Question

Is there any relatively simple way to recognize Regex pattern as simple text or as a rule?

One example. @'[A-Z0-9]' – is a rule, and @'\\[A-Z0-9\\]' is a plain simple text (C# string syntax)

Answer 1

Short of detecting ‘ [‘ i.e. escaped regular expression characters, I can’t think of anything off the top of my head.

Since using @ copies the string literal verbatim try –

1.Finding every ‘[‘/’*’/’+’/’all other regex charachters’ and ensuring that the previous charachter is a ‘\’.

2.Another way might be to write a grammar/regex to check this. I think you’ll need a grammar. In any case (1) above is simpler.

Some string methods may help check for the above (like IndexOf …).

In any case, a regex is just a string, unless and until it is compiled and used. I still cant see why you want to do this. If you want to ensure something is a well formed regex, that is easier. (I don’t know a C# specific way for it offhand — See Svish’s answer.).

Note
1.A regex is always a rule because the regex ‘XYZ’ is a rule that always matches ‘XYZ’ alone and doesn’t match anything else.

I hope this helps.