Interface IExpressionEvaluator

  • All Known Implementing Classes:
    XBaseEvaluator

    public interface IExpressionEvaluator
    An expression evaluator is used to execute arbitrary Java code during pattern matching. In order to include the evaluation in the planning seemlessly it is expected from the evaluator implementors to report all used PVariables by name.
    • Method Detail

      • getShortDescription

        java.lang.String getShortDescription()
        A textual description of the expression. Used only for debug purposes, but must not be null.
      • getInputParameterNames

        java.lang.Iterable<java.lang.String> getInputParameterNames()
        All input parameter names should be reported correctly.
      • evaluateExpression

        java.lang.Object evaluateExpression​(IValueProvider provider)
                                     throws java.lang.Exception
        The expression evaluator code
        Parameters:
        provider - the value provider is an engine-specific way of reading internal variable tuples to evaluate the expression with
        Returns:
        the result of the expression: in case of predicate evaluation the return value must be true or false; otherwise the result can be an arbitrary object. No null values should be returned.
        Throws:
        java.lang.Exception