package org.apache.lucene.analysis;
/**
* 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 org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.util.CharacterUtils;
import org.apache.lucene.util.Version;
/**
* Normalizes token text to lower case.
* <a name="version"/>
* <p>You must specify the required {@link Version}
* compatibility when creating LowerCaseFilter:
* <ul>
* <li> As of 3.1, supplementary characters are properly lowercased.
* </ul>
*/
public final class LowerCaseFilter extends TokenFilter {
private final CharacterUtils charUtils;
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
/**
* Create a new LowerCaseFilter, that normalizes token text to lower case.
*
* @param matchVersion See <a href="#version">above</a>
* @param in TokenStream to filter
*/
public LowerCaseFilter(Version matchVersion, TokenStream in) {
super(in);
charUtils = CharacterUtils.getInstance(matchVersion);
}
/**
* @deprecated Use {@link #LowerCaseFilter(Version, TokenStream)} instead.
*/
@Deprecated
public LowerCaseFilter(TokenStream in) {
this(Version.LUCENE_30, in);
}
@Override
public final boolean incrementToken() throws IOException {
if (input.incrementToken()) {
final char[] buffer = termAtt.buffer();
final int length = termAtt.length();
for (int i = 0; i < length;) {
i += Character.toChars(
Character.toLowerCase(
charUtils.codePointAt(buffer, i)), buffer, i);
}
return true;
} else
return false;
}
}