GitHub - minad/corfu: 🏝️ corfu.el - COmpletion in Region FUnction (original) (raw)
corfu.el - COmpletion in Region FUnction
Corfu enhances in-buffer completion with a small completion popup. The current candidates are shown in a popup below or above the point. The candidates can be selected by moving up and down. Corfu is the minimalistic in-buffer completion counterpart of the Vertico minibuffer UI.
Corfu is a small package, which relies on the Emacs completion facilities and concentrates on providing a polished completion UI. In-buffer completion UIs in Emacs can hook into completion-in-region
, which implements the interaction with the user. Completions at point are either provided by commands likedabbrev-completion
or by pluggable backends (completion-at-point-functions
, Capfs) and are then passed to completion-in-region
. Many programming, text and shell major modes implement a Capf. Corfu does not include its own completion backends. The Emacs built-in Capfs and the Capfs provided by third-party programming language packages are often sufficient. Additional Capfs and completion utilities are provided by the Cape package.
NOTE: Corfu relies on child frames to show the popup, such that mixed fonts and font sizes won’t interfere with the rendering. On non-graphical displays, Corfu falls back to the default setting of the completion-in-region-function
. There is an effort towards child frame support for terminal Emacs, which will hopefully arrive in Emacs 31 or 32. Until then you can use the corfu-terminal package as a stop-gap solution, which provides an alternative display based on overlays.
Features
- Timer-based auto-completions (off by default, set
corfu-auto
). - Popup display with scrollbar indicator and arrow key navigation.
- The popup can be summoned explicitly by pressing
TAB
at any time. - The current candidate is inserted with
TAB
and selected withRET
. - Candidate sorting by prefix, string length and alphabetically.
- The selected candidate is previewed (configurable via
corfu-preview-current
). - The selected candidate is automatically committed on further input by default. (configurable via
corfu-preview-current
). - Supports the Orderless completion style. The filter string can contain arbitrary characters, after inserting a space via
M-SPC
(configurable viacorfu-quit-at-boundary
andcorfu-separator
). - Lazy completion candidate highlighting for performance.
- Support for candidate annotations (
annotation-function
,affixation-function
). - Deprecated candidates are displayed as crossed out.
- Icons can be provided by an external package via margin formatter functions.
- Rich set of extensions: Quick keys, Index keys, Sorting by history, Candidate documentation in echo area, popup or separate buffer.
Installation
Corfu is available from GNU ELPA. You can install it directly via M-x package-install RET corfu RET
. After installation, activate the global minor mode with M-x global-corfu-mode RET
. Set the variable corfu-auto
to t in order to enable auto completion. For manual completion press M-TAB
(or TAB
) within a buffer.
Key bindings
Corfu uses a transient keymap corfu-map
which is active while the popup is shown. The keymap defines the following remappings of fundamental commands and bindings:
Binding/Remapping | Corfu command |
---|---|
move-beginning-of-line | corfu-prompt-beginning |
move-end-of-line | corfu-prompt-end |
beginning-of-buffer | corfu-first |
end-of-buffer | corfu-last |
scroll-down-command | corfu-scroll-down |
scroll-up-command | corfu-scroll-up |
next-line, down, M-n | corfu-next |
previous-line, up, M-p | corfu-previous |
completion-at-point, TAB | corfu-complete |
M-TAB | corfu-expand |
RET | corfu-insert |
M-g | corfu-info-location |
M-h | corfu-info-documentation |
M-SPC | corfu-insert-separator |
C-g | corfu-quit |
keyboard-escape-quit | corfu-reset |
Configuration
In order to configure Corfu and other packages in your init.el, you may want to use use-package
. Corfu is flexibly customizable via corfu-*
customization variables, such that you can adapt it precisely to your requirements. However in order to quickly try out the Corfu completion package, it should be sufficient to activate global-corfu-mode
. You can experiment with manual completion for example in an Elisp buffer or in an Eshell or Shell buffer. For auto completion, set corfu-auto
to t before turning on global-corfu-mode
.
Here is an example configuration:
(use-package corfu ;; Optional customizations ;; :custom ;; (corfu-cycle t) ;; Enable cycling for `corfu-next/previous' ;; (corfu-auto t) ;; Enable auto completion ;; (corfu-separator ?\s) ;; Orderless field separator ;; (corfu-quit-at-boundary nil) ;; Never quit at completion boundary ;; (corfu-quit-no-match nil) ;; Never quit, even if there is no match ;; (corfu-preview-current nil) ;; Disable current candidate preview ;; (corfu-preselect 'prompt) ;; Preselect the prompt ;; (corfu-on-exact-match nil) ;; Configure handling of exact matches ;; (corfu-scroll-margin 5) ;; Use scroll margin
;; Enable Corfu only for certain modes. See also `global-corfu-modes'. ;; :hook ((prog-mode . corfu-mode) ;; (shell-mode . corfu-mode) ;; (eshell-mode . corfu-mode))
;; Recommended: Enable Corfu globally. This is recommended since Dabbrev can ;; be used globally (M-/). See also the customization variable ;; `global-corfu-modes' to exclude certain modes. :init (global-corfu-mode))
;; A few more useful configurations... (use-package emacs :custom ;; TAB cycle if there are only few candidates ;; (completion-cycle-threshold 3)
;; Enable indentation+completion using the TAB key. ;; `completion-at-point' is often bound to M-TAB. (tab-always-indent 'complete)
;; Emacs 30 and newer: Disable Ispell completion function. As an alternative, ;; try `cape-dict'. (text-mode-ispell-word-completion nil)
;; Hide commands in M-x which do not apply to the current mode. Corfu ;; commands are hidden, since they are not used via M-x. This setting is ;; useful beyond Corfu. (read-extended-command-predicate #'command-completion-default-include-p))
Dabbrev completion is based on completion-in-region
and can be used with Corfu. You may want to swap the dabbrev-completion
with the dabbrev-expand
key for easier access, if you prefer completion. Also take a look at the cape-dabbrev
completion at point function provided by my Cape package.
;; Use Dabbrev with Corfu!
(use-package dabbrev
;; Swap M-/ and C-M-/
:bind (("M-/" . dabbrev-completion)
("C-M-/" . dabbrev-expand))
:config
(add-to-list 'dabbrev-ignored-buffer-regexps "\") ;; Since 29.1, use
dabbrev-ignored-buffer-regexps' on older.
(add-to-list 'dabbrev-ignored-buffer-modes 'doc-view-mode)
(add-to-list 'dabbrev-ignored-buffer-modes 'pdf-view-mode)
(add-to-list 'dabbrev-ignored-buffer-modes 'tags-table-mode))
If you start to configure Corfu more deeply, I recommend to give the Orderless completion style a try for filtering. Orderless completion offers more flexible filtering than the default completion styles. Note that Orderless is not a necessity; Corfu can be used just as well with the default completion styles.
;; Optionally use the `orderless' completion style. (use-package orderless :custom ;; (orderless-style-dispatchers '(orderless-affix-dispatch)) ;; (orderless-component-separator #'orderless-escapable-split-on-space) (completion-styles '(orderless basic)) (completion-category-defaults nil) (completion-category-overrides '((file (styles partial-completion)))))
The basic
completion style is specified as fallback in addition to orderless
in order to ensure that completion commands which rely on dynamic completion tables, e.g., completion-table-dynamic
or completion-table-in-turn
, work correctly. Additionally enable partial-completion
for file path expansion.partial-completion
is important for file wildcard support. Multiple files can be opened at once with find-file
if you enter a wildcard. You may also give theinitials
completion style a try.
See also the Corfu Wiki and the Cape manual for additional Capf configuration tips. For more general documentation read the chapter about completion in theEmacs manual. If you want to create your own Capfs, you can find documentation about completion in the Elisp manual.
Auto completion
Auto completion is disabled by default, but can be enabled by setting corfu-auto
to t. Furthermore you may want to configure Corfu to quit completion eagerly, such that the completion popup stays out of your way when it appeared unexpectedly.
;; Enable auto completion and configure quitting (setq corfu-auto t corfu-quit-no-match 'separator) ;; or t
I suggest to experiment with the various settings and key bindings to find a configuration which works for you. There is no one perfect configuration which fits all. Some people like auto completion, some like manual completion, some want to cycle with TAB and some with the arrow keys.
In case you like auto completion settings, where the completion popup appears immediately, better use a cheap completion style like basic
, which performs prefix filtering. In this case Corfu completion should still be fast in buffers with efficient completion backends. You can try the following settings in an Elisp buffer or the Emacs scratch buffer. Note that such settings can slow down Emacs due to the high load on the Lisp runtime and garbage collector.
(setq-local corfu-auto t corfu-auto-delay 0 ;; TOO SMALL - NOT RECOMMENDED corfu-auto-prefix 1 ;; TOO SMALL - NOT RECOMMENDED completion-styles '(basic))
If you want to combine fast prefix filtering and Orderless filtering you can still do that by defining a custom Orderless completion style viaorderless-define-completion-style
. We use a custom style dispatcher, which enables efficient prefix filtering for input shorter than 4 characters. Note that such a setup is advanced. Please refer to the Orderless documentation and source code for further details.
(defun orderless-fast-dispatch (word index total) (and (= index 0) (= total 1) (length< word 4) (cons 'orderless-literal-prefix word)))
(orderless-define-completion-style orderless-fast (orderless-style-dispatchers '(orderless-fast-dispatch)) (orderless-matching-styles '(orderless-literal orderless-regexp)))
(setq-local corfu-auto t corfu-auto-delay 0 ;; TOO SMALL - NOT RECOMMENDED corfu-auto-prefix 1 ;; TOO SMALL - NOT RECOMMENDED completion-styles '(orderless-fast basic))
Completing in the minibuffer
Corfu can be used for completion in the minibuffer, since it relies on child frames to display the candidates. The Corfu popup can be shown even if it doesn’t fully fit inside the minibuffer.
global-corfu-mode
activates corfu-mode
in the minibuffer if the variableglobal-corfu-minibuffer
is non-nil. In order to avoid interference with specialised minibuffer completion UIs like Vertico or Mct, Corfu is only enabled if the minibuffer sets the variable completion-at-point-functions
locally. This way minibuffers with completion can be detected, such that minibuffer commands like M-:
(eval-expression
) or M-!
(shell-command
) are enhanced with Corfu completion.
If needed, one can also enable Corfu more generally in all minibuffers, as long as no completion UI is active. In the following example we setglobal-corfu-minibuffer
to a predicate function, which checks for Mct and Vertico. Furthermore we ensure that Corfu is not enabled if a password is read from the minibuffer.
(setq global-corfu-minibuffer (lambda () (not (or (bound-and-true-p mct--active) (bound-and-true-p vertico--input) (eq (current-local-map) read-passwd-map)))))
Completing in the Eshell or Shell
When completing in the Eshell I recommend conservative local settings without auto completion, such that the completion behavior is similar to widely used shells like Bash, Zsh or Fish.
(add-hook 'eshell-mode-hook (lambda () (setq-local corfu-auto nil) (corfu-mode)))
When pressing RET
while the Corfu popup is visible, the corfu-insert
command will be invoked. This command does inserts the currently selected candidate, but it does not send the prompt input to Eshell or the Comint process. Therefore you often have to press RET
twice which feels like an unnecessary double confirmation. Fortunately it is easy to improve this by using the commandcorfu-send
instead.
(keymap-set corfu-map "RET" #'corfu-send)
Shell completion uses the flexible Pcomplete mechanism internally, which allows you to program the completions per shell command. If you want to know more, look into this blog post, which shows how to configure Pcomplete for git commands. Since Emacs 29, Pcomplete offers the pcomplete-from-help
function which parses the --help
output of a command and produces completions for command line options.
Pcomplete has a few bugs on Emacs 28 and older. We can work around the issues with the Cape library (Completion at point extensions). Cape provides wrappers which sanitize the Pcomplete function. On Emacs 29 the advices should not be necessary anymore, since most relevant bugs have been fixed. In case you discover any remaining Pcomplete issues, please report them upstream.
;; Sanitize the `pcomplete-completions-at-point' Capf. The Capf has undesired ;; side effects on Emacs 28 and earlier. These advices are not needed on Emacs ;; 29 and newer. (when (< emacs-major-version 29) (advice-add 'pcomplete-completions-at-point :around #'cape-wrap-silent) (advice-add 'pcomplete-completions-at-point :around #'cape-wrap-purify))
Orderless completion
Orderless is an advanced completion style that supports multi-component search filters separated by a configurable character (space, by default). Normally, entering characters like space which lie outside the completion region boundaries (words, typically) causes Corfu to quit. This behavior is helpful with auto-completion, which may pop-up when not desired, e.g. on entering a new variable name. Just keep typing and Corfu will get out of the way.
But orderless search terms can contain arbitrary characters; they are also interpreted as regular expressions. To use orderless, set corfu-separator
(a space, by default) to the primary character of your orderless component separator.
Then, when a new orderless component is desired, use M-SPC
(corfu-insert-separator
) to enter the first component separator in the input, and arbitrary orderless search terms and new separators can be entered thereafter.
To treat the entire input as Orderless input, you can set the customization option corfu-quit-at-boundary
to nil. This disables the predicate which checks if the current completion boundary has been left. In contrast, if you always want to quit at the boundary, set corfu-quit-at-boundary
to t. By defaultcorfu-quit-at-boundary
is set to separator
which quits at completion boundaries as long as no separator has been inserted with corfu-insert-separator
.
Finally, there exists the user option corfu-quit-no-match
which is set toseparator
by default. With this setting Corfu stays alive as soon as you start advanced filtering with a corfu-separator
even if there are no matches, for example due to a typo. As long as no separator character has been inserted withcorfu-insert-separator
, Corfu will still quit if there are no matches. This ensures that the Corfu popup goes away quickly if completion is not possible.
In the following we show two configurations, one which works best with auto completion and one which may work better with manual completion if you prefer to always use SPC
to separate the Orderless components.
;; Auto completion example (use-package corfu :custom (corfu-auto t) ;; Enable auto completion ;; (corfu-separator ?_) ;; Set to orderless separator, if not using space :bind ;; Another key binding can be used, such as S-SPC. ;; (:map corfu-map ("M-SPC" . corfu-insert-separator)) :init (global-corfu-mode))
;; Manual completion example (use-package corfu :custom ;; (corfu-separator ?_) ;; Set to orderless separator, if not using space :bind ;; Configure SPC for separator insertion (:map corfu-map ("SPC" . corfu-insert-separator)) :init (global-corfu-mode))
TAB-only completion
By default, Corfu steals both the RET
and TAB
keys, when the Corfu popup is open. This can feel intrusive, in particular in combination with auto completion. RET
may accidentally commit an automatically selected candidate, while you actually wanted to start a new line. As an alternative we can unbind the RET
key completely from corfu-map
or reserve the RET
key only in shell modes using a menu-item filter.
;; TAB-only configuration (use-package corfu :custom (corfu-auto t) ;; Enable auto completion (corfu-preselect 'directory) ;; Select the first candidate, except for directories
:init (global-corfu-mode)
:config ;; Free the RET key for less intrusive behavior. ;; Option 1: Unbind RET completely ;; (keymap-unset corfu-map "RET") ;; Option 2: Use RET only in shell modes (keymap-set corfu-map "RET" `( menu-item "" nil :filter ,(lambda (&optional _) (and (derived-mode-p 'eshell-mode 'comint-mode) #'corfu-send)))))
TAB-and-Go completion
You may be interested in configuring Corfu in TAB-and-Go style. Pressing TAB moves to the next candidate and further input will then commit the selection. Note that further input will not expand snippets or templates, which may not be desired but which leads overall to a more predictable behavior. In order to force snippet expansion, confirm a candidate explicitly with RET
.
(use-package corfu ;; TAB-and-Go customizations :custom (corfu-cycle t) ;; Enable cycling for `corfu-next/previous' (corfu-preselect 'prompt) ;; Always preselect the prompt
;; Use TAB for cycling, default is `corfu-complete'. :bind (:map corfu-map ("TAB" . corfu-next) ([tab] . corfu-next) ("S-TAB" . corfu-previous) ([backtab] . corfu-previous))
:init (global-corfu-mode))
Transfer completion to the minibuffer
Sometimes it is useful to transfer the Corfu completion session to the minibuffer, since the minibuffer offers richer interaction features. In particular, Embark is available in the minibuffer, such that you can act on the candidates or export/collect the candidates to a separate buffer. We could add Corfu support to Embark in the future, such that export or collect is possible directly from Corfu. Nevertheless, the ability to transfer the Corfu completion to the minibuffer is even more powerful, since further completion is possible.
The command corfu-move-to-minibuffer
is defined here in terms ofconsult-completion-in-region
, which uses the minibuffer completion UI viacompleting-read
.
(defun corfu-move-to-minibuffer () (interactive) (pcase completion-in-region--data (`(,beg ,end ,table ,pred ,extras) (let ((completion-extra-properties extras) completion-cycle-threshold completion-cycling) (consult-completion-in-region beg end table pred))))) (keymap-set corfu-map "M-m" #'corfu-move-to-minibuffer) (add-to-list 'corfu-continue-commands #'corfu-move-to-minibuffer)
Extensions
We maintain small extension packages to Corfu in this repository in the subdirectory extensions/. The extensions are installed together with Corfu if you pull the package from ELPA. The extensions are inactive by default and can be enabled manually if desired. Furthermore it is possible to install all of the files separately, both corfu.el
and the corfu-*.el
extensions. Currently the following extensions come with the Corfu ELPA package:
- corfu-echo:
corfu-echo-mode
displays a brief candidate documentation in the echo area. - corfu-history:
corfu-history-mode
remembers selected candidates and sorts the candidates by their history position. - corfu-indexed:
corfu-indexed-mode
allows you to select indexed candidates with prefix arguments. - corfu-info: Actions to access the candidate location and documentation.
- corfu-popupinfo: Display candidate documentation or source in a popup next to the candidate menu.
- corfu-quick: Commands to select using Avy-style quick keys.
See the Commentary of those files for configuration details.
Complementary packages
Corfu works well together with all packages providing code completion via thecompletion-at-point-functions
. Many modes and packages already provide a Capf out of the box. Nevertheless you may want to look into complementary packages to enhance your setup.
- corfu-terminal: The corfu-terminal package provides an overlay-based display for Corfu. This is needed until child frame support for terminal Emacs arrives.
- corfu-candidate-overlay: Shows as-you-type auto-suggestion candidate overlay with a visual indication of whether there are many or exactly one candidate available (works only with
corfu-auto
disabled). - Orderless: Corfu supports completion styles, including the advanced
orderless
completion style, where the filter expressions are separated by spaces or another character (seecorfu-separator
). - Cape: Provides additional Capf backends and
completion-in-region
commands. Among others, the package supplies the file completion backendcape-file
and the Dabbrev backendcape-dabbrev
. Cape provides thecape-company-to-capf
adapter to reuse Company backends in Corfu. - nerd-icons-corfu, kind-icon: Icons are supported by Corfu via external packages. The nerd-icons-corfu package relies on the Nerd icon font, which is even supported on terminal, while kind-icon uses SVGs from monochromatic icon sets.
- Tempel: Tiny template/snippet package with templates in Lisp syntax, which can be used in conjunction with Corfu.
- Vertico: You may also want to look into my Vertico package. Vertico is the minibuffer completion counterpart of Corfu.
Alternatives
- Company: Company is a widely used and mature completion package, which implements a similar UI as Corfu. While Corfu relies exclusively on the standard Emacs completion API (Capfs), Company defines its own API for the backends. Company includes its own completion backends, following its own API, which are incompatible with the Emacs completion infrastructure. Company provides an adapter
company-capf
to handle Capfs as a Company backend. As a result of this design, Company is a more complex package than Corfu. Company by default uses overlays for the popup in contrast to the child frames used by Corfu. Overall both packages work well, but Company integrates less tightly with Emacs. Thecompletion-styles
support is more limited and thecompletion-at-point
command and thecompletion-in-region
function do not invoke Company. - consult-completion-in-region: The Consult package provides the function
consult-completion-in-region
which can be set ascompletion-in-region-function
such that it handlescompletion-at-point
. The function works by transferring the in-buffer completion to the minibuffer. In the minibuffer, the minibuffer completion UI, for example Vertico takes over. If you prefer to perform all your completions in the minibufferconsult-completion-in-region
is your best option.
Debugging Corfu
When you observe an error in the corfu--post-command
post command hook, you should install an advice to enforce debugging. This allows you to obtain a stack trace in order to narrow down the location of the error. The reason is that post command hooks are automatically disabled (and not debugged) by Emacs. Otherwise Emacs would become unusable, given that the hooks are executed after every command.
(setq debug-on-error t)
(defun force-debug (func &rest args) (condition-case e (apply func args) ((debug error) (signal (car e) (cdr e)))))
(advice-add #'corfu--post-command :around #'force-debug)
When Capfs do not yield the expected result you can use cape-capf-debug
to add debug messages to a Capf. The Capf will then produce a completion log in the messages buffer.
(setq completion-at-point-functions (list (cape-capf-debug #'cape-dict)))
Contributions
Since this package is part of GNU ELPA contributions require a copyright assignment to the FSF.