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package org.infinispan.commons.util;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.Consumer;
/**
* Abstract iterator that allows overriding just the {@link AbstractIterator#getNext()} method to implement it.
* This iterator works on the premise that a null value returned from {@link AbstractIterator#getNext()} means
* that this iterator is complete.
* Note this iterator does not implement {@link Iterator#remove()} and is up to implementors to do so.
* @author wburns
* @since 9.2
*/
public abstract class AbstractIterator implements Iterator {
E next;
/**
* Method to implement to provide an iterator implementation. When this method returns null, the iterator is complete.
* @return the next value for the iterator to return or null for it to be complete.
*/
protected abstract E getNext();
@Override
public boolean hasNext() {
return next != null || (next = getNext()) != null;
}
@Override
public E next() {
if (hasNext()) {
E returnValue = next;
next = null;
return returnValue;
}
throw new NoSuchElementException();
}
@Override
public void forEachRemaining(Consumer action) {
if (next != null) {
action.accept(next);
}
E next;
while ((next = getNext()) != null) {
action.accept(next);
}
}
}