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/*******************************************************************************
 * Copyright (C) 2018, Antonin Delpeuch
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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package com.google.refine.clustering.knn;

import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import edu.mit.simile.vicino.distances.LevenshteinDistance;
import edu.mit.simile.vicino.distances.PPMDistance;

/**
 * Registry of distances for kNN clustering.
 * 
 * @author Antonin Delpeuch
 */
public class DistanceFactory {

    static final protected Map _distances = new HashMap<>();
    // We cannot derive this from the hashmap as the order matters
    private static List _distanceNames = new LinkedList<>();

    static {
        put("levenshtein", new VicinoDistance(new LevenshteinDistance()));
        put("ppm", new VicinoDistance(new PPMDistance()));

        // Distances not activated as they are not very useful:
        // See https://github.com/OpenRefine/OpenRefine/pull/1906
        /*
         * put("jaccard", new VicinoDistance(new JaccardDistance())); put("jaro", new VicinoDistance(new
         * JaroDistance())); put("jaro-winkler", new VicinoDistance(new JaroWinklerDistance()));
         * put("jaro-winkler-tfidf", new VicinoDistance(new JaroWinklerTFIDFDistance())); put("gzip", new
         * VicinoDistance(new GZipDistance())); put("bzip2", new VicinoDistance(new BZip2Distance()));
         */
    }

    /**
     * Returns the distance registered under this name, or null if it does not exist.
     */
    public static SimilarityDistance get(String name) {
        return _distances.get(name);
    }

    /**
     * Registers a new distance under a name.
     */
    public static void put(String name, SimilarityDistance distance) {
        _distances.put(name, distance);
        _distanceNames.add(name);
    }

    /**
     * Lists the available distances, by name.
     */
    public static List getDistanceNames() {
        return Collections.unmodifiableList(_distanceNames);
    }
}