Added KeyedSet data structure

1 files changed, 129 insertions, 0 deletions

diff --git a/jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/KeyedSet.java b/jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/KeyedSet.java
new file mode 100644
index 0000000000..ead2951d97
--- /dev/null
+++ b/jpa/plugins/org.eclipse.jpt.utility/src/org/eclipse/jpt/utility/internal/KeyedSet.java
@@ -0,0 +1,129 @@
+/*******************************************************************************
+ *  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.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;
+	}
+}