org.apache.lucene.search

Class FieldComparator.RelevanceComparator

java.lang.Object

org.apache.lucene.search.FieldComparator<Float>

org.apache.lucene.search.FieldComparator.RelevanceComparator

All Implemented Interfaces:

LeafFieldComparator

Enclosing class:

FieldComparator<T>

public static final class FieldComparator.RelevanceComparator
extends FieldComparator<Float>
implements LeafFieldComparator

Sorts by descending relevance. NOTE: if you are sorting only by descending relevance and then secondarily by ascending docID, performance is faster using TopScoreDocCollector directly (which IndexSearcher.search(org.apache.lucene.search.Query, int) uses when no Sort is specified).

Nested Class Summary

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

FieldComparator.RelevanceComparator, FieldComparator.TermOrdValComparator, FieldComparator.TermValComparator

Constructor Summary

Constructors

Constructor and Description
RelevanceComparator(int numHits) Creates a new comparator based on relevance for numHits.

Method Summary

Modifier and Type	Method and Description
int	compare(int slot1, int slot2) Compare hit at slot1 with hit at slot2.
int	compareBottom(int doc) Compare the bottom of the queue with this doc.
int	compareTop(int doc) Compare the top value with this doc.
int	compareValues(Float first, Float second) Returns a negative integer if first is less than second, 0 if they are equal and a positive integer otherwise.
void	copy(int slot, int doc) This method is called when a new hit is competitive.
LeafFieldComparator	getLeafComparator(LeafReaderContext context) Get a per-segment LeafFieldComparator to collect the given LeafReaderContext.
void	setBottom(int bottom) Set the bottom slot, ie the "weakest" (sorted last) entry in the queue.
void	setScorer(Scorable scorer) Sets the Scorer to use in case a document's score is needed.
void	setTopValue(Float value) Record the top value, for future calls to LeafFieldComparator.compareTop(int).
Float	value(int slot) Return the actual value in the slot.

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

disableSkipping, setSingleSort

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.lucene.search.LeafFieldComparator

competitiveIterator, setHitsThresholdReached

Constructor Detail

RelevanceComparator

public RelevanceComparator(int numHits)

Creates a new comparator based on relevance for numHits.

Method Detail

compare

public int compare(int slot1,
                   int slot2)

Description copied from class: FieldComparator

Compare hit at slot1 with hit at slot2.

Specified by:

compare in class FieldComparator<Float>

Parameters:

slot1 - first slot to compare

slot2 - second slot to compare

Returns:

any N < 0 if slot2's value is sorted after slot1, any N > 0 if the slot2's value is sorted before slot1 and 0 if they are equal

compareBottom

public int compareBottom(int doc)
                  throws IOException

Description copied from interface: LeafFieldComparator

Compare the bottom of the queue with this doc. This will only invoked after setBottom has been called. This should return the same result as FieldComparator.compare(int,int)} as if bottom were slot1 and the new document were slot 2.

For a search that hits many results, this method will be the hotspot (invoked by far the most frequently).

Specified by:

compareBottom in interface LeafFieldComparator

Parameters:

doc - that was hit

Returns:

any N < 0 if the doc's value is sorted after the bottom entry (not competitive), any N > 0 if the doc's value is sorted before the bottom entry and 0 if they are equal.

Throws:

IOException

copy

public void copy(int slot,
                 int doc)
          throws IOException

Description copied from interface: LeafFieldComparator

This method is called when a new hit is competitive. You should copy any state associated with this document that will be required for future comparisons, into the specified slot.

Specified by:

copy in interface LeafFieldComparator

Parameters:

slot - which slot to copy the hit to

doc - docID relative to current reader

Throws:

IOException

getLeafComparator

public LeafFieldComparator getLeafComparator(LeafReaderContext context)

Description copied from class: FieldComparator

Get a per-segment LeafFieldComparator to collect the given LeafReaderContext. All docIDs supplied to this LeafFieldComparator are relative to the current reader (you must add docBase if you need to map it to a top-level docID).

Specified by:

getLeafComparator in class FieldComparator<Float>

Parameters:

context - current reader context

Returns:

the comparator to use for this segment

setBottom

public void setBottom(int bottom)

Description copied from interface: LeafFieldComparator

Set the bottom slot, ie the "weakest" (sorted last) entry in the queue. When LeafFieldComparator.compareBottom(int) is called, you should compare against this slot. This will always be called before LeafFieldComparator.compareBottom(int).

Specified by:

setBottom in interface LeafFieldComparator

Parameters:

bottom - the currently weakest (sorted last) slot in the queue

setTopValue

public void setTopValue(Float value)

Description copied from class: FieldComparator

Record the top value, for future calls to LeafFieldComparator.compareTop(int). This is only called for searches that use searchAfter (deep paging), and is called before any calls to FieldComparator.getLeafComparator(LeafReaderContext).

Specified by:

setTopValue in class FieldComparator<Float>

setScorer

public void setScorer(Scorable scorer)

Description copied from interface: LeafFieldComparator

Sets the Scorer to use in case a document's score is needed.

Specified by:

setScorer in interface LeafFieldComparator

Parameters:

scorer - Scorer instance that you should use to obtain the current hit's score, if necessary.

value

public Float value(int slot)

Description copied from class: FieldComparator

Return the actual value in the slot.

Specified by:

value in class FieldComparator<Float>

Parameters:

slot - the value

Returns:

value in this slot

compareValues

public int compareValues(Float first,
                         Float second)

Description copied from class: FieldComparator

Returns a negative integer if first is less than second, 0 if they are equal and a positive integer otherwise. Default impl to assume the type implements Comparable and invoke .compareTo; be sure to override this method if your FieldComparator's type isn't a Comparable or if your values may sometimes be null

Overrides:

compareValues in class FieldComparator<Float>

compareTop

public int compareTop(int doc)
               throws IOException

Description copied from interface: LeafFieldComparator

Compare the top value with this doc. This will only invoked after setTopValue has been called. This should return the same result as FieldComparator.compare(int,int)} as if topValue were slot1 and the new document were slot 2. This is only called for searches that use searchAfter (deep paging).

Specified by:

compareTop in interface LeafFieldComparator

Parameters:

doc - that was hit

Returns:

any N < 0 if the doc's value is sorted after the top entry (not competitive), any N > 0 if the doc's value is sorted before the top entry and 0 if they are equal.

Throws:

IOException