QueryScorer Constructor (Query, IndexReader, String)

public QueryScorer(
   Query query,
   IndexReader reader,
   string fieldName
);

query: a Lucene query (ideally rewritten using query.rewrite before being passed to this class and the searcher)
reader: used to compute IDF which can be used to a) score selected fragments better b) use graded highlights eg set font color intensity
fieldName: the field on which Inverse Document Frequency (IDF) calculations are based