container-search/src/main/java/com/yahoo/search/grouping/request/YmumValue.java


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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.grouping.request;

/**
 * This class represents a document checksum in a {@link GroupingExpression}. It evaluates to the YMUM checksum of the
 * input {@link com.yahoo.search.result.Hit}.
 *
 * @author Simon Thoresen Hult
 * @author bratseth
 */
public class YmumValue extends DocumentValue {

    /**
     * Constructs a new instance of this class.
     */
    public YmumValue() {
        this(null, null);
    }

    private YmumValue(String label, Integer level) {
        super("ymum()", label, level);
    }

    @Override
    public YmumValue copy() {
        return new YmumValue(getLabel(), getLevelOrNull());
    }

}