Seperate face for directories and files

[mohkale]

Something I quite miss from ivy is the ability to quickly distinguish files from directories using colors. Ivy uses ivy-subdir face to color directoriesin ivy-find-file. I'd like selectrum to have something similair.

[clemera]

I think this could be a job for the upcoming affixation-function (Emacs 28). @minad @oantolin Dealing with this seems like a good fit for marginalia? Related: I reported a bug to improve the affixation/annotation face handling, though this doesn't directly affect how we proceed with this here.

@mohkale
For now you can do the following to get the desired behaviour:

(setq selectrum-highlight-candidates-function
      (defun highlight-matches-and-dirs+ (input cands)
        (let ((cands (if (eq 'file (completion-metadata-get
                                    (completion-metadata
                                     input
                                     minibuffer-completion-table
                                     minibuffer-completion-predicate)
                                    'category))
                         (cl-loop for cand in cands
                                  for len = (length cand)
                                  if (and (> len 0)
                                          (eq (aref cand (1- len)) ?/))
                                  collect (progn (add-face-text-property
                                                  0 (length cand)
                                                  'success
                                                  'append cand)
                                                 cand)
                                  else
                                  collect cand)
                       cands)))
          (<your-default-highlight-function> input cands))))

[mohkale]

All right, I've managed to get it working thanks to @clemera, I had some issues due to prescient overriding my selectrum-highlight-candidates-function so I just adapted it for prescient only:

(use-package selectrum-prescient
  :ensure t
  :defer  t
  :hook (selectrum-mode . selectrum-prescient-mode)
  :config
  (defun selectrum-highlight-candidates-function+ (input cands)
    (let ((cands (if (eq 'file (completion-metadata-get
                                (completion-metadata
                                 input
                                 minibuffer-completion-table
                                 minibuffer-completion-predicate)
                                'category))
                     (cl-loop for cand in cands
                              for len = (length cand)
                              if (and (> len 0)
                                      (eq (aref cand (1- len)) ?/))
                              collect (progn (add-face-text-property
                                              0 (length cand)
                                              'dired-directory
                                              'append cand)
                                             cand)
                              else
                              collect cand)
                   cands)))
      (selectrum-prescient--highlight input cands)))

  (add-hook 'selectrum-prescient-mode-hook
            (defun selectrum-prescient-custom-highlight+ ()
              (setq selectrum-highlight-candidates-function
                    #'selectrum-highlight-candidates-function+))))

This works pretty well but it doesn't mix well with my selectrum-current-candidate face. I've had similair issues with marginalia (See here).

In ivy it just highlights the entire line for the current candidate with the same face, ensuring readability. What're your thoughts on adding a new option selectrum-override-current-candidate-face or a face selectrum-override-face which takes precedence over other faces (eg. marginalia-file-modes) when on the current candidate?

[mohkale]

this is a similair issue in consult-line as well.

Compare swiper

with consult-line.

[minad]

@mohkale For comparison can you please cross check with a theme like modus-operandi which has full support for selectrum, prescient, orderless, consult etc?

[mohkale]

@minad

I'm not sure what you'd like me to check, but here's a similair comparison.

NOTE: Title keeps original background.

The original foreground of each of the original characters is unchanged, like before. This theme seems to have a nicer contrast between different colors but the issue still remains. When the contrast isn't that good (eg. last image) it hurts readability.

Here's the same affect with ivy.

With ivy the entire line of each input recieves the same face which makes it predictable and consistent.

S.N. Here's my theme file (it's custom so I guess its fair to say it doesn't yet have selectrum support)

[mohkale]

This makes selectrum-current-candidate face highlighting more like ivy:

(defvar selectrum-override-current-candidate-face+ t
  "When true selectrum overrides any existing faces on the current candidate
      with `selectrum-current-candidate'.")

(advice-add 'selectrum--add-face :around
            (defun selectrum-override-current-candidate-face+ (func str face)
              (if (and selectrum-override-current-candidate-face+
                       (eq face 'selectrum-current-candidate))
                  (progn
                    (setq str (copy-sequence str))
                    ;; Adapted from `selectrum--add-face' but prepend instead of append.
                    (if (version< emacs-version "27")
                        (font-lock-prepend-text-property 0 (length str) 'face face str)
                      (add-face-text-property 0 (length str) face nil str))
                    str)
                (funcall func str face))))

But there're some edge cases. Eg.

describe-face with selectrum vs. counsel-describe-face .

It might be more apropriate to let the highlight function know which candidate is current and then leave it upto them to override the face as appropriate. That's why I initially opened the issue on marginalia.

S.N. This approach also overrides prescient highlighting 😭.