From: Martin Stone Davis <m0davis@pacbell.net>
Subject: Re: rx vs sregex - a "match" to the death
Date: Mon, 06 Oct 2003 01:41:13 -0700 [thread overview]
Message-ID: <blr9r5$753$1@sea.gmane.org> (raw)
In-Reply-To: <uvfr2g75c.fsf@ID-87814.user.dfncis.de>
Oliver Scholz wrote:
> Martin Stone Davis <m0davis@pacbell.net> writes:
> [...]
>
>>While I was comparing the two functions, I could not find if/how rx
>>handles numbered backreferences. It's done in sregex like this:
>>
>>;; (sregexq (group (or "Go" "Run"))
>>;; ", Spot, "
>>;; (backref 1)) => "\\(Go\\|Run\\), Spot, \\1"
>>
>>How do you do the same using rx?
>
> [...]
>
> Well, you could use (regexp "\\1"), but this is of course not
> satisfying. I am not aware of any other way to use backrefs with `rx'.
>
> However, I was not aware that you actually can use backrefs within a
> regexp. I tried
>
> (progn (looking-at "\\w+")
> (forward-char 1)
> (re-search-forward "\\0" nil t))
>
> But that did not lead to the result that you would expect if backrefs
> are/were supported within regexps.
>
> Could you provide an example where this is meaningful?
I think you're using backreference wrongly. Try the one I gave.It
matches "Go, Spot, Go" OR "Run, Spot, Run". If I run
(re-search-forward (sregexq (group (or "Go" "Run"))
", Spot, "
(backref 1))
It finds either of those two phrases.
-Martin
next prev parent reply other threads:[~2003-10-06 8:41 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <mailman.1134.1065355880.21628.help-gnu-emacs@gnu.org>
2003-10-05 15:45 ` rx vs sregex - a "match" to the death Oliver Scholz
2003-10-05 17:08 ` Martin Stone Davis
[not found] ` <mailman.1139.1065373803.21628.help-gnu-emacs@gnu.org>
2003-10-06 7:25 ` Oliver Scholz
2003-10-06 8:41 ` Martin Stone Davis [this message]
[not found] ` <mailman.1154.1065429721.21628.help-gnu-emacs@gnu.org>
2003-10-06 8:55 ` Oliver Scholz
2003-10-05 12:07 Martin Stone Davis
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