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Relational Persistence for Java
There is a newer version: 3.6.0.Beta2
//$Id: PersistentIdentifierBag.java 10739 2006-11-06 22:00:41Z [email protected] $
package org.hibernate.collection;

import java.io.Serializable;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;

import org.hibernate.EntityMode;
import org.hibernate.HibernateException;
import org.hibernate.loader.CollectionAliases;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.type.Type;

/**
 * An IdentifierBag implements "bag" semantics more efficiently than
 * a regular Bag by adding a synthetic identifier column to the
 * table. This identifier is unique for all rows in the table, allowing very
 * efficient updates and deletes. The value of the identifier is never exposed
 * to the application.

 * 

 * IdentifierBags may not be used for a many-to-one association.
 * Furthermore, there is no reason to use inverse="true".
 *
 * @author Gavin King
 */
public class PersistentIdentifierBag extends AbstractPersistentCollection implements List {

	protected List values; //element
	protected Map identifiers; //index -> id

	public PersistentIdentifierBag(SessionImplementor session) {
		super(session);
	}

	public PersistentIdentifierBag() {} //needed for SOAP libraries, etc

	public PersistentIdentifierBag(SessionImplementor session, Collection coll) {
		super(session);
		if (coll instanceof List) {
			values = (List) coll;
		}
		else {
			values = new ArrayList();
			Iterator iter = coll.iterator();
			while ( iter.hasNext() ) {
				values.add( iter.next() );
			}
		}
		setInitialized();
		setDirectlyAccessible(true);
		identifiers = new HashMap();
	}

	public void initializeFromCache(CollectionPersister persister, Serializable disassembled, Object owner)
	throws HibernateException {
		Serializable[] array = (Serializable[]) disassembled;
		int size = array.length;
		beforeInitialize( persister, size );
		for ( int i = 0; i < size; i+=2 ) {
			identifiers.put(
				new Integer(i/2),
				persister.getIdentifierType().assemble( array[i], getSession(), owner )
			);
			values.add( persister.getElementType().assemble( array[i+1], getSession(), owner ) );
		}
	}

	public Object getIdentifier(Object entry, int i) {
		return identifiers.get( new Integer(i) );
	}
	
	public boolean isWrapper(Object collection) {
		return values==collection;
	}
	
	public boolean add(Object o) {
		write();
		values.add(o);
		return true;
	}

	public void clear() {
		initialize( true );
		if ( ! values.isEmpty() || ! identifiers.isEmpty() ) {
			values.clear();
			identifiers.clear();
			dirty();
		}
	}

	public boolean contains(Object o) {
		read();
		return values.contains(o);
	}

	public boolean containsAll(Collection c) {
		read();
		return values.containsAll(c);
	}

	public boolean isEmpty() {
		return readSize() ? getCachedSize()==0 : values.isEmpty();
	}

	public Iterator iterator() {
		read();
		return new IteratorProxy( values.iterator() );
	}

	public boolean remove(Object o) {
		initialize( true );
		int index = values.indexOf(o);
		if (index>=0) {
			beforeRemove(index);
			values.remove(index);
			dirty();
			return true;
		}
		else {
			return false;
		}
	}

	public boolean removeAll(Collection c) {
		if ( c.size() > 0 ) {
			boolean result = false;
			Iterator iter = c.iterator();
			while ( iter.hasNext() ) {
				if ( remove( iter.next() ) ) result=true;
			}
			return result;
		}
		else {
			return false;
		}
	}

	public boolean retainAll(Collection c) {
		initialize( true );
		if ( values.retainAll( c ) ) {
			dirty();
			return true;
		}
		else {
			return false;
		}
	}

	public int size() {
		return readSize() ? getCachedSize() : values.size();
	}

	public Object[] toArray() {
		read();
		return values.toArray();
	}

	public Object[] toArray(Object[] a) {
		read();
		return values.toArray(a);
	}

	public void beforeInitialize(CollectionPersister persister, int anticipatedSize) {
		identifiers = anticipatedSize <= 0 ? new HashMap() : new HashMap( anticipatedSize + 1 + (int)( anticipatedSize * .75f ), .75f );
		values = anticipatedSize <= 0 ? new ArrayList() : new ArrayList( anticipatedSize );
	}

	public Serializable disassemble(CollectionPersister persister)
			throws HibernateException {
		Serializable[] result = new Serializable[ values.size() * 2 ];
		int i=0;
		for (int j=0; j< values.size(); j++) {
			Object value = values.get(j);
			result[i++] = persister.getIdentifierType().disassemble( identifiers.get( new Integer(j) ), getSession(), null );
			result[i++] = persister.getElementType().disassemble( value, getSession(), null );
		}
		return result;
	}

	public boolean empty() {
		return values.isEmpty();
	}

	public Iterator entries(CollectionPersister persister) {
		return values.iterator();
	}

	public boolean entryExists(Object entry, int i) {
		return entry!=null;
	}

	public boolean equalsSnapshot(CollectionPersister persister) throws HibernateException {
		Type elementType = persister.getElementType();
		Map snap = (Map) getSnapshot();
		if ( snap.size()!= values.size() ) return false;
		for ( int i=0; i 0 ) {
			Iterator iter = c.iterator();
			while ( iter.hasNext() ) {
				add( index++, iter.next() );
			}
			return true;
		}
		else {
			return false;
		}
	}

	public Object get(int index) {
		read();
		return values.get(index);
	}

	public int indexOf(Object o) {
		read();
		return values.indexOf(o);
	}

	public int lastIndexOf(Object o) {
		read();
		return values.lastIndexOf(o);
	}

	public ListIterator listIterator() {
		read();
		return new ListIteratorProxy( values.listIterator() );
	}

	public ListIterator listIterator(int index) {
		read();
		return new ListIteratorProxy( values.listIterator(index) );
	}

	private void beforeRemove(int index) {
		Object removedId = identifiers.get( new Integer(index) );
		int last = values.size()-1;
		for ( int i=index; i 0 ) {
			write();
			return values.addAll(c);
		}
		else {
			return false;
		}
	}

	public void afterRowInsert(
		CollectionPersister persister,
		Object entry,
		int i)
		throws HibernateException {
		//TODO: if we are using identity columns, fetch the identifier
	}

}