cucumber.runtime.io.FlatteningIterator Maven / Gradle / Ivy
package cucumber.runtime.io;
import java.util.ArrayDeque;
import java.util.Deque;
import java.util.Iterator;
import java.util.NoSuchElementException;
public class FlatteningIterator implements Iterator {
private final Deque> iterators = new ArrayDeque>();
private T next;
private boolean nextBlank = true;
public void push(Iterator iterator) {
iterators.addFirst(iterator);
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
private void moveToNext() {
if (nextBlank && !this.iterators.isEmpty()) {
if (!iterators.peek().hasNext()) {
iterators.removeFirst();
moveToNext();
} else {
final Object next = iterators.peekFirst().next();
if (next instanceof Iterator) {
push((Iterator) next);
moveToNext();
} else {
this.next = (T) next;
nextBlank = false;
}
}
}
}
@Override
public T next() {
moveToNext();
if (nextBlank) {
throw new NoSuchElementException();
} else {
T next = this.next;
this.next = null;
nextBlank = true;
return next;
}
}
@Override
public boolean hasNext() {
moveToNext();
return !nextBlank;
}
}