Aggregator.java

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 * Nazgul Project: nazgul-core-algorithms-api
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 * Copyright (C) 2010 - 2017 jGuru Europe AB
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 *      http://www.jguru.se/licenses/jguruCorporateSourceLicense-2.0.txt
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package se.jguru.nazgul.core.algorithms.api.collections.predicate;

/**
 * Generic type aggregator.
 *
 * @author <a href="mailto:lj@jguru.se">Lennart Jörelid</a>, jGuru Europe AB
 */
public interface Aggregator<T, R> {

    /**
     * Performs aggregation of the candidate and the current (aggregate) result.
     *
     * @param candidate The candidate to be reduced / aggregated into the current value.
     * @param current   The current aggregate value. Note that this value is null on the first call to aggregate.
     * @return The result of the aggregate operation between the current result and the provided candidate.
     */
    R aggregate(R current, T candidate);
}