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/*******************************************************************************
* Copyright (c) 2007, 2010 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.utility.internal.node;
import org.eclipse.jpt.common.utility.internal.StringTools;
import org.eclipse.jpt.common.utility.internal.SynchronizedBoolean;
/**
* This implementation of the Validator interface implements the
* pause/resume portion of the protocol, but delegates the actual
* validation to a "pluggable" delegate.
*/
public class PluggableValidator
implements Node.Validator
{
private boolean pause;
private boolean validateOnResume;
private final Delegate delegate;
/**
* Convenience factory method.
*/
public static Node.Validator buildAsynchronousValidator(SynchronizedBoolean validateFlag) {
return new PluggableValidator(new AsynchronousValidator(validateFlag));
}
/**
* Convenience factory method.
*/
public static Node.Validator buildSynchronousValidator(Node node) {
return new PluggableValidator(new SynchronousValidator(node));
}
/**
* Construct a validator with the specified delegate.
*/
public PluggableValidator(Delegate delegate) {
super();
this.pause = false;
this.validateOnResume = false;
this.delegate = delegate;
}
public synchronized void validate() {
if (this.pause) {
this.validateOnResume = true;
} else {
this.delegate.validate();
}
}
public synchronized void pause() {
if (this.pause) {
throw new IllegalStateException("already paused"); //$NON-NLS-1$
}
this.pause = true;
}
public synchronized void resume() {
if ( ! this.pause) {
throw new IllegalStateException("not paused"); //$NON-NLS-1$
}
this.pause = false;
// validate any changes that occurred while the validation was paused
if (this.validateOnResume) {
this.validateOnResume = false;
this.delegate.validate();
}
}
@Override
public String toString() {
return StringTools.buildToStringFor(this, this.delegate);
}
// ********** member interface **********
/**
* Interface implemented by any delegates of a pluggable validator.
*/
public interface Delegate {
/**
* The validator is not "paused" - perform the appropriate validation.
*/
void validate();
/**
* This delegate does nothing.
*/
final class Null implements Delegate {
public static final Delegate INSTANCE = new Null();
public static Delegate instance() {
return INSTANCE;
}
// ensure single instance
private Null() {
super();
}
public void validate() {
// do nothing
}
@Override
public String toString() {
return "PluggableValidator.Delegate.Null"; //$NON-NLS-1$
}
}
}
}
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