org.apache.lucene.search.spans

Class Spans

java.lang.Object

org.apache.lucene.search.DocIdSetIterator

org.apache.lucene.search.Scorer

org.apache.lucene.search.spans.Spans

Direct Known Subclasses:

FilterSpans, NearSpansOrdered, NearSpansUnordered, PayloadNearQuery.PayloadNearSpanScorer, ScoringWrapperSpans, TermSpans

public abstract class Spans
extends Scorer

Iterates through combinations of start/end positions per-doc. Each start/end position represents a range of term positions within the current document. These are enumerated in order, by increasing document number, within that by increasing start position and finally by increasing end position.

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 Similarity.SimScorer	docScorer
protected float	freq accumulated sloppy freq (computed in setFreqCurrentDoc)
static int	NO_MORE_POSITIONS
protected int	numMatches number of matches (computed in setFreqCurrentDoc)

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

weight

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

NO_MORE_DOCS

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	Spans(SpanWeight weight, Similarity.SimScorer docScorer)

Method Summary

Methods

Modifier and Type	Method and Description
abstract void	collect(SpanCollector collector) Collect postings data from the leaves of the current Spans.
protected void	doCurrentSpans() Called each time the scorer's SpanScorer is advanced during frequency calculation
protected void	doStartCurrentDoc() Called before the current doc's frequency is calculated
abstract int	endPosition() Returns the end position for the current start position, or -1 when nextStartPosition() was not yet called on the current doc.
int	freq() Returns the freq of this Scorer on the current document
abstract int	nextStartPosition() Returns the next start position for the current doc.
abstract float	positionsCost() Return an estimation of the cost of using the positions of this Spans for any single document, but only after Scorer.asTwoPhaseIterator() returned null.
float	score() Returns the score of the current document matching the query.
protected float	scoreCurrentDoc() Score the current doc.
protected void	setFreqCurrentDoc() Sets freq and numMatches for the current document.
float	sloppyFreq() Returns the intermediate "sloppy freq" adjusted for edit distance
abstract int	startPosition() Returns the start position in the current doc, or -1 when nextStartPosition() was not yet called on the current doc.
String	toString()
abstract int	width() Return the width of the match, which is typically used to compute the slop factor.

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

asTwoPhaseIterator, getChildren, getWeight

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

advance, all, cost, docID, empty, nextDoc, slowAdvance

Methods inherited from class java.lang.Object

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

Field Detail

NO_MORE_POSITIONS

public static final int NO_MORE_POSITIONS

See Also:

Constant Field Values

docScorer

protected final Similarity.SimScorer docScorer

freq

protected float freq

accumulated sloppy freq (computed in setFreqCurrentDoc)

numMatches

protected int numMatches

number of matches (computed in setFreqCurrentDoc)

Constructor Detail

Spans

protected Spans(SpanWeight weight,
     Similarity.SimScorer docScorer)

Method Detail

nextStartPosition

public abstract int nextStartPosition()
                               throws IOException

Returns the next start position for the current doc. There is always at least one start/end position per doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

Throws:

IOException

startPosition

public abstract int startPosition()

Returns the start position in the current doc, or -1 when nextStartPosition() was not yet called on the current doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

endPosition

public abstract int endPosition()

Returns the end position for the current start position, or -1 when nextStartPosition() was not yet called on the current doc. After the last start/end position at the current doc this returns NO_MORE_POSITIONS.

width

public abstract int width()

Return the width of the match, which is typically used to compute the slop factor. It is only legal to call this method when the iterator is on a valid doc ID and positioned. The return value must be positive, and lower values means that the match is better.

collect

public abstract void collect(SpanCollector collector)
                      throws IOException

Collect postings data from the leaves of the current Spans. This method should only be called after nextStartPosition(), and before NO_MORE_POSITIONS has been reached.

Parameters:

collector - a SpanCollector

Throws:

IOException

positionsCost

public abstract float positionsCost()

Return an estimation of the cost of using the positions of this Spans for any single document, but only after Scorer.asTwoPhaseIterator() returned null. Otherwise this method should not be called. The returned value is independent of the current document.

toString

public String toString()

Overrides:

toString in class Object

setFreqCurrentDoc

protected final void setFreqCurrentDoc()
                                throws IOException

Sets freq and numMatches for the current document.

This will be called at most once per document.

Throws:

IOException

doStartCurrentDoc

protected void doStartCurrentDoc()
                          throws IOException

Called before the current doc's frequency is calculated

Throws:

IOException

doCurrentSpans

protected void doCurrentSpans()
                       throws IOException

Called each time the scorer's SpanScorer is advanced during frequency calculation

Throws:

IOException

scoreCurrentDoc

protected float scoreCurrentDoc()
                         throws IOException

Score the current doc. The default implementation scores the doc with the similarity using the slop-adjusted freq.

Throws:

IOException

score

public final float score()
                  throws 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 the first time, or when called from within LeafCollector.collect(int).

Specified by:

score in class Scorer

Throws:

IOException

freq

public final int freq()
               throws IOException

Description copied from class: Scorer

Returns the freq of this Scorer on the current document

Specified by:

freq in class Scorer

Throws:

IOException

sloppyFreq

public final float sloppyFreq()
                       throws IOException

Returns the intermediate "sloppy freq" adjusted for edit distance

Throws:

IOException