 +338,7 @@ public Collection<E> getNeighborhood(final E point, final double range) {
 
 				// Create a set of nearest neighbor candidates
 				for (final Node<E> nextCandidate : nextCandidates) {
-					if (nextCandidate.getDistance() < range + Math.pow(base, level)) {
+					if (nextCandidate.getDistance() <= range + Math.pow(base, level)) {
 						candidates.add(nextCandidate);
 					}
 				}
@@ -399,7 +399,7 @@ public boolean add(final E element) {
 							child.setDistance(node.getDistance());
 						}
 
-						if (child.getDistance() < Math.pow(base, level)) {
+						if (child.getDistance() <= Math.pow(base, level)) {
 							candidates.add(child);
 							parentFound = false;
 						}
@@ -414,7 +414,7 @@ public boolean add(final E element) {
 
 				// Select one node of the cover-set as the parent of the node
 				for (final Node<E> node : coverset) {
-					if (node.getDistance() < Math.pow(base, level)) {
+					if (node.getDistance() <= Math.pow(base, level)) {
 						parent = node;
 						parentLevel = level;
 						break;

de.zabuza.closy/src/de/zabuza/closy/internal/Node.java

@@ -43,6 +43,15 @@ final class Node<E> implements Comparable<Node<E>> {
 		children = new ArrayList<>();
 	}
 
+	/**
+	 * Compares nodes ascending based on their distance.
+	 */
+	@Override
+	public int compareTo(final Node<E> o) {
+		//noinspection CompareToUsesNonFinalVariable
+		return Double.compare(distance, o.getDistance());
+	}
+
 	@Override
 	public boolean equals(final Object obj) {
 		if (this == obj) {
@@ -52,29 +61,19 @@ public boolean equals(final Object obj) {
 			return false;
 		}
 		final Node<?> node = (Node<?>) obj;
-		//noinspection ChainedMethodCall
-		return Double.compare(node.getDistance(), getDistance()) == 0 && getChildren().equals(node.getChildren())
-				&& Objects.equals(getElement(), node.getElement()) && Objects.equals(getParent(), node.getParent());
-	}
-
-	/**
-	 * Compares nodes ascending based on their distance.
-	 */
-	@Override
-	public int compareTo(final Node<E> o) {
-		//noinspection CompareToUsesNonFinalVariable
-		return Double.compare(distance, o.getDistance());
+		return Double.compare(node.getDistance(), getDistance()) == 0 && Objects.equals(getElement(),
+				node.getElement());
 	}
 
 	@Override
 	public int hashCode() {
-		return Objects.hash(getChildren(), getDistance(), getElement(), getParent());
+		return Objects.hash(getDistance(), getElement());
 	}
 
 	@Override
 	public String toString() {
-		return "Node{" + "children=" + children + ", distance=" + distance + ", element=" + element + ", parent="
-				+ parent + '}';
+		return "Node{" + "children size=" + children.size() + ", distance=" + distance + ", element=" + element
+				+ ", has parent=" + (parent != null) + '}';
 	}
 
 	/**