/*
* 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.miscellaneous;
import org.apache.lucene.analysis.FilteringTokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
/**
* Removes words that are too long or too short from the stream.
* <p>
* Note: Length is calculated as the number of Unicode codepoints.
* </p>
*/
public final class CodepointCountFilter extends FilteringTokenFilter {
private final int min;
private final int max;
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
/**
* Create a new {@link CodepointCountFilter}. This will filter out tokens whose
* {@link CharTermAttribute} is either too short ({@link Character#codePointCount(char[], int, int)}
* < min) or too long ({@link Character#codePointCount(char[], int, int)} > max).
* @param in the {@link TokenStream} to consume
* @param min the minimum length
* @param max the maximum length
*/
public CodepointCountFilter(TokenStream in, int min, int max) {
super(in);
if (min < 0) {
throw new IllegalArgumentException("minimum length must be greater than or equal to zero");
}
if (min > max) {
throw new IllegalArgumentException("maximum length must not be greater than minimum length");
}
this.min = min;
this.max = max;
}
@Override
public boolean accept() {
final int max32 = termAtt.length();
final int min32 = max32 >> 1;
if (min32 >= min && max32 <= max) {
// definitely within range
return true;
} else if (min32 > max || max32 < min) {
// definitely not
return false;
} else {
// we must count to be sure
int len = Character.codePointCount(termAtt.buffer(), 0, termAtt.length());
return (len >= min && len <= max);
}
}
}