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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.Collection;
import java.util.Iterator;
import org.eclipse.jpt.utility.internal.StringTools;
import org.eclipse.jpt.utility.internal.iterators.CloneIterator;
/**
* A <code>SnapshotCloneIterable</code> returns an iterator on a "snapshot" of a
* collection, allowing for concurrent access to the original collection. A
* copy of the collection is created when the iterable is constructed.
* As a result, the contents of the collection will be the same with
* every call to {@link #iterator()}.
* <p>
* The original collection passed to the <code>SnapshotCloneIterable</code>'s
* constructor should be thread-safe (e.g. {@link java.util.Vector});
* otherwise you run the risk of a corrupted collection.
* <p>
* By default, the iterator returned by a <code>SnapshotCloneIterable</code> does not
* support the {@link Iterator#remove()} operation; this is because it does not
* have access to the original collection. But if the <code>SnapshotCloneIterable</code>
* is supplied with a {@link CloneIterator.Remover} it will delegate the
* {@link Iterator#remove()} operation to the <code>Remover</code>.
* Alternatively, a subclass can override the iterable's {@link #remove(Object)}
* method.
* <p>
* This iterable is useful for multiple passes over a collection that should not
* be changed (e.g. by another thread) between passes.
*
* @param <E> the type of elements returned by the iterable's iterator
*
* @see CloneIterator
* @see LiveCloneIterable
* @see SnapshotCloneListIterable
*/
public class SnapshotCloneIterable<E>
extends CloneIterable<E>
{
private final Object[] array;
// ********** constructors **********
/**
* Construct a "snapshot" iterable for the specified collection.
* The {@link Iterator#remove()} operation will not be supported
* by the iterator returned by {@link #iterator()}
* unless a subclass overrides the iterable's {@link #remove(Object)}
* method.
*/
public SnapshotCloneIterable(Collection<? extends E> collection) {
super();
this.array = collection.toArray();
}
/**
* Construct a "snapshot" iterable for the specified collection.
* The specified remover will be used by any generated iterators to
* remove objects from the original collection.
*/
public SnapshotCloneIterable(Collection<? extends E> collection, CloneIterator.Remover<E> remover) {
super(remover);
this.array = collection.toArray();
}
// ********** Iterable implementation **********
public Iterator<E> iterator() {
return new LocalCloneIterator<E>(this.remover, this.array);
}
@Override
public String toString() {
return StringTools.buildToStringFor(this, Arrays.toString(this.array));
}
// ********** clone iterator **********
/**
* provide access to "internal" constructor
*/
protected static class LocalCloneIterator<E> extends CloneIterator<E> {
protected LocalCloneIterator(Remover<E> remover, Object[] array) {
super(remover, array);
}
}
}
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