org.apache.lucene.search

Class Scorer

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.search.Scorer

Direct Known Subclasses:

ConstantScoreQuery.ConstantScorer, ScoreCachingWrappingScorer, SpanScorer

public abstract class Scorer
extends DocIdSetIterator

Expert: Common scoring functionality for different types of queries.

A Scorer iterates over documents matching a query in increasing order of doc Id.

Document scores are computed using a given Similarity implementation.

NOTE: The values Float.Nan, Float.NEGATIVE_INFINITY and Float.POSITIVE_INFINITY are not valid scores. Certain collectors (eg TopScoreDocCollector) will not properly collect hits with these scores.

See Also:

BooleanQuery.setAllowDocsOutOfOrder(boolean)

Field Summary

Fields inherited from class org.apache.lucene.search.DocIdSetIterator

NO_MORE_DOCS

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Scorer(Similarity similarity) Constructs a Scorer.

Method Summary

Methods

Modifier and Type	Method and Description
Explanation	explain(int doc) Deprecated. Please use IndexSearcher.explain(org.apache.lucene.search.Weight, int) or Weight.explain(org.apache.lucene.index.IndexReader, int) instead.
Similarity	getSimilarity() Returns the Similarity implementation used by this scorer.
abstract float	score() Returns the score of the current document matching the query.
void	score(Collector collector) Scores and collects all matching documents.
protected boolean	score(Collector collector, int max, int firstDocID) Expert: Collects matching documents in a range.
void	score(HitCollector hc) Deprecated. use score(Collector) instead.
protected boolean	score(HitCollector hc, int max) Deprecated. use score(Collector, int, int) instead.

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

advance, doc, docID, next, nextDoc, skipTo

Methods inherited from class java.lang.Object

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

Constructor Detail

Scorer

protected Scorer(Similarity similarity)

Constructs a Scorer.

Parameters:

similarity - The Similarity implementation used by this scorer.

Method Detail

getSimilarity

public Similarity getSimilarity()

Returns the Similarity implementation used by this scorer.

score

public void score(HitCollector hc)
           throws IOException

Deprecated. use score(Collector) instead.

Scores and collects all matching documents.

Parameters:

hc - The collector to which all matching documents are passed through HitCollector.collect(int, float).
When this method is used the explain(int) method should not be used.

Throws:

IOException

score

public void score(Collector collector)
           throws IOException

Scores and collects all matching documents.

Parameters:

collector - The collector to which all matching documents are passed.
When this method is used the explain(int) method should not be used.

Throws:

IOException

score

protected boolean score(HitCollector hc,
            int max)
                 throws IOException

Deprecated. use score(Collector, int, int) instead.

Expert: Collects matching documents in a range. Hook for optimization. Note that DocIdSetIterator.next() must be called once before this method is called for the first time.

Parameters:

hc - The collector to which all matching documents are passed through HitCollector.collect(int, float).

max - Do not score documents past this.

Returns:

true if more matching documents may remain.

Throws:

IOException

score

protected boolean score(Collector collector,
            int max,
            int firstDocID)
                 throws IOException

Expert: Collects matching documents in a range. Hook for optimization. Note, firstDocID is added to ensure that DocIdSetIterator.nextDoc() was called before this method.

Parameters:

collector - The collector to which all matching documents are passed.

max - Do not score documents past this.

firstDocID - The first document ID (ensures DocIdSetIterator.nextDoc() is called before this method.

Returns:

true if more matching documents may remain.

Throws:

IOException

score

public abstract float score()
                     throws IOException

Returns the score of the current document matching the query. Initially invalid, until DocIdSetIterator.next() or DocIdSetIterator.skipTo(int) is called the first time, or when called from within Collector.collect(int).

Throws:

IOException

explain

public Explanation explain(int doc)
                    throws IOException

Deprecated. Please use IndexSearcher.explain(org.apache.lucene.search.Weight, int) or Weight.explain(org.apache.lucene.index.IndexReader, int) instead.

Returns an explanation of the score for a document.
When this method is used, the DocIdSetIterator.next(), DocIdSetIterator.skipTo(int) and score(HitCollector) methods should not be used.

Parameters:

doc - The document number for the explanation.

Throws:

IOException