CIDER completion system overhaul

[heyitscassio]

I'm starting this discussion topic to gather some opinions and findings regarding the CIDER completions.

Some context of this is at #3006 #3226 #3019 #3653

[heyitscassio]

I think I got CIDER to play nicer with flex completion:

In that picture I was using (add-to-list 'completion-category-overrides '(cider (styles flex)))

The main thing is not relying on the prefix passed by the completion function:

cider/cider-completion.el

Line 196 in 176a8e7

(lambda (prefix pred action)

But getting the prefix using symbol-at-point

(defun cider--get-prefix () "Return the prefix at point as a string" (symbol-name (symbol-at-point)))

And using this in a function to return the completions, instead of using cider-complete directly in complete-with-action

(defun cider--capf-complete () (let* ((prefix (cider--get-prefix)) (results (cider-complete prefix))) (if results (setq cider--completion-cache results) cider--completion-cache)))

I'm using cider--completion-cache there because it's possible that the prefix passed to cider-complete returns no completions, like when typing util/relongfuncname for example. But we can just return the last completions results an let the "frontend" do the filtering.

Here's how the capf is, it's basically the same, I just remade the behavior of complete-with-action to ease debugging, and used cider--capf-complete instead of cider-complete directly.

(defun cider-complete-at-point () "Complete the symbol at point." (when-let* ((bounds (bounds-of-thing-at-point 'symbol))) (when (and (cider-connected-p) (not (or (cider-in-string-p) (cider-in-comment-p)))) (list (car bounds) (cdr bounds) (lambda (prefix pred action) ;; When the 'action is 'metadata, this lambda returns metadata about this ;; capf, when action is (boundaries . suffix), it returns nil. With every ;; other value of 'action (t, nil, or lambda), 'action is forwarded to ;; (complete-with-action), together with (cider-complete), prefix and pred. ;; And that function performs the completion based on those arguments. ;; ;; This api is better described in the section ;; '21.6.7 Programmed Completion' of the elisp manual. (cond ((eq action 'metadata) `(metadata (category . cider))) ;; defines a completion category named 'cider, used later in our `completion-category-overrides` logic. ((eq (car-safe action) 'boundaries) nil) ((null action) (try-completion prefix (cider--capf-complete))) ((eq action t) (all-completions prefix (cider--capf-complete))) (t (test-completion prefix (cider-complete prefix))))) :annotation-function #'cider-annotate-symbol :company-kind #'cider-company-symbol-kind :company-doc-buffer #'cider-create-compact-doc-buffer :company-location #'cider-company-location :company-docsig #'cider-company-docsig))))

I've been using this for some time now, seems to be working fine. Still needs to be tested with orderless and other completions styles and compatibility with company-mode (I use corfu)

@minad do you think this looks sound?