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/* 
 * Copyright 2015 Rhythm & Hues Studios.
 *
 * Licensed 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 com.rhythm.louie.util;

import java.util.List;

/**
 *
 * @author cjohnson
 */
public class Lists {
    private Lists() {}
    
    /**
     * Merges 2 lists as efficiently as possible.  If either argument is null or empty,
     * the other is returned, favoring the first if both are.
     * 
     * If both are non-empty, then the second list is added to the first and the first is returned.
     * 
     * @param 
     * @param first
     * @param second
     * @return returns either the first list or the second list, possibly modifying the first
     */
    public static  List mutableMerge(List first, List second) {
        if (first == null || first.isEmpty()) {
            if (second != null && !second.isEmpty()) {
                return second;
            } else {
                return first;
            }
        } else if (second == null || second.isEmpty()) {
            return first;
        } else {
            first.addAll(second);
            return first;
        }
    }
}