Package org.apache.lucene.search.grouping

Class AllGroupHeadsCollector<T>

java.lang.Object

org.apache.lucene.search.SimpleCollector

org.apache.lucene.search.grouping.AllGroupHeadsCollector<T>

All Implemented Interfaces:

Collector, LeafCollector

public abstract class AllGroupHeadsCollector<T>
extends SimpleCollector

This collector specializes in collecting the most relevant document (group head) for each group that matches the query.

Clients should create new collectors by calling newCollector(GroupSelector, Sort)

WARNING: This API is experimental and might change in incompatible ways in the next release.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	AllGroupHeadsCollector.GroupHead<T>	Represents a group head.

Field Summary

Fields

Modifier and Type	Field	Description
protected final int	compIDXEnd
protected LeafReaderContext	context
protected Map<T,AllGroupHeadsCollector.GroupHead<T>>	heads
protected final int[]	reversed
protected Scorable	scorer
protected final Sort	sort

Method Summary

Modifier and Type	Method	Description
void	collect(int doc)
protected void	doSetNextReader(LeafReaderContext context)
protected Collection<? extends AllGroupHeadsCollector.GroupHead<T>>	getCollectedGroupHeads()	Returns the collected group heads.
int	groupHeadsSize()
static <T> AllGroupHeadsCollector<T>	newCollector(GroupSelector<T> selector, Sort sort)	Create a new AllGroupHeadsCollector based on the type of within-group Sort required
protected abstract AllGroupHeadsCollector.GroupHead<T>	newGroupHead(int doc, T value, LeafReaderContext context, Scorable scorer)	Create a new GroupHead for the given group value, initialized with a doc, context and scorer
int[]	retrieveGroupHeads()
FixedBitSet	retrieveGroupHeads(int maxDoc)
ScoreMode	scoreMode()
void	setScorer(Scorable scorer)

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

getLeafCollector

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.Collector

setWeight

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

collect, collectRange, competitiveIterator, finish

Field Details

sort

protected final Sort sort

reversed

protected final int[] reversed

compIDXEnd

protected final int compIDXEnd

heads

protected Map<T,AllGroupHeadsCollector.GroupHead<T>> heads

context

protected LeafReaderContext context

scorer

protected Scorable scorer

Method Details

newCollector

public static <T> AllGroupHeadsCollector<T> newCollector(GroupSelector<T> selector,
 Sort sort)

Create a new AllGroupHeadsCollector based on the type of within-group Sort required

Type Parameters:

T - the group value type

Parameters:

selector - a GroupSelector to define the groups

sort - the within-group sort to use to choose the group head document

retrieveGroupHeads

public FixedBitSet retrieveGroupHeads(int maxDoc)

Parameters:

maxDoc - The maxDoc of the top level IndexReader.

Returns:

a FixedBitSet containing all group heads.

retrieveGroupHeads

public int[] retrieveGroupHeads()

Returns:

an int array containing all group heads. The size of the array is equal to number of collected unique groups.

groupHeadsSize

public int groupHeadsSize()

Returns:

the number of group heads found for a query.

getCollectedGroupHeads

protected Collection<? extends AllGroupHeadsCollector.GroupHead<T>> getCollectedGroupHeads()

Returns the collected group heads. Subsequent calls should return the same group heads.

Returns:

the collected group heads

collect

public void collect(int doc)
             throws IOException

Specified by:

collect in interface LeafCollector

Specified by:

collect in class SimpleCollector

Throws:

IOException

scoreMode

public ScoreMode scoreMode()

doSetNextReader

protected void doSetNextReader(LeafReaderContext context)
                        throws IOException

Overrides:

doSetNextReader in class SimpleCollector

Throws:

IOException

setScorer

public void setScorer(Scorable scorer)
               throws IOException

Specified by:

setScorer in interface LeafCollector

Overrides:

setScorer in class SimpleCollector

Throws:

IOException

newGroupHead

protected abstract AllGroupHeadsCollector.GroupHead<T> newGroupHead(int doc,
 T value,
 LeafReaderContext context,
 Scorable scorer)
                                                             throws IOException

Create a new GroupHead for the given group value, initialized with a doc, context and scorer

Throws:

IOException