Re: Convert bla to $bla$ automatically when be highlighted and typeset a $.

[Hongyi Zhao]

On Sun, May 21, 2023 at 9:33 PM Hongyi Zhao <hongyi.zhao@gmail.com> wrote:
>
> On Sun, May 21, 2023 at 7:14 PM Mosè Giordano <mose@gnu.org> wrote:
> >
> > Hi Zhao
> >
> > On Sun, 21 May 2023 at 09:41, Hongyi Zhao <hongyi.zhao@gmail.com> wrote:
> > > I want to convert `bla` to `$bla$` automatically when be highlighted
> > > and typeset a `$'.
> >
> > I believe you want to look at `TeX-electric-math'
> > (https://www.gnu.org/software/auctex/manual/auctex/Quotes.html#index-TeX_002delectric_002dmath):
> >
> > --8<---------------cut here---------------start------------->8---
> > TeX-electric-math is a variable defined in ‘tex.el’.
> >
> > Its value is ("\\(" . "\\)")
> > Original value was nil
> > Local in buffer foo.tex; global value is nil
> >
> > If non-nil, when outside math mode ‘TeX-insert-dollar’ will
> > insert symbols for opening and closing inline equation and put
> > the point between them.  If there is an active region,
> > ‘TeX-insert-dollar’ will put around it symbols for opening and
> > closing inline equation and keep the region active, with point
> > after closing symbol.  If you press ‘$’ again, you can toggle
> > between inline equation, display equation, and no equation.
> >
> > If non-nil and point is inside math mode right between a couple
> > of single dollars, pressing ‘$’ will insert another pair of
> > dollar signs and leave the point between them.
> >
> > If nil, ‘TeX-insert-dollar’ will simply insert "$" at point,
> > this is the default.
> >
> > If non-nil, this variable is a cons cell whose CAR is the string
> > to insert before point, the CDR is the string to insert after
> > point.  You can choose between "$...$" and "\(...\)".
> >
> >   Automatically becomes buffer-local when set.
> >   You can customize this variable.
> > --8<---------------cut here---------------end--------------->8---
>
> Based on the above document, I've added the following hook entry in
> AUCTeX's use-package configuration:
>
> (LaTeX-mode . (lambda () (set (make-local-variable 'TeX-electric-math)
>                 (cons "$" "$"))))
>
> But I still cannot observe the desired behavior, as shown in the
> attached screenshot.

I tried a lot, and only find the following code snippet does the trick:

(defun xah-insert-bracket-pair (LBracket RBracket &optional WrapMethod)
  "Insert brackets around selection, word, at point, and maybe move
cursor in between.

 LBracket and RBracket are strings. WrapMethod must be either `line'
or `block'. `block' means between empty lines.

• if there is a region, add brackets around region.
• If WrapMethod is `line', wrap around line.
• If WrapMethod is `block', wrap around block.
• if cursor is at beginning of line and its not empty line and contain
at least 1 space, wrap around the line.
• If cursor is at end of a word or buffer, one of the following will happen:
 xyz▮ → xyz(▮)
 xyz▮ → (xyz▮)       if in one of the lisp modes.
• wrap brackets around word if any. e.g. xy▮z → (xyz▮). Or just (▮)

URL `http://xahlee.info/emacs/emacs/elisp_insert_brackets_by_pair.html'
Version: 2017-01-17 2021-08-12"
  (if (region-active-p)
      (progn
        (let ( ($p1 (region-beginning)) ($p2 (region-end)))
          (goto-char $p2) (insert RBracket)
          (goto-char $p1) (insert LBracket)
          (goto-char (+ $p2 2))))
    (let ($p1 $p2)
      (cond
       ((eq WrapMethod 'line)
        (setq $p1 (line-beginning-position) $p2 (line-end-position))
        (goto-char $p2)
        (insert RBracket)
        (goto-char $p1)
        (insert LBracket)
        (goto-char (+ $p2 (length LBracket))))
       ((eq WrapMethod 'block)
        (save-excursion
          (let (($bds (xah-get-bounds-of-block-or-region))) (setq $p1
(car $bds) $p2 (cdr $bds)))
          (goto-char $p2)
          (insert RBracket)
          (goto-char $p1)
          (insert LBracket)
          (goto-char (+ $p2 (length LBracket)))))
       ( ;  do line. line must contain space
        (and
         (eq (point) (line-beginning-position))
         ;; (string-match " " (buffer-substring-no-properties
(line-beginning-position) (line-end-position)))
         (not (eq (line-beginning-position) (line-end-position))))
        (insert LBracket )
        (end-of-line)
        (insert  RBracket))
       ((and
         (or ; cursor is at end of word or buffer. i.e. xyz▮
          (looking-at "[^-_[:alnum:]]")
          (eq (point) (point-max)))
         (not (or
               (string-equal major-mode "xah-elisp-mode")
               (string-equal major-mode "emacs-lisp-mode")
               (string-equal major-mode "lisp-mode")
               (string-equal major-mode "lisp-interaction-mode")
               (string-equal major-mode "common-lisp-mode")
               (string-equal major-mode "clojure-mode")
               (string-equal major-mode "xah-clojure-mode")
               (string-equal major-mode "scheme-mode"))))
        (progn
          (setq $p1 (point) $p2 (point))
          (insert LBracket RBracket)
          (search-backward RBracket )))
       (t (progn
            ;; wrap around “word”. basically, want all alphanumeric,
plus hyphen and underscore, but don't want space or punctuations. Also
want chinese chars
            ;; 我有一帘幽梦，不知与谁能共。多少秘密在其中，欲诉无人能懂。
            (skip-chars-backward "-_[:alnum:]")
            (setq $p1 (point))
            (skip-chars-forward "-_[:alnum:]")
            (setq $p2 (point))
            (goto-char $p2)
            (insert RBracket)
            (goto-char $p1)
            (insert LBracket)
            (goto-char (+ $p2 (length LBracket)))))))))

(defun xah-insert-dollar () (interactive) (xah-insert-bracket-pair "$" "$") )
(global-set-key (kbd "M-4") 'xah-insert-dollar) ; $$

Best,
Zhao