/*
* Hibernate, Relational Persistence for Idiomatic Java
*
* Copyright (c) 2011, Red Hat, Inc. and/or its affiliates or third-party contributors as
* indicated by the @author tags or express copyright attribution
* statements applied by the authors. All third-party contributions are
* distributed under license by Red Hat, Inc.
*
* This copyrighted material is made available to anyone wishing to use, modify,
* copy, or redistribute it subject to the terms and conditions of the GNU
* Lesser General Public License, as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
* for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this distribution; if not, write to:
* Free Software Foundation, Inc.
* 51 Franklin Street, Fifth Floor
* Boston, MA 02110-1301 USA
*/
package org.hibernate.search.query.collector.impl;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.Term;
import org.apache.lucene.index.TermEnum;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.Scorer;
import org.hibernate.search.query.dsl.impl.DiscreteFacetRequest;
import org.hibernate.search.query.dsl.impl.FacetRange;
import org.hibernate.search.query.dsl.impl.FacetingRequestImpl;
import org.hibernate.search.query.dsl.impl.RangeFacetImpl;
import org.hibernate.search.query.dsl.impl.RangeFacetRequest;
import org.hibernate.search.query.facet.Facet;
import org.hibernate.search.query.facet.FacetSortOrder;
import org.hibernate.search.query.fieldcache.impl.FieldCacheLoadingType;
import org.hibernate.search.query.fieldcache.impl.FieldLoadingStrategy;
import static org.hibernate.search.util.impl.CollectionHelper.newArrayList;
import static org.hibernate.search.util.impl.CollectionHelper.newHashMap;
/**
* A custom {@code Collector} used for handling facet requests.
*
* @author Hardy Ferentschik
*/
public class FacetCollector extends Collector {
/**
* The next collector in the delegation chain
*/
private final Collector nextInChainCollector;
/**
* Facet request this collector handles
*/
private final FacetingRequestImpl facetRequest;
/**
* Used to load field values from the Lucene field cache
*/
private final FieldLoadingStrategy fieldLoader;
/**
* A counter mapped to the field name for which it is counting
*/
private final FacetCounter facetCounts;
/**
* Flag indicating whether the data structure has been initialised. Initialisation happens on the first call
* to {@link #setNextReader(org.apache.lucene.index.IndexReader, int)}.
*/
private boolean initialised = false;
public FacetCollector(Collector nextInChainCollector, FacetingRequestImpl facetRequest) {
this.nextInChainCollector = nextInChainCollector;
this.facetRequest = facetRequest;
this.facetCounts = createFacetCounter( facetRequest );
fieldLoader = FieldCacheLoadingType.getLoadingStrategy(
this.facetRequest.getFieldName(), this.facetRequest.getFieldCacheType()
);
}
@Override
public void setNextReader(IndexReader reader, int docBase) throws IOException {
if ( !initialised ) {
initialiseCollector( reader );
}
initialiseFieldCaches( reader );
nextInChainCollector.setNextReader( reader, docBase );
}
@Override
public void collect(int doc) throws IOException {
Object value = fieldLoader.collect( doc );
if ( value != null ) {
facetCounts.countValue( value );
}
nextInChainCollector.collect( doc );
}
@Override
public void setScorer(Scorer scorer) throws IOException {
nextInChainCollector.setScorer( scorer );
}
@Override
public boolean acceptsDocsOutOfOrder() {
return nextInChainCollector.acceptsDocsOutOfOrder();
}
public String getFacetName() {
return facetRequest.getFacetingName();
}
public List<Facet> getFacetList() {
return createSortedFacetList( facetCounts, facetRequest );
}
private List<Facet> createSortedFacetList(FacetCounter counter, FacetingRequestImpl request) {
List<Facet> facetList;
// handle RANGE_DEFINITION_ODER differently from count based orders. we try to avoid the creation of
// Facet instances which we can only do for count based ordering
if ( FacetSortOrder.RANGE_DEFINITION_ODER.equals( request.getSort() ) ) {
facetList = createRangeFacetList( counter.getCounts().entrySet(), request, counter.getCounts().size() );
Collections.sort( facetList, new RangeDefinitionOrderFacetComparator( ) );
if ( facetRequest.getMaxNumberOfFacets() > 0 ) {
facetList = facetList.subList( 0, Math.min( facetRequest.getMaxNumberOfFacets(), facetList.size() ) );
}
}
else {
List<Map.Entry<String, Integer>> countEntryList = newArrayList();
for ( Entry<String, Integer> stringIntegerEntry : counter.getCounts().entrySet() ) {
countEntryList.add( stringIntegerEntry );
}
int facetCount = facetRequest.getMaxNumberOfFacets() > 0 ?
facetRequest.getMaxNumberOfFacets() : countEntryList.size();
Collections.sort( countEntryList, new FacetEntryComparator( request.getSort() ) );
facetList = createRangeFacetList( countEntryList, request, facetCount );
}
return facetList;
}
private List<Facet> createRangeFacetList(Collection<Entry<String, Integer>> countEntryList, FacetingRequestImpl request, int count) {
List<Facet> facetList = newArrayList();
int includedFacetCount = 0;
for ( Map.Entry<String, Integer> countEntry : countEntryList ) {
Facet facet = request.createFacet( countEntry.getKey(), countEntry.getValue() );
if ( !request.hasZeroCountsIncluded() && facet.getCount() == 0 ) {
continue;
}
facetList.add( facet );
includedFacetCount++;
if ( includedFacetCount == count ) {
break;
}
}
return facetList;
}
private void initialiseCollector(IndexReader reader) throws IOException {
// we only need to initialise the counts in case we have to include 0 counts as well
if ( facetRequest.hasZeroCountsIncluded() && facetRequest instanceof DiscreteFacetRequest ) {
initFacetCounts( reader );
}
initialised = true;
}
private void initialiseFieldCaches(IndexReader reader) throws IOException {
fieldLoader.loadNewCacheValues( reader );
}
private <N extends Number> FacetCounter createFacetCounter(FacetingRequestImpl request) {
if ( request instanceof DiscreteFacetRequest ) {
return new SimpleFacetCounter();
}
else if ( request instanceof RangeFacetRequest ) {
@SuppressWarnings("unchecked")
RangeFacetRequest<N> rangeFacetRequest = (RangeFacetRequest<N>) request;
return new RangeFacetCounter<N>( rangeFacetRequest );
}
else {
throw new IllegalArgumentException( "Unsupported cache type" );
}
}
private void initFacetCounts(IndexReader reader) throws IOException {
String fieldName = facetRequest.getFieldName();
// term are enumerated by field name and within field names by term value
TermEnum terms = reader.terms( new Term( fieldName, "" ) );
try {
while ( fieldName.equals( terms.term().field() ) ) {
String fieldValue = terms.term().text();
facetCounts.initCount( fieldValue );
if ( !terms.next() ) {
break;
}
}
}
finally {
terms.close();
}
}
static public class FacetEntryComparator implements Comparator<Entry<String, Integer>> {
private final FacetSortOrder sortOder;
public FacetEntryComparator(FacetSortOrder sortOrder) {
this.sortOder = sortOrder;
}
public int compare(Entry<String, Integer> entry1, Entry<String, Integer> entry2) {
if ( FacetSortOrder.COUNT_ASC.equals( sortOder ) ) {
return entry1.getValue() - entry2.getValue();
}
else if ( FacetSortOrder.COUNT_DESC.equals( sortOder ) ) {
return entry2.getValue() - entry1.getValue();
}
else {
return entry1.getKey().compareTo( entry2.getKey() );
}
}
}
static public class RangeDefinitionOrderFacetComparator implements Comparator<Facet> {
public int compare(Facet facet1, Facet facet2) {
return ( (RangeFacetImpl) facet1 ).getRangeIndex() - ( (RangeFacetImpl) facet2 ).getRangeIndex();
}
}
static public abstract class FacetCounter {
private Map<String, Integer> counts = newHashMap();
Map<String, Integer> getCounts() {
return counts;
}
void initCount(String value) {
if ( !counts.containsKey( value ) ) {
counts.put( value, 0 );
}
}
void incrementCount(String value) {
if ( !counts.containsKey( value ) ) {
counts.put( value, 1 );
}
else {
counts.put( value, counts.get( value ) + 1 );
}
}
abstract void countValue(Object value);
}
static class SimpleFacetCounter extends FacetCounter {
void countValue(Object value) {
incrementCount( (String) value );
}
}
static class RangeFacetCounter<T> extends FacetCounter {
private final List<FacetRange<T>> ranges;
RangeFacetCounter(RangeFacetRequest<T> request) {
this.ranges = request.getFacetRangeList();
for ( FacetRange<T> range : ranges ) {
initCount( range.getRangeString() );
}
}
@SuppressWarnings("unchecked")
void countValue(Object value) {
for ( FacetRange<T> range : ranges ) {
if ( range.isInRange( (T) value ) ) {
incrementCount( range.getRangeString() );
}
}
}
}
}