/*******************************************************************************
* Copyright (c) 2008, 2009 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 226765)
* Matthew Hall - bug 230296, 238296
******************************************************************************/
package org.eclipse.jface.internal.databinding.viewers;
import java.util.Iterator;
import org.eclipse.jface.databinding.viewers.IViewerUpdater;
import org.eclipse.jface.util.Util;
import org.eclipse.jface.viewers.IElementComparer;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredViewer;
/**
* NON-API - An interface for updating a viewer's elements.
*
* @since 1.2
*/
public abstract class ViewerUpdater implements IViewerUpdater {
private final StructuredViewer viewer;
/**
* Constructs a ViewerUpdater for updating the specified viewer.
*
* @param viewer
* the viewer which will be updated through this instance.
*/
protected ViewerUpdater(StructuredViewer viewer) {
this.viewer = viewer;
}
public abstract void insert(Object element, int position);
public abstract void remove(Object element, int position);
public void replace(Object oldElement, Object newElement, int position) {
remove(oldElement, position);
insert(newElement, position);
}
public void move(Object element, int oldPosition, int newPosition) {
if (isElementOrderPreserved()) {
IStructuredSelection selection = (IStructuredSelection) viewer
.getSelection();
remove(element, oldPosition);
insert(element, newPosition);
// Preserve selection
if (selectionContains(selection, element)) {
viewer.setSelection(selection);
}
}
}
boolean isElementOrderPreserved() {
return viewer.getComparator() == null
&& viewer.getFilters().length == 0;
}
private boolean selectionContains(IStructuredSelection selection,
Object element) {
if (!selection.isEmpty()) {
IElementComparer comparer = viewer.getComparer();
for (Iterator iter = selection.iterator(); iter.hasNext();) {
Object selectionElement = iter.next();
if (comparer == null ? Util.equals(element, selectionElement)
: comparer.equals(element, selectionElement)) {
return true;
}
}
}
return false;
}
public abstract void add(Object[] elements);
public abstract void remove(Object[] elements);
}