/*******************************************************************************
* Copyright (c) 2008, 2015 Matthew Hall and others.
* 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:
* Matthew Hall - initial API and implementation (bug 247997)
* Matthew Hall - bug 264306
* Stefan Xenos <sxenos@gmail.com> - Bug 335792
******************************************************************************/
package org.eclipse.core.databinding.property.list;
import java.util.Collections;
import java.util.List;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.list.IObservableList;
import org.eclipse.core.databinding.observable.list.ListDiff;
import org.eclipse.core.databinding.property.INativePropertyListener;
import org.eclipse.core.databinding.property.ISimplePropertyListener;
/**
* @param <S>
* type of the source object
* @param <E>
* type of the elements in the list
* @since 1.2
*
*/
public abstract class DelegatingListProperty<S, E> extends ListProperty<S, E> {
private final IListProperty<S, E> nullProperty;
private final Object elementType;
protected DelegatingListProperty() {
this(null);
}
protected DelegatingListProperty(Object elementType) {
this.elementType = elementType;
this.nullProperty = new NullListProperty();
}
/**
* Returns the property to delegate to for the specified source object.
* Repeated calls to this method with the same source object returns the
* same delegate instance.
*
* @param source
* the property source (may be null)
* @return the property to delegate to for the specified source object.
*/
public final IListProperty<S, E> getDelegate(S source) {
if (source == null)
return nullProperty;
IListProperty<S, E> delegate = doGetDelegate(source);
if (delegate == null)
delegate = nullProperty;
return delegate;
}
/**
* Returns the property to delegate to for the specified source object.
* Implementers must ensure that repeated calls to this method with the same
* source object returns the same delegate instance.
*
* @param source
* the property source
* @return the property to delegate to for the specified source object.
*/
protected abstract IListProperty<S, E> doGetDelegate(S source);
@Override
public Object getElementType() {
return elementType;
}
@Override
protected List<E> doGetList(S source) {
return getDelegate(source).getList(source);
}
@Override
protected void doSetList(S source, List<E> list) {
getDelegate(source).setList(source, list);
}
@Override
protected void doUpdateList(S source, ListDiff<E> diff) {
getDelegate(source).updateList(source, diff);
}
@Override
public IObservableList<E> observe(S source) {
return getDelegate(source).observe(source);
}
@Override
public IObservableList<E> observe(Realm realm, S source) {
return getDelegate(source).observe(realm, source);
}
private class NullListProperty extends SimpleListProperty<S, E> {
@Override
public Object getElementType() {
return elementType;
}
@Override
protected List<E> doGetList(S source) {
return Collections.emptyList();
}
@Override
protected void doSetList(S source, List<E> list, ListDiff<E> diff) {
}
@Override
protected void doSetList(S source, List<E> list) {
}
@Override
protected void doUpdateList(S source, ListDiff<E> diff) {
}
@Override
public INativePropertyListener<S> adaptListener(ISimplePropertyListener<S, ListDiff<E>> listener) {
return null;
}
}
}