Make argument name more concise

core/src/main/java/org/apache/calcite/runtime/SqlFunctions.java

@@ -1078,12 +1078,17 @@ public static int levenshtein(String string1, String string2) {
     return LEVENSHTEIN_DISTANCE.apply(string1, string2);
   }
 
-  /** SQL FIND_IN_SET(string, stringArray) function.
-   * Returns the index (1-based) of the given string
-   * in the comma-delimited list stringArray. Returns 0,
-   * if the string was not found or if the given string
+  /** SQL FIND_IN_SET(matchStr, textStr) function.
+   * Returns the index (1-based) of the given matchStr
+   * in the comma-delimited list textStr. Returns 0,
+   * if the matchStr is not found or if the matchStr
    * contains a comma. */
-  public static int findInSet(String matchStr, String textStr) {
+  public static @Nullable Integer findInSet(
+      @Nullable String matchStr,
+      @Nullable String textStr) {
+    if (matchStr == null || textStr == null) {
+      return null;
+    }
     if (matchStr.contains(String.valueOf(COMMA_DELIMITER))) {
       return 0;
     }

core/src/main/java/org/apache/calcite/sql/fun/SqlLibraryOperators.java

@@ -405,7 +405,7 @@ static RelDataType deriveTypeSplit(SqlOperatorBinding operatorBinding,
               OperandTypes.STRING_STRING_OPTIONAL_STRING,
               SqlFunctionCategory.STRING);
 
-  /** The "FIND_IN_SET(string, stringArray)" function. */
+  /** The "FIND_IN_SET(matchStr, textStr)" function. */
   @LibraryOperator(libraries = {HIVE, SPARK})
   public static final SqlFunction FIND_IN_SET =
       SqlBasicFunction.create("FIND_IN_SET",

site/_docs/reference.md

@@ -2729,7 +2729,7 @@ BigQuery's type system uses confusingly different names for types and functions:
 | o | EXTRACT(xml, xpath, [, namespaces ])           | Returns the XML fragment of the element or elements matched by the XPath expression. The optional namespace value that specifies a default mapping or namespace mapping for prefixes, which is used when evaluating the XPath expression
 | o | EXISTSNODE(xml, xpath, [, namespaces ])        | Determines whether traversal of a XML document using a specified xpath results in any nodes. Returns 0 if no nodes remain after applying the XPath traversal on the document fragment of the element or elements matched by the XPath expression. Returns 1 if any nodes remain. The optional namespace value that specifies a default mapping or namespace mapping for prefixes, which is used when evaluating the XPath expression.
 | m | EXTRACTVALUE(xml, xpathExpr))                  | Returns the text of the first text node which is a child of the element or elements matched by the XPath expression.
-| h s | FIND_IN_SET(string, stringArray)             | Returns the index (1-based) of the given *string* in the comma-delimited *stringArray*. Returns 0, if the given *string* was not found or if *string* contains a comma. For example, FIND_IN_SET('bc', 'a,bc,def') returns 2
+| h s | FIND_IN_SET(matchStr, textStr)               | Returns the index (1-based) of the given *matchStr* in the comma-delimited *textStr*. Returns 0, if the given *matchStr* is not found or if the *matchStr* contains a comma. For example, FIND_IN_SET('bc', 'a,bc,def') returns 2
 | b | FLOOR(value)                                   | Similar to standard `FLOOR(value)` except if *value* is an integer type, the return type is a double
 | b | FORMAT_DATE(string, date)                      | Formats *date* according to the specified format *string*
 | b | FORMAT_DATETIME(string, timestamp)             | Formats *timestamp* according to the specified format *string*