package org.infinispan.tree.impl;
import java.io.Serializable;
import java.util.Comparator;
import org.infinispan.tree.Fqn;
import net.jcip.annotations.Immutable;
/**
* Compares the order of two FQN. Sorts by name, then by depth, e.g.
* <pre>
* aaa/bbb
* xxx
* xxx/ccc
* </pre>
*
* @author Manik Surtani (<a href="mailto:manik@jboss.org">manik@jboss.org</a>)
* @author Steve Woodcock (<a href="mailto:stevew@jofti.com">stevew@jofti.com</a>)
* @since 4.0
*/
@Immutable
public class FqnComparator implements Comparator<Fqn>, Serializable {
public static final FqnComparator INSTANCE = new FqnComparator();
private static final long serialVersionUID = -1357631755443829281L;
/**
* Returns -1 if the first comes before; 0 if they are the same; 1 if the second Fqn comes before. <code>null</code>
* always comes first.
*/
@Override
public int compare(Fqn fqn1, Fqn fqn2) {
int s1 = fqn1.size();
int s2 = fqn2.size();
if (s1 == 0) {
return (s2 == 0) ? 0 : -1;
}
if (s2 == 0) {
return 1;
}
// if (fqn1.getClass().equals(StringFqn.class) && fqn2.getClass().equals(StringFqn.class))
// {
// StringFqn sfqn1 = (StringFqn) fqn1;
// StringFqn sfqn2 = (StringFqn) fqn2;
// return sfqn1.stringRepresentation.compareTo(sfqn2.stringRepresentation);
// }
int size = Math.min(s1, s2);
for (int i = 0; i < size; i++) {
Object e1 = fqn1.get(i);
Object e2 = fqn2.get(i);
if (e1 == e2) {
continue;
}
if (e1 == null) {
return 0;
}
if (e2 == null) {
return 1;
}
if (!e1.equals(e2)) {
int c = compareElements(e1, e2);
if (c != 0) {
return c;
}
}
}
return s1 - s2;
}
/**
* Compares two Fqn elements. If e1 and e2 are the same class and e1 implements Comparable, returns e1.compareTo(e2).
* Otherwise, returns e1.toString().compareTo(e2.toString()).
*/
@SuppressWarnings("unchecked")
private int compareElements(Object e1, Object e2) {
if (e1.getClass() == e2.getClass() && e1 instanceof Comparable) {
return ((Comparable<Object>) e1).compareTo(e2);
} else {
return e1.toString().compareTo(e2.toString());
}
}
}