| /* |
| * Copyright (c) 2014 Eike Stepper (Loehne, Germany) and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Eclipse Public License v2.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/epl-v20.html |
| * |
| * Contributors: |
| * Eike Stepper - initial API and implementation |
| */ |
| package org.eclipse.oomph.util; |
| |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| /** |
| * An iterator that is composed of multiple delegate iterators. |
| * |
| * @author Eike Stepper |
| */ |
| public class ComposedIterator<T> extends AbstractIterator<T> |
| { |
| private final Iterator<? extends Iterator<T>> delegates; |
| |
| private Iterator<T> currentDelegate; |
| |
| public ComposedIterator(Iterator<T>... delegates) |
| { |
| this(Arrays.asList(delegates)); |
| } |
| |
| public ComposedIterator(Collection<? extends Iterator<T>> delegates) |
| { |
| this(delegates.iterator()); |
| } |
| |
| public ComposedIterator(Iterator<? extends Iterator<T>> delegates) |
| { |
| this.delegates = delegates; |
| } |
| |
| @Override |
| protected Object computeNextElement() |
| { |
| if (currentDelegate == null) |
| { |
| if (!delegates.hasNext()) |
| { |
| return END_OF_DATA; |
| } |
| |
| currentDelegate = delegates.next(); |
| } |
| |
| if (currentDelegate.hasNext()) |
| { |
| return currentDelegate.next(); |
| } |
| |
| currentDelegate = null; |
| return computeNextElement(); |
| } |
| |
| public static <T> Iterator<T> fromIterables(Collection<? extends Iterable<T>> iterables) |
| { |
| List<Iterator<T>> iterators = new ArrayList<Iterator<T>>(); |
| for (Iterable<T> iterable : iterables) |
| { |
| iterators.add(iterable.iterator()); |
| } |
| |
| return new ComposedIterator<T>(iterators.iterator()); |
| } |
| } |