Add Persian language stemmer

docs/changelog/99106.yaml

@@ -0,0 +1,6 @@
+pr: 99106
+summary: "Add support for Persian language stemmer"
+area: Analysis
+type: feature
+issues:
+ - 98911

docs/reference/analysis/tokenfilters/stemmer-tokenfilter.asciidoc

@@ -214,6 +214,9 @@ Norwegian (Nynorsk)::
 {lucene-analysis-docs}/no/NorwegianLightStemmer.html[*`light_nynorsk`*],
 {lucene-analysis-docs}/no/NorwegianMinimalStemmer.html[`minimal_nynorsk`]
 
+Persian::
+{lucene-analysis-docs}/fa/PersianStemmer.html[*`persian`*]
+
 Portuguese::
 https://dl.acm.org/citation.cfm?id=1141523&dl=ACM&coll=DL&CFID=179095584&CFTOKEN=80067181[*`light_portuguese`*],
 pass:macros[http://www.inf.ufrgs.br/~buriol/papers/Orengo_CLEF07.pdf[`minimal_portuguese`\]],

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/CommonAnalysisPlugin.java

@@ -322,6 +322,7 @@ public TokenStream create(TokenStream tokenStream) {
         filters.put("pattern_capture", requiresAnalysisSettings(PatternCaptureGroupTokenFilterFactory::new));
         filters.put("pattern_replace", requiresAnalysisSettings(PatternReplaceTokenFilterFactory::new));
         filters.put("persian_normalization", PersianNormalizationFilterFactory::new);
+        filters.put("persian_stem", PersianStemTokenFilterFactory::new);
         filters.put("porter_stem", PorterStemTokenFilterFactory::new);
         filters.put(
             "predicate_token_filter",

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/PersianStemTokenFilterFactory.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+package org.elasticsearch.analysis.common;
+
+import org.apache.lucene.analysis.TokenStream;
+import org.apache.lucene.analysis.fa.PersianStemFilter;
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.env.Environment;
+import org.elasticsearch.index.IndexSettings;
+import org.elasticsearch.index.analysis.AbstractTokenFilterFactory;
+
+public class PersianStemTokenFilterFactory extends AbstractTokenFilterFactory {
+
+    PersianStemTokenFilterFactory(IndexSettings indexSettings, Environment environment, String name, Settings settings) {
+        super(name, settings);
+    }
+
+    @Override
+    public TokenStream create(TokenStream tokenStream) {
+        return new PersianStemFilter(tokenStream);
+    }
+}

modules/analysis-common/src/main/java/org/elasticsearch/analysis/common/StemmerTokenFilterFactory.java

@@ -23,6 +23,7 @@
 import org.apache.lucene.analysis.en.KStemFilter;
 import org.apache.lucene.analysis.en.PorterStemFilter;
 import org.apache.lucene.analysis.es.SpanishLightStemFilter;
+import org.apache.lucene.analysis.fa.PersianStemFilter;
 import org.apache.lucene.analysis.fi.FinnishLightStemFilter;
 import org.apache.lucene.analysis.fr.FrenchLightStemFilter;
 import org.apache.lucene.analysis.fr.FrenchMinimalStemFilter;
@@ -213,6 +214,10 @@ public TokenStream create(TokenStream tokenStream) {
             } else if ("minimal_nynorsk".equalsIgnoreCase(language) || "minimalNynorsk".equalsIgnoreCase(language)) {
                 return new NorwegianMinimalStemFilter(tokenStream, NorwegianLightStemmer.NYNORSK);
 
+                // Persian stemmers
+            } else if ("persian".equalsIgnoreCase(language)) {
+                return new PersianStemFilter(tokenStream);
+
                 // Portuguese stemmers
             } else if ("portuguese".equalsIgnoreCase(language)) {
                 return new SnowballFilter(tokenStream, new PortugueseStemmer());

modules/analysis-common/src/test/java/org/elasticsearch/analysis/common/CommonAnalysisFactoryTests.java

@@ -117,6 +117,7 @@ protected Map<String, Class<?>> getTokenFilters() {
         filters.put("hindinormalization", HindiNormalizationFilterFactory.class);
         filters.put("indicnormalization", IndicNormalizationFilterFactory.class);
         filters.put("persiannormalization", PersianNormalizationFilterFactory.class);
+        filters.put("persianstem", PersianStemTokenFilterFactory.class);
         filters.put("scandinaviannormalization", ScandinavianNormalizationFilterFactory.class);
         filters.put("serbiannormalization", SerbianNormalizationFilterFactory.class);
         filters.put("soraninormalization", SoraniNormalizationFilterFactory.class);