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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.BidiFilter;
import org.eclipse.jpt.utility.model.value.WritablePropertyValueModel;
/**
* A <code>FilteringWritablePropertyValueModel</code> wraps another
* <code>WritabelPropertyValueModel</code> and uses a <code>BidiFilter</code>
* to determine when the wrapped value is to be returned by calls
* to <code>value()</code> and modified by calls to
* <code>setValue(Object)</code>.
* <p>
* As an alternative to building a <code>BidiFilter</code>, a subclass
* of <code>FilteringWritablePropertyValueModel</code> can override the
* <code>accept(Object)</code> and <code>reverseAccept(Object)</code>
* methods.
* <p>
* One, possibly undesirable, side-effect of using this value model is that
* it must return *something* as the value. The default behavior is
* to return <code>null</code> whenever the wrapped value is not "accepted",
* which can be configured and/or overridden.
* <p>
* Similarly, if an incoming value is not "reverseAccepted", *nothing* will passed
* through to the wrapped value holder, not even <code>null</code>.
*/
public class FilteringWritablePropertyValueModel<T>
extends FilteringPropertyValueModel<T>
implements WritablePropertyValueModel<T>
{
// ********** constructors **********
/**
* Construct a property value model with the specified nested
* property value model and a disabled filter.
* Use this constructor if you want to override the
* <code>accept(Object)</code> and <code>reverseAccept(Object)</code>
* methods instead of building a <code>BidiFilter</code>.
* The default value will be <code>null</code>.
*/
public FilteringWritablePropertyValueModel(WritablePropertyValueModel<T> valueHolder) {
this(valueHolder, BidiFilter.Disabled.<T>instance(), null);
}
/**
* Construct a property value model with the specified nested
* property value model, specified default value, and a disabled filter.
* Use this constructor if you want to override the
* <code>accept(Object)</code> and <code>reverseAccept(Object)</code>
* methods instead of building a <code>BidiFilter</code>
* <em>and</em> you need to specify
* a default value other than <code>null</code>.
*/
public FilteringWritablePropertyValueModel(WritablePropertyValueModel<T> valueHolder, T defaultValue) {
this(valueHolder, BidiFilter.Disabled.<T>instance(), defaultValue);
}
/**
* Construct an property value model with the specified nested
* property value model and filter.
* The default value will be <code>null</code>.
*/
public FilteringWritablePropertyValueModel(WritablePropertyValueModel<T> valueHolder, BidiFilter<T> filter) {
this(valueHolder, filter, null);
}
/**
* Construct an property value model with the specified nested
* property value model, filter, and default value.
*/
public FilteringWritablePropertyValueModel(WritablePropertyValueModel<T> valueHolder, BidiFilter<T> filter, T defaultValue) {
super(valueHolder, filter, defaultValue);
}
// ********** WritablePropertyValueModel implementation **********
public void setValue(T value) {
if (this.reverseAccept(value)) {
this.valueHolder().setValue(value);
}
}
// ********** queries **********
/**
* Return whether the <code>FilteringWritablePropertyValueModel</code>
* should pass through the specified value to the nested
* writable property value model in a call to the
* <code>setValue(Object)</code> method
* <p>
* This method can be overridden by a subclass as an
* alternative to building a <code>BidiFilter</code>.
*/
protected boolean reverseAccept(T value) {
return this.getFilter().reverseAccept(value);
}
/**
* Our constructors accept only a WritablePropertyValueModel<T>.
*/
@SuppressWarnings("unchecked")
protected WritablePropertyValueModel<T> valueHolder() {
return (WritablePropertyValueModel<T>) this.valueHolder;
}
/**
* Our constructors accept only a bidirectional filter.
*/
protected BidiFilter<T> getFilter() {
return (BidiFilter<T>) this.filter;
}
}
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