content: /** 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.tier;
  
  import java.util.Map;
  import java.util.WeakHashMap;
  import java.util.HashMap;
  import java.io.IOException;
  import java.io.ObjectInputStream;
  
  import org.apache.lucene.search.Filter;
  import org.apache.lucene.spatial.tier.DistanceHandler.Precision;
  
  /**
   * <p><font color="red"><b>NOTE:</b> This API is still in
   * flux and might change in incompatible ways in the next
   * release.</font>
   */
  public abstract class DistanceFilter extends Filter {
  
    final protected Filter startingFilter;
    protected Precision precise;
    protected Map<Integer,Double> distances;
    protected double distance;
  
    protected int nextDocBase; 
    protected transient WeakHashMap<String,Double> distanceLookupCache;
  
    /** Filters the startingFilter by precise distance
     *  checking filter */
    public DistanceFilter(Filter startingFilter, double distance) {
      if (startingFilter == null) {
        throw new IllegalArgumentException("please provide a non-null startingFilter; you can use QueryWrapperFilter(MatchAllDocsQuery) as a no-op filter");
      }
      this.startingFilter = startingFilter;
      this.distance = distance;
  
      // NOTE: neither of the distance filters use precision
      // now - if we turn that on, we'll need to pass top
      // reader into here
      // setPrecision(reader.maxDoc());
  
      /* store calculated distances for reuse by other components */
      distances = new HashMap<Integer,Double>();
  
      // create an intermediate cache to avoid recomputing
      //   distances for the same point 
      //   TODO: Why is this a WeakHashMap? 
      distanceLookupCache = new WeakHashMap<String,Double>();
    }
  
    /** needed for deserialization, because the cache is transient */
    private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
      stream.defaultReadObject();
      distanceLookupCache = new WeakHashMap<String,Double>();
    }
  
    public Map<Integer,Double> getDistances(){
      return distances;
    }
    
    public Double getDistance(int docid){
      return distances.get(docid);
    }
    
    public void setDistances(Map<Integer, Double> distances) {
      this.distances = distances;
    }
  
    /** You must call this before re-using this DistanceFilter
     *  across searches */
    public void reset() {
      nextDocBase = 0;
    }
  
    /** Returns true if <code>o</code> is equal to this. */
    @Override
    public abstract boolean equals(Object o);
  
    /** Returns a hash code value for this object.*/
    @Override
    public abstract int hashCode();
  
    /*
    private void setPrecision(int maxDocs) {
      precise = Precision.EXACT;
      
      if (maxDocs > 1000 && distance > 10) {
        precise = Precision.TWENTYFEET;
      }
      
      if (maxDocs > 10000 && distance > 10){
        precise = Precision.TWOHUNDREDFEET;
      }
    }
    */
  }
  