001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  You may obtain a copy of the License at                                                              *
006// *                                                                                                                         *
007// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
008// *                                                                                                                         *
009// * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.internal;
014
015import static org.apache.juneau.common.internal.ArgUtils.*;
016
017import java.util.*;
018
019import org.apache.juneau.*;
020
021/**
022 * Wrapper around a map where the key names are overridden.
023 *
024 * <h5 class='section'>See Also:</h5><ul>
025
026 * </ul>
027 *
028 * @param <K> The key class type.
029 * @param <V> The value class type.
030 */
031public final class FilteredMap<K,V> extends AbstractMap<K,V> implements Delegate<Map<K,V>> {
032
033   final Map<K,V> innerMap;
034   final Set<Map.Entry<K,V>> entries;
035   final ClassMeta<Map<K,V>> classMeta;
036
037   /**
038    * Constructor.
039    *
040    * @param classMeta The class type of the map being wrapped.
041    * @param innerMap The map being wrapped.  Must not be <jk>null</jk>.
042    * @param keys The keys in the new map.  Must not be <jk>null</jk>.
043    */
044   public FilteredMap(ClassMeta<Map<K,V>> classMeta, Map<K,V> innerMap, K[] keys) {
045      assertArgNotNull("innerMap", innerMap);
046      assertArgNotNull("keys", keys);
047
048      this.classMeta = classMeta;
049      this.innerMap = innerMap;
050         List<Map.Entry<K,V>> l = new ArrayList<>(keys.length);
051         for (K k : keys)
052            if (innerMap.containsKey(k))
053               l.add(createEntry(k));
054         entries = new ListSet<>(l);
055      }
056
057   private Map.Entry<K,V> createEntry(final K key) {
058      return new Map.Entry<>() {
059
060         @Override /* Map.Entry */
061         public K getKey() {
062            return key;
063         }
064
065         @Override /* Map.Entry */
066         public V getValue() {
067            return innerMap.get(key);
068         }
069
070         @Override /* Map.Entry */
071         public V setValue(V v) {
072            return innerMap.put(key, v);
073         }
074      };
075   }
076
077
078   @Override /* Map */
079   public Set<Map.Entry<K,V>> entrySet() {
080      return entries;
081   }
082
083   /**
084    * A set with ordered entries (a List with a Set API).
085    */
086   private static final class ListSet<E> extends AbstractSet<E> {
087
088      private List<E> entries;
089
090      public ListSet(List<E> entries) {
091         this.entries = entries;
092      }
093
094      @Override /* Set */
095      public Iterator<E> iterator() {
096         return entries.iterator();
097      }
098
099      @Override /* Set */
100      public int size() {
101         return entries.size();
102      }
103   }
104
105   @Override /* Delegate */
106   public ClassMeta<Map<K,V>> getClassMeta() {
107      return classMeta;
108   }
109}