Add support for inlined user dictionary in Nori (#36123)

Add support for inlined user dictionary in Nori

This change adds a new option called `user_dictionary_rules` to the
Nori a tokenizer`. It can be used to set additional tokenization rules
to the Korean tokenizer directly in the settings (instead of using a file).

Closes #35842

Author: jimczi

docs/plugins/analysis-nori.asciidoc

@@ -70,7 +70,7 @@ The first token is mandatory and represents the custom noun that should be added
 the dictionary. For compound nouns the custom segmentation can be provided
 after the first token (`[<token 1> ... <token n>]`). The segmentation of the
 custom compound nouns is controlled by the `decompound_mode` setting.
---
+
 
 As a demonstration of how the user dictionary can be used, save the following
 dictionary to `$ES_HOME/config/userdict_ko.txt`:
@@ -153,6 +153,42 @@ The above `analyze` request returns the following:
 // TESTRESPONSE
 
 <1> This is a compound token that spans two positions (`mixed` mode).
+--
+
+`user_dictionary_rules`::
++
+--
+
+You can also inline the rules directly in the tokenizer definition using
+the `user_dictionary_rules` option:
+
+[source,js]
+--------------------------------------------------
+PUT nori_sample
+{
+  "settings": {
+    "index": {
+      "analysis": {
+        "tokenizer": {
+          "nori_user_dict": {
+            "type": "nori_tokenizer",
+            "decompound_mode": "mixed",
+            "user_dictionary_rules": ["c++", "C샤프", "세종", "세종시 세종 시"]
+          }
+        },
+        "analyzer": {
+          "my_analyzer": {
+            "type": "custom",
+            "tokenizer": "nori_user_dict"
+          }
+        }
+      }
+    }
+  }
+}
+--------------------------------------------------
+// CONSOLE
+--
 
 The `nori_tokenizer` sets a number of additional attributes per token that are used by token filters
 to modify the stream.

plugins/analysis-nori/src/main/java/org/elasticsearch/index/analysis/NoriTokenizerFactory.java

@@ -29,10 +29,13 @@
 
 import java.io.IOException;
 import java.io.Reader;
+import java.io.StringReader;
+import java.util.List;
 import java.util.Locale;
 
 public class NoriTokenizerFactory extends AbstractTokenizerFactory {
-    private static final String USER_DICT_OPTION = "user_dictionary";
+    private static final String USER_DICT_PATH_OPTION = "user_dictionary";
+    private static final String USER_DICT_RULES_OPTION = "user_dictionary_rules";
 
     private final UserDictionary userDictionary;
     private final KoreanTokenizer.DecompoundMode decompoundMode;
@@ -44,12 +47,20 @@ public NoriTokenizerFactory(IndexSettings indexSettings, Environment env, String
     }
 
     public static UserDictionary getUserDictionary(Environment env, Settings settings) {
-        try (Reader reader = Analysis.getReaderFromFile(env, settings, USER_DICT_OPTION)) {
-            if (reader == null) {
-                return null;
-            } else {
-                return UserDictionary.open(reader);
-            }
+        if (settings.get(USER_DICT_PATH_OPTION) != null && settings.get(USER_DICT_RULES_OPTION) != null) {
+            throw new IllegalArgumentException("It is not allowed to use [" + USER_DICT_PATH_OPTION + "] in conjunction" +
+                " with [" + USER_DICT_RULES_OPTION + "]");
+        }
+        List<String> ruleList = Analysis.getWordList(env, settings, USER_DICT_PATH_OPTION, USER_DICT_RULES_OPTION);
+        StringBuilder sb = new StringBuilder();
+        if (ruleList == null || ruleList.isEmpty()) {
+            return null;
+        }
+        for (String line : ruleList) {
+            sb.append(line).append(System.lineSeparator());
+        }
+        try (Reader rulesReader = new StringReader(sb.toString())) {
+            return UserDictionary.open(rulesReader);
         } catch (IOException e) {
             throw new ElasticsearchException("failed to load nori user dictionary", e);
         }

plugins/analysis-nori/src/test/java/org/elasticsearch/index/analysis/NoriAnalysisTests.java

@@ -38,6 +38,7 @@
 import java.nio.file.Files;
 import java.nio.file.Path;
 
+import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.instanceOf;
 
 public class NoriAnalysisTests extends ESTokenStreamTestCase {
@@ -76,6 +77,22 @@ public void testNoriAnalyzer() throws Exception {
     }
 
     public void testNoriAnalyzerUserDict() throws Exception {
+        Settings settings = Settings.builder()
+            .put("index.analysis.analyzer.my_analyzer.type", "nori")
+            .putList("index.analysis.analyzer.my_analyzer.user_dictionary_rules", "c++", "C샤프", "세종", "세종시 세종 시")
+            .build();
+        TestAnalysis analysis = createTestAnalysis(settings);
+        Analyzer analyzer = analysis.indexAnalyzers.get("my_analyzer");
+        try (TokenStream stream = analyzer.tokenStream("", "세종시")) {
+            assertTokenStreamContents(stream, new String[]{"세종", "시"});
+        }
+
+        try (TokenStream stream = analyzer.tokenStream("", "c++world")) {
+            assertTokenStreamContents(stream, new String[]{"c++", "world"});
+        }
+    }
+
+    public void testNoriAnalyzerUserDictPath() throws Exception {
         Settings settings = Settings.builder()
             .put("index.analysis.analyzer.my_analyzer.type", "nori")
             .put("index.analysis.analyzer.my_analyzer.user_dictionary", "user_dict.txt")
@@ -91,6 +108,17 @@ public void testNoriAnalyzerUserDict() throws Exception {
         }
     }
 
+    public void testNoriAnalyzerInvalidUserDictOption() throws Exception {
+        Settings settings = Settings.builder()
+            .put("index.analysis.analyzer.my_analyzer.type", "nori")
+            .put("index.analysis.analyzer.my_analyzer.user_dictionary", "user_dict.txt")
+            .putList("index.analysis.analyzer.my_analyzer.user_dictionary_rules", "c++", "C샤프", "세종", "세종시 세종 시")
+            .build();
+        IllegalArgumentException exc = expectThrows(IllegalArgumentException.class, () -> createTestAnalysis(settings));
+        assertThat(exc.getMessage(), containsString("It is not allowed to use [user_dictionary] in conjunction " +
+            "with [user_dictionary_rules]"));
+    }
+
     public void testNoriTokenizer() throws Exception {
         Settings settings = Settings.builder()
             .put("index.analysis.tokenizer.my_tokenizer.type", "nori_tokenizer")

server/src/main/java/org/elasticsearch/index/analysis/Analysis.java

@@ -228,10 +228,21 @@ public static CharArraySet getWordSet(Environment env, org.elasticsearch.Version
      *          If the word list cannot be found at either key.
      */
     public static List<String> getWordList(Environment env, Settings settings, String settingPrefix) {
-        String wordListPath = settings.get(settingPrefix + "_path", null);
+        return getWordList(env, settings, settingPrefix + "_path", settingPrefix);
+    }
+
+    /**
+     * Fetches a list of words from the specified settings file. The list should either be available at the key
+     * specified by <code>settingList</code> or in a file specified by <code>settingPath</code>.
+     *
+     * @throws IllegalArgumentException
+     *          If the word list cannot be found at either key.
+     */
+    public static List<String> getWordList(Environment env, Settings settings, String settingPath, String settingList) {
+        String wordListPath = settings.get(settingPath, null);
 
         if (wordListPath == null) {
-            List<String> explicitWordList = settings.getAsList(settingPrefix, null);
+            List<String> explicitWordList = settings.getAsList(settingList, null);
             if (explicitWordList == null) {
                 return null;
             } else {
@@ -245,11 +256,11 @@ public static List<String> getWordList(Environment env, Settings settings, Strin
             return loadWordList(reader, "#");
         } catch (CharacterCodingException ex) {
             String message = String.format(Locale.ROOT,
-                "Unsupported character encoding detected while reading %s_path: %s - files must be UTF-8 encoded",
-                settingPrefix, path.toString());
+                "Unsupported character encoding detected while reading %s: %s - files must be UTF-8 encoded",
+                settingPath, path.toString());
             throw new IllegalArgumentException(message, ex);
         } catch (IOException ioe) {
-            String message = String.format(Locale.ROOT, "IOException while reading %s_path: %s", settingPrefix, path.toString());
+            String message = String.format(Locale.ROOT, "IOException while reading %s: %s", settingPath, path.toString());
             throw new IllegalArgumentException(message, ioe);
         }
     }