[jexl] - Lazy evaluation

[udit gupta]

Hi,

The use case is to lazily evaluate variables in expression, as they are
costly.

Jexl already supports boolean short circuiting. Expression = ((A || B) &&C)

if A = True, B doesn't have to be set during expression evaluation.

However if A = False and B is not set, the evaluation throws JexlException
exception - undefined variable B.

One approach I tried Is to catch JexlException and then proceeding to
evaluate missing variable.


private String getNextVariableToEvaluate(){

try { expression.evaluate(context);

} catch (JexlException.Variable jexl) {

return jexl.getVariable();

}

return null;

}


This works, but because of throwing Exceptions it can be costly as it
generates stack trace every time.

Is there a clean way to find out if the expression can be short circuited
with what variables value we know currently?

If not, which is the variable that should be evaluated?