bundles/org.eclipse.ui.glance/src/org/eclipse/ui/glance/viewers/utils/ViewerUtils.java

/*******************************************************************************
 * Copyright (c) 2017 Exyte
 * 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:
 *     Yuri Strot - initial API and Implementation
 ******************************************************************************/
package org.eclipse.ui.glance.viewers.utils;

import java.lang.reflect.Field;

import org.eclipse.jface.text.ITextViewer;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TypedListener;

public class ViewerUtils {

	public static ITextViewer getTextViewer(StyledText text) {
		return getViewer(ITextViewer.class, text, SWT.Selection);
	}

	public static TreeViewer getTreeViewer(Tree tree) {
		return getViewer(TreeViewer.class, tree, SWT.Expand);
	}

	private static <T> T getViewer(Class<T> clazz, Control control, int event) {
		Listener[] listeners = control.getListeners(event);
		for (Listener listener : listeners) {
			Object lookFor = listener;
			if (listener instanceof TypedListener) {
				lookFor = ((TypedListener) listener).getEventListener();
			}
			try {
				Field this$0 = lookFor.getClass().getDeclaredField("this$0");
				this$0.setAccessible(true);
				Object viewer = this$0.get(lookFor);
				if (clazz.isInstance(viewer)) {
					return clazz.cast(viewer);
				}
			} catch (Exception e) {
				// ignore exceptions
			}
		}
		return null;
	}

}