/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 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.event.service.internal;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;
import org.hibernate.event.service.spi.DuplicationStrategy;
import org.hibernate.event.service.spi.EventListenerGroup;
import org.hibernate.event.service.spi.EventListenerRegistrationException;
import org.hibernate.event.spi.EventType;
/**
* @author Steve Ebersole
*/
public class EventListenerGroupImpl<T> implements EventListenerGroup<T> {
private EventType<T> eventType;
private final Set<DuplicationStrategy> duplicationStrategies = new LinkedHashSet<DuplicationStrategy>();
private List<T> listeners;
public EventListenerGroupImpl(EventType<T> eventType) {
this.eventType = eventType;
duplicationStrategies.add(
// At minimum make sure we do not register the same exact listener class multiple times.
new DuplicationStrategy() {
@Override
public boolean areMatch(Object listener, Object original) {
return listener.getClass().equals( original.getClass() );
}
@Override
public Action getAction() {
return Action.ERROR;
}
}
);
}
@Override
public EventType<T> getEventType() {
return eventType;
}
@Override
public boolean isEmpty() {
return count() <= 0;
}
@Override
public int count() {
return listeners == null ? 0 : listeners.size();
}
@Override
public void clear() {
if ( duplicationStrategies != null ) {
duplicationStrategies.clear();
}
if ( listeners != null ) {
listeners.clear();
}
}
@Override
public void addDuplicationStrategy(DuplicationStrategy strategy) {
duplicationStrategies.add( strategy );
}
public Iterable<T> listeners() {
return listeners == null ? Collections.<T>emptyList() : listeners;
}
@Override
public void appendListeners(T... listeners) {
for ( T listener : listeners ) {
appendListener( listener );
}
}
@Override
public void appendListener(T listener) {
if ( listenerShouldGetAdded( listener ) ) {
internalAppend( listener );
}
}
@Override
public void prependListeners(T... listeners) {
for ( T listener : listeners ) {
prependListener( listener );
}
}
@Override
public void prependListener(T listener) {
if ( listenerShouldGetAdded( listener ) ) {
internalPrepend( listener );
}
}
private boolean listenerShouldGetAdded(T listener) {
if ( listeners == null ) {
listeners = new ArrayList<T>();
return true;
// no need to do de-dup checks
}
boolean doAdd = true;
strategy_loop: for ( DuplicationStrategy strategy : duplicationStrategies ) {
final ListIterator<T> itr = listeners.listIterator();
while ( itr.hasNext() ) {
final T existingListener = itr.next();
if ( strategy.areMatch( listener, existingListener ) ) {
switch ( strategy.getAction() ) {
// todo : add debug logging of what happens here...
case ERROR: {
throw new EventListenerRegistrationException( "Duplicate event listener found" );
}
case KEEP_ORIGINAL: {
doAdd = false;
break strategy_loop;
}
case REPLACE_ORIGINAL: {
itr.set( listener );
doAdd = false;
break strategy_loop;
}
}
}
}
}
return doAdd;
}
private void internalPrepend(T listener) {
checkAgainstBaseInterface( listener );
listeners.add( 0, listener );
}
private void checkAgainstBaseInterface(T listener) {
if ( !eventType.baseListenerInterface().isInstance( listener ) ) {
throw new EventListenerRegistrationException(
"Listener did not implement expected interface [" + eventType.baseListenerInterface().getName() + "]"
);
}
}
private void internalAppend(T listener) {
checkAgainstBaseInterface( listener );
listeners.add( listener );
}
}