org.apache.lucene.util

Class ScorerDocQueue

java.lang.Object

org.apache.lucene.util.ScorerDocQueue

public class ScorerDocQueue
extends java.lang.Object

A ScorerDocQueue maintains a partial ordering of its Scorers such that the least Scorer can always be found in constant time. Put()'s and pop()'s require log(size) time. The ordering is by Scorer.doc().

Constructor Summary

Constructors

Constructor and Description
ScorerDocQueue(int maxSize) Create a ScorerDocQueue with a maximum size.

Method Summary

Modifier and Type	Method and Description
void	adjustTop() Should be called when the scorer at top changes doc() value.
void	clear() Removes all entries from the ScorerDocQueue.
boolean	insert(Scorer scorer) Adds a Scorer to the ScorerDocQueue in log(size) time if either the ScorerDocQueue is not full, or not lessThan(scorer, top()).
Scorer	pop() Removes and returns the least scorer of the ScorerDocQueue in log(size) time.
void	put(Scorer scorer) Adds a Scorer to a ScorerDocQueue in log(size) time.
int	size() Returns the number of scorers currently stored in the ScorerDocQueue.
Scorer	top() Returns the least Scorer of the ScorerDocQueue in constant time.
int	topDoc() Returns document number of the least Scorer of the ScorerDocQueue in constant time.
boolean	topNextAndAdjustElsePop()
float	topScore()
boolean	topSkipToAndAdjustElsePop(int target)

Methods inherited from class java.lang.Object

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

Constructor Detail

ScorerDocQueue

public ScorerDocQueue(int maxSize)

Create a ScorerDocQueue with a maximum size.

Method Detail

put

public final void put(Scorer scorer)

Adds a Scorer to a ScorerDocQueue in log(size) time. If one tries to add more Scorers than maxSize a RuntimeException (ArrayIndexOutOfBound) is thrown.

insert

public boolean insert(Scorer scorer)

Adds a Scorer to the ScorerDocQueue in log(size) time if either the ScorerDocQueue is not full, or not lessThan(scorer, top()).

Parameters:

scorer -

Returns:

true if scorer is added, false otherwise.

top

public final Scorer top()

Returns the least Scorer of the ScorerDocQueue in constant time. Should not be used when the queue is empty.

topDoc

public final int topDoc()

Returns document number of the least Scorer of the ScorerDocQueue in constant time. Should not be used when the queue is empty.

topScore

public final float topScore()
                     throws java.io.IOException

Throws:

java.io.IOException

topNextAndAdjustElsePop

public final boolean topNextAndAdjustElsePop()
                                      throws java.io.IOException

Throws:

java.io.IOException

topSkipToAndAdjustElsePop

public final boolean topSkipToAndAdjustElsePop(int target)
                                        throws java.io.IOException

Throws:

java.io.IOException

pop

public final Scorer pop()

Removes and returns the least scorer of the ScorerDocQueue in log(size) time. Should not be used when the queue is empty.

adjustTop

public final void adjustTop()

Should be called when the scorer at top changes doc() value. Still log(n) worst case, but it's at least twice as fast to

  { pq.top().change(); pq.adjustTop(); }
 

instead of

  { o = pq.pop(); o.change(); pq.push(o); }
 

size

public final int size()

Returns the number of scorers currently stored in the ScorerDocQueue.

clear

public final void clear()

Removes all entries from the ScorerDocQueue.