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Re: bash core dumps doing glob pattern on long string
From: |
Dennis Williamson |
Subject: |
Re: bash core dumps doing glob pattern on long string |
Date: |
Tue, 11 Oct 2022 15:40:02 -0500 |
On Tue, Oct 11, 2022, 3:12 PM Greg Wooledge <greg@wooledge.org> wrote:
> On Tue, Oct 11, 2022 at 12:38:44PM -0700, Koichi Murase wrote:
> > As far as I know, glob/extglob
> > does not have constructs that cannot be represented by formal regular
> > languages so should always be able to be represented by NFAs and thus
> DFAs.
>
> It's been too many decades since I studied this stuff in college, but
> earlier while reading the thread I was pondering converting extglobs
> into (ERE) regular expressions.
>
> Extglobs add 5 features:
>
> ?(pattern-list)
> Matches zero or one occurrence of the given patterns
> *(pattern-list)
> Matches zero or more occurrences of the given patterns
> +(pattern-list)
> Matches one or more occurrences of the given patterns
> @(pattern-list)
> Matches one of the given patterns
> !(pattern-list)
> Matches anything except one of the given patterns
>
> The first 4 can be converted directly into ERE without any issues at all.
> The last one cannot. At least not easily.
>
> The part I can't remember is whether !(foo) can be expressed in a regular
> language. My gut says "no", but there might be some trick that I've
> forgotten. A regular language has concatenation (abc), union (abc|def),
> and close (a*bc*) but not negation.
>
Can't you just match and negate?
>
- Re: bash core dumps doing glob pattern on long string, (continued)
- Re: bash core dumps doing glob pattern on long string, Martin D Kealey, 2022/10/11
- Re: bash core dumps doing glob pattern on long string, Phi Debian, 2022/10/11
- Re: bash core dumps doing glob pattern on long string, Martin D Kealey, 2022/10/11
- Re: bash core dumps doing glob pattern on long string, Phi Debian, 2022/10/11
- Re: bash core dumps doing glob pattern on long string, Koichi Murase, 2022/10/11
- Re: bash core dumps doing glob pattern on long string, Greg Wooledge, 2022/10/11
- Re: bash core dumps doing glob pattern on long string, Koichi Murase, 2022/10/11
- Re: bash core dumps doing glob pattern on long string,
Dennis Williamson <=