juneau-core/juneau-marshall/src/main/java/org/apache/juneau/internal/DelegateMap.java

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// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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// ***************************************************************************************************************************
package org.apache.juneau.internal;

import java.util.*;

import org.apache.juneau.*;

/**
 * Represents a wrapped {@link Map} where entries in the map can be removed without affecting the underlying map.
 *
 * @param <T> The class type of the wrapped bean.
 */
@SuppressWarnings("rawtypes")
public class DelegateMap<T extends Map> extends ObjectMap implements Delegate<T> {
	private static final long serialVersionUID = 1L;

	private transient ClassMeta<T> classMeta;

	/**
	 * Constructor.
	 *
	 * @param m The metadata object that created this delegate object.
	 * @param session The current bean session.
	 */
	public DelegateMap(T m, BeanSession session) {
		this.classMeta = session.getClassMetaForObject(m);
		for (Map.Entry e : (Set<Map.Entry>)m.entrySet())
			put(StringUtils.stringify(e.getKey()), e.getValue());
	}

	@Override /* Delegate */
	public ClassMeta<T> getClassMeta() {
		return classMeta;
	}

	/**
	 * Remove all but the specified keys from this map.
	 *
	 * <p>
	 * This does not affect the underlying map.
	 *
	 * @param keys The remaining keys in the map (in the specified order).
	 * @return This object (for method chaining).
	 */
	public DelegateMap<T> filterKeys(List<String> keys) {
		ObjectMap m2 = new ObjectMap();
		for (String k : keys)
			if (containsKey(k))
				m2.put(k, get(k));
		this.clear();
		this.putAll(m2);
		return this;
	}
}