From: Peter Stephenson <p.stephenson@samsung.com>
To: <zsh-workers@zsh.org>
Subject: Re: [BUG] Glob handling is brittle
Date: Tue, 27 Nov 2018 15:08:52 +0000 [thread overview]
Message-ID: <1543331332.4259.24.camel@samsung.com> (raw)
In-Reply-To: <942D7657-1371-4A04-B2E7-1CBFE9DC0966@kba.biglobe.ne.jp>
On Tue, 2018-11-27 at 21:14 +0900, Jun T wrote:
> > 2018/11/26 14:38, Martijn Dekker <martijn@inlv.org> wrote:
> > The script below reliably makes zsh hang.
> (snip)
> >
> > case '\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\' in
> > ( *\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\*\\\
> > *\\*\\*\\*\\*\\*\\*\\*\\*\\*\\* )
> > echo ok ;;
> > esac
> zsh is not hanging; it is just very slow.
Yes, you can see that by gradually increasing the length of the
pattern. Depending on the machine, it starts to get really slow after
about half a dozen or so \\* groups.
> I don't know whether this can be 'fixed' easily.
There's something a bit similar that does improve the case of excluded
matches, ~ and ^ --- where you hit pathological cases quite quickly, and
which aren't so commonly used in patterns. That's not nice. It's
almost certainly not a good idea to do it that way here, as * is very
widely used indeed. I can't offhand think of a good way of fixing up
pathological cases without having a much more noticeable effect on more
typical cases. But I don't think offhand thinking is what's required
here.
Really, this is at the point where you need an algorithm expert rather
than a bunch of hackers.
pws
prev parent reply other threads:[~2018-11-27 15:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 5:38 Martijn Dekker
2018-11-27 12:14 ` Jun T
2018-11-27 15:08 ` Peter Stephenson [this message]
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