platform/util/src/com/intellij/util/containers/BidirectionalMap.java

/*
 * Copyright 2000-2009 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.intellij.util.containers;

import gnu.trove.THashMap;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.*;

public class BidirectionalMap<K,V> implements Map<K,V>{
  private final Map<K,V> myKeyToValueMap = new THashMap<K,V>();
  private final Map<V,List<K>> myValueToKeysMap = new THashMap<V,List<K>>();

  @Override
  public V put(K key, V value){
    V oldValue = myKeyToValueMap.put(key, value);
    if (oldValue != null){
      if (oldValue.equals(value)) return oldValue;
      List<K> array = myValueToKeysMap.get(oldValue);
      array.remove(key);
    }

    List<K> array = myValueToKeysMap.get(value);
    if (array == null){
      array = new ArrayList<K>();
      myValueToKeysMap.put(value, array);
    }
    array.add(key);
    return oldValue;
  }

  @Override
  public void clear() {
    myKeyToValueMap.clear();
    myValueToKeysMap.clear();
  }

  @Nullable
  public List<K> getKeysByValue(V value){
    return myValueToKeysMap.get(value);
  }

  @NotNull
  @Override
  public Set<K> keySet() {
    return myKeyToValueMap.keySet();
  }

  @Override
  public int size(){
    return myKeyToValueMap.size();
  }

  @Override
  public boolean isEmpty(){
    return myKeyToValueMap.isEmpty();
  }

  @Override
  public boolean containsKey(Object key){
    return myKeyToValueMap.containsKey(key);
  }                                                               

  @Override
  @SuppressWarnings({"SuspiciousMethodCalls"})
  public boolean containsValue(Object value){
    return myValueToKeysMap.containsKey(value);
  }

  @Override
  public V get(Object key) {
    return myKeyToValueMap.get(key);
  }

  public void removeValue(V v) {
    List<K> ks = myValueToKeysMap.remove(v);
    if (ks != null) {
      for (K k : ks) {
        myKeyToValueMap.remove(k);
      }
    }
  }

  @Override
  @SuppressWarnings({"SuspiciousMethodCalls"})
  public V remove(Object key){
    final V value = myKeyToValueMap.remove(key);
    final List<K> ks = myValueToKeysMap.get(value);
    if (ks != null) {
      if(ks.size() > 1) ks.remove(key);
      else myValueToKeysMap.remove(value);
    }
    return value;
  }

  @Override
  public void putAll(@NotNull Map<? extends K, ? extends V> t){
    for (final K k1 : t.keySet()) {
      put(k1, t.get(k1));
    }
  }

  @NotNull
  @Override
  public Collection<V> values(){
    return myValueToKeysMap.keySet();
  }

  @NotNull
  @Override
  public Set<Entry<K, V>> entrySet(){
    return myKeyToValueMap.entrySet();
  }

  @Override
  public String toString() {
    return new HashMap<K,V>(myKeyToValueMap).toString();
  }
}