OrderedHashMap.java

/*
 * Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

package org.antlr.v4.misc;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/** I need the get-element-i functionality so I'm subclassing
 *  LinkedHashMap.
 */
public class OrderedHashMap<K,V> extends LinkedHashMap<K,V> {
	/** Track the elements as they are added to the set */
	protected List<K> elements = new ArrayList<K>();

	public K getKey(int i) { return elements.get(i); }

	public V getElement(int i) { return get(elements.get(i)); }

	@Override
	public V put(K key, V value) {
		elements.add(key);
		return super.put(key, value);
	}

	@Override
	public void putAll(Map<? extends K, ? extends V> m) {
		for (Map.Entry<? extends K, ? extends V> entry : m.entrySet()) {
			put(entry.getKey(), entry.getValue());
		}
	}

	@Override
	public V remove(Object key) {
		elements.remove(key);
		return super.remove(key);
	}

	@Override
	public void clear() {
		elements.clear();
		super.clear();
	}
}