Regex that doesn't contain is|has prefix but ends with : Bool

Question

Sorry that I have to ask that, with all the other answers around, but I can't get my head around to think and adapt to my problem.

So I'm writing a custom SwiftLint rule that should check:

does not have is or has prefix
does have : Bool suffix

My current Regex looks like this, but it shows me the stuff that contains is or has, but I want it to show me things that don't have it

(is|has)[A-Z][A-Za-z]*(: Bool)

I also tried this, but it won't show me any message, so I guess it's wrong:

^(?!is|has)[A-Z][A-Za-z]*: Bool$

So, what's the correct Regex?

EDIT: How it should be:

`isHello: Bool` -> nothing
hello: Bool -> should alarm me, missing is or has prefix

EDIT 2:

@State private var showActionSheet: Bool = false -> should give me a warning
@State private var hasStartWorkout: Bool = false -> should not give me a warning

Does this answer your question? [Understanding positive and negative lookaheads](https://stackoverflow.com/questions/27691225/understanding-positive-and-negative-lookaheads) — njzk2, May 17 '23 at 18:45
why do you require capital at start of your regex but your sample is lowercase? — jhnc, May 17 '23 at 19:06
@jhnc I actually dont know, but you are right, thats an error from my side — bennyyy999, May 17 '23 at 19:13
one ugly way is you can write ([^ih]|i[^s]|h[^a]|ha[^s]) to match some character that aren't is or has — user253751, May 17 '23 at 19:13
since you appear not to actually want to match at start/end of line, nor to require uppercase, perhaps: `\b(?!is|has)[A-Za-z]+: Bool\b` — jhnc, May 17 '23 at 19:54

Martin del Necesario · Accepted Answer · 2023-05-17T20:06:13.490

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Your problem is, that in a successful case of the negative lookahead the following regex part is not matching: "^(?!is|has)[A-Z][A-Za-z]*: Bool$". In your example, the line that doesn't start with is/has ("hello") starts with a lower character. So you have to move said part inside of the negative lookahead like in this regex:

(^| )(?!has[A-Z]|is[A-Z])[A-Za-z]+: Bool

edited May 17 '23 at 20:06

answered May 17 '23 at 19:17

Martin del Necesario

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I understand what you mean, but the problem persists. Sadly, I still get errors, even if it has the is or has as a prefix. – bennyyy999 May 17 '23 at 19:23
Can you give me some example lines which are wrongly matched / not matched? – Martin del Necesario May 17 '23 at 19:26
I updated my question with an edit at the bottom, both get flagged tho – bennyyy999 May 17 '23 at 19:30
I updated my solution. If you encounter further cases my regex handles incorrectly, please update your question with the corresponding lines – Martin del Necesario May 17 '23 at 20:06
It works if you change (or eliminate) the anchoring (^$). I see it’s been fixed. – Jeff Y May 17 '23 at 20:25

Jeff Y · Answer 2 · 2023-05-17T20:09:31.830

0

Unfortunately, you need something rather ugly like this:

/^([^ih]|i[^s]|h[^a]|ha[^s])[A-Za-z]*: Bool$/gm

And it gets even uglier if you need to enforce an uppercase after the “is” or “has”.

That’s only if you need pure regex. If you can use something like grep -v, life is simpler…

Updated for your “Edit 2”: /( |^)([^ih]|i[^s]|h[^a]|ha[^s])[A-Za-z]*: Bool/gm

edited May 17 '23 at 20:09

answered May 17 '23 at 19:52

Jeff Y

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Regex that doesn't contain is|has prefix but ends with : Bool

2 Answers2