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/*

 * Hibernate, Relational Persistence for Idiomatic Java

 *

 * Copyright (c) 2008-2011, Red Hat Inc. or third-party contributors as

 * indicated by the @author tags or express copyright attribution

 * statements applied by the authors.  All third-party contributions are

 * distributed under license by Red Hat Inc.

 *

 * This copyrighted material is made available to anyone wishing to use, modify,

 * copy, or redistribute it subject to the terms and conditions of the GNU

 * Lesser General Public License, as published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License

 * for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this distribution; if not, write to:

 * Free Software Foundation, Inc.

 * 51 Franklin Street, Fifth Floor

 * Boston, MA  02110-1301  USA

 */

package org.hibernate.collection.internal;

import java.io.Serializable;

import java.lang.reflect.Field;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Collections;

import java.util.HashSet;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import javax.naming.NamingException;

import org.hibernate.AssertionFailure;

import org.hibernate.HibernateException;

import org.hibernate.LazyInitializationException;

import org.hibernate.Session;

import org.hibernate.collection.spi.PersistentCollection;

import org.hibernate.engine.internal.ForeignKeys;

import org.hibernate.engine.spi.CollectionEntry;

import org.hibernate.engine.spi.EntityEntry;

import org.hibernate.engine.spi.SessionFactoryImplementor;

import org.hibernate.engine.spi.SessionImplementor;

import org.hibernate.engine.spi.Status;

import org.hibernate.engine.spi.TypedValue;

import org.hibernate.internal.SessionFactoryRegistry;

import org.hibernate.internal.util.MarkerObject;

import org.hibernate.internal.util.collections.EmptyIterator;

import org.hibernate.internal.util.collections.IdentitySet;

import org.hibernate.persister.collection.CollectionPersister;

import org.hibernate.persister.entity.EntityPersister;

import org.hibernate.pretty.MessageHelper;

import org.hibernate.type.Type;

import org.jboss.logging.Logger;

import eu.etaxonomy.cdm.api.application.CdmApplicationRemoteConfiguration;

import eu.etaxonomy.cdm.cache.ProxyUtils;

import eu.etaxonomy.cdm.model.common.CdmBase;

import eu.etaxonomy.taxeditor.remoting.CdmEagerLoadingException;

import eu.etaxonomy.taxeditor.service.ICachedCommonService;

/**

 * Base class implementing {@link org.hibernate.collection.spi.PersistentCollection}

 *

 * This a extended copy of the original class from hibernate. It has been extended to

 * allow making remote service calls to spring httpinvoker services (see section at the bottom

 * of this class).

 *

 *

 * @author Gavin King

 * @author Cherian Mathew

 */

public abstract class AbstractPersistentCollection implements Serializable, PersistentCollection {

	private static final Logger log = Logger.getLogger( AbstractPersistentCollection.class );

	/**

	 * <b>IMPORTANT:</b><br>

	 * This serialVersionUID must be kept in sync with the serialVersionUID which is generated

	 * on the fly for serialized AbstractPersistentCollection objects coming from the httpInvoker

	 * service.

	 * This is most probably necessary after updating hibernate to a newer version. In any case

	 * it the need for updating this <code>serialVersionUID</code> becomes obvious when the attempt

	 * to connect to the server side fails with an  <code>InvalidClassException</code>:

	 *

	 * <pre>

	 * java.io.InvalidClassException: org.hibernate.collection.internal.AbstractPersistentCollection;

	 * local class incompatible:

	 * stream classdesc serialVersionUID = 2742261122392386159,

	 * local class serialVersionUID = -7238232378593030571

	 * </pre>

	 * The correct <code>serialVersionUID</code> is the <code>stream classdesc serialVersionUID</code>

	 * from the error message.

	 */

	private static final long serialVersionUID = 2742261122392386159L;

	private transient SessionImplementor session;

	private boolean initialized;

	private transient List<DelayedOperation> operationQueue;

	private transient boolean directlyAccessible;

	private transient boolean initializing;

	private Object owner;

	private int cachedSize = -1;

	private String role;

	private Serializable key;

	// collections detect changes made via their public interface and mark

	// themselves as dirty as a performance optimization

	private boolean dirty;

	private Serializable storedSnapshot;

	private String sessionFactoryUuid;

	private boolean specjLazyLoad = false;

	@Override

    public final String getRole() {

		return role;

	}

	@Override

    public final Serializable getKey() {

		return key;

	}

	@Override

    public final boolean isUnreferenced() {

		return role == null;

	}

	@Override

    public final boolean isDirty() {

		return dirty;

	}

	@Override

    public final void clearDirty() {

		dirty = false;

	}

	@Override

    public final void dirty() {

		dirty = true;

	}

	@Override

    public final Serializable getStoredSnapshot() {

		return storedSnapshot;

	}

	//Careful: these methods do not initialize the collection.

	/**

	 * Is the initialized collection empty?

	 */

	@Override

    public abstract boolean empty();

	/**

	 * Called by any read-only method of the collection interface

	 */

	protected final void read() {

		initialize( false );

	}

	/**

	 * Called by the {@link Collection#size} method

	 */

	@SuppressWarnings({"JavaDoc"})

	protected boolean readSize() {

		if ( !initialized ) {

			if ( cachedSize != -1 && !hasQueuedOperations() ) {

				return true;

			}

			else {

				// In remoting we are sure that session is null

				// both when using property paths and switching off conversations

				if(session == null && remoting) {

					log.info("--> readSize, of " + getRole() + " with key " + getKey());

					read();

				} else {

					boolean isExtraLazy = withTemporarySessionIfNeeded(

							new LazyInitializationWork<Boolean>() {

								@Override

								public Boolean doWork() {

									CollectionEntry entry = session.getPersistenceContext().getCollectionEntry( AbstractPersistentCollection.this );

									if ( entry != null ) {

										CollectionPersister persister = entry.getLoadedPersister();

										if ( persister.isExtraLazy() ) {

											if ( hasQueuedOperations() ) {

												session.flush();

											}

											cachedSize = persister.getSize( entry.getLoadedKey(), session );

											return true;

										}

										else {

											read();

										}

									}

									else{

										throwLazyInitializationExceptionIfNotConnected();

									}

									return false;

								}

							}

							);

					if ( isExtraLazy ) {

						return true;

					}

				}

			}

		}

		return false;

	}

	public static interface LazyInitializationWork<T> {

		public T doWork();

	}

	private <T> T withTemporarySessionIfNeeded(LazyInitializationWork<T> lazyInitializationWork) {

		SessionImplementor originalSession = null;

		boolean isTempSession = false;

		boolean isJTA = false;

		if ( session == null ) {

			if ( specjLazyLoad ) {

				session = openTemporarySessionForLoading();

				isTempSession = true;

			}

			else {

				throwLazyInitializationException( "could not initialize proxy - no Session" );

			}

		}

		else if ( !session.isOpen() ) {

			if ( specjLazyLoad ) {

				originalSession = session;

				session = openTemporarySessionForLoading();

				isTempSession = true;

			}

			else {

				throwLazyInitializationException( "could not initialize proxy - the owning Session was closed" );

			}

		}

		else if ( !session.isConnected() ) {

			if ( specjLazyLoad ) {

				originalSession = session;

				session = openTemporarySessionForLoading();

				isTempSession = true;

			}

			else {

				throwLazyInitializationException( "could not initialize proxy - the owning Session is disconnected" );

			}

		}

		if ( isTempSession ) {

			// TODO: On the next major release, add an

			// 'isJTA' or 'getTransactionFactory' method to Session.

			/*isJTA = session.getTransactionCoordinator()

					.getTransactionContext().getTransactionEnvironment()

					.getTransactionFactory()

					.compatibleWithJtaSynchronization();*/

			isJTA = session.getTransactionCoordinator().getTransactionCoordinatorBuilder().isJta();

			if ( !isJTA ) {

				// Explicitly handle the transactions only if we're not in

				// a JTA environment.  A lazy loading temporary session can

				// be created even if a current session and transaction are

				// open (ex: session.clear() was used).  We must prevent

				// multiple transactions.

				( ( Session) session ).beginTransaction();

			}

			session.getPersistenceContext().addUninitializedDetachedCollection(

					session.getFactory().getCollectionPersister( getRole() ),

					this

			);

		}

		try {

			return lazyInitializationWork.doWork();

		}

		finally {

			if ( isTempSession ) {

				// make sure the just opened temp session gets closed!

				try {

					if ( !isJTA ) {

						( ( Session) session ).getTransaction().commit();

					}

					( (Session) session ).close();

				}

				catch (Exception e) {

					log.warn( "Unable to close temporary session used to load lazy collection associated to no session" );

				}

				session = originalSession;

			}

		}

	}

	private SessionImplementor openTemporarySessionForLoading() {

		if ( sessionFactoryUuid == null ) {

			throwLazyInitializationException( "SessionFactory UUID not known to create temporary Session for loading" );

		}

		SessionFactoryImplementor sf = (SessionFactoryImplementor)

				SessionFactoryRegistry.INSTANCE.getSessionFactory( sessionFactoryUuid );

		return (SessionImplementor) sf.openSession();

	}

	protected Boolean readIndexExistence(final Object index) {

		if ( !initialized ) {

			// In remoting we are sure that session is null

			// both when using property paths and switching off conversations

			if(session == null && remoting) {

				log.info("--> readIndexExistence, of " + getRole() + " with key " + getKey());

				read();

			} else {

				Boolean extraLazyExistenceCheck = withTemporarySessionIfNeeded(

						new LazyInitializationWork<Boolean>() {

							@Override

							public Boolean doWork() {

								CollectionEntry entry = session.getPersistenceContext().getCollectionEntry( AbstractPersistentCollection.this );

								CollectionPersister persister = entry.getLoadedPersister();

								if ( persister.isExtraLazy() ) {

									if ( hasQueuedOperations() ) {

										session.flush();

									}

									return persister.indexExists( entry.getLoadedKey(), index, session );

								}

								else {

									read();

								}

								return null;

							}

						}

						);

				if ( extraLazyExistenceCheck != null ) {

					return extraLazyExistenceCheck;

				}

			}

		}

		return null;

	}

	protected Boolean readElementExistence(final Object element) {

		if ( !initialized ) {

			// In remoting we are sure that session is null

			// both when using property paths and switching off conversations

			if(session == null && remoting) {

				log.info("--> readElementExistence, of " + getRole() + " with key " + getKey());

				read();

			} else {

				Boolean extraLazyExistenceCheck = withTemporarySessionIfNeeded(

						new LazyInitializationWork<Boolean>() {

							@Override

							public Boolean doWork() {

								CollectionEntry entry = session.getPersistenceContext().getCollectionEntry( AbstractPersistentCollection.this );

								CollectionPersister persister = entry.getLoadedPersister();

								if ( persister.isExtraLazy() ) {

									if ( hasQueuedOperations() ) {

										session.flush();

									}

									return persister.elementExists( entry.getLoadedKey(), element, session );

								}

								else {

									read();

								}

								return null;

							}

						}

						);

				if ( extraLazyExistenceCheck != null ) {

					return extraLazyExistenceCheck;

				}

			}

		}

		return null;

	}

	protected static final Object UNKNOWN = new MarkerObject( "UNKNOWN" );

	protected Object readElementByIndex(final Object index) {

		if ( !initialized ) {

			// In remoting we are sure that session is null

			// both when using property paths and switching off conversations

			if(session == null && remoting) {

				log.info("--> readElementByIndex, of " + getRole() + " with key " + getKey());

				read();

			} else {

				class ExtraLazyElementByIndexReader implements LazyInitializationWork {

					private boolean isExtraLazy;

					private Object element;

					@Override

					public Object doWork() {

						CollectionEntry entry = session.getPersistenceContext().getCollectionEntry( AbstractPersistentCollection.this );

						CollectionPersister persister = entry.getLoadedPersister();

						isExtraLazy = persister.isExtraLazy();

						if ( isExtraLazy ) {

							if ( hasQueuedOperations() ) {

								session.flush();

							}

							element = persister.getElementByIndex( entry.getLoadedKey(), index, session, owner );

						}

						else {

							read();

						}

						return null;

					}

				}

				ExtraLazyElementByIndexReader reader = new ExtraLazyElementByIndexReader();

				//noinspection unchecked

				withTemporarySessionIfNeeded( reader );

				if ( reader.isExtraLazy ) {

					return reader.element;

				}

			}

		}

		return UNKNOWN;

	}

	protected int getCachedSize() {

		return cachedSize;

	}

	private boolean isConnectedToSession() {

		return session != null &&

				session.isOpen() &&

				session.getPersistenceContext().containsCollection( this );

	}

	/**

	 * Called by any writer method of the collection interface

	 */

	protected final void write() {

		initialize( true );

		dirty();

	}

	/**

	 * Is this collection in a state that would allow us to

	 * "queue" operations?

	 */

	@SuppressWarnings({"JavaDoc"})

	protected boolean isOperationQueueEnabled() {

		return !initialized &&

				isConnectedToSession() &&

				isInverseCollection();

	}

	/**

	 * Is this collection in a state that would allow us to

	 * "queue" puts? This is a special case, because of orphan

	 * delete.

	 */

	@SuppressWarnings({"JavaDoc"})

	protected boolean isPutQueueEnabled() {

		return !initialized &&

				isConnectedToSession() &&

				isInverseOneToManyOrNoOrphanDelete();

	}

	/**

	 * Is this collection in a state that would allow us to

	 * "queue" clear? This is a special case, because of orphan

	 * delete.

	 */

	@SuppressWarnings({"JavaDoc"})

	protected boolean isClearQueueEnabled() {

		return !initialized &&

				isConnectedToSession() &&

				isInverseCollectionNoOrphanDelete();

	}

	/**

	 * Is this the "inverse" end of a bidirectional association?

	 */

	@SuppressWarnings({"JavaDoc"})

	private boolean isInverseCollection() {

		CollectionEntry ce = session.getPersistenceContext().getCollectionEntry( this );

		return ce != null && ce.getLoadedPersister().isInverse();

	}

	/**

	 * Is this the "inverse" end of a bidirectional association with

	 * no orphan delete enabled?

	 */

	@SuppressWarnings({"JavaDoc"})

	private boolean isInverseCollectionNoOrphanDelete() {

		CollectionEntry ce = session.getPersistenceContext().getCollectionEntry( this );

		return ce != null &&

				ce.getLoadedPersister().isInverse() &&

				!ce.getLoadedPersister().hasOrphanDelete();

	}

	/**

	 * Is this the "inverse" end of a bidirectional one-to-many, or

	 * of a collection with no orphan delete?

	 */

	@SuppressWarnings({"JavaDoc"})

	private boolean isInverseOneToManyOrNoOrphanDelete() {

		CollectionEntry ce = session.getPersistenceContext().getCollectionEntry( this );

		return ce != null && ce.getLoadedPersister().isInverse() && (

				ce.getLoadedPersister().isOneToMany() ||

						!ce.getLoadedPersister().hasOrphanDelete()

		);

	}

	/**

	 * Queue an addition

	 */

	@SuppressWarnings({"JavaDoc"})

	protected final void queueOperation(DelayedOperation operation) {

		if ( operationQueue == null ) {

			operationQueue = new ArrayList<DelayedOperation>( 10 );

		}

		operationQueue.add( operation );

		dirty = true; //needed so that we remove this collection from the second-level cache

	}

	/**

	 * After reading all existing elements from the database,

	 * add the queued elements to the underlying collection.

	 */

	protected final void performQueuedOperations() {

		for ( DelayedOperation operation : operationQueue ) {

			operation.operate();

		}

	}

	/**

	 * After flushing, re-init snapshot state.

	 */

	@Override

    public void setSnapshot(Serializable key, String role, Serializable snapshot) {

		this.key = key;

		this.role = role;

		this.storedSnapshot = snapshot;

	}

	/**

	 * After flushing, clear any "queued" additions, since the

	 * database state is now synchronized with the memory state.

	 */

	@Override

    public void postAction() {

		operationQueue = null;

		cachedSize = -1;

		clearDirty();

	}

	/**

	 * Not called by Hibernate, but used by non-JDK serialization,

	 * eg. SOAP libraries.

	 */

	public AbstractPersistentCollection() {

	}

	protected AbstractPersistentCollection(SessionImplementor session) {

		this.session = session;

	}

	/**

	 * return the user-visible collection (or array) instance

	 */

	@Override

    public Object getValue() {

		return this;

	}

	/**

	 * Called just before reading any rows from the JDBC result set

	 */

	@Override

    public void beginRead() {

		// override on some subclasses

		initializing = true;

	}

	/**

	 * Called after reading all rows from the JDBC result set

	 */

	@Override

    public boolean endRead() {

		//override on some subclasses

		return afterInitialize();

	}

	@Override

    public boolean afterInitialize() {

		setInitialized();

		//do this bit after setting initialized to true or it will recurse

		if ( operationQueue != null ) {

			performQueuedOperations();

			operationQueue = null;

			cachedSize = -1;

			return false;

		}

		else {

			return true;

		}

	}

	/**

	 * Initialize the collection, if possible, wrapping any exceptions

	 * in a runtime exception

	 *

	 * @param writing currently obsolete

	 *

	 * @throws LazyInitializationException if we cannot initialize

	 */

	protected final void initialize(final boolean writing) {

	    if ( initialized ) {

	        return;

	    }

	    // In remoting we are sure that session is null

	    // both when using property paths and switching off conversations

	    if(session == null && remoting) {

	        remoteInitialize();

	    } else {

	        withTemporarySessionIfNeeded(

	                new LazyInitializationWork<Object>() {

	                    @Override

	                    public Object doWork() {

	                        session.initializeCollection( AbstractPersistentCollection.this, writing );

	                        return null;

	                    }

	                }

	                );

	    }

	}

	private void throwLazyInitializationExceptionIfNotConnected() {

		if ( !isConnectedToSession() ) {

			throwLazyInitializationException( "no session or session was closed" );

		}

		if ( !session.isConnected() ) {

			throwLazyInitializationException( "session is disconnected" );

		}

	}

	private void throwLazyInitializationException(String message) {

		throw new LazyInitializationException(

				"failed to lazily initialize a collection" +

						(role == null ? "" : " of role: " + role) +

						", " + message

		);

	}

	protected final void setInitialized() {

		this.initializing = false;

		this.initialized = true;

	}

	protected final void setDirectlyAccessible(boolean directlyAccessible) {

		this.directlyAccessible = directlyAccessible;

	}

	/**

	 * Could the application possibly have a direct reference to

	 * the underlying collection implementation?

	 */

	@Override

    public boolean isDirectlyAccessible() {

		return directlyAccessible;

	}

	/**

	 * Disassociate this collection from the given session.

	 *

	 * @return true if this was currently associated with the given session

	 */

	@Override

    public final boolean unsetSession(SessionImplementor currentSession) {

		prepareForPossibleSpecialSpecjInitialization();

		if ( currentSession == this.session ) {

			this.session = null;

			return true;

		}

		else {

			return false;

		}

	}

	protected void prepareForPossibleSpecialSpecjInitialization() {

		if ( session != null ) {

			specjLazyLoad = session.getFactory().getSettings().isInitializeLazyStateOutsideTransactionsEnabled();

			if ( specjLazyLoad && sessionFactoryUuid == null ) {

				try {

					sessionFactoryUuid = (String) session.getFactory().getReference().get( "uuid" ).getContent();

				}

				catch (NamingException e) {

					//not much we can do if this fails...

				}

			}

		}

	}

	/**

	 * Associate the collection with the given session.

	 *

	 * @return false if the collection was already associated with the session

	 *

	 * @throws HibernateException if the collection was already associated

	 * with another open session

	 */

	@Override

    public final boolean setCurrentSession(SessionImplementor session) throws HibernateException {

		if ( session == this.session ) {

			return false;

		}

		else {

			if ( isConnectedToSession() ) {

				CollectionEntry ce = session.getPersistenceContext().getCollectionEntry( this );

				if ( ce == null ) {

					throw new HibernateException(

							"Illegal attempt to associate a collection with two open sessions"

					);

				}

				else {

					throw new HibernateException(

							"Illegal attempt to associate a collection with two open sessions: " +

									MessageHelper.collectionInfoString(

											ce.getLoadedPersister(), this,

											ce.getLoadedKey(), session

									)

					);

				}

			}

			else {

				this.session = session;

				return true;

			}

		}

	}

	/**

	 * Do we need to completely recreate this collection when it changes?

	 */

	@Override

    public boolean needsRecreate(CollectionPersister persister) {

		return false;

	}

	/**

	 * To be called internally by the session, forcing

	 * immediate initialization.

	 */

	@Override

    public final void forceInitialization() throws HibernateException {

		if ( !initialized ) {

			if ( initializing ) {

				throw new AssertionFailure( "force initialize loading collection" );

			}

			if ( session == null ) {

				throw new HibernateException( "collection is not associated with any session" );

			}

			if ( !session.isConnected() ) {

				throw new HibernateException( "disconnected session" );

			}

			session.initializeCollection( this, false );

		}

	}

	/**

	 * Get the current snapshot from the session

	 */

	@SuppressWarnings({"JavaDoc"})

	protected final Serializable getSnapshot() {

		return session.getPersistenceContext().getSnapshot( this );

	}

	/**

	 * Is this instance initialized?

	 */

	@Override

    public final boolean wasInitialized() {

		return initialized;

	}

	@Override

    public boolean isRowUpdatePossible() {

		return true;

	}

	/**

	 * Does this instance have any "queued" additions?

	 */

	@Override

    public final boolean hasQueuedOperations() {

		return operationQueue != null;

	}

	/**

	 * Iterate the "queued" additions

	 */

	@Override

    public final Iterator queuedAdditionIterator() {

		if ( hasQueuedOperations() ) {

			return new Iterator() {

				int i = 0;

				@Override

                public Object next() {

					return operationQueue.get( i++ ).getAddedInstance();

				}

				@Override

                public boolean hasNext() {

					return i < operationQueue.size();

				}

				@Override

                public void remove() {

					throw new UnsupportedOperationException();

				}

			};

		}

		else {

			return EmptyIterator.INSTANCE;

		}

	}

	/**

	 * Iterate the "queued" additions

	 */

	@Override

    @SuppressWarnings({"unchecked"})

	public final Collection getQueuedOrphans(String entityName) {

		if ( hasQueuedOperations() ) {

			Collection additions = new ArrayList( operationQueue.size() );

			Collection removals = new ArrayList( operationQueue.size() );

			for ( DelayedOperation operation : operationQueue ) {

				additions.add( operation.getAddedInstance() );

				removals.add( operation.getOrphan() );

			}

			return getOrphans( removals, additions, entityName, session );

		}

		else {

			return Collections.EMPTY_LIST;

		}

	}

	/**

	 * Called before inserting rows, to ensure that any surrogate keys

	 * are fully generated

	 */

	@Override

    public void preInsert(CollectionPersister persister) throws HibernateException {

	}

	/**

	 * Called after inserting a row, to fetch the natively generated id

	 */

	@Override

    public void afterRowInsert(CollectionPersister persister, Object entry, int i) throws HibernateException {

	}

	/**

	 * get all "orphaned" elements

	 */

	@Override

    public abstract Collection getOrphans(Serializable snapshot, String entityName) throws HibernateException;

	/**

	 * Get the current session

	 */

	@SuppressWarnings({"JavaDoc"})

	public final SessionImplementor getSession() {

		return session;

	}

	protected final class IteratorProxy implements Iterator {

		protected final Iterator itr;

		public IteratorProxy(Iterator itr) {

			this.itr = itr;

		}

		@Override

        public boolean hasNext() {

			return itr.hasNext();

		}

		@Override

        public Object next() {

			return itr.next();

		}

		@Override

        public void remove() {

			write();

			itr.remove();

		}

	}

	protected final class ListIteratorProxy implements ListIterator {

		protected final ListIterator itr;

		public ListIteratorProxy(ListIterator itr) {

			this.itr = itr;

		}

		@Override

        @SuppressWarnings({"unchecked"})

		public void add(Object o) {

			write();

			itr.add( o );

		}

		@Override

        public boolean hasNext() {

			return itr.hasNext();

		}

		@Override

        public boolean hasPrevious() {

			return itr.hasPrevious();

		}

		@Override

        public Object next() {

			return itr.next();

		}

		@Override

        public int nextIndex() {

			return itr.nextIndex();

		}

		@Override

        public Object previous() {

			return itr.previous();

		}

		@Override

        public int previousIndex() {

			return itr.previousIndex();

		}

		@Override

        public void remove() {

			write();

			itr.remove();

		}

		@Override

        @SuppressWarnings({"unchecked"})

		public void set(Object o) {

			write();

			itr.set( o );

		}

	}

	protected class SetProxy implements java.util.Set {

		protected final Collection set;

		public SetProxy(Collection set) {