org.apache.lucene.search
Class ReqOptSumScorer

java.lang.Object
  org.apache.lucene.search.DocIdSetIterator
      org.apache.lucene.search.Scorer
          org.apache.lucene.search.ReqOptSumScorer

public class ReqOptSumScorer
extends Scorer

A Scorer for queries with a required part and an optional part. Delays skipTo() on the optional part until a score() is needed.
This Scorer implements DocIdSetIterator.skipTo(int).

Constructor Summary

ReqOptSumScorer(Scorer reqScorer, Scorer optScorer)
Construct a ReqOptScorer.

Method Summary

int	doc() Returns the current document number.
Explanation	explain(int doc) Explain the score of a document.
boolean	next() Moves to the next docId in the set.
float	score() Returns the score of the current document matching the query.
boolean	skipTo(int target) Skips entries to the first beyond the current whose document number is greater than or equal to target.

Methods inherited from class org.apache.lucene.search.Scorer

getSimilarity, score, score

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReqOptSumScorer

public ReqOptSumScorer(Scorer reqScorer,
                       Scorer optScorer)

Construct a ReqOptScorer.

Parameters:

reqScorer - The required scorer. This must match.

optScorer - The optional scorer. This is used for scoring only.

Method Detail

next

public boolean next()
             throws IOException

Description copied from class: DocIdSetIterator

Moves to the next docId in the set. Returns true, iff there is such a docId.

Specified by:

next in class DocIdSetIterator

Throws:

IOException

skipTo

public boolean skipTo(int target)
               throws IOException

Description copied from class: DocIdSetIterator

Skips entries to the first beyond the current whose document number is greater than or equal to target.

Returns true iff there is such an entry.

Behaves as if written:

   boolean skipTo(int target) {
     do {
       if (!next())
         return false;
     } while (target > doc());
     return true;
   }
 

Some implementations are considerably more efficient than that.

Specified by:

skipTo in class DocIdSetIterator

Throws:

IOException

doc

public int doc()

Description copied from class: DocIdSetIterator

Returns the current document number.

This is invalid until DocIdSetIterator.next() is called for the first time.

Specified by:

doc in class DocIdSetIterator

score

public float score()
            throws IOException

Returns the score of the current document matching the query. Initially invalid, until next() is called the first time.

Specified by:

score in class Scorer

Returns:

The score of the required scorer, eventually increased by the score of the optional scorer when it also matches the current document.

Throws:

IOException

explain

public Explanation explain(int doc)
                    throws IOException

Explain the score of a document.

Specified by:

explain in class Scorer

Parameters:

doc - The document number for the explanation.

Throws:

IOException

To Do:

Also show the total score. See BooleanScorer.explain() on how to do this.