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/*******************************************************************************
* Copyright (c) 2008 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.utility.internal.model.value;
import org.eclipse.jpt.utility.internal.BidiTransformer;
import org.eclipse.jpt.utility.model.value.WritablePropertyValueModel;
/**
* A <code>TransformationWritablePropertyValueModel</code> wraps another
* <code>WritablePropertyValueModel</code> and uses a <code>BidiTransformer</code>
* to:<ul>
* <li>transform the wrapped value before it is returned by <code>value()</code>
* <li>"reverse-transform" the new value that comes in via
* <code>setValue(Object)</code>
* </ul>
* As an alternative to building a <code>BidiTransformer</code>,
* a subclass of <code>TransformationWritablePropertyValueModel</code> can
* override the <code>transform_(Object)</code> and
* <code>reverseTransform_(Object)</code> methods; or,
* if something other than null should be returned when the wrapped value
* is null or the new value is null, override the <code>transform(Object)</code>
* and <code>reverseTransform(Object)</code> methods.
*/
public class TransformationWritablePropertyValueModel<T1, T2>
extends TransformationPropertyValueModel<T1, T2>
implements WritablePropertyValueModel<T2>
{
// ********** constructors/initialization **********
/**
* Construct a writable property value model with the specified nested
* writable property value model and the default bidi transformer.
* Use this constructor if you want to override the
* <code>transform_(Object)</code> and <code>reverseTransform_(Object)</code>
* (or <code>transform(Object)</code> and <code>reverseTransform(Object)</code>)
* methods instead of building a <code>BidiTransformer</code>.
*/
public TransformationWritablePropertyValueModel(WritablePropertyValueModel<T1> valueHolder) {
super(valueHolder);
}
/**
* Construct a writable property value model with the specified nested
* writable property value model and bidi transformer.
*/
public TransformationWritablePropertyValueModel(WritablePropertyValueModel<T1> valueHolder, BidiTransformer<T1, T2> transformer) {
super(valueHolder, transformer);
}
@Override
protected BidiTransformer<T1, T2> buildTransformer() {
return new DefaultBidiTransformer();
}
// ********** WritablePropertyValueModel implementation **********
public void setValue(T2 value) {
// "reverse-transform" the object before passing it to the the nested value model
this.valueHolder().setValue(this.reverseTransform(value));
}
// ********** behavior **********
/**
* "Reverse-transform" the specified value and return the result.
* This is called by #setValue(Object).
*/
protected T1 reverseTransform(T2 value) {
return this.transformer().reverseTransform(value);
}
/**
* "Reverse-transform" the specified, non-null, value and return the result.
*/
protected T1 reverseTransform_(T2 value) {
throw new UnsupportedOperationException();
}
// ********** queries **********
/**
* Our constructors accept only a WritablePropertyValueModel<T1>.
*/
@SuppressWarnings("unchecked")
protected WritablePropertyValueModel<T1> valueHolder() {
return (WritablePropertyValueModel<T1>) this.valueHolder;
}
/**
* Our constructors accept only a bidirectional transformer.
*/
protected BidiTransformer<T1, T2> transformer() {
return (BidiTransformer<T1, T2>) this.transformer;
}
// ********** default bidi transformer **********
/**
* The default bidi transformer will return null if the wrapped value is null.
* If the wrapped value is not null, it is transformed by a subclass
* implementation of #transform_(Object).
* The default bidi transformer will also return null if the new value is null.
* If the new value is not null, it is reverse-transformed by a subclass
* implementation of #reverseTransform_(Object).
*/
protected class DefaultBidiTransformer
extends DefaultTransformer
implements BidiTransformer<T1, T2>
{
public T1 reverseTransform(T2 value) {
return (value == null) ? null : TransformationWritablePropertyValueModel.this.reverseTransform_(value);
}
}
}
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