change the lexer

src/parser.y

@@ -103,12 +103,7 @@ BlockItem: { $$ = NULL; }
          | VarDecl BlockItem { $$ = new_node(BlockItem, $2, NULL, $1, 0, 0, NULL, NonType); }
          | Stmt BlockItem { $$ = new_node(BlockItem, $2, NULL, $1, 0, 0, NULL, NonType); };
 
-// 以下是你需要完成的语法规则和语义计算规则
-//Stmt → LVal '=' Exp ';' | [Exp] ';' | Block
-//| 'if' '(' Cond ')' Stmt [ 'else' Stmt ]
-//| 'while' '(' Cond ')' Stmt
-//| 'break' ';' | 'continue' ';'
-//| 'return' [Exp] ';'
+
 Stmt:  LVal ASSIGN Exp SEMICOLON{$$ = new_node(Stmt,$1,NULL,$3,0,0,NULL,NonType);}
 | Exp SEMICOLON {$$ = new_node(Stmt,NULL,NULL,$1,0,0,NULL,NonType);}
 | SEMICOLON {$$ = NULL;}