Re: Support for leftmost-shortest matches in EREs in POSIX-2024

[Bruno Haible]

Ed Morton wrote:
> I asked in the bug-gawk mailing list (see 
> https://lists.gnu.org/archive/html/bug-gawk/2024-08/msg00026.html) 
> if/when GNU awk would support the `.*?` ERE construct described in the 
> latest POSIX spec 
> (https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/V1_chap09.html#tag_09_04_06)
>  
> as:
> 
> ----
> Each of the duplication symbols ('+', '*', '?', and intervals) can be 
> suffixed by the repetition modifier '?' (<question-mark>), in which case 
> matching behavior for that repetition shall be changed from the leftmost 
> longest possible match to the leftmost shortest possible match, 
> including the null match (see A.9 Regular Expressions ). For example, 
> the ERE ".*c" matches up to and including the last character ('c') in 
> the string "abc abc", whereas the ERE ".*?c" matches up to and including 
> the first character 'c', the third character in the string.
> ----
> 
> and was told:
> 
> ----
> Support for this feature can't happen unless and until GNU regex and GNU 
> dfa, which are both part of Gnulib, support it. So you might consider 
> asking on the bug-gnulib list what their plans are for it.
> ----
> 
> so - what are the plans, if any, for supporting that functionality?

What Arnold said [1], holds for me as well: It's well beyond my capabilities.
All I could help with are a test suite and some configure tests.

Bruno

[1] https://lists.gnu.org/archive/html/bug-gawk/2024-08/msg00030.html