Just as the question says, I'm stuck with .Net 2.0 here in my company and there is no chance of upgrading. Is there a way to make Irony work in .NET 2.0.
I'll briefly try to explain what I'm trying to achieve. We at our company have a payroll system where we let customer define there own formulas for payslip items. These formulas must use some keywords/functions which we check through Regex(very unreliable). Then we create a Microsoft script control object and use its eval function to parse the snippet. These snippets in turn call keywords/functions defined in class to get the output.
But to say this system has drawback is being very polite. Sometimes the it just overflows with error.
A very silly e.g. -
FVAL(A)/(FVAL(B)+FVAL(C))
Obviously there the tow stages this formula passes through.
First the validation stage where we do the following -
Check through regex whether there are any keywords used which are not present in predefined arrayList of keywords
Then check whether there are any variables(in this case - A, B, C are the ones) used which are not present in an arraylist of variable.
If all validation passes then we pass the formula string to a ScriptControlClass object's eval function and also add a static class with all functions defined in it(in this case consider FVAL()) and this function returns boolean true if the variable is a valid one to use in this context(like adding a date and number would return false)
Now after evaluating this expression the result is - DivideByZeroException, why because eval typecasts all boolean true to 1 and performs normal arithmetic to it.
FVAL(A)/(FVAL(B)+FVAL(C)) => 1/(1-1)
The second phase is almost similar but without any validation check, like without returning true we actually return the value of the variable from a DataTable which consists of values for each variables.
The system is antiquated and its seriously getting on my nerves and I really need help. Please suggest.
If you're just talking about excel style formulas, it's pretty easy to write a good interpreter, especially if you only have to deal with one data type. Someone with a background in compilers (or even parsers) could probably write you up on in less than a day. I've written a bunch myself.
Embedding a scripting language is another option, but you'd have to be comfortable with the quirks of the given language. Ensuring that high-precision numbers are used could be difficult, if that's a business requirement.