PostgreSQL: Support OPERATOR CLASS members in ALTER EXTENSION

fuzz/fuzz_seeds/postgres_alter_extension.sql

@@ -32,3 +32,4 @@ ALTER EXTENSION citext ADD ROUTINE public.r(int);
 ALTER EXTENSION citext DROP AGGREGATE agg(int ORDER BY text);
 ALTER EXTENSION citext ADD AGGREGATE cnt(*);
 ALTER EXTENSION citext ADD OPERATOR - (NONE, int);
+ALTER EXTENSION citext DROP OPERATOR CLASS oc USING btree;

src/ast/ddl.rs

@@ -4963,6 +4963,13 @@ pub enum AlterExtensionMember {
     MaterializedView(ObjectName),
     /// `OPERATOR operator_name (left_type, right_type)`
     Operator(DropOperatorSignature),
+    /// `OPERATOR CLASS object_name USING index_method`
+    OperatorClass {
+        /// Operator class name.
+        name: ObjectName,
+        /// Index method.
+        using: Ident,
+    },
     /// `PROCEDURE procedure_name [ ( [ [ argmode ] [ argname ] argtype [, ...] ] ) ]`
     Procedure(FunctionDesc),
     /// `PUBLICATION object_name`
@@ -5041,6 +5048,9 @@ impl fmt::Display for AlterExtensionMember {
             }
             AlterExtensionMember::MaterializedView(name) => write!(f, "MATERIALIZED VIEW {name}"),
             AlterExtensionMember::Operator(signature) => write!(f, "OPERATOR {signature}"),
+            AlterExtensionMember::OperatorClass { name, using } => {
+                write!(f, "OPERATOR CLASS {name} USING {using}")
+            }
             AlterExtensionMember::Procedure(function) => write!(f, "PROCEDURE {function}"),
             AlterExtensionMember::Publication(name) => write!(f, "PUBLICATION {name}"),
             AlterExtensionMember::Routine(function) => write!(f, "ROUTINE {function}"),

src/parser/mod.rs

@@ -12577,9 +12577,16 @@ impl<'a> Parser<'a> {
                 self.parse_object_name(false)?,
             ))
         } else if self.parse_keyword(Keyword::OPERATOR) {
-            Ok(AlterExtensionMember::Operator(
-                self.parse_drop_operator_signature()?,
-            ))
+            if self.parse_keyword(Keyword::CLASS) {
+                let name = self.parse_object_name(false)?;
+                self.expect_keyword_is(Keyword::USING)?;
+                let using = self.parse_identifier()?;
+                Ok(AlterExtensionMember::OperatorClass { name, using })
+            } else {
+                Ok(AlterExtensionMember::Operator(
+                    self.parse_drop_operator_signature()?,
+                ))
+            }
         } else if self.parse_keyword(Keyword::PROCEDURE) {
             Ok(AlterExtensionMember::Procedure(self.parse_function_desc()?))
         } else if self.parse_keyword(Keyword::PUBLICATION) {

tests/sqlparser_postgres.rs

@@ -13560,6 +13560,7 @@ fn alter_extension_member_round_trip_forms(action: &str) {
         format!("ALTER EXTENSION ext_name {action} MATERIALIZED VIEW mv"),
         format!("ALTER EXTENSION ext_name {action} OPERATOR + (INT, TEXT)"),
         format!("ALTER EXTENSION ext_name {action} OPERATOR - (NONE, INT)"),
+        format!("ALTER EXTENSION ext_name {action} OPERATOR CLASS oc USING btree"),
         format!("ALTER EXTENSION ext_name {action} PROCEDURE p"),
         format!("ALTER EXTENSION ext_name {action} PROCEDURE p()"),
         format!("ALTER EXTENSION ext_name {action} PROCEDURE p(INT)"),
@@ -13809,6 +13810,18 @@ fn parse_alter_extension_add_member() {
             "ALTER EXTENSION ext_name ADD OPERATOR +",
             "Expected: (, found: EOF",
         ),
+        (
+            "ALTER EXTENSION ext_name ADD OPERATOR CLASS oc",
+            "Expected: USING, found: EOF",
+        ),
+        (
+            "ALTER EXTENSION ext_name ADD OPERATOR CLASS oc USING",
+            "Expected: identifier, found: EOF",
+        ),
+        (
+            "ALTER EXTENSION ext_name ADD OPERATOR CLASS",
+            "Expected: identifier, found: EOF",
+        ),
     ] {
         assert_eq!(
             pg_and_generic().parse_sql_statements(sql).unwrap_err(),