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 }