org.apache.lucene.spatial.prefix.tree.SpatialPrefixTreeFactory.java Source code

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Here is the source code for org.apache.lucene.spatial.prefix.tree.SpatialPrefixTreeFactory.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.lucene.spatial.prefix.tree;

import java.text.ParseException;
import java.util.Map;

import org.apache.lucene.util.Version;
import org.locationtech.spatial4j.context.SpatialContext;
import org.locationtech.spatial4j.distance.DistanceUtils;

/**
 * Abstract Factory for creating {@link SpatialPrefixTree} instances with useful
 * defaults and passed on configurations defined in a Map.
 *
 * @lucene.experimental
 */
public abstract class SpatialPrefixTreeFactory {

    private static final double DEFAULT_GEO_MAX_DETAIL_KM = 0.001;//1m
    public static final String PREFIX_TREE = "prefixTree";
    public static final String MAX_LEVELS = "maxLevels";
    public static final String MAX_DIST_ERR = "maxDistErr";
    public static final String VERSION = "version";

    protected Map<String, String> args;
    protected SpatialContext ctx;
    protected Integer maxLevels;
    private Version version;

    /**
     * The factory is looked up via "prefixTree" in args, expecting "geohash" or "quad".
     * If it's neither of these, then "geohash" is chosen for a geo context, otherwise "quad" is chosen.
     * The "version" arg, if present, is parsed with {@link Version} and the prefix tree might be sensitive to it.
     */
    public static SpatialPrefixTree makeSPT(Map<String, String> args, ClassLoader classLoader, SpatialContext ctx) {
        //TODO refactor to use Java SPI like how Lucene already does for codecs/postingsFormats, etc
        SpatialPrefixTreeFactory instance;
        String cname = args.get(PREFIX_TREE);
        if (cname == null)
            cname = ctx.isGeo() ? "geohash" : "quad";
        if ("geohash".equalsIgnoreCase(cname))
            instance = new GeohashPrefixTree.Factory();
        else if ("quad".equalsIgnoreCase(cname))
            instance = new QuadPrefixTree.Factory();
        else if ("packedQuad".equalsIgnoreCase(cname))
            instance = new PackedQuadPrefixTree.Factory();
        else if ("s2".equalsIgnoreCase(cname))
            instance = new S2PrefixTree.Factory();
        else {
            try {
                Class<?> c = classLoader.loadClass(cname);
                instance = (SpatialPrefixTreeFactory) c.newInstance();
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
        instance.init(args, ctx);
        return instance.newSPT();
    }

    protected void init(Map<String, String> args, SpatialContext ctx) {
        this.args = args;
        this.ctx = ctx;
        initVersion();
        initMaxLevels();
    }

    protected void initVersion() {
        String versionStr = args.get(VERSION);
        try {
            setVersion(versionStr == null ? Version.LATEST : Version.parseLeniently(versionStr));
        } catch (ParseException e) {
            throw new RuntimeException(e);
        }
    }

    protected void initMaxLevels() {
        String mlStr = args.get(MAX_LEVELS);
        if (mlStr != null) {
            maxLevels = Integer.valueOf(mlStr);
            return;
        }

        double degrees;
        String maxDetailDistStr = args.get(MAX_DIST_ERR);
        if (maxDetailDistStr == null) {
            if (!ctx.isGeo()) {
                return;//let default to max
            }
            degrees = DistanceUtils.dist2Degrees(DEFAULT_GEO_MAX_DETAIL_KM, DistanceUtils.EARTH_MEAN_RADIUS_KM);
        } else {
            degrees = Double.parseDouble(maxDetailDistStr);
        }
        maxLevels = getLevelForDistance(degrees);
    }

    /**
     * Set the version of Lucene this tree should mimic the behavior for for analysis.
     */
    public void setVersion(Version v) {
        version = v;
    }

    /**
     * Return the version of Lucene this tree will mimic the behavior of for analysis.
     */
    public Version getVersion() {
        return version;
    }

    /** Calls {@link SpatialPrefixTree#getLevelForDistance(double)}. */
    protected abstract int getLevelForDistance(double degrees);

    protected abstract SpatialPrefixTree newSPT();

}