Content of file ECPObserverCall.java

/*******************************************************************************
 * Copyright (c) 2011-2012 EclipseSource Muenchen GmbH and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 * wesendon - initial API and implementation
 *
 *******************************************************************************/

package org.eclipse.emf.ecp.internal.core.util.observer;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.emf.ecp.core.util.observer.ECPObserver;

/**
 * ProxyObserver, returned by the {@link ECPObserverBusImpl} when calling {@link ECPObserverBusImpl#notify(Class)},
 * normally it
 * has
 * the type of the class extending IObserver in order to call the observer interface with type safety.
 * However, the same proxies can be casted into {@link ECPObserverCall} in order to access the results by all registered
 * observers.
 *
 * @author wesendon
 *
 */
public interface ECPObserverCall {

	/**
	 * Returns the results of each notified observer. This method will always return the returns from the last call
	 * executed on the proxy.
	 *
	 * @return list of results
	 */
	List<Result> getObserverCallResults();

	/**
	 * This class represents an result from an observer call. It contains the observer, the called method and the result
	 * or an exception, if occured.
	 *
	 *
	 * @author wesendon
	 *
	 */
	class Result {

		private final ECPObserver observer;
		private final Method method;
		private final Object result;
		private final Throwable exception;

		/**
		 * This constructor is used if <b>NO</b> exception occurred.
		 *
		 * @param observer observer
		 * @param method method
		 * @param result result
		 */
		public Result(ECPObserver observer, Method method, Object result) {
			this.observer = observer;
			this.method = method;
			this.result = result;
			exception = null;
		}

		/**
		 * This constructor is used if an exception <b>HAS</b> occurred.
		 *
		 * @param observer observer
		 * @param e exception
		 * @param method method
		 */
		public Result(ECPObserver observer, Throwable e, Method method) {
			this.observer = observer;
			exception = e;
			this.method = method;
			result = null;
		}

		/**
		 * Specifies whether this Result contains an exception.
		 *
		 * @return boolean
		 */
		public boolean exceptionOccurred() {
			return exception != null;
		}

		/**
		 * .
		 *
		 * @return exception or null
		 */
		public Throwable getException() {
			return exception;
		}

		/**
		 * The observer.
		 *
		 * @return this can't be null
		 */
		public ECPObserver getObserver() {
			return observer;
		}

		/**
		 * The result.
		 *
		 * @return the result or null
		 */
		public Object getResult() {
			return result;
		}

		/**
		 * Returns the result or the default value for primitive types.
		 *
		 * @return result, null or in case of primitive type, the default value.
		 */
		public Object getResultOrDefaultValue() {
			Object result = getResult();
			if (result == null) {
				result = getDefaultValue(method);
			}
			return result;
		}

		/**
		 * Returns the default value for a given method. Which is null or the default primitive value.
		 *
		 * @param m method
		 * @return null or default primitive value
		 */
		public static Object getDefaultValue(Method m) {
			if (m.getReturnType().isPrimitive()) {
				return DEFAULTPRIMITIVEVALUES.get(m.getReturnType().getSimpleName());
			}
			return null;
		}

		private static final Map<String, Object> DEFAULTPRIMITIVEVALUES = new HashMap<String, Object>();

		static {
			DEFAULTPRIMITIVEVALUES.put("int", new Integer(0)); //$NON-NLS-1$
			DEFAULTPRIMITIVEVALUES.put("boolean", new Boolean(false)); //$NON-NLS-1$
			DEFAULTPRIMITIVEVALUES.put("long", new Long(0)); //$NON-NLS-1$
			DEFAULTPRIMITIVEVALUES.put("float", new Float(0)); //$NON-NLS-1$
			DEFAULTPRIMITIVEVALUES.put("double", new Double(0)); //$NON-NLS-1$
			DEFAULTPRIMITIVEVALUES.put("byte", Byte.MIN_VALUE); //$NON-NLS-1$
			DEFAULTPRIMITIVEVALUES.put("short", Short.MIN_VALUE); //$NON-NLS-1$
		}
	}
}