bug#59678: [PATCH] sh-script: use completion-table-with-cache to improve performance

[Eli Zaretskii <eliz@gnu.org>]

> Cc: Yikai Zhao <yikai@z1k.dev>
> From: yikai@z1k.dev
> Date: Tue, 29 Nov 2022 22:30:14 +0800
> 
> Hi,
> 
> I found that the auto-completion on .sh files (with company-mode) was pretty slow (takes several seconds).
> It turns out that company-mode would call the capf function with 'metadata action for each candidate,
> where each function call would need to list all the cmds. In this patch, I modified the code to use
> completion-table-with-cache which fixes the problem for me.

Stefan, any comments?

>  lisp/progmodes/sh-script.el | 26 ++++++++++++--------------
>  1 file changed, 12 insertions(+), 14 deletions(-)
> 
> diff --git a/lisp/progmodes/sh-script.el b/lisp/progmodes/sh-script.el
> index 408ebfc0451..188b3b73125 100644
> --- a/lisp/progmodes/sh-script.el
> +++ b/lisp/progmodes/sh-script.el
> @@ -1688,19 +1688,17 @@ sh--vars-before-point
>  ;; (defun sh--var-completion-table (string pred action)
>  ;;   (complete-with-action action (sh--vars-before-point) string pred))
>  
> -(defun sh--cmd-completion-table (string pred action)
> -  (let ((cmds
> -         (append (when (fboundp 'imenu--make-index-alist)
> -                   (mapcar #'car
> -                           (condition-case nil
> -                               (imenu--make-index-alist)
> -                             (imenu-unavailable nil))))
> -                 (mapcar (lambda (v) (concat v "="))
> -                         (sh--vars-before-point))
> -                 (locate-file-completion-table
> -                  exec-path exec-suffixes string pred t)
> -                 sh--completion-keywords)))
> -    (complete-with-action action cmds string pred)))
> +(defun sh--cmd-completion-table-gen (string)
> +  (append (when (fboundp 'imenu--make-index-alist)
> +            (mapcar #'car
> +                    (condition-case nil
> +                        (imenu--make-index-alist)
> +                      (imenu-unavailable nil))))
> +          (mapcar (lambda (v) (concat v "="))
> +                  (sh--vars-before-point))
> +          (locate-file-completion-table
> +           exec-path exec-suffixes string nil t)
> +          sh--completion-keywords))
>  
>  (defun sh-completion-at-point-function ()
>    (save-excursion
> @@ -1713,7 +1711,7 @@ sh-completion-at-point-function
>          (list start end (sh--vars-before-point)
>                :company-kind (lambda (_) 'variable)))
>         ((sh-smie--keyword-p)
> -        (list start end #'sh--cmd-completion-table
> +        (list start end (completion-table-with-cache #'sh--cmd-completion-table-gen)
>                :company-kind
>                (lambda (s)
>                  (cond
> -- 
> 2.38.1
> 
> 
> 
> 
>