package org.etk.orm.plugins.common.collection;
import java.util.Iterator;
import java.util.NoSuchElementException;
/**
* An iterator that filter the elements of a delegate iterator allowing to skip some elements and
* to perform type conversion.
*
*/
public abstract class AbstractFilterIterator<E, I> implements Iterator<E> {
/** . */
private Iterator<I> iterator;
/** . */
private E next;
/**
* Create a new filter iterator.
*
* @param iterator the iterator
* @throws NullPointerException if the iterator is null
*/
public AbstractFilterIterator(Iterator<I> iterator) throws NullPointerException {
if (iterator == null) {
throw new NullPointerException();
}
//
this.iterator = iterator;
}
public final boolean hasNext() {
if (next == null) {
bilto:
if (iterator != null) {
while (iterator.hasNext()) {
I internal = iterator.next();
E external = adapt(internal);
if (external != null) {
next = external;
break bilto;
}
}
iterator = null;
}
}
//
return next != null;
}
public final E next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
//
E tmp = next;
next = null;
//
return tmp;
}
public void remove() {
iterator.remove();
}
/**
* Adapts the internal element as an external element. Returning a null external element means that
* the element must be skipped and not considered by the iterator.
*
* @param internal the internal element
* @return the external element
*/
protected abstract E adapt(I internal);
}