feat: 添加对数组和对象字面量的尾随逗号支持，更新相关测试用例

src/parser/parser.rs

@@ -567,6 +567,10 @@ impl Parser {
                 if !self.match_kind(&[TokenKind::Comma]) {
                     break;
                 }
+                // Allow trailing comma
+                if self.check(&TokenKind::RightBrace) {
+                    break;
+                }
             }
         }
         self.consume(TokenKind::RightBrace, "Expected '}' after object literal")?;
@@ -581,6 +585,10 @@ impl Parser {
                 if !self.match_kind(&[TokenKind::Comma]) {
                     break;
                 }
+                // Allow trailing comma
+                if self.check(&TokenKind::RightBracket) {
+                    break;
+                }
             }
         }
         self.consume(TokenKind::RightBracket, "Expected ']' after array literal")?;

src/parser/tests.rs

@@ -551,6 +551,22 @@
         }
     }
 
+    #[test]
+    fn parse_array_trailing_comma() {
+        match parse_expr("[1, 2, 3,]") {
+            Expr::ArrayLiteral { elements } => assert_eq!(elements.len(), 3),
+            e => panic!("Expected ArrayLiteral, got {:?}", e),
+        }
+    }
+
+    #[test]
+    fn parse_object_trailing_comma() {
+        match parse_expr("{a: 1, b: 2,}") {
+            Expr::ObjectLiteral { properties } => assert_eq!(properties.len(), 2),
+            e => panic!("Expected ObjectLiteral, got {:?}", e),
+        }
+    }
+
     // ----- statements -----
 
     #[test]