/**
* Closes every CloseableIterator in this MergingIterator. After calling, calls to hasNext() will
* always return false.
*/
@Override
public void close() {
for (final ComparableIterator iterator : this.queue) {
iterator.close();
this.queue.remove(iterator);
}
}
@Override
public int compareTo(final ComparableIterator that) {
if (comparator.getClass() != comparator.getClass()) {
throw new IllegalStateException(
"Can't compare two ComparableIterators that have different orderings.");
}
return comparator.compare(this.peek(), that.peek());
}
/** @see java.util.Iterator<T>.next */
@Override
public T next() {
if (!this.hasNext()) throw new NoSuchElementException();
final ComparableIterator recordIterator = this.queue.poll();
// Assumes the iterator is closed & removed from the queue before recordIterator.hasNext() ==
// false
final T next = recordIterator.next();
// I don't like having to test for null here -- it's really only null before the first call
// to next() -- but I don't see any other way
if (this.lastReturned != null && this.comparator.compare(lastReturned, next) > 0) {
throw new IllegalStateException(
"The elements of the input Iterators are not sorted according to the comparator "
+ this.comparator.getClass().getName());
}
addIfNotEmpty(recordIterator);
this.lastReturned = next;
return next;
}
private void addIfNotEmpty(final ComparableIterator iterator) {
if (iterator.hasNext()) queue.offer(iterator);
else iterator.close();
}