BasicWeightedSuggestion.java

/* Copyright (2006-2012) Schibsted ASA
 * This file is part of Possom.
 *
 *   Possom is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   Possom is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with Possom.  If not, see <http://www.gnu.org/licenses/>.

 */
package no.sesat.search.result;

import java.lang.ref.Reference;
import java.util.concurrent.ConcurrentHashMap;
import no.sesat.commons.ref.ReferenceMap;
import org.apache.log4j.Logger;

/**
 * <b> Immutable </b>
 *
 * @version <tt>$Id$</tt>
 */
public final class BasicWeightedSuggestion extends BasicSuggestion implements WeightedSuggestion {

    private static final int WEAK_CACHE_INITIAL_CAPACITY = 2000;
    private static final float WEAK_CACHE_LOAD_FACTOR = 0.5f;
    private static final int WEAK_CACHE_CONCURRENCY_LEVEL = 16;

    private static final ReferenceMap<Integer,BasicWeightedSuggestion> WEAK_CACHE
            = new ReferenceMap<Integer,BasicWeightedSuggestion>(
                ReferenceMap.Type.WEAK,
                new ConcurrentHashMap<Integer,Reference<BasicWeightedSuggestion>>(
                    WEAK_CACHE_INITIAL_CAPACITY,
                    WEAK_CACHE_LOAD_FACTOR,
                    WEAK_CACHE_CONCURRENCY_LEVEL));

    private static final Logger LOG = Logger.getLogger(BasicWeightedSuggestion.class);

    private int weight;

    /**
     *
     * @param original
     * @param suggestion
     * @param htmlSuggestion
     * @param weight
     * @return
     */
    public static BasicWeightedSuggestion instanceOf(
            final String original,
            final String suggestion,
            final String htmlSuggestion,
            final int weight){

        final int hashCode = hashCode(original, suggestion, htmlSuggestion, weight);

        BasicWeightedSuggestion bws = WEAK_CACHE.get(hashCode);

        if(null == bws){

            bws = new BasicWeightedSuggestion(original, suggestion, htmlSuggestion, weight);

            WEAK_CACHE.put(hashCode, bws);
        }

        return bws;
    }

    /** TODO comment me. *
     * @param original
     * @param suggestion
     * @param htmlSuggestion
     * @param weight
     */
    protected BasicWeightedSuggestion(
            final String original,
            final String suggestion,
            final String htmlSuggestion,
            final int weight) {

        super(original, suggestion, htmlSuggestion);
        this.weight = weight;
    }

    /** TODO comment me. *
     * @return
     */
    public int getWeight() {
        return weight;
    }

    /** TODO comment me. **/
    @Override
    public String toString() {
        return getOriginal() + " " + getSuggestion() + "(" + getWeight() + ")";
    }


    public int compareTo(WeightedSuggestion o) {
        return o.getWeight() - getWeight();
    }

    @Override
    public boolean equals(Object obj) {

        if( obj instanceof BasicWeightedSuggestion){

            final BasicWeightedSuggestion bws = (BasicWeightedSuggestion)obj;
            return super.equals(bws)
                    && weight == bws.weight;

        }else{
            return super.equals(obj);
        }
    }


    @Override
    public int hashCode() {

        return hashCode(getOriginal(), getSuggestion(), getHtmlSuggestion(), weight);
    }

    private static final int hashCode(
            final String original,
            final String suggestion,
            final String htmlSuggestion,
            final int weight){

        int result = hashCode(original, suggestion, htmlSuggestion);
        result = 37*result + weight;
        return result;
    }
}