| /******************************************************************************* |
| * Copyright (c) 2008, 2012 Oracle. 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: |
| * Oracle - initial API and implementation |
| ******************************************************************************/ |
| package org.eclipse.jpt.common.core.utility.command; |
| |
| import java.io.Serializable; |
| |
| import org.eclipse.core.runtime.IProgressMonitor; |
| import org.eclipse.core.runtime.IStatus; |
| import org.eclipse.core.runtime.Status; |
| import org.eclipse.jpt.common.utility.internal.StringTools; |
| |
| /** |
| * Simple interface for implementing the GOF Command design pattern in an |
| * Eclipse job. |
| * <p> |
| * Provisional API: This interface is part of an interim API that is still |
| * under development and expected to change significantly before reaching |
| * stability. It is available at this early stage to solicit feedback from |
| * pioneering adopters on the understanding that any code that uses this API |
| * will almost certainly be broken (repeatedly) as the API evolves. |
| */ |
| public interface JobCommand |
| extends InterruptibleJobCommand |
| { |
| /** |
| * Execute the command. The semantics of the command |
| * is determined by the contract between the client and server. |
| * The command should check, as appropriate, whether the specified progress |
| * monitor is {@link IProgressMonitor#isCanceled() "canceled"}; if it is, |
| * the command should return a result |
| * status of severity {@link IStatus#CANCEL}. The singleton |
| * cancel status {@link Status#CANCEL_STATUS} can be used for |
| * this purpose. |
| * <p> |
| * Nested methods can also check the progress monitor |
| * and, if it is "canceled", throw an |
| * {@link org.eclipse.core.runtime.OperationCanceledException OperationCanceledException}. |
| * |
| * @see IProgressMonitor#isCanceled() |
| * @see org.eclipse.core.runtime.jobs.Job#run(IProgressMonitor monitor) |
| */ |
| IStatus execute(IProgressMonitor monitor); |
| |
| |
| /** |
| * Singleton implementation of the job command interface that will do |
| * nothing when executed. |
| */ |
| final class Null |
| implements JobCommand, Serializable |
| { |
| public static final JobCommand INSTANCE = new Null(); |
| public static JobCommand instance() { |
| return INSTANCE; |
| } |
| // ensure single instance |
| private Null() { |
| super(); |
| } |
| public IStatus execute(IProgressMonitor monitor) { |
| return Status.OK_STATUS; |
| } |
| @Override |
| public String toString() { |
| return StringTools.buildSingletonToString(this); |
| } |
| private static final long serialVersionUID = 1L; |
| private Object readResolve() { |
| // replace this object with the singleton |
| return INSTANCE; |
| } |
| } |
| |
| |
| /** |
| * Singleton implementation of the job command interface that will throw an |
| * exception when executed. |
| */ |
| final class Disabled |
| implements JobCommand, Serializable |
| { |
| public static final JobCommand INSTANCE = new Disabled(); |
| public static JobCommand instance() { |
| return INSTANCE; |
| } |
| // ensure single instance |
| private Disabled() { |
| super(); |
| } |
| // throw an exception |
| public IStatus execute(IProgressMonitor monitor) { |
| throw new UnsupportedOperationException(); |
| } |
| @Override |
| public String toString() { |
| return StringTools.buildSingletonToString(this); |
| } |
| private static final long serialVersionUID = 1L; |
| private Object readResolve() { |
| // replace this object with the singleton |
| return INSTANCE; |
| } |
| } |
| } |