Re: Shy groups and * ...eh, what?

[Heime <heimeborgia@protonmail.com>]

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------- Original Message -------
On Saturday, October 22nd, 2022 at 4:24 AM, Michael Heerdegen <michael_heerdegen@web.de> wrote:


> Hello,
> 
> I wanted to be sure I correctly understood that if you give multiple RX
> arguments to the `rx'` ' operator, they are implicitly interpreted as a
> sequence (AFAIU, that's the case. An implicit `or' would also make
> sense, that's why I wondered).
> 
> Anyway, here is what I tried:
> 
> (string-match-p
> (rx bos ( "a" "b") eos)
> "a")
> ==> 0
> 
> 
> (string-match-p
> (rx bos (* "a" "b") eos)
> "b")
> ==> nil
 
I usually do

(string-match-p (rx (seq bos (or "aa" "bb" "cc") (zero-or-more any) eos)) "bboeuoeu")

 
> Eh - what? With evaluated `rx' forms this is (string-match-p "\\\\`\\(?:ab\\)*\\'"
> "a")
> ==> 0
> 
> 
> (string-match-p
> "\\`\\(?:ab\\)*\\'"
> "b")
> ==> nil
> 
> 
> Makes no sense to me. When I change the wrapping shy groups to normal
> groups the result makes more sense to me:
> 
> (string-match-p
> "\\`\\(ab\\)*\\'"
> "a")
> ==> nil
> 
> 
> (string-match-p
> "\\`\\(ab\\)*\\'"
> "b")
> ==> nil
> 
> 
> Do I miss something or is it just a bug?
> 
> 
> TIA,
> 
> Michael.