// *************************************************************************************************************************** | |
// * 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.juneau.internal; | |
import static org.apache.juneau.internal.ThrowableUtils.*; | |
import java.util.*; | |
/** | |
* Utility class for defining an iterator over one or more iterables. | |
* | |
* @param <E> The element class type. | |
*/ | |
public class MultiIterable<E> implements Iterable<E> { | |
final List<Iterator<E>> iterators = new LinkedList<>(); | |
/** | |
* Constructor. | |
* | |
* @param iterators The list of iterators to iterate over. | |
*/ | |
@SuppressWarnings("unchecked") | |
public MultiIterable(Iterator<E>...iterators) { | |
for (Iterator<E> i : iterators) | |
append(i); | |
} | |
/** | |
* Appends the specified iterator to this list of iterators. | |
* | |
* @param iterator The iterator to append. | |
* @return This object (for method chaining). | |
*/ | |
public MultiIterable<E> append(Iterator<E> iterator) { | |
assertFieldNotNull(iterator, "iterator"); | |
this.iterators.add(iterator); | |
return this; | |
} | |
@Override /* Iterable */ | |
public Iterator<E> iterator() { | |
return new Iterator<E>() { | |
Iterator<Iterator<E>> i1 = iterators.iterator(); | |
Iterator<E> i2 = i1.hasNext() ? i1.next() : null; | |
@Override /* Iterator */ | |
public boolean hasNext() { | |
while (i2 != null && ! i2.hasNext()) | |
i2 = (i1.hasNext() ? i1.next() : null); | |
return (i2 != null); | |
} | |
@Override /* Iterator */ | |
public E next() { | |
hasNext(); | |
if (i2 == null) | |
throw new NoSuchElementException(); | |
return i2.next(); | |
} | |
@Override /* Iterator */ | |
public void remove() { | |
if (i2 == null) | |
throw new NoSuchElementException(); | |
i2.remove(); | |
} | |
}; | |
} | |
} |