To install this package, run in Emacs:
M-x package-install RET cape RET
Cape provides a bunch of Completion At Point Extensions which can be used in
combination with my Corfu completion UI or the default completion UI. The
completion backends used by
completion-at-point are so called
completion-at-point-functions (Capfs). In principle, the Capfs provided by Cape
can also be used by Company.
You can register the
cape-* functions in the
This makes the backends available for completion, which is usually invoked by
M-TAB. The functions can also be invoked interactively to
trigger the respective completion at point. You can bind them directly to a key
in your user configuration. Notable commands/capfs are
cape-line for completion
of a line from the current buffer and
cape-file for completion of a file name.
cape-symbol is particularily useful for documentation of Elisp
packages or configurations, since it completes elisp symbols anywhere.
On the more experimental side, Cape has the super power to transform Company backends into Capfs and merge multiple Capfs into a Super-Capf! These transformers allow you to still take advantage of Company backends even if you are not using Company as frontend.
cape-dabbrev: Complete word from current buffers
cape-file: Complete file name
cape-keyword: Complete programming language keyword
cape-symbol: Complete Elisp symbol
cape-abbrev: Complete abbreviation (
cape-ispell: Complete word from Ispell dictionary
cape-dict: Complete word from dictionary file
cape-line: Complete entire line from current buffer
cape-tex: Complete unicode char from TeX command, e.g.
cape-sgml: Complete unicode char from Sgml entity, e.g.,
cape-rfc1345: Complete unicode char using RFC 1345 mnemonics.
Cape is available on GNU ELPA and MELPA. You can install the package with
package-install. In the long term some of the Capfs provided by this package
could be upstreamed into Emacs itself.
;; Enable Corfu completion UI ;; See the Corfu README for more configuration tips. (use-package corfu :init (corfu-global-mode)) ;; Add extensions (use-package cape ;; Bind dedicated completion commands :bind (("C-c p p" . completion-at-point) ;; capf ("C-c p t" . complete-tag) ;; etags ("C-c p d" . cape-dabbrev) ;; or dabbrev-completion ("C-c p f" . cape-file) ("C-c p k" . cape-keyword) ("C-c p s" . cape-symbol) ("C-c p a" . cape-abbrev) ("C-c p i" . cape-ispell) ("C-c p l" . cape-line) ("C-c p w" . cape-dict) ("C-c p \\" . cape-tex) ("C-c p _" . cape-tex) ("C-c p ^" . cape-tex) ("C-c p &" . cape-sgml) ("C-c p r" . cape-rfc1345)) :init ;; Add `completion-at-point-functions', used by `completion-at-point'. (add-to-list 'completion-at-point-functions #'cape-file) (add-to-list 'completion-at-point-functions #'cape-tex) (add-to-list 'completion-at-point-functions #'cape-dabbrev) (add-to-list 'completion-at-point-functions #'cape-keyword) ;;(add-to-list 'completion-at-point-functions #'cape-sgml) ;;(add-to-list 'completion-at-point-functions #'cape-rfc1345) ;;(add-to-list 'completion-at-point-functions #'cape-abbrev) ;;(add-to-list 'completion-at-point-functions #'cape-ispell) ;;(add-to-list 'completion-at-point-functions #'cape-dict) ;;(add-to-list 'completion-at-point-functions #'cape-symbol) ;;(add-to-list 'completion-at-point-functions #'cape-line) )
Wrap your Company backend in a Cape and turn it into a Capf!
Cape provides an adapter for Company backends
cape-company-to-capf. The adapter
transforms Company backends to Capfs which are understood by the built-in Emacs
completion mechanism. The function is approximately the inverse of the
company-capf backend from Company. The adapter is still experimental and may
have certain edge cases. The adapter can be used as follows:
;; Use Company backends as Capfs. (setq-local completion-at-point-functions (mapcar #'cape-company-to-capf (list #'company-files #'company-ispell #'company-dabbrev)))
Note that the adapter does not require Company to be installed. Backends
implementing the Company specification do not necessarily have to depend on
Company, however in practice most backends do. The following shows a small
example completion backend, which can be used with both
(Corfu, default completion) and Company.
(defvar emojis '((":-D" . "😀") (";-)" . "😉") (":-/" . "😕") (":-(" . "🙁") (":-*" . "😙"))) (defun emoji-backend (action &optional arg &rest _) (pcase action ('prefix (and (memq (char-before) '(?: ?\;)) (cons (string (char-before)) t))) ('candidates (all-completions arg emojis)) ('annotation (concat " " (cdr (assoc arg emojis)))) ('post-completion (let ((str (buffer-substring (- (point) 3) (point)))) (delete-region (- (point) 3) (point)) (insert (cdr (assoc str emojis))))))) ;; Register emoji backend with `completion-at-point' (setq completion-at-point-functions (list (cape-company-to-capf #'emoji-backend))) ;; Register emoji backend with Company. (setq company-backends '(emoji-backend))
It is possible to merge/group multiple Company backends and use them as a single
Capf using the
company--multi-backend-adapter function from Company. The adapter
transforms multiple Company backends into a single Company backend, which can
then be used as a Capf via
(require 'company) ;; Use the company-dabbrev and company-elisp backends together. (setq completion-at-point-functions (list (cape-company-to-capf (apply-partially #'company--multi-backend-adapter '(company-dabbrev company-elisp)))))
Throw multiple Capfs under the Cape and get a Super-Capf!
Cape supports merging multiple Capfs using the function
feature is experimental and should only be used in special scenarios.
Don't use cape-super-capf if you are not 100% sure that you need it!
cape-super-capf is not needed if you want to use multiple Capfs which
are tried one by one, e.g., it is perfectly possible to use
with the lsp-mode Capf or other programming mode Capfs by adding
completion-at-point-functions list. The file completion will be available in
comments and string literals.
cape-super-capf is only needed if you want to
combine multiple Capfs, such that the candidates from multiple sources appear
together in the completion list at the same time.
Completion table merging works only for tables which are sufficiently
well-behaved and tables which do not define completion boundaries.
cape-super-capf has the same restrictions as
completion-table-in-turn. As a simple rule of thumb,
cape-super-capf works only
well for static completion functions like
cape-ispell, etc., but not for complex multi-step completions like
;; Merge the dabbrev, dict and keyword capfs, display candidates together. (setq-local completion-at-point-functions (list (cape-super-capf #'cape-dabbrev #'cape-dict #'cape-keyword)))
See also the aforementioned
company--multi-backend-adapter from Company, which
allows you to merge multiple Company backends.
The Capf-Buster ensures that you always get a fresh set of candidates!
If a Capf caches the candidates for too long we can use a cache busting
Capf-transformer. For example the Capf merging function
a Capf, which caches the candidates for the whole lifetime of the Capf.
Therefore you may want to combine a merged Capf with a cache buster under some
circumstances. It is noteworthy that the
company-capf backend from Company
refreshes the completion table frequently. With the
cape-capf-buster we can
achieve a similarly refreshing strategy.
(setq-local completion-at-point-functions (list (cape-capf-buster #'some-caching-capf)))
cape-interactive-capf: Create a Capf which can be called interactively.
cape-capf-silent: Wrap a chatty Capf and silence it.
cape-capf-purify: Purify a broken Capf and ensure that it does not modify the buffer.
cape-capf-noninterruptible:Protect a Capf which does not like to be interrupted.
cape-capf-case-fold: Create a Capf which is case insensitive.
cape-capf-properties: Add completion properties to a Capf.
cape-capf-predicate: Add candidate predicate to a Capf.
Since this package is part of GNU ELPA contributions require a copyright assignment to the FSF.