package org.apache.lucene.search.vectorhighlight;
/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.io.IOException;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Set;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.WhitespaceAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.Field.Index;
import org.apache.lucene.document.Field.Store;
import org.apache.lucene.document.Field.TermVector;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.TermFreqVector;
import org.apache.lucene.index.TermPositionVector;
import org.apache.lucene.index.TermVectorOffsetInfo;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.Query;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.util.Version;
/**
* <code>FieldTermStack</code> is a stack that keeps query terms in the specified field
* of the document to be highlighted.
*/
public class FieldTermStack {
private final String fieldName;
LinkedList<TermInfo> termList = new LinkedList<TermInfo>();
public static void main( String[] args ) throws Exception {
Analyzer analyzer = new WhitespaceAnalyzer(Version.LUCENE_CURRENT);
QueryParser parser = new QueryParser(Version.LUCENE_CURRENT, "f", analyzer );
Query query = parser.parse( "a x:b" );
FieldQuery fieldQuery = new FieldQuery( query, true, false );
Directory dir = new RAMDirectory();
IndexWriter writer = new IndexWriter(dir, new IndexWriterConfig(Version.LUCENE_CURRENT, analyzer));
Document doc = new Document();
doc.add( new Field( "f", "a a a b b c a b b c d e f", Store.YES, Index.ANALYZED, TermVector.WITH_POSITIONS_OFFSETS ) );
doc.add( new Field( "f", "b a b a f", Store.YES, Index.ANALYZED, TermVector.WITH_POSITIONS_OFFSETS ) );
writer.addDocument( doc );
writer.close();
IndexReader reader = IndexReader.open( dir, true );
new FieldTermStack( reader, 0, "f", fieldQuery );
reader.close();
}
/**
* a constructor.
*
* @param reader IndexReader of the index
* @param docId document id to be highlighted
* @param fieldName field of the document to be highlighted
* @param fieldQuery FieldQuery object
* @throws IOException
*/
public FieldTermStack( IndexReader reader, int docId, String fieldName, final FieldQuery fieldQuery ) throws IOException {
this.fieldName = fieldName;
Set<String> termSet = fieldQuery.getTermSet( fieldName );
// just return to make null snippet if un-matched fieldName specified when fieldMatch == true
if( termSet == null ) return;
TermFreqVector tfv = reader.getTermFreqVector( docId, fieldName );
if( tfv == null ) return; // just return to make null snippets
TermPositionVector tpv = null;
try{
tpv = (TermPositionVector)tfv;
}
catch( ClassCastException e ){
return; // just return to make null snippets
}
for( String term : tpv.getTerms() ){
if( !termSet.contains( term ) ) continue;
int index = tpv.indexOf( term );
TermVectorOffsetInfo[] tvois = tpv.getOffsets( index );
if( tvois == null ) return; // just return to make null snippets
int[] poss = tpv.getTermPositions( index );
if( poss == null ) return; // just return to make null snippets
for( int i = 0; i < tvois.length; i++ )
termList.add( new TermInfo( term, tvois[i].getStartOffset(), tvois[i].getEndOffset(), poss[i] ) );
}
// sort by position
Collections.sort( termList );
}
/**
* @return field name
*/
public String getFieldName(){
return fieldName;
}
/**
* @return the top TermInfo object of the stack
*/
public TermInfo pop(){
return termList.poll();
}
/**
* @param termInfo the TermInfo object to be put on the top of the stack
*/
public void push( TermInfo termInfo ){
// termList.push( termInfo ); // avoid Java 1.6 feature
termList.addFirst( termInfo );
}
/**
* to know whether the stack is empty
*
* @return true if the stack is empty, false if not
*/
public boolean isEmpty(){
return termList == null || termList.size() == 0;
}
public static class TermInfo implements Comparable<TermInfo>{
final String text;
final int startOffset;
final int endOffset;
final int position;
TermInfo( String text, int startOffset, int endOffset, int position ){
this.text = text;
this.startOffset = startOffset;
this.endOffset = endOffset;
this.position = position;
}
public String getText(){ return text; }
public int getStartOffset(){ return startOffset; }
public int getEndOffset(){ return endOffset; }
public int getPosition(){ return position; }
@Override
public String toString(){
StringBuilder sb = new StringBuilder();
sb.append( text ).append( '(' ).append(startOffset).append( ',' ).append( endOffset ).append( ',' ).append( position ).append( ')' );
return sb.toString();
}
public int compareTo( TermInfo o ) {
return ( this.position - o.position );
}
}
}