feat(corfu,vertico): use equal orderless config

This removes the old `&` separator for Vertico (does anyone use that
instead of just space?) in favor of escapable space and unifies
orderless config with Corfu. Also implements smart separator
insert/escape/reset on `C-SPC`

Co-authored-by: Liam Hupfer <liam@hpfr.net>

modules/completion/corfu/README.org

@@ -148,7 +148,10 @@ completing inserts a space as separator. This allows searching with
 space-separated terms; each piece will match individually and in any order, with
 smart casing. Pressing just [[kbd:][SPC]] acts as normal and quits completion, so that
 when typing sentences it doesn't try to complete the whole sentence instead of
-just the word.
+just the word. Pressing [[kdb:][C-SPC]] with point after a separator escapes it with a
+backslash, including the space in the search term, and pressing it with an
+already escaped separator before point deletes it. Thus, you can cycle back if
+you accidentaly press more than needed.
 
 | Keybind | Description                                     |
 |---------+-------------------------------------------------|

modules/completion/corfu/autoload.el

@@ -8,3 +8,15 @@
   (let ((completion-extra-properties corfu--extra)
         (completion-cycle-threshold completion-cycling))
     (apply #'consult-completion-in-region completion-in-region--data)))
+
+;;;###autoload
+(defun +corfu-smart-sep-toggle-escape ()
+  "Insert `corfu-separator' or toggle escape if it's already there."
+  (interactive)
+  (cond ((and (char-equal (char-before) corfu-separator)
+              (char-equal (char-before (1- (point))) ?\\))
+         (save-excursion (delete-char -2)))
+        ((char-equal (char-before) corfu-separator)
+         (save-excursion (backward-char 1)
+                         (insert-char ?\\)))
+        (t (call-interactively #'corfu-insert-separator))))

modules/completion/corfu/config.el

@@ -46,6 +46,7 @@ Possible values are:
   (add-to-list 'completion-category-overrides `(lsp-capf (styles ,@completion-styles)))
   (add-to-list 'corfu-auto-commands #'lispy-colon)
   (add-to-list 'corfu-continue-commands #'+corfu-move-to-minibuffer)
+  (add-to-list 'corfu-continue-commands #'+corfu-smart-sep-toggle-escape)
   (add-hook 'evil-insert-state-exit-hook #'corfu-quit))
 
 (use-package! cape
@@ -118,3 +119,15 @@ Possible values are:
   :init
   (after! corfu
     (add-to-list 'corfu-margin-formatters #'nerd-icons-corfu-formatter)))
+
+;; If vertico is not enabled, orderless will be installed but not configured.
+;; That may break smart separator behavior, so we conditionally configure it.
+(use-package! orderless
+  :when (and (not (modulep! :completion vertico))
+             (modulep! +orderless))
+  :config
+  (setq completion-styles '(orderless basic)
+        completion-category-defaults nil
+        completion-category-overrides '((file (styles orderless partial-completion)))
+        orderless-component-separator #'orderless-escapable-split-on-space)
+  (set-face-attribute 'completions-first-difference nil :inherit nil))

modules/completion/vertico/config.el

@@ -107,7 +107,7 @@ orderless."
         ;; find-file etc.
         completion-category-overrides '((file (styles +vertico-basic-remote orderless partial-completion)))
         orderless-style-dispatchers '(+vertico-orderless-dispatch)
-        orderless-component-separator "[ &]")
+        orderless-component-separator #'orderless-escapable-split-on-space)
   ;; ...otherwise find-file gets different highlighting than other commands
   (set-face-attribute 'completions-first-difference nil :inherit nil))
 

modules/config/default/config.el

@@ -461,6 +461,7 @@ Continues comments if executed from a commented line. Consults
   (map! :when (modulep! :completion corfu)
         :after corfu
         (:map corfu-map
+         [remap corfu-insert-separator] #'+corfu-smart-sep-toggle-escape
          "C-S-s" #'+corfu-move-to-minibuffer
          "C-p" #'corfu-previous
          "C-n" #'corfu-next