org.apache.solr.common.util.SimpleOrderedMap.java Source code

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Here is the source code for org.apache.solr.common.util.SimpleOrderedMap.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.solr.common.util;

import java.util.*;

/** <code>SimpleOrderedMap</code> is a {@link NamedList} where access by key is more
 * important than maintaining order when it comes to representing the
 * held data in other forms, as ResponseWriters normally do.
 * It's normally not a good idea to repeat keys or use null keys, but this
 * is not enforced.  If key uniqueness enforcement is desired, use a regular {@link Map}.
 * <p>
 * For example, a JSON response writer may choose to write a SimpleOrderedMap
 * as {"foo":10,"bar":20} and may choose to write a NamedList as
 * ["foo",10,"bar",20].  An XML response writer may choose to render both
 * the same way.
 * </p>
 * <p>
 * This class does not provide efficient lookup by key, its main purpose is
 * to hold data to be serialized.  It aims to minimize overhead and to be
 * efficient at adding new elements.
 * </p>
 */
public class SimpleOrderedMap<T> extends NamedList<T> {
    /** Creates an empty instance */
    public SimpleOrderedMap() {
        super();
    }

    public SimpleOrderedMap(int sz) {
        super(sz);
    }

    /**
     * Creates an instance backed by an explicitly specified list of
     * pairwise names/values.
     *
     * <p>
     * TODO: this method was formerly public, now that it's not we can change the impl details of 
     * this class to be based on a Map.Entry[] 
     * </p>
     *
     * @param nameValuePairs underlying List which should be used to implement a SimpleOrderedMap; modifying this List will affect the SimpleOrderedMap.
     * @lucene.internal
     */
    private SimpleOrderedMap(List<Object> nameValuePairs) {
        super(nameValuePairs);
    }

    public SimpleOrderedMap(Map.Entry<String, T>[] nameValuePairs) {
        super(nameValuePairs);
    }

    @Override
    public SimpleOrderedMap<T> clone() {
        ArrayList<Object> newList = new ArrayList<>(nvPairs.size());
        newList.addAll(nvPairs);
        return new SimpleOrderedMap<>(newList);
    }
}