lucene/highlighter/src/java/org/apache/lucene/search/vectorhighlight/ScoreOrderFragmentsBuilder.java

/*
 * 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.search.vectorhighlight;

import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import org.apache.lucene.search.vectorhighlight.FieldFragList.WeightedFragInfo;

/** An implementation of FragmentsBuilder that outputs score-order fragments. */
public class ScoreOrderFragmentsBuilder extends BaseFragmentsBuilder {

  /** a constructor. */
  public ScoreOrderFragmentsBuilder() {
    super();
  }

  /**
   * a constructor.
   *
   * @param preTags array of pre-tags for markup terms.
   * @param postTags array of post-tags for markup terms.
   */
  public ScoreOrderFragmentsBuilder(String[] preTags, String[] postTags) {
    super(preTags, postTags);
  }

  public ScoreOrderFragmentsBuilder(BoundaryScanner bs) {
    super(bs);
  }

  public ScoreOrderFragmentsBuilder(String[] preTags, String[] postTags, BoundaryScanner bs) {
    super(preTags, postTags, bs);
  }

  /** Sort by score the list of WeightedFragInfo */
  @Override
  public List<WeightedFragInfo> getWeightedFragInfoList(List<WeightedFragInfo> src) {
    Collections.sort(src, new ScoreComparator());
    return src;
  }

  /** Comparator for {@link WeightedFragInfo} by boost, breaking ties by offset. */
  public static class ScoreComparator implements Comparator<WeightedFragInfo> {

    @Override
    public int compare(WeightedFragInfo o1, WeightedFragInfo o2) {
      if (o1.getTotalBoost() > o2.getTotalBoost()) return -1;
      else if (o1.getTotalBoost() < o2.getTotalBoost()) return 1;
      // if same score then check startOffset
      else {
        if (o1.getStartOffset() < o2.getStartOffset()) return -1;
        else if (o1.getStartOffset() > o2.getStartOffset()) return 1;
      }
      return 0;
    }
  }
}