001 /*--------------------------------------------------------------------------+
002 $Id: IdentityPairMap.java 26283 2010-02-18 11:18:57Z juergens $
003 | |
004 | Copyright 2005-2010 Technische Universitaet Muenchen |
005 | |
006 | Licensed under the Apache License, Version 2.0 (the "License"); |
007 | you may not use this file except in compliance with the License. |
008 | You may obtain a copy of the License at |
009 | |
010 | http://www.apache.org/licenses/LICENSE-2.0 |
011 | |
012 | Unless required by applicable law or agreed to in writing, software |
013 | distributed under the License is distributed on an "AS IS" BASIS, |
014 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
015 | See the License for the specific language governing permissions and |
016 | limitations under the License. |
017 +--------------------------------------------------------------------------*/
018 package edu.tum.cs.commons.collections;
019
020 import java.util.IdentityHashMap;
021 import java.util.Map;
022
023 /**
024 * A map using (unordered) pairs as key which are compared by reference.
025 *
026 * @author hummelb
027 * @author $Author: juergens $
028 * @version $Rev: 26283 $
029 * @levd.rating GREEN Hash: 048446DAEE51D1CCA53E05BB3D4283F1
030 */
031 public class IdentityPairMap<T, V> {
032
033 /** Internal storage. */
034 private final Map<T, Map<T, V>> map = new IdentityHashMap<T, Map<T, V>>();
035
036 /** Adds the given value for the given pair. */
037 public void put(ImmutablePair<T, T> pair, V value) {
038 put(pair.getFirst(), pair.getSecond(), value);
039 }
040
041 /** Adds the given value for the given pair. */
042 public void put(T t1, T t2, V value) {
043 insert(t1, t2, value);
044 insert(t2, t1, value);
045 }
046
047 /** Helper method for insertion */
048 private void insert(T t1, T t2, V value) {
049 Map<T, V> m = map.get(t1);
050 if (m == null) {
051 m = new IdentityHashMap<T, V>();
052 map.put(t1, m);
053 }
054 m.put(t2, value);
055 }
056
057 /** Returns whether the pair is contained. */
058 public boolean contains(ImmutablePair<T, T> pair) {
059 return contains(pair.getFirst(), pair.getSecond());
060 }
061
062 /** Returns whether the pair (t1, t2) is contained. */
063 public boolean contains(T t1, T t2) {
064 Map<T, V> m = map.get(t1);
065 if (m == null) {
066 return false;
067 }
068 return m.containsKey(t2);
069 }
070
071 /**
072 * Returns the element stored at the pair or <code>null</code> if not
073 * stored.
074 */
075 public V get(ImmutablePair<T, T> pair) {
076 return get(pair.getFirst(), pair.getSecond());
077 }
078
079 /**
080 * Returns the element stored at pair (t1, t2) or <code>null</code> if not
081 * stored.
082 */
083 public V get(T t1, T t2) {
084 Map<T, V> m = map.get(t1);
085 if (m == null) {
086 return null;
087 }
088 return m.get(t2);
089 }
090
091 /** Clears the map. */
092 public void clear() {
093 map.clear();
094 }
095 }