Package it.unimi.di.big.mg4j.search.score

Class AbstractScorer

java.lang.Object

it.unimi.di.big.mg4j.search.score.AbstractScorer

All Implemented Interfaces:

Scorer, FlyweightPrototype<Scorer>

Direct Known Subclasses:

AbstractWeightedScorer, ConstantScorer, DecreasingDocumentRankScorer, DocumentRankScorer

public abstract class AbstractScorer
extends Object
implements Scorer

An abstract implementation of Scorer. It provides internal caching of the underlying document iterator during wrapping, and a nextDocument() method that delegates to the underlying document iterator (implementing subclasses that do not alter this behaviour should implement DelegatingScorer). The setWeights(Reference2DoubleMap) method simply returns false.

Field Summary

Fields

Modifier and Type	Field	Description
protected DocumentIterator	documentIterator	The current document iterator.
protected IndexIterator[]	indexIterator	In case the current iterator is just made of one or more index iterators.

Constructor Summary

Constructors

Constructor	Description
AbstractScorer()

Method Summary

Modifier and Type	Method	Description
Reference2DoubleMap<Index>	getWeights()	Returns an empty map.
long	nextDocument()	Returns the next document provided by this scorer, or -1 if no more documents are available.
boolean	setWeights(Reference2DoubleMap<Index> index2Weight)	Returns false.
void	wrap(DocumentIterator documentIterator)	Wraps the given document iterator.

Methods inherited from class java.lang.Object

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

Methods inherited from interface it.unimi.di.big.mg4j.search.score.Scorer

copy, score, score, usesIntervals

Field Detail

documentIterator

protected DocumentIterator documentIterator

The current document iterator.

indexIterator

protected IndexIterator[] indexIterator

In case the current iterator is just made of one or more index iterators. This field can be used by implementing subclasses to perform optimized evaluations that do not rely on visitors).

Constructor Detail

AbstractScorer

public AbstractScorer()

Method Detail

wrap

public void wrap(DocumentIterator documentIterator)
          throws IOException

Wraps the given document iterator.

This method records internally the provided iterator.

Specified by:

wrap in interface Scorer

Parameters:

documentIterator - the document iterator that will be used in subsequent calls to Scorer.score() and Scorer.score(Index).

Throws:

IOException

setWeights

public boolean setWeights(Reference2DoubleMap<Index> index2Weight)

Returns false.

Specified by:

setWeights in interface Scorer

Parameters:

index2Weight - a map from indices to weights.

Returns:

true if this scorer supports weights.

getWeights

public Reference2DoubleMap<Index> getWeights()

Returns an empty map.

Specified by:

getWeights in interface Scorer

Returns:

a copy of the weight map of this scorer.

nextDocument

public long nextDocument()
                  throws IOException

Description copied from interface: Scorer

Returns the next document provided by this scorer, or -1 if no more documents are available.

Specified by:

nextDocument in interface Scorer

Returns:

the next document, or -1 if no more documents are available.

Throws:

IOException