/*
* 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.analysis.core;
import java.io.IOException;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.util.StemmerUtil;
/**
* Folds all Unicode digits in {@code [:General_Category=Decimal_Number:]}
* to Basic Latin digits ({@code 0-9}).
*/
public final class DecimalDigitFilter extends TokenFilter {
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
/**
* Creates a new DecimalDigitFilter over {@code input}
*/
public DecimalDigitFilter(TokenStream input) {
super(input);
}
@Override
public boolean incrementToken() throws IOException {
if (input.incrementToken()) {
char buffer[] = termAtt.buffer();
int length = termAtt.length();
for (int i = 0; i < length; i++) {
int ch = Character.codePointAt(buffer, i, length);
// look for digits outside of basic latin
if (ch > 0x7F && Character.isDigit(ch)) {
// replace with equivalent basic latin digit
buffer[i] = (char) ('0' + Character.getNumericValue(ch));
// if the original was supplementary, shrink the string
if (ch > 0xFFFF) {
length = StemmerUtil.delete(buffer, i+1, length);
termAtt.setLength(length);
}
}
}
return true;
} else {
return false;
}
}
}