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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.result;
import java.util.Comparator;
/**
* Superclass of hit comparators which delegates comparisons of hits which are
* equal according to this comparator, to a secondary comparator.
*
* @author bratseth
*/
public abstract class ChainableComparator implements Comparator<Hit> {
private final Comparator<Hit> secondaryComparator;
/** Creates this comparator, given a secondary comparator, or null if there is no secondary */
public ChainableComparator(Comparator<Hit> secondaryComparator) {
this.secondaryComparator=secondaryComparator;
}
/** Returns the comparator to use to compare hits which are equal according to this, or null if none */
public Comparator<Hit> getSecondaryComparator() { return secondaryComparator; }
/**
* Returns the comparison form the secondary comparison, or 0 if the secondary is null.
* When overriding this in the subclass, always <code>return super.compare(first,second)</code>
* at the end of the subclass' implementation.
*/
@Override
public int compare(Hit first, Hit second) {
if (secondaryComparator == null) return 0;
return secondaryComparator.compare(first, second);
}
}
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