| /******************************************************************************* |
| * Copyright (c) 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.iterables; |
| |
| import java.util.Arrays; |
| import java.util.List; |
| import java.util.ListIterator; |
| |
| import org.eclipse.jpt.utility.internal.StringTools; |
| import org.eclipse.jpt.utility.internal.iterators.CloneListIterator; |
| |
| /** |
| * A <code>SnapshotCloneListIterable</code> returns a list iterator on a |
| * "snapshot" of a list, allowing for concurrent access to the original list. |
| * A copy of the list is created when the list iterable is constructed. |
| * As a result, the contents of the list will be the same with |
| * every call to {@link #iterator()}, even if the original list is modified via |
| * the list iterator's mutation methods. |
| * <p> |
| * The original list passed to the <code>SnapshotCloneListIterable</code>'s |
| * constructor should be thread-safe (e.g. {@link java.util.Vector}); |
| * otherwise you run the risk of a corrupted list. |
| * <p> |
| * By default, the list iterator returned by a <code>SnapshotCloneListIterable</code> does not |
| * support the {@link ListIterator} mutation operations; this is because it does not |
| * have access to the original list. But if the <code>SnapshotCloneListIterable</code> |
| * is supplied with a {@link CloneListIterator.Mutator} it will delegate the |
| * {@link ListIterator} mutation operations to the <code>Mutator</code>. |
| * Alternatively, a subclass can override the list iterable's mutation |
| * methods. |
| * <p> |
| * This list iterable is useful for multiple passes over a list that should not |
| * be changed (e.g. by another thread) between passes. |
| * |
| * @param <E> the type of elements returned by the list iterable's list iterator |
| * |
| * @see CloneListIterator |
| * @see LiveCloneListIterable |
| * @see SnapshotCloneIterable |
| */ |
| public class SnapshotCloneListIterable<E> |
| extends CloneListIterable<E> |
| { |
| private final Object[] array; |
| |
| |
| // ********** constructors ********** |
| |
| /** |
| * Construct a "snapshot" list iterable for the specified list. |
| * The {@link ListIterator} modify operations will not be supported |
| * by the list iterator returned by {@link #iterator()} |
| * unless a subclass overrides the list iterable's modify |
| * method. |
| */ |
| public SnapshotCloneListIterable(List<? extends E> list) { |
| super(); |
| this.array = list.toArray(); |
| } |
| |
| /** |
| * Construct a "snapshot" list iterable for the specified list. |
| * The specified mutator will be used by any generated list iterators to |
| * modify the original list. |
| */ |
| public SnapshotCloneListIterable(List<? extends E> list, CloneListIterator.Mutator<E> mutator) { |
| super(mutator); |
| this.array = list.toArray(); |
| } |
| |
| |
| // ********** ListIterable implementation ********** |
| |
| public ListIterator<E> iterator() { |
| return new LocalCloneListIterator<E>(this.mutator, this.array); |
| } |
| |
| @Override |
| public String toString() { |
| return StringTools.buildToStringFor(this, Arrays.toString(this.array)); |
| } |
| |
| |
| // ********** clone iterator ********** |
| |
| /** |
| * provide access to "internal" constructor |
| */ |
| protected static class LocalCloneListIterator<E> extends CloneListIterator<E> { |
| protected LocalCloneListIterator(Mutator<E> mutator, Object[] array) { |
| super(mutator, array); |
| } |
| } |
| |
| } |