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/*******************************************************************************
* 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);
}
}
}
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