How can I evaluate a string containing a binary formula in Delphi?

Question

In Delphi XE I have a routine that breaks down some complicated formulas to a binary formula result like this:

(1&((1|0)|1)&1)

Since my application is on SQL Server I can easily do a SELECT (1&((1|0)|1)&1) As Result and SQL Server will evaluate the logic to give me a 1 or 0 result.

I cannot seem to find a native Delphi way of taking a string representation of a binary formula and evaluating it.

I looked into the Live Bindings Evaluators added to XE but any attempt at the and/or operators throws parser errors so I believe that to be more of a mathematical process.

I also looked at a few parsers but none really seemed to jump out at me.

So how can I do something similar to:

iSomeInt := Evaluate('(1&((1|0)|1)&1)');

BTW.. I can totally rework the formula and use and/or instead of &|.. that was just to make it work with SQL Server.

Answer 1

The problem isn't that it's "a mathematical process" so much as that the LiveBindings parser expects your mathematical process to be expressed with Pascal operators, but & and | are C operators.

Try something like this, assuming you have a function called LiveBindingsEval which evaluates a string with the LiveBindings parser:

function PreprocessExpression(const expr: string): string;
begin
   result := StringReplace(expr, '|', ' or ', [rfReplaceAll]);
   result := StringReplace(result, '&', ' and ', [rfReplaceAll]);
end;

iSomeInt := LiveBindingsEval(PreprocessExpression('(1&((1|0)|1)&1)'));

You may need to improve on this a little, but this should be enough to get you started on the right path...