help / color / mirror / code / Atom feed
From: Peter Stephenson <p.w.stephenson@ntlworld.com>
To: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: Extending regexes
Date: Mon, 4 Jul 2022 14:47:39 +0100 (BST)	[thread overview]
Message-ID: <76883431.1281129.1656942459330@mail2.virginmedia.com> (raw)
In-Reply-To: <CAKc7PVAa718cFk2n1W=oxgxxRh-DEs8Cjvc5sKpqe8C3D+M-ig@mail.gmail.com>

> On 04 July 2022 at 13:03 Sebastian Gniazdowski <sgniazdowski@gmail.com> wrote:
> Hi,
> Zsh has extensions to regular regexes - the ~ and ^ negations.
> Therefore I thought that it's weird that such an useful feature is missing
> from the commonly used regex syntax. So maybe an attempt of updating it has
> sense?

You're quite right both that they're very useful in zsh and there's nothing
like this in normal regular expressions, but unfortunately I've got a strong
feeling this is a big can of worms [hope that image is graphic enough that
I don't need to explain the phrase for non-native English speakers].

I say that as although I'm not very up on the mathematics of regular expressions
I did write the basics of the current zsh implementation of glob negations.
(Before that, there was an even less efficient implementation that created a
structure for each part of the pattern, which wasn't good for memory management
--- this is going back to the 1990s, I think.)  There are some pretty pathological
details to make sure this works in every case, so I'd really want a real expert in
the subject area to think about this before it got much further.


  reply	other threads:[~2022-07-04 13:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-04 12:03 Sebastian Gniazdowski
2022-07-04 13:47 ` Peter Stephenson [this message]
2022-07-04 19:15   ` Bart Schaefer
2022-07-04 19:41     ` Peter Stephenson
2022-07-06 10:03       ` Daniel Shahaf
2022-07-06 18:40   ` stephane
2022-07-06 23:07 ` Phil Pennock
2022-07-07  0:22   ` Bart Schaefer

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=76883431.1281129.1656942459330@mail2.virginmedia.com \
    --to=p.w.stephenson@ntlworld.com \
    --cc=zsh-workers@zsh.org \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
Code repositories for project(s) associated with this public inbox


This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).