public Task <EvaluationResult> Evaluate(CancellationToken cancellationToken)
{
// wrap the AST task so that instead of returning only one boolean, it returns also the error message
return(new Task <EvaluationResult>(() =>
{
var astTask = _ast.Evaluate(cancellationToken);
astTask.Start();
return new EvaluationResult
{
RuleId = _ruleId,
ConcernedProperties = _concernedProperties,
AstResult = astTask.Result,
ErrorMessage = _errorMessage
};
}, cancellationToken));
}