Re: Plug treesit.el into other emacs constructs

[Theodor Thornhill <theo@thornhill.no>]

On 24 December 2022 15:01:36 CET, Stefan Monnier <monnier@iro.umontreal.ca> wrote:
>> -(eval-when-compile (require 'cl-lib))
>> +(eval-when-compile (require 'cl-lib)
>> +                   (require 'treesit))
>
>I don't see any part of `treesit` used during compilation.
>Is it a left over, maybe?
>
>> @@ -8453,36 +8455,37 @@ transpose-sexps
>>            (transpose-sexps arg nil)
>>          (scan-error (user-error "Not between two complete sexps")))
>>      (transpose-subr
>> -     (lambda (arg)
>> -       ;; Here we should try to simulate the behavior of
>> -       ;; (cons (progn (forward-sexp x) (point))
>> -       ;;       (progn (forward-sexp (- x)) (point)))
>> -       ;; Except that we don't want to rely on the second forward-sexp
>> -       ;; putting us back to where we want to be, since forward-sexp-function
>> -       ;; might do funny things like infix-precedence.
>> -       (if (if (> arg 0)
>> -	       (looking-at "\\sw\\|\\s_")
>> -	     (and (not (bobp))
>> -		  (save-excursion
>> -                    (forward-char -1)
>> -                    (looking-at "\\sw\\|\\s_"))))
>> -	   ;; Jumping over a symbol.  We might be inside it, mind you.
>> -	   (progn (funcall (if (> arg 0)
>> -			       'skip-syntax-backward 'skip-syntax-forward)
>> -			   "w_")
>> -		  (cons (save-excursion (forward-sexp arg) (point)) (point)))
>> -         ;; Otherwise, we're between sexps.  Take a step back before jumping
>> -         ;; to make sure we'll obey the same precedence no matter which
>> -         ;; direction we're going.
>> -         (funcall (if (> arg 0) 'skip-syntax-backward 'skip-syntax-forward)
>> -                  " .")
>> -         (cons (save-excursion (forward-sexp arg) (point))
>> -	       (progn (while (or (forward-comment (if (> arg 0) 1 -1))
>> -			         (not (zerop (funcall (if (> arg 0)
>> -							  'skip-syntax-forward
>> -						        'skip-syntax-backward)
>> -						      ".")))))
>> -		      (point)))))
>> +     (if (treesit-parser-list) #'treesit-transpose-sexps
>> +       (lambda (arg)
>> +         ;; Here we should try to simulate the behavior of
>> +         ;; (cons (progn (forward-sexp x) (point))
>> +         ;;       (progn (forward-sexp (- x)) (point)))
>> +         ;; Except that we don't want to rely on the second forward-sexp
>> +         ;; putting us back to where we want to be, since forward-sexp-function
>> +         ;; might do funny things like infix-precedence.
>> +         (if (if (> arg 0)
>> +	         (looking-at "\\sw\\|\\s_")
>> +	       (and (not (bobp))
>> +		    (save-excursion
>> +                      (forward-char -1)
>> +                      (looking-at "\\sw\\|\\s_"))))
>> +             ;; Jumping over a symbol.  We might be inside it, mind you.
>> +	     (progn (funcall (if (> arg 0)
>> +			         'skip-syntax-backward 'skip-syntax-forward)
>> +			     "w_")
>> +		    (cons (save-excursion (forward-sexp arg) (point)) (point)))
>> +           ;; Otherwise, we're between sexps.  Take a step back before jumping
>> +           ;; to make sure we'll obey the same precedence no matter which
>> +           ;; direction we're going.
>> +           (funcall (if (> arg 0) 'skip-syntax-backward 'skip-syntax-forward)
>> +                    " .")
>> +           (cons (save-excursion (forward-sexp arg) (point))
>> +	         (progn (while (or (forward-comment (if (> arg 0) 1 -1))
>> +			           (not (zerop (funcall (if (> arg 0)
>> +							    'skip-syntax-forward
>> +						          'skip-syntax-backward)
>> +						        ".")))))
>> +		        (point))))))
>>       arg 'special)))
>
>Could we use a `transpose-sexp-function` variable, which `treesit` can
>then set, so `simple.el` doesn't need to know about `treesit` at all?
>

Yes absolutely! I'll make that change. It makes sense, because we need not really rely on forward-foo anyways:)

>>  (defun transpose-lines (arg)
>> @@ -8521,6 +8524,9 @@ transpose-subr
>>  		       (progn (funcall mover (- x)) (point))))))
>>  	pos1 pos2)
>>      (cond
>> +     ((treesit-parser-list)
>> +      (cl-multiple-value-bind (p1 p2) (funcall aux arg)
>> +        (transpose-subr-1 p1 p2)))
>>       ((= arg 0)
>>        (save-excursion
>>  	(setq pos1 (funcall aux 1))
>
>Please use `pcase-let` instead of `cl-multiple-value-bind` (especially
>since you use it to decompose something built with `list` rather than
>with `cl-values`).
>
>Also to avid re-testing `treesit-parser-list`, I'd recommend you extend
>the semantics of `mover` so it can either return a position (the old
>protocol) or directly return a pair of positions.  You could even add
>a 3rd kind of return value to explicitly trigger the error message
>instead of relying on the (cons 0 1) hack.
>
>
>        Stefan
>

Yeah! I believe this either wasn't the latest patch, or i forgot to send it. I'll see what lies around my system and wrap things up.