| /******************************************************************************* |
| * Copyright (c) 2005, 2007 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 <code>Iterator</code> |
| * and transforms its results for client consumption. To use, supply a |
| * <code>Transformer</code> or subclass <code>TransformationIterator</code> |
| * and override the <code>transform(Object)</code> method. |
| * Objects of type E1 are transformed into objects of type E2; |
| * i.e. the iterator returns objects of type E2. |
| */ |
| public class TransformationIterator<E1, E2> |
| implements Iterator<E2> |
| { |
| private final Iterator<? extends E1> nestedIterator; |
| private final Transformer<E1, ? extends E2> transformer; |
| |
| |
| /** |
| * Construct an iterator with the specified nested iterator |
| * and a disabled transformer. |
| * Use this constructor if you want to override the |
| * <code>transform(Object)</code> method instead of building |
| * a <code>Transformer</code>. |
| */ |
| public TransformationIterator(Iterator<? extends E1> nestedIterator) { |
| this(nestedIterator, Transformer.Disabled.<E1, E2>instance()); |
| } |
| |
| /** |
| * Construct an iterator with the specified nested iterator |
| * and transformer. |
| */ |
| public TransformationIterator(Iterator<? extends E1> nestedIterator, Transformer<E1, ? extends E2> transformer) { |
| super(); |
| this.nestedIterator = nestedIterator; |
| this.transformer = transformer; |
| } |
| |
| public boolean hasNext() { |
| // delegate to the nested iterator |
| return this.nestedIterator.hasNext(); |
| } |
| |
| public E2 next() { |
| // transform the object returned by the nested iterator before returning it |
| return this.transform(this.nestedIterator.next()); |
| } |
| |
| public void remove() { |
| // delegate to the nested iterator |
| this.nestedIterator.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.nestedIterator); |
| } |
| |
| } |