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From: Tassilo Horn <tsdh@gnu.org>
To: Alan Mackenzie <acm@muc.de>
Cc: help-gnu-emacs@gnu.org
Subject: Re: How to grok a complicated regex?
Date: Thu, 19 Mar 2015 09:15:54 +0100	[thread overview]
Message-ID: <87h9th8ksl.fsf@gnu.org> (raw)
In-Reply-To: <mec9q3$g8o$1@colin.muc.de> (Alan Mackenzie's message of "Wed, 18 Mar 2015 16:40:35 +0000 (UTC)")

Alan Mackenzie <acm@muc.de> writes:

> I wrote myself the following tool.  It's not production quality, but
> you might find it useful nonetheless.  To use it, Type
>
>      M-: (pp-regexp re-horror).
>
> It displays the regexp at the end of the *scratch* buffer, dropping
> the contents of any \(..\) construct by one line.

Interesting idea, and it helps a bit.  What would be really cool was a
transformation from regexp to rx form.  Oh, and that seems to exist
already (available from Marmalade and MELPA)!

  https://github.com/joddie/pcre2el

Example:

--8<---------------cut here---------------start------------->8---
(rxt-elisp-to-rx "\\`\\(?:\\\\[([]\\|\\$+\\)?\\(.*?\\)\\(?:\\\\[])]\\|\\$+\\)?\\'")
;; Evals to...
(seq bos
     (\? (or (seq "\\" (any "[" "("))
	     (+ "$")))
     (submatch (*\? nonl))
     (\? (or (seq "\\" (any ")" "]"))
	     (+ "$")))
     eos)
--8<---------------cut here---------------end--------------->8---

Bye,
Tassilo



  reply	other threads:[~2015-03-19  8:15 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <mailman.1979.1426282552.31049.help-gnu-emacs@gnu.org>
2015-03-13 22:46 ` How to grok a complicated regex? Emanuel Berg
2015-03-13 23:16   ` Marcin Borkowski
2015-03-14  0:12     ` Rasmus
2015-03-14 13:18       ` Stefan Monnier
     [not found]       ` <mailman.2003.1426339118.31049.help-gnu-emacs@gnu.org>
2015-03-15  4:31         ` Rusi
2015-03-22  2:29       ` Tom Tromey
2015-03-22  2:44         ` Rasmus
2015-03-14  5:14     ` Yuri Khan
2015-03-14  7:03     ` Drew Adams
     [not found]   ` <mailman.1984.1426288628.31049.help-gnu-emacs@gnu.org>
2015-03-14  3:58     ` Emanuel Berg
2015-03-14  4:44       ` Emanuel Berg
2015-03-14  4:58         ` Emanuel Berg
2015-03-14  8:43         ` Thien-Thi Nguyen
     [not found]         ` <mailman.1997.1426324089.31049.help-gnu-emacs@gnu.org>
2015-03-20  1:05           ` Emanuel Berg
2015-03-18 16:40 ` Alan Mackenzie
2015-03-19  8:15   ` Tassilo Horn [this message]
2015-04-25  4:23 ` Rusi
2015-04-27 13:26   ` Julien Cubizolles
2015-03-14  8:16 martin rudalics
  -- strict thread matches above, loose matches on Subject: below --
2015-03-13 21:35 Marcin Borkowski
2015-03-13 21:45 ` Marcin Borkowski
2015-03-13 21:47 ` Alexis
2015-03-13 21:57   ` Marcin Borkowski
2015-03-23 12:18 ` Vaidheeswaran C

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