org.infinispan.commons.util.RemovableIterator Maven / Gradle / Ivy
package org.infinispan.commons.util;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.function.Consumer;
/**
* An Iterator implementation that allows for a Iterator that doesn't allow remove operations to
* implement remove by delegating the call to the provided consumer to remove the previously read value.
*
* @author wburns
* @since 9.1
*/
public class RemovableIterator implements Iterator {
protected final Iterator realIterator;
protected final Consumer consumer;
protected C previousValue;
protected C currentValue;
public RemovableIterator(Iterator realIterator, Consumer consumer) {
this.realIterator = realIterator;
this.consumer = consumer;
}
protected C getNextFromIterator() {
if (realIterator.hasNext()) {
return realIterator.next();
} else {
return null;
}
}
@Override
public boolean hasNext() {
return currentValue != null || (currentValue = getNextFromIterator()) != null;
}
@Override
public C next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
previousValue = currentValue;
currentValue = null;
return previousValue;
}
@Override
public void remove() {
if (previousValue == null) {
throw new IllegalStateException();
}
consumer.accept(previousValue);
previousValue = null;
}
}