Support DuckDB struct syntax and support list of struct syntax (#1372)

Signed-off-by: jayzhan211 <jayzhan211@gmail.com>
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>
Co-authored-by: Ifeanyi Ubah <ify1992@yahoo.com>

src/ast/data_type.rs

@@ -302,7 +302,7 @@ pub enum DataType {
     ///
     /// [hive]: https://docs.cloudera.com/cdw-runtime/cloud/impala-sql-reference/topics/impala-struct.html
     /// [bigquery]: https://cloud.google.com/bigquery/docs/reference/standard-sql/data-types#struct_type
-    Struct(Vec<StructField>),
+    Struct(Vec<StructField>, StructBracketKind),
     /// Union
     ///
     /// [duckdb]: https://duckdb.org/docs/sql/data_types/union.html
@@ -517,9 +517,16 @@ impl fmt::Display for DataType {
                 }
                 write!(f, ")")
             }
-            DataType::Struct(fields) => {
+            DataType::Struct(fields, bracket) => {
                 if !fields.is_empty() {
-                    write!(f, "STRUCT<{}>", display_comma_separated(fields))
+                    match bracket {
+                        StructBracketKind::Parentheses => {
+                            write!(f, "STRUCT({})", display_comma_separated(fields))
+                        }
+                        StructBracketKind::AngleBrackets => {
+                            write!(f, "STRUCT<{}>", display_comma_separated(fields))
+                        }
+                    }
                 } else {
                     write!(f, "STRUCT")
                 }
@@ -618,6 +625,17 @@ fn format_clickhouse_datetime_precision_and_timezone(
     Ok(())
 }
 
+/// Type of brackets used for `STRUCT` literals.
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+#[cfg_attr(feature = "visitor", derive(Visit, VisitMut))]
+pub enum StructBracketKind {
+    /// Example: `STRUCT(a INT, b STRING)`
+    Parentheses,
+    /// Example: `STRUCT<a INT, b STRING>`
+    AngleBrackets,
+}
+
 /// Timestamp and Time data types information about TimeZone formatting.
 ///
 /// This is more related to a display information than real differences between each variant. To

src/ast/mod.rs

@@ -28,7 +28,8 @@ use serde::{Deserialize, Serialize};
 use sqlparser_derive::{Visit, VisitMut};
 
 pub use self::data_type::{
-    ArrayElemTypeDef, CharLengthUnits, CharacterLength, DataType, ExactNumberInfo, TimezoneInfo,
+    ArrayElemTypeDef, CharLengthUnits, CharacterLength, DataType, ExactNumberInfo,
+    StructBracketKind, TimezoneInfo,
 };
 pub use self::dcl::{AlterRoleOperation, ResetConfig, RoleOption, SetConfigValue};
 pub use self::ddl::{

src/parser/mod.rs

@@ -2266,6 +2266,23 @@ impl<'a> Parser<'a> {
         ))
     }
 
+    /// Duckdb Struct Data Type <https://duckdb.org/docs/sql/data_types/struct.html#retrieving-from-structs>
+    fn parse_duckdb_struct_type_def(&mut self) -> Result<Vec<StructField>, ParserError> {
+        self.expect_keyword(Keyword::STRUCT)?;
+        self.expect_token(&Token::LParen)?;
+        let struct_body = self.parse_comma_separated(|parser| {
+            let field_name = parser.parse_identifier(false)?;
+            let field_type = parser.parse_data_type()?;
+
+            Ok(StructField {
+                field_name: Some(field_name),
+                field_type,
+            })
+        });
+        self.expect_token(&Token::RParen)?;
+        struct_body
+    }
+
     /// Parse a field definition in a [struct] or [tuple].
     /// Syntax:
     ///
@@ -7495,12 +7512,20 @@ impl<'a> Parser<'a> {
                         ))))
                     }
                 }
+                Keyword::STRUCT if dialect_of!(self is DuckDbDialect) => {
+                    self.prev_token();
+                    let field_defs = self.parse_duckdb_struct_type_def()?;
+                    Ok(DataType::Struct(field_defs, StructBracketKind::Parentheses))
+                }
                 Keyword::STRUCT if dialect_of!(self is BigQueryDialect | GenericDialect) => {
                     self.prev_token();
                     let (field_defs, _trailing_bracket) =
                         self.parse_struct_type_def(Self::parse_struct_field_def)?;
                     trailing_bracket = _trailing_bracket;
-                    Ok(DataType::Struct(field_defs))
+                    Ok(DataType::Struct(
+                        field_defs,
+                        StructBracketKind::AngleBrackets,
+                    ))
                 }
                 Keyword::UNION if dialect_of!(self is DuckDbDialect | GenericDialect) => {
                     self.prev_token();