Support ALTER INDEX {INDEX_NAME} RENAME TO {NEW_INDEX_NAME} (#767)

* test: add a case `rename_index`

* feat: add AlterIndex match arm

* fix: remove todo with self.expected

* chore: add comment to unreachable

Author: devgony

src/ast/ddl.rs

@@ -94,6 +94,12 @@ pub enum AlterTableOperation {
     },
 }
 
+#[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
+#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
+pub enum AlterIndexOperation {
+    RenameIndex { index_name: ObjectName },
+}
+
 impl fmt::Display for AlterTableOperation {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
@@ -200,6 +206,16 @@ impl fmt::Display for AlterTableOperation {
     }
 }
 
+impl fmt::Display for AlterIndexOperation {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            AlterIndexOperation::RenameIndex { index_name } => {
+                write!(f, "RENAME TO {}", index_name)
+            }
+        }
+    }
+}
+
 /// An `ALTER COLUMN` (`Statement::AlterTable`) operation
 #[derive(Debug, Clone, PartialEq, PartialOrd, Eq, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]

src/ast/mod.rs

@@ -26,8 +26,8 @@ pub use self::data_type::{
     CharLengthUnits, CharacterLength, DataType, ExactNumberInfo, TimezoneInfo,
 };
 pub use self::ddl::{
-    AlterColumnOperation, AlterTableOperation, ColumnDef, ColumnOption, ColumnOptionDef, IndexType,
-    KeyOrIndexDisplay, ReferentialAction, TableConstraint,
+    AlterColumnOperation, AlterIndexOperation, AlterTableOperation, ColumnDef, ColumnOption,
+    ColumnOptionDef, IndexType, KeyOrIndexDisplay, ReferentialAction, TableConstraint,
 };
 pub use self::operator::{BinaryOperator, UnaryOperator};
 pub use self::query::{
@@ -1250,6 +1250,10 @@ pub enum Statement {
         name: ObjectName,
         operation: AlterTableOperation,
     },
+    AlterIndex {
+        name: ObjectName,
+        operation: AlterIndexOperation,
+    },
     /// DROP
     Drop {
         /// The type of the object to drop: TABLE, VIEW, etc.
@@ -2275,6 +2279,9 @@ impl fmt::Display for Statement {
             Statement::AlterTable { name, operation } => {
                 write!(f, "ALTER TABLE {} {}", name, operation)
             }
+            Statement::AlterIndex { name, operation } => {
+                write!(f, "ALTER INDEX {} {}", name, operation)
+            }
             Statement::Drop {
                 object_type,
                 if_exists,