/*
* 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.lucene.queryparser.flexible.standard.processors;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.apache.lucene.analysis.Analyzer;
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.QueryNode;
import org.apache.lucene.queryparser.flexible.core.nodes.QuotedFieldQueryNode;
import org.apache.lucene.queryparser.flexible.core.processors.QueryNodeProcessorImpl;
import org.apache.lucene.queryparser.flexible.core.util.UnescapedCharSequence;
import org.apache.lucene.queryparser.flexible.standard.config.StandardQueryConfigHandler.ConfigurationKeys;
import org.apache.lucene.queryparser.flexible.standard.nodes.PrefixWildcardQueryNode;
import org.apache.lucene.queryparser.flexible.standard.nodes.TermRangeQueryNode;
import org.apache.lucene.queryparser.flexible.standard.nodes.WildcardQueryNode;
import org.apache.lucene.queryparser.flexible.standard.parser.StandardSyntaxParser;
import org.apache.lucene.search.PrefixQuery;
import org.apache.lucene.util.BytesRef;
/**
* The {@link StandardSyntaxParser} creates {@link PrefixWildcardQueryNode} nodes which
* have values containing the prefixed wildcard. However, Lucene
* {@link PrefixQuery} cannot contain the prefixed wildcard. So, this processor
* basically removed the prefixed wildcard from the
* {@link PrefixWildcardQueryNode} value.
*
* @see PrefixQuery
* @see PrefixWildcardQueryNode
*/
public class WildcardQueryNodeProcessor extends QueryNodeProcessorImpl {
private static final Pattern WILDCARD_PATTERN = Pattern.compile("(\\.)|([?*]+)");
// because we call utf8ToString, this will only work with the default TermToBytesRefAttribute
private static String analyzeWildcard(Analyzer a, String field, String wildcard) {
// best effort to not pass the wildcard characters through #normalize
Matcher wildcardMatcher = WILDCARD_PATTERN.matcher(wildcard);
StringBuilder sb = new StringBuilder();
int last = 0;
while (wildcardMatcher.find()){
// continue if escaped char
if (wildcardMatcher.group(1) != null){
continue;
}
if (wildcardMatcher.start() > 0){
String chunk = wildcard.substring(last, wildcardMatcher.start());
BytesRef normalized = a.normalize(field, chunk);
sb.append(normalized.utf8ToString());
}
//append the wildcard character
sb.append(wildcardMatcher.group(2));
last = wildcardMatcher.end();
}
if (last < wildcard.length()){
String chunk = wildcard.substring(last);
BytesRef normalized = a.normalize(field, chunk);
sb.append(normalized.utf8ToString());
}
return sb.toString();
}
public WildcardQueryNodeProcessor() {
// empty constructor
}
@Override
protected QueryNode postProcessNode(QueryNode node) throws QueryNodeException {
// the old Lucene Parser ignores FuzzyQueryNode that are also PrefixWildcardQueryNode or WildcardQueryNode
// we do the same here, also ignore empty terms
if (node instanceof FieldQueryNode || node instanceof FuzzyQueryNode) {
FieldQueryNode fqn = (FieldQueryNode) node;
CharSequence text = fqn.getText();
// do not process wildcards for TermRangeQueryNode children and
// QuotedFieldQueryNode to reproduce the old parser behavior
if (fqn.getParent() instanceof TermRangeQueryNode
|| fqn instanceof QuotedFieldQueryNode
|| text.length() <= 0){
// Ignore empty terms
return node;
}
// Code below simulates the old lucene parser behavior for wildcards
if (isWildcard(text)) {
Analyzer analyzer = getQueryConfigHandler().get(ConfigurationKeys.ANALYZER);
if (analyzer != null) {
text = analyzeWildcard(analyzer, fqn.getFieldAsString(), text.toString());
}
if (isPrefixWildcard(text)) {
return new PrefixWildcardQueryNode(fqn.getField(), text, fqn.getBegin(), fqn.getEnd());
} else {
return new WildcardQueryNode(fqn.getField(), text, fqn.getBegin(), fqn.getEnd());
}
}
}
return node;
}
private boolean isWildcard(CharSequence text) {
if (text ==null || text.length() <= 0) return false;
// If a un-escaped '*' or '?' if found return true
// start at the end since it's more common to put wildcards at the end
for(int i=text.length()-1; i>=0; i--){
if ((text.charAt(i) == '*' || text.charAt(i) == '?') && !UnescapedCharSequence.wasEscaped(text, i)){
return true;
}
}
return false;
}
private boolean isPrefixWildcard(CharSequence text) {
if (text == null || text.length() <= 0 || !isWildcard(text)) return false;
// Validate last character is a '*' and was not escaped
// If single '*' is is a wildcard not prefix to simulate old queryparser
if (text.charAt(text.length()-1) != '*') return false;
if (UnescapedCharSequence.wasEscaped(text, text.length()-1)) return false;
if (text.length() == 1) return false;
// Only make a prefix if there is only one single star at the end and no '?' or '*' characters
// If single wildcard return false to mimic old queryparser
for(int i=0; i<text.length(); i++){
if (text.charAt(i) == '?') return false;
if (text.charAt(i) == '*' && !UnescapedCharSequence.wasEscaped(text, i)){
if (i == text.length()-1)
return true;
else
return false;
}
}
return false;
}
@Override
protected QueryNode preProcessNode(QueryNode node) throws QueryNodeException {
return node;
}
@Override
protected List<QueryNode> setChildrenOrder(List<QueryNode> children)
throws QueryNodeException {
return children;
}
}