Making a regex string that matches (

Making a regex string that matches (

[angelomolina--- via Users list for the GNU Emacs text editor]

How can I make a regex string if I want to search for (. 

Re: Making a regex string that matches (

[Emanuel Berg via Users list for the GNU Emacs text editor]

angelomolina--- via Users list for the GNU Emacs text editor wrote:

> How can I make a regex string if I want to search for (.

Uhm ... how much is a 50¢ stamp?

(re-search-forward "(")

(

-- 
underground experts united
https://dataswamp.org/~incal

Re: Making a regex string that matches (

[Leo Butler]

angelomolina--- via Users list for the GNU Emacs text editor
<help-gnu-emacs@gnu.org> writes:

> How can I make a regex string if I want to search for (. 

For interactive use, the key sequence (C=Control, M=Alt/Mod):

C-M s (

For programmatic use, you can use

M-x regexp-builder RET

to start up regexp-builder which will let you build regexps
interactively and show the matches in the buffer where you were
working. You will see that

"("

works.

C-c C-q

deletes the *RE-Builder* window that was created (the buffer remains, so
you can re-use it).

-----

Btw, I noticed that regexp-builder is part of GNU Emacs, but there is no
documentation in the manual. The only documentation is found by looking
at the docstring of the function.

Leo

Re: Making a regex string that matches (

[Robert Pluim]

>>>>> On Thu, 10 Mar 2022 15:39:03 +0100, Emanuel Berg via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> said:

    Emanuel> angelomolina--- via Users list for the GNU Emacs text editor wrote:
    >> How can I make a regex string if I want to search for (.

    Emanuel> Uhm ... how much is a 50¢ stamp?

    Emanuel> (re-search-forward "(")

And since youʼre searching for a literal '(', you can use
`search-forward'.

Robert
-- 

Re: Making a regex string that matches (

[goncholden]

------- Original Message -------
On Thursday, March 10th, 2022 at 3:51 PM, Robert Pluim <rpluim@gmail.com> wrote:
> > > > > > On Thu, 10 Mar 2022 15:39:03 +0100, Emanuel Berg via Users list for the GNU Emacs text editor help-gnu-emacs@gnu.org said:
>
> Emanuel> angelomolina--- via Users list for the GNU Emacs text editor wrote:
>
> >> How can I make a regex string if I want to search for (.
>
> Emanuel> Uhm ... how much is a 50¢ stamp?
>
> Emanuel> (re-search-forward "(")
>
> And since youʼre searching for a literal '(', you can use
>
> `search-forward'.
>
> Robert

Have come up with the following function.  Would this be enough to count the number
oy opening parantheses in a region ?

(defun bracketing-count (region-start region-end)
  "Counts opening and closing bracketing marks.
Interactive functions enable them to be called using `M-x`"
  (interactive "r")  ; gets region start and end

  (message "Counting bracketing marks ...")
  (save-excursion
    (let (count)
      (setq count 0)
      (goto-char region-start)

      (while (and (< (point) region-end)
		  (search-forward "\(" region-end t))
        (setq count (1+ count))) ))))

Re: Making a regex string that matches (

[Eric Abrahamsen]

goncholden <goncholden@protonmail.com> writes:

> ------- Original Message -------
> On Thursday, March 10th, 2022 at 3:51 PM, Robert Pluim <rpluim@gmail.com> wrote:
>> > > > > > On Thu, 10 Mar 2022 15:39:03 +0100, Emanuel Berg via Users
>> > list for the GNU Emacs text editor help-gnu-emacs@gnu.org said:
>>
>> Emanuel> angelomolina--- via Users list for the GNU Emacs text editor wrote:
>>
>> >> How can I make a regex string if I want to search for (.
>>
>> Emanuel> Uhm ... how much is a 50¢ stamp?
>>
>> Emanuel> (re-search-forward "(")
>>
>> And since youʼre searching for a literal '(', you can use
>>
>> `search-forward'.
>>
>> Robert
>
> Have come up with the following function.  Would this be enough to count the number
> oy opening parantheses in a region ?
>
> (defun bracketing-count (region-start region-end)
>   "Counts opening and closing bracketing marks.
> Interactive functions enable them to be called using `M-x`"
>   (interactive "r")  ; gets region start and end
>
>   (message "Counting bracketing marks ...")
>   (save-excursion
>     (let (count)
>       (setq count 0)
>       (goto-char region-start)
>
>       (while (and (< (point) region-end)
> 		  (search-forward "\(" region-end t))
>         (setq count (1+ count))) ))))

Not to detract from your achievement, but there's already a
`count-matches' function, if you go back to using a regexp.

RE: [External] : Re: Making a regex string that matches (

[Drew Adams]

> Have come up with the following function.  Would this be enough to
> count the number oy opening parantheses in a region ?
> 
> (defun bracketing-count (region-start region-end)
>   "Counts opening and closing bracketing marks.
> Interactive functions enable them to be called using `M-x`"
>   (interactive "r")  ; gets region start and end
>   (message "Counting bracketing marks ...")
>   (save-excursion
>     (let (count)
>       (setq count 0)
>       (goto-char region-start)
>       (while (and (< (point) region-end)
> 		        (search-forward "\(" region-end t))
>         (setq count (1+ count))) ))))

1. You can just use function `count-matches', with "("
   as the regexp.

https://emacs.stackexchange.com/q/70870/105

2. (let (count) (setq count 0)...)
->
   (let ((count  0)...)

3. (search-forward "(" ...)  ; You don't need "\(".

4. If your user uses your command, s?he sees only the
   message "Counting bracketing marks...".  She likely
   would like to see the count at the end, no?

Re: Making a regex string that matches (

[Emanuel Berg via Users list for the GNU Emacs text editor]

goncholden wrote:

> Have come up with the following function. Would this be
> enough to count the number oy opening parantheses in
> a region ? [...]

(how-many "(" (point)) ; 2

((

-- 
underground experts united
https://dataswamp.org/~incal

Re: [External] : Re: Making a regex string that matches (

[Emanuel Berg via Users list for the GNU Emacs text editor]

Drew Adams wrote:

> You can just use function `count-matches' [...]

Fact For Fans, `count-matches' is an alias for `how-many' ...

-- 
underground experts united
https://dataswamp.org/~incal

Re: Making a regex string that matches (

[Leo Butler]

goncholden <goncholden@protonmail.com> writes:

> ------- Original Message -------
> On Thursday, March 10th, 2022 at 3:51 PM, Robert Pluim <rpluim@gmail.com> wrote:
>> > > > > > On Thu, 10 Mar 2022 15:39:03 +0100, Emanuel Berg via Users
>> > list for the GNU Emacs text editor help-gnu-emacs@gnu.org said:
>>
>> Emanuel> angelomolina--- via Users list for the GNU Emacs text editor wrote:
>>
>> >> How can I make a regex string if I want to search for (.
>>
>> Emanuel> Uhm ... how much is a 50¢ stamp?

Sarcasm is generally counter-productive.

>
> Have come up with the following function.  Would this be enough to count the number
> oy opening parantheses in a region ?
>
> (defun bracketing-count (region-start region-end)
>   "Counts opening and closing bracketing marks.
> Interactive functions enable them to be called using `M-x`"
>   (interactive "r")  ; gets region start and end
>
>   (message "Counting bracketing marks ...")
>   (save-excursion
>     (let (count)
>       (setq count 0)
>       (goto-char region-start)
>
>       (while (and (< (point) region-end)
> 		  (search-forward "\(" region-end t))
>         (setq count (1+ count))) ))))

In addition to other points made, your function doesn't deal with corner
cases, such as

\([(]+\)

Should the count be 1 or 2?

Leo

Re: Making a regex string that matches (

[Emanuel Berg via Users list for the GNU Emacs text editor]

Leo Butler wrote:

>>> How can I make a regex string if I want to search for (.
>>
>> Uhm ... how much is a 50¢ stamp?
>
> Sarcasm is generally counter-productive.

It isn't sarcasm, it is a question where the answer is so
obvious you get perplexed thinking there is some other layer
to it ...

And maybe this is what happened to the OP who didn't just try
"(" but instead wrote a bunch of Elisp :)

That has happened to all of us BTW, perhaps this is an extreme
case tho ;)

-- 
underground experts united
https://dataswamp.org/~incal

Re: Making a regex string that matches (

[Eduardo Ochs]

On Thu, 10 Mar 2022 at 11:31, angelomolina--- via Users list for the
GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:
>
> How can I make a regex string if I want to search for (.


On Thu, 10 Mar 2022 at 11:31, angelomolina--- via Users list for the
GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:
>
> How can I make a regex string if I want to search for (.

Hi Angelo,

Slightly off-topic, but I learned a lot about obscure-ish regexp
tricks by using rx and xr to convert regexps to the rx notation and
back... see:

  (info "(elisp)Rx Notation")
  https://github.com/mattiase/xr

Try:

  (rx "/*"
      (zero-or-more
       (or (not (any "*"))
           (seq "*" (not (any "/")))))
      (one-or-more "*")
      "/")

  (xr "/\\*\\(?:[^*]\\|\\*[^/]\\)*\\*+/")
  (xr find-function-regexp)

Here are some examples of things that I didn't know how to write in
regexp syntax, and that I only discovered using rx:

  (rx (any "[]"))
  (rx (any ""))
  (rx (not (any "")))

Now let's wait for Emanuel Berg's reaction... =)

  Cheers,
    Eduardo Ochs
    http://angg.twu.net/#eev