Add support for parsing empty dictionary expressions (apache#1684)

Author: yoavcloud

src/parser/mod.rs

@@ -2854,7 +2854,8 @@ impl<'a> Parser<'a> {
     fn parse_duckdb_struct_literal(&mut self) -> Result<Expr, ParserError> {
         self.expect_token(&Token::LBrace)?;
 
-        let fields = self.parse_comma_separated(Self::parse_duckdb_dictionary_field)?;
+        let fields =
+            self.parse_comma_separated0(Self::parse_duckdb_dictionary_field, Token::RBrace)?;
 
         self.expect_token(&Token::RBrace)?;
 

tests/sqlparser_common.rs

@@ -11291,6 +11291,8 @@ fn test_dictionary_syntax() {
         );
     }
 
+    check("{}", Expr::Dictionary(vec![]));
+
     check(
         "{'Alberta': 'Edmonton', 'Manitoba': 'Winnipeg'}",
         Expr::Dictionary(vec![