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/*******************************************************************************
* Copyright (c) 2010 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.common.utility.internal;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;
/**
* This class maintains a {@link Set} of items, and a {@link Map} of keys to those items.
* An item may have multiple keys, but an item may have no keys and remain in the set. Once an
* item's last key is removed, the item is also removed.
*/
public class KeyedSet<K, V> {
private final Set<V> itemSet;
private final Set<V> unmodifiableItemSet;
private final Map<K,V> map;
public KeyedSet() {
this.itemSet = new HashSet<V>();
this.unmodifiableItemSet = Collections.unmodifiableSet(this.itemSet);
this.map = new HashMap<K,V>();
}
/**
* Return an unmodifiable representation of the set of items.
*/
public Set<V> getItemSet() {
return this.unmodifiableItemSet;
}
/**
* Return the item stored under the given key.
*/
public V getItem(K key) {
return this.map.get(key);
}
/**
* Return whether an item is stored under the given key.
*/
public boolean containsKey(K key) {
return this.map.containsKey(key);
}
/**
* Return whether the item is stored under *any* key.
*/
public boolean containsItem(V item) {
return this.itemSet.contains(item);
}
/**
* Add an item to be stored under the given key.
* The item must not already be stored.
*/
public void addItem(K key, V item) {
addItem(item);
addKey(key, item);
}
private void addItem(V item) {
if (item == null) {
throw new IllegalArgumentException();
}
this.itemSet.add(item);
}
/**
* Add an additional key to an item already stored under an alternate key.
*/
public void addKey(K key, V item) {
if (key == null || item == null) {
throw new IllegalArgumentException();
}
if (! this.itemSet.contains(item)) {
throw new IllegalArgumentException();
}
this.map.put(key, item);
}
/**
* Remove the given item and remove any key-to-item mapping it may have.
*/
public boolean removeItem(V item) {
if (this.itemSet.remove(item)) {
for (Map.Entry<K,V> entry : CollectionTools.collection(this.map.entrySet())) {
if (entry.getValue() == item) {
map.remove(entry.getKey());
}
}
return true;
}
return false;
}
/**
* Remove the key-to-item mapping for the given key.
* If it is the last key to the item, also remove the item.
*/
public boolean removeKey(K key) {
final V item = this.map.get(key);
if (item != null) {
this.map.remove(key);
boolean otherKey = false;
for (Map.Entry<K,V> entry : CollectionTools.collection(this.map.entrySet())) {
if (otherKey | entry.getValue() == item) {
otherKey = true;
}
}
if (! otherKey) {
removeItem(item);
}
return true;
}
return false;
}
}
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