Adding completion-at-point support (company-capf)

[hubisan]

Is it possible to add completion-at-point support for plantuml? Or is this already implemented and I was just not able to get it working?

Looks like this should work, not really sure if this is the right way to implement it (taken from https://emacs.stackexchange.com/a/15277/19819, https://www.gnu.org/software/emacs/manual/html_node/elisp/Completion-in-Buffers.html and elisp-mode.el):

(defun my-plantuml-completion-at-point ()
  "Function used for `completion-at-point-functions' in `plantuml-mode'."
  (let ((completion-ignore-case t) ; Not working for company-capf.
        (bounds (bounds-of-thing-at-point 'symbol))
        (keywords plantuml-kwdList))
    (when (and bounds keywords)
      (list (car bounds)
            (cdr bounds)
            keywords
            :exclusve 'no
            :company-docsig #'identity))))

Then add a hook on mode init, should be added to (define-derived-mode plantuml-mode prog-mode "plantuml" ...:

(add-hook 'completion-at-point-functions
            #'plantuml-completion-at-point nil 'local)

Then completion-at-point is supported in plantuml-mode. And this also makes company-capf work:

For some reason ignoring case with my solution works with completion-at-point but company stays case-sensitive unless using (setq-local completion-ignore-case t).