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.internal.ThrowableUtils.*;
016
017import java.util.*;
018
019import org.apache.juneau.*;
020
021/**
022 * Wrapper around a map where the key names are overridden.
023 *
024 * @param <K> The key class type.
025 * @param <V> The value class type.
026 */
027public final class FilteredMap<K,V> extends AbstractMap<K,V> implements Delegate<Map<K,V>> {
028
029   final Map<K,V> innerMap;
030   final Set<Map.Entry<K,V>> entries;
031   final ClassMeta<Map<K,V>> classMeta;
032
033   /**
034    * Constructor.
035    *
036    * @param classMeta The class type of the map being wrapped.
037    * @param innerMap The map being wrapped.  Must not be <jk>null</jk>.
038    * @param keys The keys in the new map.  Must not be <jk>null</jk>.
039    */
040   public FilteredMap(ClassMeta<Map<K,V>> classMeta, Map<K,V> innerMap, K[] keys) {
041      assertFieldNotNull(innerMap, "innerMap");
042      assertFieldNotNull(keys, "keys");
043
044      this.classMeta = classMeta;
045      this.innerMap = innerMap;
046         List<Map.Entry<K,V>> l = new ArrayList<>(keys.length);
047         for (K k : keys)
048            if (innerMap.containsKey(k))
049               l.add(createEntry(k));
050         entries = new ListSet<>(l);
051      }
052
053   private Map.Entry<K,V> createEntry(final K key) {
054      return new Map.Entry<K,V>() {
055
056         @Override /* Map.Entry */
057         public K getKey() {
058            return key;
059         }
060
061         @Override /* Map.Entry */
062         public V getValue() {
063            return innerMap.get(key);
064         }
065
066         @Override /* Map.Entry */
067         public V setValue(V v) {
068            return innerMap.put(key, v);
069         }
070      };
071   }
072
073
074   @Override /* Map */
075   public Set<Map.Entry<K,V>> entrySet() {
076      return entries;
077   }
078
079   /**
080    * A set with ordered entries (a List with a Set API).
081    */
082   private static final class ListSet<E> extends AbstractSet<E> {
083
084      private List<E> entries;
085
086      public ListSet(List<E> entries) {
087         this.entries = entries;
088      }
089
090      @Override /* Set */
091      public Iterator<E> iterator() {
092         return entries.iterator();
093      }
094
095      @Override /* Set */
096      public int size() {
097         return entries.size();
098      }
099   }
100
101   @Override /* Delegate */
102   public ClassMeta<Map<K,V>> getClassMeta() {
103      return classMeta;
104   }
105}