--- /dev/null
+package org.apache.lucene.collation;
+
+/**
+ * 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 org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.KeywordTokenizer;
+import org.apache.lucene.analysis.Tokenizer;
+
+import java.text.Collator;
+import java.io.Reader;
+import java.io.IOException;
+
+/**
+ * <p>
+ * Filters {@link KeywordTokenizer} with {@link CollationKeyFilter}.
+ * </p>
+ * <p>
+ * Converts the token into its {@link java.text.CollationKey}, and then
+ * encodes the CollationKey with
+ * {@link org.apache.lucene.util.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. Since {@link java.text.RuleBasedCollator}s are not
+ * independently versioned, it is unsafe to search against stored
+ * CollationKeys unless 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>JVM vendor</li>
+ * <li>JVM version, including patch version</li>
+ * <li>
+ * The language (and country and variant, if specified) of the Locale
+ * used when constructing the collator via
+ * {@link Collator#getInstance(java.util.Locale)}.
+ * </li>
+ * <li>
+ * The collation strength used - see {@link Collator#setStrength(int)}
+ * </li>
+ * </ol>
+ * <p>
+ * The <code>ICUCollationKeyAnalyzer</code> in the icu package of Lucene's
+ * contrib area uses ICU4J's Collator, which makes its
+ * its version available, thus allowing collation to be versioned
+ * independently from the JVM. ICUCollationKeyAnalyzer is also significantly
+ * faster and generates significantly shorter keys than CollationKeyAnalyzer.
+ * 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>
+ * <p>
+ * CollationKeys generated by java.text.Collators are not compatible
+ * with those those generated by ICU Collators. Specifically, if you use
+ * CollationKeyAnalyzer to generate index terms, do not use
+ * ICUCollationKeyAnalyzer on the query side, or vice versa.
+ * </p>
+ */
+public final class CollationKeyAnalyzer extends Analyzer {
+ private Collator collator;
+
+ public CollationKeyAnalyzer(Collator collator) {
+ this.collator = collator;
+ }
+
+ @Override
+ public TokenStream tokenStream(String fieldName, Reader reader) {
+ TokenStream result = new KeywordTokenizer(reader);
+ result = new CollationKeyFilter(result, collator);
+ return result;
+ }
+
+ private class SavedStreams {
+ Tokenizer source;
+ TokenStream result;
+ }
+
+ @Override
+ public TokenStream reusableTokenStream(String fieldName, Reader reader)
+ throws IOException {
+
+ SavedStreams streams = (SavedStreams)getPreviousTokenStream();
+ if (streams == null) {
+ streams = new SavedStreams();
+ streams.source = new KeywordTokenizer(reader);
+ streams.result = new CollationKeyFilter(streams.source, collator);
+ setPreviousTokenStream(streams);
+ } else {
+ streams.source.reset(reader);
+ }
+ return streams.result;
+ }
+}