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Relational Persistence for Java
//$Id: PersistentBag.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.Iterator;
import java.util.List;
import java.util.ListIterator;
import org.hibernate.EntityMode;
import org.hibernate.HibernateException;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.loader.CollectionAliases;
import org.hibernate.persister.collection.CollectionPersister;
import org.hibernate.type.Type;
/**
* An unordered, unkeyed collection that can contain the same element
* multiple times. The Java collections API, curiously, has no Bag.
* Most developers seem to use Lists to represent bag semantics,
* so Hibernate follows this practice.
*
* @author Gavin King
*/
public class PersistentBag extends AbstractPersistentCollection implements List {
protected List bag;
public PersistentBag(SessionImplementor session) {
super(session);
}
public PersistentBag(SessionImplementor session, Collection coll) {
super(session);
if (coll instanceof List) {
bag = (List) coll;
}
else {
bag = new ArrayList();
Iterator iter = coll.iterator();
while ( iter.hasNext() ) {
bag.add( iter.next() );
}
}
setInitialized();
setDirectlyAccessible(true);
}
public PersistentBag() {} //needed for SOAP libraries, etc
public boolean isWrapper(Object collection) {
return bag==collection;
}
public boolean empty() {
return bag.isEmpty();
}
public Iterator entries(CollectionPersister persister) {
return bag.iterator();
}
public Object readFrom(ResultSet rs, CollectionPersister persister, CollectionAliases descriptor, Object owner)
throws HibernateException, SQLException {
// note that if we load this collection from a cartesian product
// the multiplicity would be broken ... so use an idbag instead
Object element = persister.readElement( rs, owner, descriptor.getSuffixedElementAliases(), getSession() ) ;
if (element!=null) bag.add(element);
return element;
}
public void beforeInitialize(CollectionPersister persister, int anticipatedSize) {
this.bag = ( List ) persister.getCollectionType().instantiate( anticipatedSize );
}
public boolean equalsSnapshot(CollectionPersister persister) throws HibernateException {
Type elementType = persister.getElementType();
EntityMode entityMode = getSession().getEntityMode();
List sn = (List) getSnapshot();
if ( sn.size()!=bag.size() ) return false;
Iterator iter = bag.iterator();
while ( iter.hasNext() ) {
Object elt = iter.next();
final boolean unequal = countOccurrences(elt, bag, elementType, entityMode) !=
countOccurrences(elt, sn, elementType, entityMode);
if ( unequal ) return false;
}
return true;
}
public boolean isSnapshotEmpty(Serializable snapshot) {
return ( (Collection) snapshot ).isEmpty();
}
private int countOccurrences(Object element, List list, Type elementType, EntityMode entityMode)
throws HibernateException {
Iterator iter = list.iterator();
int result=0;
while ( iter.hasNext() ) {
if ( elementType.isSame( element, iter.next(), entityMode ) ) result++;
}
return result;
}
public Serializable getSnapshot(CollectionPersister persister)
throws HibernateException {
EntityMode entityMode = getSession().getEntityMode();
ArrayList clonedList = new ArrayList( bag.size() );
Iterator iter = bag.iterator();
while ( iter.hasNext() ) {
clonedList.add( persister.getElementType().deepCopy( iter.next(), entityMode, persister.getFactory() ) );
}
return clonedList;
}
public Collection getOrphans(Serializable snapshot, String entityName) throws HibernateException {
List sn = (List) snapshot;
return getOrphans( sn, bag, entityName, getSession() );
}
public Serializable disassemble(CollectionPersister persister)
throws HibernateException {
int length = bag.size();
Serializable[] result = new Serializable[length];
for ( int i=0; i is not really a bag;
// it is *really* a set, since it can't contain the
// same element twice. It could be considered a bug
// in the mapping dtd that allows .
// Anyway, here we implement semantics for a
// !
public Iterator getDeletes(CollectionPersister persister, boolean indexIsFormula) throws HibernateException {
//if ( !persister.isOneToMany() ) throw new AssertionFailure("Not implemented for Bags");
Type elementType = persister.getElementType();
EntityMode entityMode = getSession().getEntityMode();
ArrayList deletes = new ArrayList();
List sn = (List) getSnapshot();
Iterator olditer = sn.iterator();
int i=0;
while ( olditer.hasNext() ) {
Object old = olditer.next();
Iterator newiter = bag.iterator();
boolean found = false;
if ( bag.size()>i && elementType.isSame( old, bag.get(i++), entityMode ) ) {
//a shortcut if its location didn't change!
found = true;
}
else {
//search for it
//note that this code is incorrect for other than one-to-many
while ( newiter.hasNext() ) {
if ( elementType.isSame( old, newiter.next(), entityMode ) ) {
found = true;
break;
}
}
}
if (!found) deletes.add(old);
}
return deletes.iterator();
}
public boolean needsInserting(Object entry, int i, Type elemType) throws HibernateException {
//if ( !persister.isOneToMany() ) throw new AssertionFailure("Not implemented for Bags");
List sn = (List) getSnapshot();
final EntityMode entityMode = getSession().getEntityMode();
if ( sn.size()>i && elemType.isSame( sn.get(i), entry, entityMode ) ) {
//a shortcut if its location didn't change!
return false;
}
else {
//search for it
//note that this code is incorrect for other than one-to-many
Iterator olditer = sn.iterator();
while ( olditer.hasNext() ) {
Object old = olditer.next();
if ( elemType.isSame( old, entry, entityMode ) ) return false;
}
return true;
}
}
public boolean isRowUpdatePossible() {
return false;
}
public boolean needsUpdating(Object entry, int i, Type elemType) {
//if ( !persister.isOneToMany() ) throw new AssertionFailure("Not implemented for Bags");
return false;
}
/**
* @see java.util.Collection#size()
*/
public int size() {
return readSize() ? getCachedSize() : bag.size();
}
/**
* @see java.util.Collection#isEmpty()
*/
public boolean isEmpty() {
return readSize() ? getCachedSize()==0 : bag.isEmpty();
}
/**
* @see java.util.Collection#contains(Object)
*/
public boolean contains(Object object) {
Boolean exists = readElementExistence(object);
return exists==null ?
bag.contains(object) :
exists.booleanValue();
}
/**
* @see java.util.Collection#iterator()
*/
public Iterator iterator() {
read();
return new IteratorProxy( bag.iterator() );
}
/**
* @see java.util.Collection#toArray()
*/
public Object[] toArray() {
read();
return bag.toArray();
}
/**
* @see java.util.Collection#toArray(Object[])
*/
public Object[] toArray(Object[] a) {
read();
return bag.toArray(a);
}
/**
* @see java.util.Collection#add(Object)
*/
public boolean add(Object object) {
if ( !isOperationQueueEnabled() ) {
write();
return bag.add(object);
}
else {
queueOperation( new SimpleAdd(object) );
return true;
}
}
/**
* @see java.util.Collection#remove(Object)
*/
public boolean remove(Object o) {
initialize( true );
if ( bag.remove( o ) ) {
dirty();
return true;
}
else {
return false;
}
}
/**
* @see java.util.Collection#containsAll(Collection)
*/
public boolean containsAll(Collection c) {
read();
return bag.containsAll(c);
}
/**
* @see java.util.Collection#addAll(Collection)
*/
public boolean addAll(Collection values) {
if ( values.size()==0 ) return false;
if ( !isOperationQueueEnabled() ) {
write();
return bag.addAll(values);
}
else {
Iterator iter = values.iterator();
while ( iter.hasNext() ) {
queueOperation( new SimpleAdd( iter.next() ) );
}
return values.size()>0;
}
}
/**
* @see java.util.Collection#removeAll(Collection)
*/
public boolean removeAll(Collection c) {
if ( c.size()>0 ) {
initialize( true );
if ( bag.removeAll( c ) ) {
dirty();
return true;
}
else {
return false;
}
}
else {
return false;
}
}
/**
* @see java.util.Collection#retainAll(Collection)
*/
public boolean retainAll(Collection c) {
initialize( true );
if ( bag.retainAll( c ) ) {
dirty();
return true;
}
else {
return false;
}
}
/**
* @see java.util.Collection#clear()
*/
public void clear() {
if ( isClearQueueEnabled() ) {
queueOperation( new Clear() );
}
else {
initialize( true );
if ( ! bag.isEmpty() ) {
bag.clear();
dirty();
}
}
}
public Object getIndex(Object entry, int i, CollectionPersister persister) {
throw new UnsupportedOperationException("Bags don't have indexes");
}
public Object getElement(Object entry) {
return entry;
}
public Object getSnapshotElement(Object entry, int i) {
List sn = (List) getSnapshot();
return sn.get(i);
}
public int occurrences(Object o) {
read();
Iterator iter = bag.iterator();
int result=0;
while ( iter.hasNext() ) {
if ( o.equals( iter.next() ) ) result++;
}
return result;
}
// List OPERATIONS:
/**
* @see java.util.List#add(int, Object)
*/
public void add(int i, Object o) {
write();
bag.add(i, o);
}
/**
* @see java.util.List#addAll(int, Collection)
*/
public boolean addAll(int i, Collection c) {
if ( c.size()>0 ) {
write();
return bag.addAll(i, c);
}
else {
return false;
}
}
/**
* @see java.util.List#get(int)
*/
public Object get(int i) {
read();
return bag.get(i);
}
/**
* @see java.util.List#indexOf(Object)
*/
public int indexOf(Object o) {
read();
return bag.indexOf(o);
}
/**
* @see java.util.List#lastIndexOf(Object)
*/
public int lastIndexOf(Object o) {
read();
return bag.lastIndexOf(o);
}
/**
* @see java.util.List#listIterator()
*/
public ListIterator listIterator() {
read();
return new ListIteratorProxy( bag.listIterator() );
}
/**
* @see java.util.List#listIterator(int)
*/
public ListIterator listIterator(int i) {
read();
return new ListIteratorProxy( bag.listIterator(i) );
}
/**
* @see java.util.List#remove(int)
*/
public Object remove(int i) {
write();
return bag.remove(i);
}
/**
* @see java.util.List#set(int, Object)
*/
public Object set(int i, Object o) {
write();
return bag.set(i, o);
}
/**
* @see java.util.List#subList(int, int)
*/
public List subList(int start, int end) {
read();
return new ListProxy( bag.subList(start, end) );
}
public String toString() {
read();
return bag.toString();
}
/*public boolean equals(Object other) {
read();
return bag.equals(other);
}
public int hashCode(Object other) {
read();
return bag.hashCode();
}*/
public boolean entryExists(Object entry, int i) {
return entry!=null;
}
/**
* Bag does not respect the collection API and do an
* JVM instance comparison to do the equals.
* The semantic is broken not to have to initialize a
* collection for a simple equals() operation.
* @see java.lang.Object#equals(java.lang.Object)
*/
public boolean equals(Object obj) {
return super.equals(obj);
}
/**
* @see java.lang.Object#hashCode()
*/
public int hashCode() {
return super.hashCode();
}
final class Clear implements DelayedOperation {
public void operate() {
bag.clear();
}
public Object getAddedInstance() {
return null;
}
public Object getOrphan() {
throw new UnsupportedOperationException("queued clear cannot be used with orphan delete");
}
}
final class SimpleAdd implements DelayedOperation {
private Object value;
public SimpleAdd(Object value) {
this.value = value;
}
public void operate() {
bag.add(value);
}
public Object getAddedInstance() {
return value;
}
public Object getOrphan() {
return null;
}
}
}
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