Re: Matching labels with buttons

[Heime <heimeborgia@protonmail.com>]

On Monday, July 15th, 2024 at 11:56 PM, Stephen Berman <stephen.berman@gmx.net> wrote:

> On Mon, 15 Jul 2024 11:25:28 +0000 Heime heimeborgia@protonmail.com wrote:
> 
> > Sent with Proton Mail secure email.
> > 
> > On Monday, July 15th, 2024 at 11:17 PM, Heime heimeborgia@protonmail.com wrote:
> > 
> > > I want to match cases such as
> > > 
> > > Label [-]
> > > 
> > > Have constructed the following regexp, but it does not match the above
> > > 
> > > "\\(.\\)\\(\\s-\\[\\-\\]\\s-\\)"
> > > 
> > > I aw using
> > > 
> > > (when (string-match "\\(.\\)\\(\\s-\\[\\-\\]\\s-\\)" text)
> > 
> > In the code I have
> > 
> > (if (string-match "\\(\\s-\\[\\-\\]\\s-\\)\\(.*\\)" label) ; [-] LB
> > 
> > (progn
> > (setq bt (match-string 1 label))
> > (setq lb (match-string 2 label))
> > (setq result
> > (concat bt (propertize lb 'face '(:foreground "red")))))
> > 
> > (when (string-match "\\(.\\)\\(\\s-\\[\\-\\]\\s-*\\)" label) ; LB [-]
> > 
> > (setq lb (match-string 1 label))
> > (setq bt (match-string 2 label))
> > (setq result
> > (concat (propertize lb 'face '(:foreground "red")) bt)))
> > 
> > Doing some tests with
> > 
> > "OFF [-]"
> > 
> > keeps matching the first string-match
> 
> 
> That's because your regexp isn't anchored, so string-match succeeds if
> it finds a match anywhere in the string passed to it. To avoid this,
> start the regexp with "\\`", which anchors it to the start of the string
> being matched against; see (info "(elisp) Regexp Backslash").
> 
> Steve Berman


I would like to have two regex expressions, one to match only " [-] LABEL " and 
another to match only " LABEL [-] ".  With any number of whitespace.

Can one use "^" ?  Or is "\\`" preferred ? And can one use "[[:space:]]*" rather
than "\\s-*" ?  Which is preferred ?