Abstract: A technique is used in embodiments of the invention such that backtracking programs can be written in a general purpose computer language (e.g., C++ or Java) without requiring the control structure of the program to reflect the structure of the decision tree. A data state and a control state are restored during backtracking. For restoring the data state, embodiments of the invention keep track of the changes made to variables and the point in execution at which the changes are made. When backtracking occurs, the data state can be restored by undoing the changes to the desired point in execution. For restoring the control state, the method of the invention provides a “failure” exception state that is invoked upon failure in the program (e.g., a failure to find a solution in a search program). The failure exception is “caught” by catch points established in the execution stack.

Abstract: A technique is used in embodiments of the invention such that backtracking programs can be written in a general purpose computer language (e.g., C++ or Java) without requiring the control structure of the program to reflect the structure of the decision tree. A data state and a control state are restored during backtracking. For restoring the data state, embodiments of the invention keep track of the changes made to variables and the point in execution at which the changes are made. When backtracking occurs, the data state can be restored by undoing the changes to the desired point in execution. For restoring the control state, the method of the invention provides a "failure" exception state that is invoked upon failure in the program (e.g., a failure to find a solution in a search program).. The failure exception is "caught" by catch points established in the execution stack.