content: package org.apache.solr.search.function.distance;
  /**
   * 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.
   */
  
  import org.apache.solr.search.function.ValueSource;
  import org.apache.solr.search.function.DocValues;
  import org.apache.lucene.index.IndexReader;
  import org.apache.lucene.spatial.geohash.GeoHashUtils;
  
  import java.util.Map;
  import java.io.IOException;
  
  
  /**
   * Takes in a latitude and longitude ValueSource and produces a GeoHash.
   * <p/>
   * Ex: geohash(lat, lon)
   *
   * <p/>
   * Note, there is no reciprocal function for this.
   **/
  public class GeohashFunction extends ValueSource {
    protected ValueSource lat, lon;
  
    public GeohashFunction(ValueSource lat, ValueSource lon) {
      this.lat = lat;
      this.lon = lon;
    }
  
    protected String name() {
      return "geohash";
    }
  
    @Override
    public DocValues getValues(Map context, IndexReader reader) throws IOException {
      final DocValues latDV = lat.getValues(context, reader);
      final DocValues lonDV = lon.getValues(context, reader);
  
  
      return new DocValues() {
  
        @Override
        public String strVal(int doc) {
          return GeoHashUtils.encode(latDV.doubleVal(doc), lonDV.doubleVal(doc));
        }
  
        @Override
        public String toString(int doc) {
          StringBuilder sb = new StringBuilder();
          sb.append(name()).append('(');
          sb.append(latDV.toString(doc)).append(',').append(lonDV.toString(doc));
          sb.append(')');
          return sb.toString();
        }
      };
    }
  
    @Override
    public boolean equals(Object o) {
      if (this == o) return true;
      if (!(o instanceof GeohashFunction)) return false;
  
      GeohashFunction that = (GeohashFunction) o;
  
      if (!lat.equals(that.lat)) return false;
      if (!lon.equals(that.lon)) return false;
  
      return true;
    }
  
    @Override
    public int hashCode() {
      int result = lat.hashCode();
      result = 29 * result - lon.hashCode();
      return result;
    }
  
    @Override  
    public String description() {
      StringBuilder sb = new StringBuilder();
      sb.append(name()).append('(');
      sb.append(lat).append(',').append(lon);
      sb.append(')');
      return sb.toString();
    }
  }
  