Method and apparatus for goal processing memory management

Abstract

The present invention is a method and apparatus for managing memory in goal processing. The present invention creates search states that contain an alternative subgoal (i.e., subgoal with alternatives) and non-alternative subgoals. Problem state modifications associated with the goals contained in a search state are associated with a search state object. A search state object contains information about the search process and the goals included in the search state, and a pointer to previous search state objects. Processed goals are kept on a goal stack, and the search state object points to the first and last goal stack entry included in the search state object. A search state object includes a list of alternatives available in the search state. When a goal processing failure occurs, an alternative solution search begins with the latest search state object until an alternative is found, or a determination is made that no alternatives exist and the goal cannot be satisfied. When a goal processing failure occurs, an alternative subgoal is directly accessible without visiting each subgoal individually. Goals included in the failed processing may be collectively popped from the goal stack. Problem state modifications associated with the failed processing may be collectively undone from the problem state. Goal processing reverts to a state prior to the failed state without examining each goal within the failed state, individually removing the failed state's modifications, and individually releasing the memory used by the failed state.