PostgreSQL: Support TRANSFORM members in ALTER EXTENSION

fuzz/fuzz_seeds/postgres_alter_extension.sql

@@ -35,3 +35,4 @@ ALTER EXTENSION citext ADD OPERATOR - (NONE, int);
 ALTER EXTENSION citext DROP OPERATOR CLASS oc USING btree;
 ALTER EXTENSION citext DROP OPERATOR FAMILY of USING btree;
 ALTER EXTENSION citext ADD CAST (int AS text);
+ALTER EXTENSION citext ADD TRANSFORM FOR int LANGUAGE plpgsql;

src/ast/ddl.rs

@@ -5014,6 +5014,13 @@ pub enum AlterExtensionMember {
     TextSearchParser(ObjectName),
     /// `TEXT SEARCH TEMPLATE object_name`
     TextSearchTemplate(ObjectName),
+    /// `TRANSFORM FOR type_name LANGUAGE lang_name`
+    Transform {
+        /// Transformed type.
+        type_name: DataType,
+        /// Language name.
+        language: Ident,
+    },
     /// `VIEW object_name`
     View(ObjectName),
 }
@@ -5093,6 +5100,10 @@ impl fmt::Display for AlterExtensionMember {
             AlterExtensionMember::TextSearchTemplate(name) => {
                 write!(f, "TEXT SEARCH TEMPLATE {name}")
             }
+            AlterExtensionMember::Transform {
+                type_name,
+                language,
+            } => write!(f, "TRANSFORM FOR {type_name} LANGUAGE {language}"),
             AlterExtensionMember::View(name) => write!(f, "VIEW {name}"),
         }
     }

src/keywords.rs

@@ -1118,6 +1118,7 @@ define_keywords!(
     TRAILING,
     TRAN,
     TRANSACTION,
+    TRANSFORM,
     TRANSIENT,
     TRANSLATE,
     TRANSLATE_REGEX,

src/parser/mod.rs

@@ -12644,6 +12644,14 @@ impl<'a> Parser<'a> {
             Ok(AlterExtensionMember::TextSearchTemplate(
                 self.parse_object_name(false)?,
             ))
+        } else if self.parse_keywords(&[Keyword::TRANSFORM, Keyword::FOR]) {
+            let type_name = self.parse_data_type()?;
+            self.expect_keyword_is(Keyword::LANGUAGE)?;
+            let language = self.parse_identifier()?;
+            Ok(AlterExtensionMember::Transform {
+                type_name,
+                language,
+            })
         } else if self.parse_keyword(Keyword::VIEW) {
             Ok(AlterExtensionMember::View(self.parse_object_name(false)?))
         } else {

tests/sqlparser_postgres.rs

@@ -13583,6 +13583,7 @@ fn alter_extension_member_round_trip_forms(action: &str) {
         format!("ALTER EXTENSION ext_name {action} TEXT SEARCH DICTIONARY dict"),
         format!("ALTER EXTENSION ext_name {action} TEXT SEARCH PARSER pgrm"),
         format!("ALTER EXTENSION ext_name {action} TEXT SEARCH TEMPLATE tpl"),
+        format!("ALTER EXTENSION ext_name {action} TRANSFORM FOR my_type LANGUAGE plpgsql"),
         format!("ALTER EXTENSION ext_name {action} VIEW v"),
     ];
     for sql in sqls {
@@ -13801,6 +13802,26 @@ fn parse_alter_extension_add_member() {
         other => panic!("unexpected statement: {other:?}"),
     }
 
+    match pg_and_generic()
+        .verified_stmt("ALTER EXTENSION ext_name ADD TRANSFORM FOR my_type LANGUAGE plpgsql")
+    {
+        Statement::AlterExtension(AlterExtension {
+            operation:
+                AlterExtensionOperation::Add(AlterExtensionMember::Transform {
+                    type_name,
+                    language,
+                }),
+            ..
+        }) => {
+            assert_eq!(
+                type_name,
+                DataType::Custom(ObjectName::from(Ident::new("my_type")), vec![])
+            );
+            assert_eq!(language, Ident::new("plpgsql"));
+        }
+        other => panic!("unexpected statement: {other:?}"),
+    }
+
     for (sql, error) in [
         (
             "ALTER EXTENSION ext_name ADD",
@@ -13834,6 +13855,10 @@ fn parse_alter_extension_add_member() {
             "ALTER EXTENSION ext_name ADD CAST (INT)",
             "Expected: AS, found: )",
         ),
+        (
+            "ALTER EXTENSION ext_name ADD TRANSFORM FOR my_type",
+            "Expected: LANGUAGE, found: EOF",
+        ),
         (
             "ALTER EXTENSION ext_name ADD OPERATOR +",
             "Expected: (, found: EOF",
@@ -13878,6 +13903,14 @@ fn parse_alter_extension_add_member() {
             "ALTER EXTENSION ext_name ADD OPERATOR FAMILY of USING",
             "Expected: identifier, found: EOF",
         ),
+        (
+            "ALTER EXTENSION ext_name ADD TRANSFORM FOR",
+            "Expected: a data type name, found: EOF",
+        ),
+        (
+            "ALTER EXTENSION ext_name ADD TRANSFORM FOR my_type LANGUAGE",
+            "Expected: identifier, found: EOF",
+        ),
     ] {
         assert_eq!(
             pg_and_generic().parse_sql_statements(sql).unwrap_err(),