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Exposing filtering capabilities via the unicodeSetFilter attribute

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1 parent 7c87f2a commit 96e38eca6183646c77d4fde99eec457b22e5df4b @barsk barsk committed Feb 28, 2012
Showing with 34 additions and 7 deletions.
  1. +34 −7 src/main/java/org/elasticsearch/index/analysis/IcuFoldingTokenFilterFactory.java
@@ -1,8 +1,8 @@
/*
- * Licensed to ElasticSearch and Shay Banon under one
+ * Licensed to Elastic Search and Shay Banon under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
- * regarding copyright ownership. ElasticSearch licenses this
+ * regarding copyright ownership. Elastic Search 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
@@ -27,19 +27,46 @@
import org.elasticsearch.index.Index;
import org.elasticsearch.index.settings.IndexSettings;
+import com.ibm.icu.text.FilteredNormalizer2;
+import com.ibm.icu.text.Normalizer2;
+import com.ibm.icu.text.UnicodeSet;
+
/**
+ * Uses the {@link org.apache.lucene.analysis.icu.ICUFoldingFilter}.
+ * Applies foldings from UTR#30 Character Foldings.
+ * <p>
+ * Can be filtered to handle certain characters in a specified way (see http://icu-project.org/apiref/icu4j/com/ibm/icu/text/UnicodeSet.html)
+ * E.g national chars that should be retained (filter : "[^åäöÅÄÖ]").
+ *
+ * <p>The <tt>unicodeSetFilter</tt> attribute can be used to provide the UniCodeSet for filtering.
*
+ * @author kimchy (shay.banon)
*/
public class IcuFoldingTokenFilterFactory extends AbstractTokenFilterFactory {
+ private final String unicodeSetFilter;
- @Inject
- public IcuFoldingTokenFilterFactory(Index index, @IndexSettings Settings indexSettings, @Assisted String name, @Assisted Settings settings) {
+ @Inject public IcuFoldingTokenFilterFactory(Index index, @IndexSettings Settings indexSettings, @Assisted String name, @Assisted Settings settings) {
super(index, indexSettings, name, settings);
+ this.unicodeSetFilter = settings.get("unicodeSetFilter");
}
- @Override
- public TokenStream create(TokenStream tokenStream) {
- return new ICUFoldingFilter(tokenStream);
+ @Override public TokenStream create(TokenStream tokenStream) {
+
+ // The ICUFoldingFilter is in fact implemented as a ICUNormalizer2Filter.
+ // ICUFoldingFilter lacks a constructor for adding filtering so we implemement it here
+ if (unicodeSetFilter != null) {
+ Normalizer2 base = Normalizer2.getInstance(
+ ICUFoldingFilter.class.getResourceAsStream("utr30.nrm"),
+ "utr30", Normalizer2.Mode.COMPOSE);
+ UnicodeSet unicodeSet = new UnicodeSet(unicodeSetFilter);
+
+ unicodeSet.freeze();
+ Normalizer2 filtered = new FilteredNormalizer2(base, unicodeSet);
+ return new org.apache.lucene.analysis.icu.ICUNormalizer2Filter(tokenStream, filtered);
+ }
+ else {
+ return new ICUFoldingFilter(tokenStream);
+ }
}
}

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