org.apache.lucene.search.grouping.function
Class FunctionFirstPassGroupingCollector

java.lang.Object
  org.apache.lucene.search.Collector
      org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector<MutableValue>
          org.apache.lucene.search.grouping.function.FunctionFirstPassGroupingCollector

public class FunctionFirstPassGroupingCollector
extends AbstractFirstPassGroupingCollector<MutableValue>

Concrete implementation of AbstractFirstPassGroupingCollector that groups based on ValueSource instances.

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

Field Summary

Fields inherited from class org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector

orderedGroups

Constructor Summary

FunctionFirstPassGroupingCollector(ValueSource groupByVS, Map<?,?> vsContext, Sort groupSort, int topNGroups)
Creates a first pass collector.

Method Summary

protected MutableValue	copyDocGroupValue(MutableValue groupValue, MutableValue reuse) Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance.
protected MutableValue	getDocGroupValue(int doc) Returns the group value for the specified doc.
void	setNextReader(AtomicReaderContext readerContext)

Methods inherited from class org.apache.lucene.search.grouping.AbstractFirstPassGroupingCollector

acceptsDocsOutOfOrder, collect, getTopGroups, setScorer

Methods inherited from class java.lang.Object

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

Constructor Detail

FunctionFirstPassGroupingCollector

public FunctionFirstPassGroupingCollector(ValueSource groupByVS,
                                          Map<?,?> vsContext,
                                          Sort groupSort,
                                          int topNGroups)
                                   throws IOException

Creates a first pass collector.

Parameters:

groupByVS - The ValueSource instance to group by

vsContext - The ValueSource context

groupSort - The Sort used to sort the groups. The top sorted document within each group according to groupSort, determines how that group sorts against other groups. This must be non-null, ie, if you want to groupSort by relevance use Sort.RELEVANCE.

topNGroups - How many top groups to keep.

Throws:

IOException - When I/O related errors occur

Method Detail

getDocGroupValue

protected MutableValue getDocGroupValue(int doc)

Description copied from class: AbstractFirstPassGroupingCollector

Returns the group value for the specified doc.

Specified by:

getDocGroupValue in class AbstractFirstPassGroupingCollector<MutableValue>

Parameters:

doc - The specified doc

Returns:

the group value for the specified doc

copyDocGroupValue

protected MutableValue copyDocGroupValue(MutableValue groupValue,
                                         MutableValue reuse)

Description copied from class: AbstractFirstPassGroupingCollector

Returns a copy of the specified group value by creating a new instance and copying the value from the specified groupValue in the new instance. Or optionally the reuse argument can be used to copy the group value in.

Specified by:

copyDocGroupValue in class AbstractFirstPassGroupingCollector<MutableValue>

Parameters:

groupValue - The group value to copy

reuse - Optionally a reuse instance to prevent a new instance creation

Returns:

a copy of the specified group value

setNextReader

public void setNextReader(AtomicReaderContext readerContext)
                   throws IOException

Overrides:

setNextReader in class AbstractFirstPassGroupingCollector<MutableValue>

Throws:

IOException