Package org.apache.lucene.search.grouping

Class GroupSelector<T>

java.lang.Object

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

Type Parameters:

T - the type of the group value

Direct Known Subclasses:

DoubleRangeGroupSelector, LongRangeGroupSelector, TermGroupSelector, ValueSourceGroupSelector

public abstract class GroupSelector<T>
extends Object

Defines a group, for use by grouping collectors

A GroupSelector acts as an iterator over documents. For each segment, clients should call setNextReader(LeafReaderContext), and then advanceTo(int) for each matching document.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	GroupSelector.State	What to do with the current value

Constructor Summary

Constructors

Constructor	Description
GroupSelector()

Method Summary

Modifier and Type	Method	Description
abstract GroupSelector.State	advanceTo(int doc)	Advance the GroupSelector's iterator to the given document
abstract T	copyValue()
abstract T	currentValue()	Get the group value of the current document
abstract void	setGroups(Collection<SearchGroup<T>> groups)	Set a restriction on the group values returned by this selector
abstract void	setNextReader(LeafReaderContext readerContext)	Set the LeafReaderContext
abstract void	setScorer(Scorable scorer)	Set the current Scorer

Methods inherited from class java.lang.Object

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

Constructor Details

GroupSelector

public GroupSelector()

Method Details

setNextReader

public abstract void setNextReader(LeafReaderContext readerContext)
                            throws IOException

Set the LeafReaderContext

Throws:

IOException

setScorer

public abstract void setScorer(Scorable scorer)
                        throws IOException

Set the current Scorer

Throws:

IOException

advanceTo

public abstract GroupSelector.State advanceTo(int doc)
                                       throws IOException

Advance the GroupSelector's iterator to the given document

Throws:

IOException

currentValue

public abstract T currentValue()
                        throws IOException

Get the group value of the current document

N.B. this object may be reused, for a persistent version use copyValue()

Throws:

IOException

copyValue

public abstract T copyValue()
                     throws IOException

Returns:

a copy of the group value of the current document

Throws:

IOException

setGroups

public abstract void setGroups(Collection<SearchGroup<T>> groups)

Set a restriction on the group values returned by this selector

If the selector is positioned on a document whose group value is not contained within this set, then advanceTo(int) will return GroupSelector.State.SKIP

Parameters:

groups - a set of SearchGroup objects to limit selections to