org.apache.lucene.search
Class ReqOptSumScorer

java.lang.Object
  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 Scorer.skipTo(int).

Constructor Summary

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

Method Summary

int	doc() Returns the current document number matching the query.
Explanation	explain(int doc) Explain the score of a document.
boolean	next() Advances to the document matching this Scorer with the lowest doc Id greater than the current value of Scorer.doc() (or to the matching document with the lowest doc Id if next has never been called on this Scorer).
float	score() Returns the score of the current document matching the query.
boolean	skipTo(int target) Skips to the document matching this Scorer with the lowest doc Id greater than or equal to a given 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: Scorer

Advances to the document matching this Scorer with the lowest doc Id greater than the current value of Scorer.doc() (or to the matching document with the lowest doc Id if next has never been called on this Scorer).

When this method is used the Scorer.explain(int) method should not be used.

Specified by:

next in class Scorer

Returns:

true iff there is another document matching the query.

Throws:

IOException

See Also:

BooleanQuery.setAllowDocsOutOfOrder(boolean)

skipTo

public boolean skipTo(int target)
               throws IOException

Description copied from class: Scorer

Skips to the document matching this Scorer with the lowest doc Id greater than or equal to a given target.

The behavior of this method is undefined if the target specified is less than or equal to the current value of Scorer.doc().

Behaves as if written:

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

Most implementations are considerably more efficient than that.

When this method is used the Scorer.explain(int) method should not be used.

Specified by:

skipTo in class Scorer

Parameters:

target - The target document number.

Returns:

true iff there is such a match.

Throws:

IOException

See Also:

BooleanQuery.setAllowDocsOutOfOrder(boolean)

doc

public int doc()

Description copied from class: Scorer

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

Specified by:

doc in class Scorer

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.