I'm trying to evaluate an expression with an array not containing all variables of the expression.

When i evaluate the expression with my array, the evaluation return a exception :

Variable XXXX is not valid around position 1.

My problem is when i have a expression like

( ( var1 != 2 ) or ( var2 != 2 ) ),

and an array

array(
        'var1' => 3,
) 

this evaluation throw an exception. Should we not return a boolean instead of an exception ?

For exemple if we have the expression :

(a and b and c) or (d and e and f)

and e does not exist in the array, the expression (d and e and f) return false and not an exception.