Add PostgreSQL specfic "CREATE TYPE t AS ENUM (...)" support.

See: https://www.postgresql.org/docs/current/sql-createtype.html

src/ast/mod.rs

@@ -3181,6 +3181,14 @@ pub enum Statement {
         representation: UserDefinedTypeRepresentation,
     },
     /// ```sql
+    /// CREATE TYPE <name> AS ENUM
+    /// ```
+    /// Note: this is a PostgreSQL-specific statement. See <https://www.postgresql.org/docs/current/sql-createtype.html>
+    CreateTypeAsEnum {
+        name: ObjectName,
+        labels: Vec<Ident>,
+    },
+    /// ```sql
     /// PRAGMA <schema-name>.<pragma-name> = <pragma-value>
     /// ```
     Pragma {
@@ -4795,6 +4803,13 @@ impl fmt::Display for Statement {
             } => {
                 write!(f, "CREATE TYPE {name} AS {representation}")
             }
+            Statement::CreateTypeAsEnum { name, labels } => {
+                write!(
+                    f,
+                    "CREATE TYPE {name} AS ENUM ({})",
+                    display_comma_separated(labels)
+                )
+            }
             Statement::Pragma { name, value, is_eq } => {
                 write!(f, "PRAGMA {name}")?;
                 if value.is_some() {

src/dialect/postgresql.rs

@@ -28,7 +28,7 @@
 // limitations under the License.
 use log::debug;
 
-use crate::ast::{CommentObject, Statement};
+use crate::ast::{CommentObject, ObjectName, Statement};
 use crate::dialect::{Dialect, Precedence};
 use crate::keywords::Keyword;
 use crate::parser::{Parser, ParserError};
@@ -138,6 +138,14 @@ impl Dialect for PostgreSqlDialect {
     fn parse_statement(&self, parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
         if parser.parse_keyword(Keyword::COMMENT) {
             Some(parse_comment(parser))
+        } else if parser.parse_keyword(Keyword::CREATE) {
+            match parse_create(parser) {
+                Some(result) => Some(result),
+                None => {
+                    parser.prev_token(); // unconsume the CREATE if we didn't end up parsing anything
+                    None
+                }
+            }
         } else {
             None
         }
@@ -221,3 +229,29 @@ pub fn parse_comment(parser: &mut Parser) -> Result<Statement, ParserError> {
         if_exists,
     })
 }
+
+pub fn parse_create(parser: &mut Parser) -> Option<Result<Statement, ParserError>> {
+    let name = parser.maybe_parse(|parser| -> Result<ObjectName, ParserError> {
+        parser.expect_keyword(Keyword::TYPE)?;
+        let name = parser.parse_object_name(false)?;
+        parser.expect_keyword(Keyword::AS)?;
+        parser.expect_keyword(Keyword::ENUM)?;
+        Ok(name)
+    });
+    name.map(|name| parse_create_type_as_enum(parser, name))
+}
+
+// https://www.postgresql.org/docs/current/sql-createtype.html
+pub fn parse_create_type_as_enum(
+    parser: &mut Parser,
+    name: ObjectName,
+) -> Result<Statement, ParserError> {
+    if !parser.consume_token(&Token::LParen) {
+        return parser.expected("'(' after CREATE TYPE AS ENUM", parser.peek_token());
+    }
+
+    let labels = parser.parse_comma_separated0(|p| p.parse_identifier(false), Token::RParen)?;
+    parser.expect_token(&Token::RParen)?;
+
+    Ok(Statement::CreateTypeAsEnum { name, labels })
+}

tests/sqlparser_postgres.rs

@@ -5113,3 +5113,29 @@ fn arrow_cast_precedence() {
         }
     )
 }
+
+#[test]
+fn parse_create_type_as_enum() {
+    let statement = pg().one_statement_parses_to(
+        r#"CREATE TYPE public.my_type AS ENUM (
+            'label1',
+            'label2',
+            'label3',
+            'label4'
+        );"#,
+        "CREATE TYPE public.my_type AS ENUM ('label1', 'label2', 'label3', 'label4')",
+    );
+    match statement {
+        Statement::CreateTypeAsEnum { name, labels } => {
+            assert_eq!("public.my_type", name.to_string());
+            assert_eq!(
+                vec!["label1", "label2", "label3", "label4"]
+                    .into_iter()
+                    .map(|l| Ident::with_quote('\'', l))
+                    .collect::<Vec<Ident>>(),
+                labels
+            );
+        }
+        _ => unreachable!(),
+    }
+}