Copyright (c) 2000, 2015 IBM Corporation and others.
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:
    IBM Corporation - initial API and implementation
    Stephan Herrmann - Contribution for
							Bug 458577 - IClassFile.getWorkingCopy() may lead to NPE in BecomeWorkingCopyOperation
/*******************************************************************************
 * Copyright (c) 2000, 2015 IBM Corporation and others.
 *
 * 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:
 *     IBM Corporation - initial API and implementation
 *     Stephan Herrmann - Contribution for
 *								Bug 458577 - IClassFile.getWorkingCopy() may lead to NPE in BecomeWorkingCopyOperation
 *******************************************************************************/
package org.eclipse.jdt.internal.core;

import org.eclipse.core.resources.IResource;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IJavaElementDelta;
import org.eclipse.jdt.core.IJavaProject;
import org.eclipse.jdt.core.JavaModelException;

Discards a working copy (decrement its use count and remove its working copy info if the use count is 0)
and signal its removal through a delta.
/**
 * Discards a working copy (decrement its use count and remove its working copy info if the use count is 0)
 * and signal its removal through a delta.
 */
public class DiscardWorkingCopyOperation extends JavaModelOperation {

	public DiscardWorkingCopyOperation(IJavaElement workingCopy) {
		super(new IJavaElement[] {workingCopy});
	}
	@Override
	protected void executeOperation() throws JavaModelException {
		CompilationUnit workingCopy = getWorkingCopy();

		JavaModelManager manager = JavaModelManager.getJavaModelManager();
		int useCount = manager.discardPerWorkingCopyInfo(workingCopy);
		if (useCount == 0) {
			IJavaProject javaProject = workingCopy.getJavaProject();
			if (ExternalJavaProject.EXTERNAL_PROJECT_NAME.equals(javaProject.getElementName())) {
				manager.removePerProjectInfo((JavaProject) javaProject, true /* remove external jar files indexes and timestamps*/);
				manager.containerRemove(javaProject);
			}
			if (!workingCopy.isPrimary()) {
				// report removed java delta for a non-primary working copy
				JavaElementDelta delta = new JavaElementDelta(getJavaModel());
				delta.removed(workingCopy);
				addDelta(delta);
				removeReconcileDelta(workingCopy);
			} else {
				IResource resource = workingCopy.getResource();
				if (resource != null) {
					if (resource.isAccessible()) {
						// report a F_PRIMARY_WORKING_COPY change delta for a primary working copy
						JavaElementDelta delta = new JavaElementDelta(getJavaModel());
						delta.changed(workingCopy, IJavaElementDelta.F_PRIMARY_WORKING_COPY);
						addDelta(delta);
					} else {
						// report a REMOVED delta
						JavaElementDelta delta = new JavaElementDelta(getJavaModel());
						delta.removed(workingCopy, IJavaElementDelta.F_PRIMARY_WORKING_COPY);
						addDelta(delta);
					}
				}
			}
		}
	}
	
Returns the working copy this operation is working on.
/**
	 * Returns the working copy this operation is working on.
	 */
	protected CompilationUnit getWorkingCopy() {
		return (CompilationUnit)getElementToProcess();
	}
	
See Also:
isReadOnly.isReadOnly/**
	 * @see JavaModelOperation#isReadOnly
	 */
	@Override
	public boolean isReadOnly() {
		return true;
	}
}