org.apache.lucene.queries.function

Class ValueSourceScorer

java.lang.Object

org.apache.lucene.search.Scorer

org.apache.lucene.queries.function.ValueSourceScorer

public abstract class ValueSourceScorer
extends Scorer

Scorer which returns the result of FunctionValues.floatVal(int) as the score for a document, and which filters out documents that don't match matches(int). This Scorer has a TwoPhaseIterator. This is similar to FunctionQuery, but this one has no Weight normalization factors/multipliers and that one doesn't filter either.

Note: If the scores are needed, then the underlying value will probably be fetched/computed twice -- once to filter and next to return the score. If that's non-trivial then consider wrapping it in an implementation that will cache the current value.

See Also:

FunctionQuery

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.lucene.search.Scorer

Scorer.ChildScorer

Field Summary

Fields

Modifier and Type	Field and Description
protected FunctionValues	values

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

weight

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ValueSourceScorer(LeafReaderContext readerContext, FunctionValues values)

Method Summary

Modifier and Type	Method and Description
int	docID() Returns the doc ID that is currently being scored.
DocIdSetIterator	iterator() Return a DocIdSetIterator over matching documents.
abstract boolean	matches(int doc) Override to decide if this document matches.
float	score() Returns the score of the current document matching the query.
TwoPhaseIterator	twoPhaseIterator() Optional method: Return a TwoPhaseIterator view of this Scorer.

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

getChildren, getWeight

Methods inherited from class java.lang.Object

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

Field Detail

values

protected final FunctionValues values

Constructor Detail

ValueSourceScorer

protected ValueSourceScorer(LeafReaderContext readerContext,
                            FunctionValues values)

Method Detail

matches

public abstract boolean matches(int doc)
                         throws java.io.IOException

Override to decide if this document matches. It's called by TwoPhaseIterator.matches().

Throws:

java.io.IOException

iterator

public DocIdSetIterator iterator()

Description copied from class: Scorer

Return a DocIdSetIterator over matching documents. The returned iterator will either be positioned on -1 if no documents have been scored yet, DocIdSetIterator.NO_MORE_DOCS if all documents have been scored already, or the last document id that has been scored otherwise. The returned iterator is a view: calling this method several times will return iterators that have the same state.

Specified by:

iterator in class Scorer

twoPhaseIterator

public TwoPhaseIterator twoPhaseIterator()

Description copied from class: Scorer

Optional method: Return a TwoPhaseIterator view of this Scorer. A return value of null indicates that two-phase iteration is not supported. Note that the returned TwoPhaseIterator's approximation must advance synchronously with the Scorer.iterator(): advancing the approximation must advance the iterator and vice-versa. Implementing this method is typically useful on Scorers that have a high per-document overhead in order to confirm matches. The default implementation returns null.

Overrides:

twoPhaseIterator in class Scorer

docID

public int docID()

Description copied from class: Scorer

Returns the doc ID that is currently being scored. This will return -1 if the Scorer.iterator() is not positioned or DocIdSetIterator.NO_MORE_DOCS if it has been entirely consumed.

Specified by:

docID in class Scorer

See Also:

DocIdSetIterator.docID()

score

public float score()
            throws java.io.IOException

Description copied from class: Scorer

Returns the score of the current document matching the query. Initially invalid, until DocIdSetIterator.nextDoc() or DocIdSetIterator.advance(int) is called on the Scorer.iterator() the first time, or when called from within LeafCollector.collect(int).

Specified by:

score in class Scorer

Throws:

java.io.IOException