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package org.elasticsearch.index.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 com.ibm.icu.text.Collator;
import com.ibm.icu.text.RawCollationKey;
import org.apache.lucene.analysis.TokenFilter;
import org.apache.lucene.analysis.TokenStream;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.collation.ICUCollationDocValuesField;
import java.io.IOException;
/**
* <p>
* Converts each token into its {@link com.ibm.icu.text.CollationKey}, and
* then encodes the CollationKey with {@link IndexableBinaryStringTools}, to
* allow it to be stored as an index term.
* </p>
* <p>
* <strong>WARNING:</strong> Make sure you use exactly the same Collator at
* index and query time -- CollationKeys are only comparable when produced by
* the same Collator. {@link com.ibm.icu.text.RuleBasedCollator}s are
* independently versioned, so it is safe to search against stored
* CollationKeys if the following are exactly the same (best practice is
* to store this information with the index and check that they remain the
* same at query time):
* </p>
* <ol>
* <li>
* Collator version - see {@link Collator#getVersion()}
* </li>
* <li>
* The collation strength used - see {@link Collator#setStrength(int)}
* </li>
* </ol>
* <p>
* CollationKeys generated by ICU Collators are not compatible with those
* generated by java.text.Collators. Specifically, if you use
* ICUCollationKeyFilter to generate index terms, do not use
* {@code CollationKeyFilter} on the query side, or vice versa.
* </p>
* <p>
* ICUCollationKeyFilter is significantly faster and generates significantly
* shorter keys than CollationKeyFilter. See
* <a href="http://site.icu-project.org/charts/collation-icu4j-sun"
* >http://site.icu-project.org/charts/collation-icu4j-sun</a> for key
* generation timing and key length comparisons between ICU4J and
* java.text.Collator over several languages.
* </p>
* @deprecated Use {@link ICUCollationDocValuesField} instead, which encodes
* terms directly as bytes. This filter WAS removed in Lucene 5.0
*/
@Deprecated
public final class ICUCollationKeyFilter extends TokenFilter {
private Collator collator = null;
private RawCollationKey reusableKey = new RawCollationKey();
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
/**
*
* @param input Source token stream
* @param collator CollationKey generator
*/
public ICUCollationKeyFilter(TokenStream input, Collator collator) {
super(input);
// clone the collator: see http://userguide.icu-project.org/collation/architecture
try {
this.collator = (Collator) collator.clone();
} catch (CloneNotSupportedException e) {
throw new RuntimeException(e);
}
}
@Override
public boolean incrementToken() throws IOException {
if (input.incrementToken()) {
char[] termBuffer = termAtt.buffer();
String termText = new String(termBuffer, 0, termAtt.length());
collator.getRawCollationKey(termText, reusableKey);
int encodedLength = IndexableBinaryStringTools.getEncodedLength(
reusableKey.bytes, 0, reusableKey.size);
if (encodedLength > termBuffer.length) {
termAtt.resizeBuffer(encodedLength);
}
termAtt.setLength(encodedLength);
IndexableBinaryStringTools.encode(reusableKey.bytes, 0, reusableKey.size,
termAtt.buffer(), 0, encodedLength);
return true;
} else {
return false;
}
}
}
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