/**
* 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.
*/
package org.apache.jena.query.text.assembler ;
import java.util.ArrayList;
import java.util.List;
import org.apache.jena.query.text.TextIndexException;
import org.apache.jena.query.text.TextIndexLucene;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.analysis.util.CharArraySet;
import com.hp.hpl.jena.assembler.Assembler;
import com.hp.hpl.jena.assembler.Mode;
import com.hp.hpl.jena.assembler.assemblers.AssemblerBase;
import com.hp.hpl.jena.rdf.model.Literal;
import com.hp.hpl.jena.rdf.model.RDFNode;
import com.hp.hpl.jena.rdf.model.Resource;
import com.hp.hpl.jena.rdf.model.Statement;
import com.hp.hpl.jena.vocabulary.RDF;
/**
* Assembler to create standard analyzers with keyword list.
*/
public class StandardAnalyzerAssembler extends AssemblerBase {
/*
text:map (
[ text:field "text" ;
text:predicate rdfs:label;
text:analyzer [
a lucene:StandardAnalyzer ;
text:stopWords ("foo" "bar" "baz") # optional
]
]
.
*/
@Override
public Analyzer open(Assembler a, Resource root, Mode mode) {
if (root.hasProperty(TextVocab.pStopWords)) {
return analyzerWithStopWords(root);
} else {
return new StandardAnalyzer(TextIndexLucene.VER);
}
}
private Analyzer analyzerWithStopWords(Resource root) {
RDFNode node = root.getProperty(TextVocab.pStopWords).getObject();
if (! node.isResource()) {
throw new TextIndexException("text:stopWords property takes a list as a value : " + node);
}
CharArraySet stopWords = toCharArraySet((Resource) node);
return new StandardAnalyzer(TextIndexLucene.VER, stopWords);
}
private CharArraySet toCharArraySet(Resource list) {
return new CharArraySet(TextIndexLucene.VER, toList(list), false);
}
private List<String> toList(Resource list) {
List<String> result = new ArrayList<>();
Resource current = list;
while (current != null && ! current.equals(RDF.nil)){
Statement stmt = current.getProperty(RDF.first);
if (stmt == null) {
throw new TextIndexException("stop word list not well formed");
}
RDFNode node = stmt.getObject();
if (! node.isLiteral()) {
throw new TextIndexException("stop word is not a literal : " + node);
}
result.add(((Literal)node).getLexicalForm());
stmt = current.getProperty(RDF.rest);
if (stmt == null) {
throw new TextIndexException("stop word list not terminated by rdf:nil");
}
node = stmt.getObject();
if (! node.isResource()) {
throw new TextIndexException("stop word list node is not a resource : " + node);
}
current = (Resource) node;
}
return result;
}
}