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 java.util.*;
016
017import org.apache.juneau.*;
018
019/**
020 * Represents a wrapped {@link Map} where entries in the map can be removed without affecting the underlying map.
021 *
022 * @param <T> The class type of the wrapped bean.
023 */
024@SuppressWarnings("rawtypes")
025public class DelegateMap<T extends Map> extends ObjectMap implements Delegate<T> {
026   private static final long serialVersionUID = 1L;
027
028   private transient ClassMeta<T> classMeta;
029
030   /**
031    * Constructor.
032    *
033    * @param m The metadata object that created this delegate object.
034    * @param session The current bean session.
035    */
036   public DelegateMap(T m, BeanSession session) {
037      this.classMeta = session.getClassMetaForObject(m);
038      for (Map.Entry e : (Set<Map.Entry>)m.entrySet())
039         put(StringUtils.stringify(e.getKey()), e.getValue());
040   }
041
042   @Override /* Delegate */
043   public ClassMeta<T> getClassMeta() {
044      return classMeta;
045   }
046
047   /**
048    * Remove all but the specified keys from this map.
049    *
050    * <p>
051    * This does not affect the underlying map.
052    *
053    * @param keys The remaining keys in the map (in the specified order).
054    * @return This object (for method chaining).
055    */
056   public DelegateMap<T> filterKeys(List<String> keys) {
057      ObjectMap m2 = new ObjectMap();
058      for (String k : keys)
059         if (containsKey(k))
060            m2.put(k, get(k));
061      this.clear();
062      this.putAll(m2);
063      return this;
064   }
065}