/*
* Copyright 2014 - 2017 Blazebit.
*
* Licensed 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 com.blazebit.persistence.impl.hibernate;
import java.util.Iterator;
import java.util.List;
import java.util.NoSuchElementException;
/**
* @author Christian Beikov
* @since 1.2.0
*/
public class MultiIterator<T> implements Iterator<T> {
private final List<Iterator<T>> iterators;
private Iterator<T> current;
private int nextIndex;
public MultiIterator(List<Iterator<T>> iterators) {
this.iterators = iterators;
this.current = iterators.get(0);
this.nextIndex = 1;
}
@Override
public boolean hasNext() {
if (current != null && current.hasNext()) {
return true;
}
if (nextIndex >= iterators.size()) {
return false;
}
current = iterators.get(nextIndex);
nextIndex++;
return hasNext();
}
@Override
public T next() {
if (current != null && current.hasNext()) {
return current.next();
}
if (nextIndex >= iterators.size()) {
throw new NoSuchElementException();
}
current = iterators.get(nextIndex);
nextIndex++;
return next();
}
@Override
public void remove() {
if (current == null) {
throw new IllegalStateException();
}
current.remove();
}
}