PlatformElementUtil.java

/*******************************************************************************
 * Copyright (c) 2013, 2014 Obeo 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:
 *     Obeo - initial API and implementation
 *******************************************************************************/
package org.eclipse.emf.compare.ide.ui.internal.util;

import org.eclipse.compare.IResourceProvider;
import org.eclipse.compare.ITypedElement;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.Platform;

/**
 * This provides access to commonly used functions for platform elements, such as adaptation or file lookup.
 * 
 * @author <a href="mailto:laurent.goubet@obeo.fr">Laurent Goubet</a>
 */
public class PlatformElementUtil {
	/**
	 * Try and determine the resource of the given element.
	 * 
	 * @param element
	 *            The element for which we need an {@link IResource}.
	 * @return The resource corresponding to the given {@code element} if we could find it, <code>null</code>
	 *         otherwise.
	 */
	public static IFile findFile(ITypedElement element) {
		if (element == null) {
			return null;
		}

		// Can we adapt it directly?
		IResource resource = adaptAs(element, IResource.class);
		if (resource == null) {
			// We know about some types ...
			if (element instanceof IResourceProvider) {
				resource = ((IResourceProvider)element).getResource();
			}
		}

		if (resource instanceof IFile) {
			return (IFile)resource;
		}
		// Try with IFile in case adapter only checked for class equality
		return adaptAs(element, IFile.class);
	}

	/**
	 * Tries and adapt the given <em>object</em> to an instance of the given class.
	 * 
	 * @param <T>
	 *            Type to which we need to adapt <em>object</em>.
	 * @param object
	 *            The object we need to coerce to a given {@link Class}.
	 * @param clazz
	 *            Class to which we are to adapt <em>object</em>.
	 * @return <em>object</em> cast to type <em>T</em> if possible, <code>null</code> if not.
	 */
	public static <T> T adaptAs(Object object, Class<T> clazz) {
		if (object == null) {
			return null;
		}

		T result = null;
		if (clazz.isInstance(object)) {
			result = clazz.cast(object);
		} else if (object instanceof IAdaptable) {
			result = clazz.cast(((IAdaptable)object).getAdapter(clazz));
		}

		if (result == null) {
			result = clazz.cast(Platform.getAdapterManager().loadAdapter(object, clazz.getName()));
		}

		return result;
	}
}