trivial regexp problem

trivial regexp problem

[Luca Ferrari]

Hi all,
I need a little hint on a regexp that is not working within lookig-at:
I want to recognize any label of the form "label:" so I tested the
following against re-search-forward "^[ \t]*.*:" and it works.
However, the same into a looking-at call is not working, so how can I
find the following regexp?

Thanks,
Luca

Re: trivial regexp problem

[Bastien]

Hi Luca,

Luca Ferrari <fluca1978@infinito.it> writes:

> I need a little hint on a regexp that is not working within lookig-at:
> I want to recognize any label of the form "label:" so I tested the
> following against re-search-forward "^[ \t]*.*:" and it works.
> However, the same into a looking-at call is not working, so how can I
> find the following regexp?

It does work for me.

label:

(looking-at "^[ \t]*.*:")
 => t

-- 
 Bastien

Re: trivial regexp problem

[Luca Ferrari]

Sgrunt...I should have tried it into the eshell, There was another
error, not tied to the regexp, that of course is working.

Thanks,
Luca

On Tue, Jan 22, 2013 at 12:00 PM, Bastien <bzg@altern.org> wrote:
> Hi Luca,
>
> Luca Ferrari <fluca1978@infinito.it> writes:
>
>> I need a little hint on a regexp that is not working within lookig-at:
>> I want to recognize any label of the form "label:" so I tested the
>> following against re-search-forward "^[ \t]*.*:" and it works.
>> However, the same into a looking-at call is not working, so how can I
>> find the following regexp?
>
> It does work for me.
>
> label:
>
> (looking-at "^[ \t]*.*:")
>  => t
>
> --
>  Bastien

Re: trivial regexp problem

[Barry Margolin]

In article <mailman.18061.1358852367.855.help-gnu-emacs@gnu.org>,
 Luca Ferrari <fluca1978@infinito.it> wrote:

> Hi all,
> I need a little hint on a regexp that is not working within lookig-at:
> I want to recognize any label of the form "label:" so I tested the
> following against re-search-forward "^[ \t]*.*:" and it works.
> However, the same into a looking-at call is not working, so how can I
> find the following regexp?

What's the purpose of [ \t]* at the beginning of the regexp? Since it's 
immediately followed by .*, which matches anything, the regexp will 
match whether or not the line begins with whitespace.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: trivial regexp problem

[Peter Dyballa]

Am 22.01.2013 um 17:44 schrieb Barry Margolin:

> Since it's 
> immediately followed by .*, which matches anything, the regexp will 
> match whether or not the line begins with whitespace.

Yes, it not only matches the beginning of every line, it also matches the beginning of every empty line…

--
Greetings

  Pete

My sister opened a computer store in Hawaii.  She sells C shells down by the seashore.

Re: trivial regexp problem

[Barry Margolin]

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In article <mailman.18090.1358877053.855.help-gnu-emacs@gnu.org>,
 Peter Dyballa <Peter_Dyballa@Web.DE> wrote:

> Am 22.01.2013 um 17:44 schrieb Barry Margolin:
> 
> > Since it's 
> > immediately followed by .*, which matches anything, the regexp will 
> > match whether or not the line begins with whitespace.
> 
> Yes, it not only matches the beginning of every line, it also matches the 
> beginning of every empty lineŠ

That's not an issue, because the regexp includes ":". So it only matches 
on lines that contain a colon.

But there's no difference between:

^[ \t]*.*:

and:

^.*:

There *would* be a difference if you used grouping, e.g.:

^\([ \t]*\)\(.*\):

because this allows you to extract the whitespace prefix and the part of 
the line after it.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: trivial regexp problem

[Luca Ferrari]

Correct! Since I'm not interested in separating spaces from other
parts of the string I fixed the regexp to "^[ \t]*\\(.+\\):[ \t\n]*"
(at least one letter before the colon must be present).

Thanks guys!