/** 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;
}
}
*/
}