PhraseNode.java

/**
 * 
 */
package com.browseengine.bobo.search.section;

import java.io.IOException;

import org.apache.lucene.index.IndexReader;

/**
 * Phrase operator node for SectionSearchQUeryPlan
 *
 */
public class PhraseNode extends AndNode {
  private TermNode[] _termNodes;
  private int _curPos;

  public PhraseNode(TermNode[] termNodes, IndexReader reader) throws IOException {
    super(termNodes);
    _termNodes = termNodes;
  }

  @Override
  public int fetchDoc(int targetDoc) throws IOException {
    _curPos = -1;
    return super.fetchDoc(targetDoc);
  }

  @Override
  public int fetchSec(int targetSec) throws IOException {
    TermNode firstNode = _termNodes[0];

    while (fetchPos() < SectionSearchQueryPlan.NO_MORE_POSITIONS) {
      int secId = firstNode.readSecId();
      if (secId >= targetSec) {
        targetSec = secId;
        boolean matched = true;
        for (int i = 1; i < _termNodes.length; i++) {
          matched = (targetSec == _termNodes[i].readSecId());
          if (!matched) break;
        }
        if (matched) {
          _curSec = targetSec;
          return _curSec;
        }
      }
    }
    _curSec = SectionSearchQueryPlan.NO_MORE_SECTIONS;
    return _curSec;
  }

  @Override
  protected int fetchPos() throws IOException {
    int targetPhrasePos = _curPos + 1;

    int i = 0;
    while (i < _termNodes.length) {
      TermNode node = _termNodes[i];
      int targetTermPos = (targetPhrasePos + node._positionInPhrase);
      while (node._curPos < targetTermPos) {
        if (node.fetchPos() == SectionSearchQueryPlan.NO_MORE_POSITIONS) {
          _curPos = SectionSearchQueryPlan.NO_MORE_POSITIONS;
          return _curPos;
        }
      }
      if (node._curPos == targetTermPos) {
        i++;
      } else {
        targetPhrasePos = node._curPos - i;
        i = 0;
      }
    }
    _curPos = targetPhrasePos;
    return _curPos;
  }
}