--- /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 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.util.IndexableBinaryStringTools;
+
+import org.apache.lucene.collation.CollationKeyFilter; // javadocs
+
+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
+ * {@link 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>
+ */
+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;
+ }
+ }
+}