From: Dmitry Gutov <dgutov@yandex.ru>
To: Stefan Monnier <monnier@iro.umontreal.ca>, emacs-devel@gnu.org
Subject: Re: Ugly regexps
Date: Wed, 3 Mar 2021 14:17:39 +0200 [thread overview]
Message-ID: <79673252-c43d-6916-69d9-a46207137c85@yandex.ru> (raw)
In-Reply-To: <jwvk0qpjd31.fsf-monnier+emacs@gnu.org>
On 03.03.2021 02:32, Stefan Monnier wrote:
> (defun ere (re)
> "Convert an ERE-style regexp RE to an Emacs-style regexp."
> (let ((pos 0)
> (last 0)
> (chunks '()))
> (while (string-match "\\\\.\\|[{}()|]" re pos)
> (let ((beg (match-beginning 0))
> (end (match-end 0)))
> (when (subregexp-context-p re beg)
> (cond
> ;; A normal paren: add a backslash.
> ((= (1+ beg) end)
> (push (substring re last beg) chunks) (setq last beg)
> (push "\\" chunks))
> ;; A grouping paren: skip the backslash.
> ((memq (aref re (1+ beg)) '(?\( ?\) ?\{ ?\} ?\|))
> (push (substring re last beg) chunks)
> (setq last (1+ beg)))))
> (setq pos end)))
> (mapconcat #'identity (nreverse (cons (substring re last) chunks)) "")))
See also xref--regexp-to-extended, my last attempt at RE->ERE
conversion, though woefully lacking in tests.
Its goal was to move in the other direction, but (unless I'm missing
something about the syntax differences) this function is reversible.
next prev parent reply other threads:[~2021-03-03 12:17 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-03 0:32 Ugly regexps Stefan Monnier
2021-03-03 1:32 ` Stefan Kangas
2021-03-03 2:08 ` Stefan Kangas
2021-03-03 6:19 ` Eli Zaretskii
2021-03-03 20:46 ` Alan Mackenzie
2021-03-04 18:35 ` Stefan Kangas
2021-03-03 6:00 ` Eli Zaretskii
2021-03-03 15:46 ` Stefan Monnier
2021-03-03 16:30 ` Eli Zaretskii
2021-03-03 17:44 ` Stefan Monnier
2021-03-03 18:46 ` Stefan Kangas
2021-03-03 19:21 ` Eli Zaretskii
2021-03-03 19:50 ` Stefan Kangas
2021-03-03 20:16 ` Stefan Kangas
2021-03-03 19:50 ` Stefan Kangas
2021-03-03 19:58 ` Dmitry Gutov
2021-03-03 20:07 ` [External] : " Drew Adams
2021-03-03 20:31 ` Stefan Kangas
2021-03-03 22:17 ` Drew Adams
2021-03-03 22:32 ` Stefan Monnier
2021-03-03 20:32 ` Stefan Monnier
2021-03-04 5:47 ` Eli Zaretskii
2021-03-04 10:49 ` Lars Ingebrigtsen
2021-03-04 11:25 ` Mattias Engdegård
2021-03-04 11:28 ` Alan Mackenzie
2021-03-04 14:11 ` Eli Zaretskii
2021-03-04 14:25 ` Dmitry Gutov
2021-03-04 14:50 ` tomas
2021-03-04 15:04 ` Dmitry Gutov
2021-03-05 5:45 ` Richard Stallman
2021-03-05 11:47 ` Dmitry Gutov
2021-03-06 5:11 ` Richard Stallman
2021-03-04 15:05 ` Dmitry Gutov
2021-03-04 15:11 ` Eli Zaretskii
2021-03-03 19:32 ` [External] : " Drew Adams
2021-03-03 7:09 ` Helmut Eller
2021-03-03 14:11 ` Stefan Kangas
2021-03-03 16:40 ` Stefan Monnier
2021-03-03 15:49 ` Stefan Monnier
2021-03-03 12:17 ` Dmitry Gutov [this message]
2021-03-03 15:48 ` Stefan Monnier
2021-03-03 13:57 ` Lars Ingebrigtsen
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