/**
* Copyright 2014 National University of Ireland, Galway.
*
* This file is part of the SIREn project. Project and contact information:
*
* https://github.com/rdelbru/SIREn
*
* Licensed 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.sindice.siren.qparser.keyword.processors;
import java.io.IOException;
import java.io.StringReader;
import java.util.List;
import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.CachingTokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.core.WhitespaceAnalyzer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.queryparser.flexible.core.QueryNodeException;
import org.apache.lucene.queryparser.flexible.core.nodes.FieldQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.FuzzyQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.NoTokenFoundQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.RangeQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.TextableQueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.TokenizedPhraseQueryNode;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryparser.flexible.standard.nodes.RegexpQueryNode;
import org.apache.lucene.queryparser.flexible.standard.nodes.WildcardQueryNode;
import org.apache.lucene.util.Version;
/**
* This processor analyses a {@link FieldQueryNode} using a {@link WhitespaceAnalyzer}
* and outputs a {@link TokenizedPhraseQueryNode} if more than one token are returned.
*
* <p>
*
* This processor operates on every {@link FieldQueryNode} that is not
* {@link WildcardQueryNode}, {@link FuzzyQueryNode} or
* {@link RangeQueryNode} contained in the query node tree, and it applies
* a {@link WhitespaceAnalyzer} to that {@link FieldQueryNode} object.
*
* <p>
*
* If the analyzer returns only one term, the node is returned unchanged.
*
* <p>
*
* If the analyzer returns more than one term, a {@link TokenizedPhraseQueryNode}
* is created and returned.
*
* <p>
*
* If no term is returned by the analyzer, a {@link NoTokenFoundQueryNode} object
* is returned.
*/
public class PhraseQueryNodeProcessor extends QueryNodeProcessorImpl {
private final Analyzer analyzer = new WhitespaceAnalyzer(Version.LUCENE_40);
@Override
protected QueryNode postProcessNode(final QueryNode node) throws QueryNodeException {
if (node instanceof TextableQueryNode
&& !(node instanceof WildcardQueryNode)
&& !(node instanceof FuzzyQueryNode)
&& !(node instanceof RegexpQueryNode)
&& !(node.getParent() instanceof RangeQueryNode)) {
final FieldQueryNode fieldNode = ((FieldQueryNode) node);
final String text = fieldNode.getTextAsString();
final String field = fieldNode.getFieldAsString();
final TokenStream source;
try {
source = this.analyzer.tokenStream(field, new StringReader(text));
source.reset();
} catch (final IOException e1) {
throw new RuntimeException(e1);
}
final CachingTokenFilter buffer = new CachingTokenFilter(source);
int numTokens = 0;
try {
while (buffer.incrementToken()) {
numTokens++;
}
} catch (final IOException e) {
// ignore
}
try {
// rewind the buffer stream
buffer.reset();
// close original stream - all tokens buffered
source.close();
} catch (final IOException e) {
// ignore
}
if (!buffer.hasAttribute(CharTermAttribute.class)) {
return new NoTokenFoundQueryNode();
}
final CharTermAttribute termAtt = buffer.getAttribute(CharTermAttribute.class);
if (numTokens == 0) {
return new NoTokenFoundQueryNode();
} else if (numTokens != 1) {
// phrase query
final TokenizedPhraseQueryNode pq = new TokenizedPhraseQueryNode();
for (int i = 0; i < numTokens; i++) {
String term = null;
try {
final boolean hasNext = buffer.incrementToken();
assert hasNext == true;
term = termAtt.toString();
} catch (final IOException e) {
// safe to ignore, because we know the number of tokens
}
final FieldQueryNode newFieldNode = new FieldQueryNode(field, term, -1, -1);
newFieldNode.setPositionIncrement(i);
pq.add(newFieldNode);
}
return pq;
}
}
return node;
}
@Override
protected QueryNode preProcessNode(final QueryNode node) throws QueryNodeException {
return node;
}
@Override
protected List<QueryNode> setChildrenOrder(final List<QueryNode> children)
throws QueryNodeException {
return children;
}
}