/*******************************************************************************
* Copyright (c) 2005, 2012 IBM Corporation 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:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.bpel.ui.details.providers;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.jface.viewers.ViewerFilter;
/**
* Filter which adds null to the beginning of the list of objects. This is used to show
* a "none" placeholder in combo boxes.
*
* TODO: this might be incompatible with filters that aren't expecting null to appear as
* a model object. We don't use any filters yet though.
*/
public class AddNullFilter extends ViewerFilter {
// note: clients should use AddNullFilter.getInstance()
protected AddNullFilter() {
}
@Override
public Object[] filter(Viewer viewer, Object parent, Object[] elements) {
Object[] result = new Object[elements.length + 1];
result[0] = null;
System.arraycopy(elements, 0, result, 1, elements.length);
return result;
}
@Override
public boolean select(Viewer viewer, Object parentElement, Object element) {
return true;
}
protected static AddNullFilter instance;
public static AddNullFilter getInstance() {
if (instance == null) instance = new AddNullFilter();
return instance;
}
}