From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Dmitry Gutov <dgutov@yandex.ru>
Cc: emacs-devel@gnu.org
Subject: Re: Ugly regexps
Date: Wed, 03 Mar 2021 10:48:33 -0500 [thread overview]
Message-ID: <jwv35xcjl1r.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <79673252-c43d-6916-69d9-a46207137c85@yandex.ru> (Dmitry Gutov's message of "Wed, 3 Mar 2021 14:17:39 +0200")
>> (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.
Oh, thanks for the pointer.
> Its goal was to move in the other direction, but (unless I'm missing
> something about the syntax differences) this function is reversible.
Indeed it is,
Stefan
next prev parent reply other threads:[~2021-03-03 15:48 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
2021-03-03 15:48 ` Stefan Monnier [this message]
2021-03-03 13:57 ` Lars Ingebrigtsen
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