lucene/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldFragList.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.ArrayList;
import java.util.List;
import org.apache.lucene.search.vectorhighlight.FieldPhraseList.WeightedPhraseInfo;
import org.apache.lucene.search.vectorhighlight.FieldPhraseList.WeightedPhraseInfo.Toffs;

/**
 * FieldFragList has a list of "frag info" that is used by FragmentsBuilder class to create
 * fragments (snippets).
 */
public abstract class FieldFragList {

  private List<WeightedFragInfo> fragInfos = new ArrayList<>();

  /**
   * a constructor.
   *
   * @param fragCharSize the length (number of chars) of a fragment
   */
  public FieldFragList(int fragCharSize) {}

  /**
   * convert the list of WeightedPhraseInfo to WeightedFragInfo, then add it to the fragInfos
   *
   * @param startOffset start offset of the fragment
   * @param endOffset end offset of the fragment
   * @param phraseInfoList list of WeightedPhraseInfo objects
   */
  public abstract void add(int startOffset, int endOffset, List<WeightedPhraseInfo> phraseInfoList);

  /**
   * return the list of WeightedFragInfos.
   *
   * @return fragInfos.
   */
  public List<WeightedFragInfo> getFragInfos() {
    return fragInfos;
  }

  /** List of term offsets + weight for a frag info */
  public static class WeightedFragInfo {

    private List<SubInfo> subInfos;
    private float totalBoost;
    private int startOffset;
    private int endOffset;

    public WeightedFragInfo(
        int startOffset, int endOffset, List<SubInfo> subInfos, float totalBoost) {
      this.startOffset = startOffset;
      this.endOffset = endOffset;
      this.totalBoost = totalBoost;
      this.subInfos = subInfos;
    }

    public List<SubInfo> getSubInfos() {
      return subInfos;
    }

    public float getTotalBoost() {
      return totalBoost;
    }

    public int getStartOffset() {
      return startOffset;
    }

    public int getEndOffset() {
      return endOffset;
    }

    @Override
    public String toString() {
      StringBuilder sb = new StringBuilder();
      sb.append("subInfos=(");
      for (SubInfo si : subInfos) sb.append(si.toString());
      sb.append(")/")
          .append(totalBoost)
          .append('(')
          .append(startOffset)
          .append(',')
          .append(endOffset)
          .append(')');
      return sb.toString();
    }

    /** Represents the list of term offsets for some text */
    public static class SubInfo {
      private final String text; // unnecessary member, just exists for debugging purpose
      // usually termsOffsets.size() == 1,
      // but if position-gap > 1 and slop > 0 then size() could be greater than 1
      private final List<Toffs> termsOffsets;
      private final int seqnum;
      private final float boost; // used for scoring split WeightedPhraseInfos.

      public SubInfo(String text, List<Toffs> termsOffsets, int seqnum, float boost) {
        this.text = text;
        this.termsOffsets = termsOffsets;
        this.seqnum = seqnum;
        this.boost = boost;
      }

      public List<Toffs> getTermsOffsets() {
        return termsOffsets;
      }

      public int getSeqnum() {
        return seqnum;
      }

      public String getText() {
        return text;
      }

      public float getBoost() {
        return boost;
      }

      @Override
      public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(text).append('(');
        for (Toffs to : termsOffsets) sb.append(to.toString());
        sb.append(')');
        return sb.toString();
      }
    }
  }
}