Find current users DDL statement running, Oracle 11g
You really need the statements? The drop / truncate commands don't have that many options. You can get this info from these functions in the trigger (that I think is enough for what you need):

ora_sysevent
ora_login_user
ora_instance_num
ora_database_name
ora_dict_obj_type
ora_dict_obj_name
ora_dict_obj_owner


Ps: if you want to capture the statements, I would recommend you choose AUDIT feature available in the database, instead of using triggers.