public PhrasePrefixWeight(Searcher searcher) 
{
      this.searcher = searcher;
}

 public Explanation explain(IndexReader reader,
    int doc) throws IOException 
{
      Explanation result = new Explanation();
      result.setDescription("weight("+getQuery()+" in "+doc+"), product of:");
      Explanation idfExpl = new Explanation(idf, "idf("+getQuery()+")");
      // explain query weight
      Explanation queryExpl = new Explanation();
      queryExpl.setDescription("queryWeight(" + getQuery() + "), product of:");
      Explanation boostExpl = new Explanation(getBoost(), "boost");
      if (getBoost() != 1.0f)
        queryExpl.addDetail(boostExpl);
      queryExpl.addDetail(idfExpl);
      Explanation queryNormExpl = new Explanation(queryNorm,"queryNorm");
      queryExpl.addDetail(queryNormExpl);
      queryExpl.setValue(boostExpl.getValue() *
                         idfExpl.getValue() *
                         queryNormExpl.getValue());
      result.addDetail(queryExpl);
      // explain field weight
      Explanation fieldExpl = new Explanation();
      fieldExpl.setDescription("fieldWeight("+getQuery()+" in "+doc+
                               "), product of:");
      Explanation tfExpl = scorer(reader).explain(doc);
      fieldExpl.addDetail(tfExpl);
      fieldExpl.addDetail(idfExpl);
      Explanation fieldNormExpl = new Explanation();
      byte[] fieldNorms = reader.norms(field);
      float fieldNorm =
        fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
      fieldNormExpl.setValue(fieldNorm);
      fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
      fieldExpl.addDetail(fieldNormExpl);
      fieldExpl.setValue(tfExpl.getValue() *
                         idfExpl.getValue() *
                         fieldNormExpl.getValue());
      result.addDetail(fieldExpl);
      // combine them
      result.setValue(queryExpl.getValue() * fieldExpl.getValue());
      if (queryExpl.getValue() == 1.0f)
        return fieldExpl;
      return result;
}

 public Query getQuery() 
{
 return PhrasePrefixQuery.this;
}

 public float getValue() 
{
 return value;
}

 public  void normalize(float queryNorm) 
{
      this.queryNorm = queryNorm;
      queryWeight *= queryNorm;                   // normalize query weight
      value = queryWeight * idf;                  // idf for document
}

 public Scorer scorer(IndexReader reader) throws IOException 
{
      if (termArrays.size() == 0)                  // optimize zero-term case
        return null;
      TermPositions[] tps = new TermPositions[termArrays.size()];
      for (int i=0; i< tps.length; i++) {
        Term[] terms = (Term[])termArrays.get(i);
        TermPositions p;
        if (terms.length  > 1)
          p = new MultipleTermPositions(reader, terms);
        else
          p = reader.termPositions(terms[0]);
        if (p == null)
          return null;
        tps[i] = p;
      }
      if (slop == 0)
        return new ExactPhraseScorer(this, tps, getPositions(), getSimilarity(searcher),
                                     reader.norms(field));
      else
        return new SloppyPhraseScorer(this, tps, getPositions(), getSimilarity(searcher),
                                      slop, reader.norms(field));
}

 public float sumOfSquaredWeights() throws IOException 
{
      Iterator i = termArrays.iterator();
      while (i.hasNext()) {
        Term[] terms = (Term[])i.next();
        for (int j=0; j< terms.length; j++)
          idf += getSimilarity(searcher).idf(terms[j], searcher);
      }
      queryWeight = idf * getBoost();             // compute query weight
      return queryWeight * queryWeight;           // square it
}