org.apache.kafka.common.utils.FlattenedIterator Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.kafka.common.utils;
import java.util.Iterator;
import java.util.function.Function;
/**
* Provides a flattened iterator over the inner elements of an outer iterator.
*/
public final class FlattenedIterator extends AbstractIterator {
private final Iterator outerIterator;
private final Function> innerIteratorFunction;
private Iterator innerIterator;
public FlattenedIterator(Iterator outerIterator, Function> innerIteratorFunction) {
this.outerIterator = outerIterator;
this.innerIteratorFunction = innerIteratorFunction;
}
@Override
public I makeNext() {
while (innerIterator == null || !innerIterator.hasNext()) {
if (outerIterator.hasNext())
innerIterator = innerIteratorFunction.apply(outerIterator.next());
else
return allDone();
}
return innerIterator.next();
}
}