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/***************************************************************************
* Copyright (c) 2004-2007 Eike Stepper, Germany.
* 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:
* Eike Stepper - initial API and implementation
**************************************************************************/
package org.eclipse.internal.net4j.util.registry;
import org.eclipse.net4j.util.registry.IRegistry;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
/**
* Implementation note: AbstractDelegatingRegistry does not preserve the
* "modifyable view" contract of {@link Map#entrySet()} as well as of
* {@link Map#keySet()}, i.e. they are disconnected sets and modifications
* applied to them are not applied to their underlying
* AbstractDelegatingRegistry.
* <p>
*
* @author Eike Stepper
*/
public abstract class AbstractDelegatingRegistry<K, V> extends AbstractRegistry<K, V>
{
private IRegistry<K, V> delegate;
public AbstractDelegatingRegistry(IRegistry<K, V> delegate)
{
this.delegate = delegate;
}
public AbstractDelegatingRegistry(IRegistry<K, V> delegate, boolean autoCommit)
{
super(autoCommit);
this.delegate = delegate;
}
@Override
public V get(Object key)
{
V result = getMap().get(key);
if (result == null && delegate != null)
{
result = delegate.get(key);
}
return result;
}
@Override
public Set<Entry<K, V>> entrySet()
{
return mergedEntrySet();
}
@Override
public Set<K> keySet()
{
return mergedKeySet();
}
@Override
public Collection<V> values()
{
return mergedValues();
}
@Override
protected V register(K key, V value)
{
V delegated = delegate != null ? delegate.get(key) : null;
V old = getMap().put(key, value);
if (old == null)
{
if (delegated != null)
{
// Unhidden delegated element now becomes hidden
getTransaction().rememberDeregistered(key, delegated);
}
getTransaction().rememberRegistered(key, value);
return delegated;
}
else
{
getTransaction().rememberDeregistered(key, old);
getTransaction().rememberRegistered(key, value);
return old;
}
}
@Override
protected V deregister(Object key)
{
V delegated = delegate != null ? delegate.get(key) : null;
V old = getMap().remove(key);
if (old != null)
{
getTransaction().rememberDeregistered(key, old);
if (delegated != null)
{
// Hidden delegated element now becomes unhidden
getTransaction().rememberRegistered((K)key, delegated);
}
}
return old;
}
protected Set<Entry<K, V>> mergedEntrySet()
{
final Map<K, V> merged = new HashMap<K, V>();
if (delegate != null)
{
merged.putAll(delegate);
}
merged.putAll(getMap());
return merged.entrySet();
}
protected Set<K> mergedKeySet()
{
final Set<K> merged = new HashSet<K>();
if (delegate != null)
{
merged.addAll(delegate.keySet());
}
merged.addAll(getMap().keySet());
return merged;
}
protected Collection<V> mergedValues()
{
final List<V> result = new ArrayList<V>();
for (K key : keySet())
{
result.add(get(key));
}
return result;
}
}
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