Expression evaulators

 Does anyone have any knowledge of expression evaulators written in .Net?  I need an expression evaulator that can handle conditional statements such as "if" and/or "case" statements.  It would be really great if I could load this expression evaulator tool into Sqlserver in order for store procedures to call it too!

 Example
string pass_variable = "if (@a > @b) return @a + @b else return 0;"
        string returnVal;
        int aValue = 5, bValue = 3;
        pass_variable.Replace("@a", aValue.ToString());
        pass_variable.Replace("@b", bValue.ToString());
        returnVal = EvaluationProcessor.exe(pass_variable);



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