trailing comma are supported for dict, list, set, import, can.

jaclang/compiler/jac.lark

@@ -25,7 +25,7 @@ from_path: (DOT | ELLIPSIS)* import_path
          | (DOT | ELLIPSIS)+
 
 import_path: named_ref (DOT named_ref)* (KW_AS NAME)?
-import_items: (import_item COMMA)* import_item
+import_items: (import_item COMMA)* import_item COMMA?
 import_item: named_ref (KW_AS NAME)?
 sub_name: COLON NAME
 include_stmt: KW_INCLUDE sub_name? import_path SEMI
@@ -63,7 +63,7 @@ enum: decorators? enum_decl
 
 enum_decl: KW_ENUM access_tag? STRING? NAME inherited_archs? (enum_block | SEMI)
 enum_def: arch_to_enum_chain enum_block
-enum_block: LBRACE ((enum_stmt COMMA)* enum_stmt)? RBRACE
+enum_block: LBRACE ((enum_stmt COMMA)* enum_stmt COMMA?)? RBRACE
 
 enum_stmt: NAME (COLON STRING)? EQ expression
          | NAME (COLON STRING)?
@@ -83,7 +83,7 @@ abstract_ability: KW_OVERRIDE? KW_STATIC? KW_CAN access_tag? STRING? named_ref (
 genai_ability: KW_OVERRIDE? KW_STATIC? KW_CAN access_tag? STRING? named_ref (func_decl) KW_BY atomic_call SEMI
 event_clause: KW_WITH expression? (KW_EXIT | KW_ENTRY) (STRING? RETURN_HINT expression)?
 func_decl: (LPAREN func_decl_params? RPAREN)? (RETURN_HINT (STRING COLON)? expression)?
-func_decl_params: (param_var COMMA)* param_var
+func_decl_params: (param_var COMMA)* param_var COMMA?
 param_var: (STAR_POW | STAR_MUL)? NAME (COLON STRING)? type_tag (EQ expression)?
 
 // Global variables
@@ -412,10 +412,10 @@ set_compr: LBRACE expression inner_compr+ RBRACE
 dict_compr: LBRACE kv_pair inner_compr+ RBRACE
 inner_compr: KW_ASYNC? KW_FOR atomic_chain KW_IN pipe_call (KW_IF walrus_assign)*
 
-dict_val: LBRACE ((kv_pair COMMA)* kv_pair)? RBRACE
-list_val: LSQUARE expr_list? RSQUARE
+dict_val: LBRACE ((kv_pair COMMA)* kv_pair COMMA?)? RBRACE
+list_val: LSQUARE (expr_list COMMA?)? RSQUARE
 tuple_val: LPAREN tuple_list? RPAREN
-set_val: LBRACE expr_list RBRACE
+set_val: LBRACE expr_list COMMA? RBRACE
 
 kv_pair: expression COLON expression | STAR_POW expression
 expr_list: (expr_list COMMA)? expression

jaclang/tests/fixtures/trailing_comma.jac

@@ -0,0 +1,64 @@
+"""
+This test file is to ensure the valid syntax of jac lang.
+Add new jac syntax here to test if it compile without any issue.
+"""
+
+# Import statement without trailing comma.
+import:py from time {
+  sleep,
+  timezone,
+  tzname
+}
+
+
+# Import statement with trailing comma.
+import:py from os {
+  path,
+  getenv,
+  getpid,
+}
+
+
+enum WithoutTrailComma {
+    FOO = "FOO",
+    BAR = "BAR"
+}
+
+
+enum WithTrailComma {
+    FOO = "FOO",
+    BAR = "BAR",
+}
+
+
+can without_trail_comma(a:int, b:int) {}
+
+can with_trail_comma(
+      a:int,
+      b:int,
+      c:int,
+    ) {}
+
+
+with entry {
+
+    dict_without_trail_comma = { "key" : "value" };
+    dict_with_trail_comma = {
+        "key" : "val",
+    };
+
+    list_without_trail_comma = [ "foo", "bar" ];
+    list_with_trail_comma = [
+        "foo",
+        "bar",
+    ];
+
+    set_without_trail_comma = { "foo", "bar" };
+    set_with_trail_comma = {
+      "foo",
+      "bar",
+    };
+
+    print("Code compiled and ran successfully!");
+}
+

jaclang/tests/test_language.py

@@ -703,6 +703,15 @@ def test_tuple_unpack(self) -> None:
         self.assertIn("1", stdout_value[0])
         self.assertIn("[2, 3, 4]", stdout_value[1])
 
+    def test_trailing_comma(self) -> None:
+        """Test trailing comma."""
+        captured_output = io.StringIO()
+        sys.stdout = captured_output
+        jac_import("trailing_comma", base_path=self.fixture_abs_path("./"))
+        sys.stdout = sys.__stdout__
+        stdout_value = captured_output.getvalue()
+        self.assertIn("Code compiled and ran successfully!", stdout_value)
+
     def test_try_finally(self) -> None:
         """Test try finally."""
         captured_output = io.StringIO()