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Diffstat (limited to 'plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/internal/util/registry/DelegatingRegistry.java')
-rw-r--r-- | plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/internal/util/registry/DelegatingRegistry.java | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/internal/util/registry/DelegatingRegistry.java b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/internal/util/registry/DelegatingRegistry.java new file mode 100644 index 0000000000..f9e4aa76f1 --- /dev/null +++ b/plugins/org.eclipse.net4j.util/src/org/eclipse/net4j/internal/util/registry/DelegatingRegistry.java @@ -0,0 +1,154 @@ +/*************************************************************************** + * 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.net4j.internal.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 DelegatingRegistry<K, V> extends Registry<K, V> +{ + private IRegistry<K, V> delegate; + + public DelegatingRegistry(IRegistry<K, V> delegate) + { + this.delegate = delegate; + } + + public DelegatingRegistry(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((K)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; + } +} |