feat: Allow OUTER keyword as function parameter name

src/main/jjtree/net/sf/jsqlparser/parser/JSqlParserCC.jjt

@@ -4619,15 +4619,16 @@ JdbcNamedParameter JdbcNamedParameter() : {
 }
 
 OracleNamedFunctionParameter OracleNamedFunctionParameter() : {
-    String name;
+    Token token = null;
+    String name = null;
     Expression expression;
 }
 {
-    name=RelObjectNameExt2()
+    ( name=RelObjectNameExt2() | token=<K_OUTER> )
     <K_ORACLE_NAMED_PARAMETER_ASSIGNMENT>
     expression=Expression()
     {
-        return new OracleNamedFunctionParameter(name, expression);
+        return new OracleNamedFunctionParameter(name != null ? name : token.image, expression);
     }
 }
 

src/test/java/net/sf/jsqlparser/statement/select/TableFunctionTest.java

@@ -31,4 +31,20 @@ void testLateralFlat() throws JSQLParserException {
         TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
     }
 
+    /**
+     * The SQL keyword "OUTER" is a valid parameter name for Snowflake's FLATTEN table function.
+     */
+    @Test
+    void testTableFunctionWithNamedParameterWhereNameIsOuterKeyword() throws JSQLParserException {
+        String sqlStr =
+                "INSERT INTO db.schema.target\n" +
+                        "     (Name, FriendParent)\n" +
+                        " SELECT\n" +
+                        "     i.DATA_VALUE:Name AS Name,\n" +
+                        "     f1.Value:Parent:Name AS FriendParent\n" +
+                        " FROM\n" +
+                        "     db.schema.source AS i,\n" +
+                        "     lateral flatten(input => i.DATA_VALUE:Friends, outer => true) AS f1;";
+        TestUtils.assertSqlCanBeParsedAndDeparsed(sqlStr, true);
+    }
 }