| /******************************************************************************* |
| * Copyright (c) 2005, 2009 Oracle. All rights reserved. |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Public License v1.0, which accompanies this distribution |
| * and is available at http://www.eclipse.org/legal/epl-v10.html. |
| * |
| * Contributors: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.utility.internal.iterators; |
| |
| import java.util.Iterator; |
| import org.eclipse.jpt.utility.internal.StringTools; |
| import org.eclipse.jpt.utility.internal.Transformer; |
| |
| |
| /** |
| * A <code>TransformationIterator</code> wraps another {@link Iterator} |
| * and transforms its results for client consumption. To use, supply a |
| * {@link Transformer} or subclass <code>TransformationIterator</code> |
| * and override the {@link #transform(Object)} method. |
| * Objects of type <code>E1</code> are transformed into objects of type <code>E2</code>; |
| * i.e. the iterator returns objects of type <code>E2</code>. |
| * |
| * @param <E1> input: the type of elements to be transformed |
| * @param <E2> output: the type of elements returned by the iterator |
| * |
| * @see org.eclipse.jpt.utility.internal.iterables.TransformationIterable |
| */ |
| public class TransformationIterator<E1, E2> |
| implements Iterator<E2> |
| { |
| private final Iterator<? extends E1> iterator; |
| private final Transformer<E1, ? extends E2> transformer; |
| |
| |
| /** |
| * Construct an iterator with the specified iterable |
| * and a disabled transformer. |
| * Use this constructor if you want to override the |
| * {@link #transform(Object)} method instead of building |
| * a {@link Transformer}. |
| */ |
| public TransformationIterator(Iterable<? extends E1> iterable) { |
| this(iterable.iterator()); |
| } |
| |
| /** |
| * Construct an iterator with the specified nested iterator |
| * and a disabled transformer. |
| * Use this constructor if you want to override the |
| * {@link #transform(Object)} method instead of building |
| * a {@link Transformer}. |
| */ |
| public TransformationIterator(Iterator<? extends E1> iterator) { |
| this(iterator, Transformer.Disabled.<E1, E2>instance()); |
| } |
| |
| /** |
| * Construct an iterator with the specified iterable and transformer. |
| */ |
| public TransformationIterator(Iterable<? extends E1> iterable, Transformer<E1, ? extends E2> transformer) { |
| this(iterable.iterator(), transformer); |
| } |
| |
| /** |
| * Construct an iterator with the specified nested iterator |
| * and transformer. |
| */ |
| public TransformationIterator(Iterator<? extends E1> iterator, Transformer<E1, ? extends E2> transformer) { |
| super(); |
| this.iterator = iterator; |
| this.transformer = transformer; |
| } |
| |
| public boolean hasNext() { |
| // delegate to the nested iterator |
| return this.iterator.hasNext(); |
| } |
| |
| public E2 next() { |
| // transform the object returned by the nested iterator before returning it |
| return this.transform(this.iterator.next()); |
| } |
| |
| public void remove() { |
| // delegate to the nested iterator |
| this.iterator.remove(); |
| } |
| |
| /** |
| * Transform the specified object and return the result. |
| */ |
| protected E2 transform(E1 next) { |
| return this.transformer.transform(next); |
| } |
| |
| @Override |
| public String toString() { |
| return StringTools.buildToStringFor(this, this.iterator); |
| } |
| |
| } |