Package org.apache.lucene.search

Class TopScoreDocCollector

java.lang.Object

org.apache.lucene.search.Collector

org.apache.lucene.search.TopDocsCollector<ScoreDoc>

org.apache.lucene.search.TopScoreDocCollector

public abstract class TopScoreDocCollector
extends TopDocsCollector<ScoreDoc>

A Collector implementation that collects the top-scoring hits, returning them as a TopDocs. This is used by IndexSearcher to implement TopDocs-based search. Hits are sorted by score descending and then (when the scores are tied) docID ascending. When you create an instance of this collector you should know in advance whether documents are going to be collected in doc Id order or not.

NOTE: The values Float.NaN and Float.NEGATIVE_INFINITY are not valid scores. This collector will not properly collect hits with such scores.

Field Summary

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

EMPTY_TOPDOCS, pq, totalHits

Method Summary

Modifier and Type	Method	Description
static TopScoreDocCollector	create(int numHits, boolean docsScoredInOrder)	Creates a new TopScoreDocCollector given the number of hits to collect and whether documents are scored in order by the input Scorer to setScorer(Scorer).
static TopScoreDocCollector	create(int numHits, ScoreDoc after, boolean docsScoredInOrder)	Creates a new TopScoreDocCollector given the number of hits to collect, the bottom of the previous page, and whether documents are scored in order by the input Scorer to setScorer(Scorer).
protected TopDocs	newTopDocs(ScoreDoc[] results, int start)	Returns a TopDocs instance containing the given results.
void	setNextReader(AtomicReaderContext context)	Called before collecting from each AtomicReaderContext.
void	setScorer(Scorer scorer)	Called before successive calls to Collector.collect(int).

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

getTotalHits, populateResults, topDocs, topDocs, topDocs, topDocsSize

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

acceptsDocsOutOfOrder, collect

Methods inherited from class java.lang.Object

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

Method Detail

create

public static TopScoreDocCollector create(int numHits,
                                          boolean docsScoredInOrder)

Creates a new TopScoreDocCollector given the number of hits to collect and whether documents are scored in order by the input Scorer to setScorer(Scorer).

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

create

public static TopScoreDocCollector create(int numHits,
                                          ScoreDoc after,
                                          boolean docsScoredInOrder)

Creates a new TopScoreDocCollector given the number of hits to collect, the bottom of the previous page, and whether documents are scored in order by the input Scorer to setScorer(Scorer).

NOTE: The instances returned by this method pre-allocate a full array of length numHits, and fill the array with sentinel objects.

newTopDocs

protected TopDocs newTopDocs(ScoreDoc[] results,
                             int start)

Description copied from class: TopDocsCollector

Returns a TopDocs instance containing the given results. If results is null it means there are no results to return, either because there were 0 calls to collect() or because the arguments to topDocs were invalid.

Overrides:

newTopDocs in class TopDocsCollector<ScoreDoc>

setNextReader

public void setNextReader(AtomicReaderContext context)

Description copied from class: Collector

Called before collecting from each AtomicReaderContext. All doc ids in Collector.collect(int) will correspond to IndexReaderContext.reader(). Add AtomicReaderContext.docBase to the current IndexReaderContext.reader()'s internal document id to re-base ids in Collector.collect(int).

Specified by:

setNextReader in class Collector

Parameters:

context - next atomic reader context

setScorer

public void setScorer(Scorer scorer)
               throws IOException

Description copied from class: Collector

Called before successive calls to Collector.collect(int). Implementations that need the score of the current document (passed-in to Collector.collect(int)), should save the passed-in Scorer and call scorer.score() when needed.

Specified by:

setScorer in class Collector

Throws:

IOException