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/*
* Copyright (c) 2004 - 2012 Eike Stepper (Berlin, Germany) and others.
* 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:
* Christian W. Damus (CEA) - initial API and implementation
*/
package org.eclipse.emf.cdo.internal.common.model;
import org.eclipse.emf.cdo.spi.common.model.InternalCDOClassInfo.PersistenceFilter;
import org.eclipse.emf.common.util.BasicEList;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.EStructuralFeature;
import java.util.Collection;
import java.util.Collections;
/**
* Encapsulation of a rule for filtering the persistent values
* of a {@linkplain EStructuralFeature feature} in some model element.
* <p>
* Some models (such as UML's Activity metaclass) require partial persistence
* of features, persisting a subset of the values in a feature that are also
* in some other feature (the filtering feature). Other models may apply other
* transformations to features that require partial or otherwise custom
* persistence rules.
*
* @since 4.2
*/
public class CDOPersistenceFilterImpl implements PersistenceFilter
{
private final EStructuralFeature dependency;
public CDOPersistenceFilterImpl(EStructuralFeature dependency)
{
this.dependency = dependency;
}
public Object getPersistableValue(EObject owner, Object value)
{
if (value instanceof Collection<?>)
{
Collection<?> collection = (Collection<?>)value;
return filter(collection, asCollection(owner.eGet(dependency)));
}
if (asCollection(owner.eGet(dependency)).contains(value))
{
return value;
}
return null;
}
private Collection<?> asCollection(Object value)
{
if (value instanceof Collection<?>)
{
return (Collection<?>)value;
}
if (value == null)
{
return Collections.emptyList();
}
return Collections.singletonList(value);
}
private Collection<?> filter(Collection<?> elements, Collection<?> filter)
{
Collection<?> result = new BasicEList<Object>(elements);
result.retainAll(filter);
return result;
}
}
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