Regular expression grouping not working?

Regular expression grouping not working?

[Douglas Lewan]

I'm writing some code that includes the regular expression \\([^/]+/\\), 
(looking for a path on GNU/Linux) which doesn't match what I expect it 
should.

On the other hand, the regular expression [^/]+/, exactly the regular 
expression within the first, does match.

That seems wrong somehow. Is there something I'm missing?

-- 
,Doug
d.lewan2000@gmail.com
(908) 720 7908

Isn't there a difference between "acquittal" and "exoneration"?

Re: Regular expression grouping not working?

[Teemu Likonen]

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Douglas Lewan [2020-02-08T14:17:54-05] wrote:

> I'm writing some code that includes the regular expression \\([^/]+/\\), 
> (looking for a path on GNU/Linux) which doesn't match what I expect it 
> should.

Maybe your backslash escaping is wrong. In regular expressions the
grouping is made with \( \) but within Lisp strings backslash has a
special meaning too and those must be escaped "\\( \\)".

> Is there something I'm missing?

I think we need more information about your code and input data.

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Re: Regular expression grouping not working?

[Douglas Lewan]

On 2/8/20 2:30 PM, Teemu Likonen wrote:

> Douglas Lewan [2020-02-08T14:17:54-05] wrote:
>
>> I'm writing some code that includes the regular expression \\([^/]+/\\),
>> (looking for a path on GNU/Linux) which doesn't match what I expect it
>> should.
> Maybe your backslash escaping is wrong. In regular expressions the
> grouping is made with \( \) but within Lisp strings backslash has a
> special meaning too and those must be escaped "\\( \\)".

Damn! I was passing the double slash to a command I use to help me debug 
regular expressions.

Hand it the right string and it matches just as expected. (Too much 
kill-and-yank.)

Maybe now I can track down the real bug.

Thanks for helping me change my perspective.

>> Is there something I'm missing?
> I think we need more information about your code and input data.

-- 
,Doug
d.lewan2000@gmail.com
(908) 720 7908

Isn't there a difference between "acquittal" and "exoneration"?

Re: Regular expression grouping not working?

[Göktuğ Kayaalp]

FWIW, you might want to try rx for your regular expressions. It
generates regexes from a readable sexp syntax, and is included in Emacs
proper. It's way easier to modify and reason.  See "(elisp) Rx
Notation".