distancesortsource.java

Local Lucene ==================== Provide geographical based searching to lucene in an efficent ma

/**
 * * Copyright 2007 Patrick O'Leary 
 * Licensed 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 com.pjaol.search.geo.utils;

import java.io.IOException;
import java.util.HashMap;

import org.apache.lucene.index.IndexReader;
import org.apache.lucene.search.Filter;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.ScoreDocComparator;
import org.apache.lucene.search.SortComparatorSource;
import org.apache.lucene.search.SortField;

public class DistanceSortSource implements SortComparatorSource {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	private DistanceFilter distanceFilter;
	
	public DistanceSortSource (Filter distanceFilter){

		this.distanceFilter = (DistanceFilter)distanceFilter;
		
	}
	
	public ScoreDocComparator newComparator(IndexReader reader, String field) throws IOException {
		
		return new DistanceScoreDocLookupComparator(reader, distanceFilter);
	}

	

	private static class DistanceScoreDocLookupComparator implements ScoreDocComparator {

		private HashMap distances;
		private DistanceFilter distanceFilter;
		
		public DistanceScoreDocLookupComparator(IndexReader reader, DistanceFilter distanceFilter) {
			this.distanceFilter = distanceFilter;
			return;
		}
		public int compare(ScoreDoc aDoc, ScoreDoc bDoc) {
			
			if (this.distances == null) {
					distances = distanceFilter.getDistances();
			}
			double a = (Double) distances.get(aDoc.doc);
			double b = (Double) distances.get(bDoc.doc);
			if (a > b) return 1;
			if (a < b )return -1;
			
			return 0;
		}

		public int sortType() {
			return SortField.FLOAT;
		}

		public Comparable sortValue(ScoreDoc iDoc) {
			return (Double)distances.get(iDoc.doc);
		}
		
	}


}