/*
* 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.tika.eval.tokens;
import java.io.IOException;
import java.util.Map;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.util.FilteringTokenFilter;
import org.apache.lucene.analysis.util.TokenFilterFactory;
/**
* Factory for filter that only allows tokens with characters that "isAlphabetic" or "isIdeographic" through.
*/
public class AlphaIdeographFilterFactory extends TokenFilterFactory {
public AlphaIdeographFilterFactory(Map<String, String> args) {
super(args);
}
@Override
public TokenStream create(TokenStream tokenStream) {
return new AlphaFilter(tokenStream);
}
/**
* Remove tokens tokens that do not contain an "
*/
private class AlphaFilter extends FilteringTokenFilter {
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
public AlphaFilter(TokenStream in) {
super(in);
}
@Override
protected boolean accept() throws IOException {
return isAlphabetic(termAtt.buffer());
}
}
public static boolean isAlphabetic(char[] token) {
for (int i = 0; i < token.length; i++) {
int cp = token[i];
if (Character.isHighSurrogate(token[i])) {
if (i < token.length-1) {
cp = Character.toCodePoint(token[i], token[i + 1]);
i++;
}
}
if (Character.isAlphabetic(cp) ||
Character.isIdeographic(cp)) {
return true;
}
}
return false;
}
}