Auto-Complete (a.k.a auto-complete.el,
auto-complete-mode) is an extension that automates and
advances the completion-system of GNU Emacs. It is superior to the old
system. Features include:
This user manual covers from how to install and use to how to extend. Please contact me if you have any questions.
Auto Complete Mode is licensed under the terms of GPLv3. And this document is licensed under the term of GFDL.
You can download the latest auto-complete from the official site.
You can install auto-complete.el from MELPA or MELPA Stable with package.el. Add
following configurations for initializing package.el.
(require 'package)
;; If you want to use latest version
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))
;; If you want to use last tagged version
(add-to-list 'package-archives '("melpa-stable" . "https://stable.melpa.org/packages/"))
(package-initialize)Then You can install auto-complete by
M-x package-list-packages and select auto-completeM-x package-refresh-contents and
M-x package-install auto-completeType some characters in *scratch* buffer in a restarted or newly-launched Emacs. Installation has been successful if you see a completion menu. If you have an error or no completion is started, it could be a failure. Please contact me in such case with confirmation following:
Characters AC in mode-line?
If you don’t see characters AC in mode-line (a gray line
of bottom of buffer), auto-complete-mode is not enabled.
Type M-x auto-complete-mode to enable and try
again.
Error occurred
If you have *Backtrace* with errors or errors in minibuffer (bottom of frame), please contact me with the errors.
First, in a meaning, auto-complete-mode has no “usage”.
Because auto-complete-mode is designed to fade into the
Emacs editing system. Users will receive a highly-developed completion
system automatically without any difficulty. Ultimately, a goal of
auto-complete-mode is to provide a system that does what
users want without any command, but it is impossible to accomplish 100%
accuracy actually. So there is “usage” to cover those points.
Inputting characters is basic. Completions will never be shown
without any character. So when completion will be started, what
character causes completion to be started? It is a good question but it
is difficult to answer here. In simple words, completion will be started
when a character is inserted. See ac-trigger-commands for
more details.
After completion is started, completion by TAB will be enabled temporarily. Completion by TAB is the most important and most frequent used command. TAB has several meanings.
Case that only one candidate remains
If only one candidate remains, the candidate will be used to complete.
Case that there is a common part among candidates
For example, if all candidates start with “set”, it means they have a common part “set”. So TAB completes “set” at first.
Otherwise
Otherwise, select candidates in cycle by typing TAB.
It may be a little different according to settings, but basically completion by TAB works as we wrote above. A reason why TAB has several meanings is that we want users to do anything with TAB.
Like completion by TAB but some points are different:
It is necessary to type TAB a few times for completion by TAB. Completion by RET instead complete a selected candidate immediately, so when you see a candidate you want, just type RET. If the candidate has an action, the action will be executed. Take a example of builtin abbrev completion. In completion by TAB, an abbrev which expands “www” to “World Wide Web” will be completed to “www”, but in completion by RET, the abbrev will be expanded to “World Wide Web” as completion.
Following the auto-complete-mode philosophy, it is not
recommended to manually select candidates. That means it has been failed
to guess the completion, and also it requires users to do candidate
selection which is a high cost operation. We think there are so many
cases that requires to do candidate selection, because completion by TAB
will help candidate selection somehow and in recent versions, a
statistical method contributes to make a candidate suggestion more
accurate. However, actually, this is such cases. So we also think it is
not bad idea to remember how to select candidates.
Selecting candidates is not a complex operation. You can select
candidates forward or backward by cursor key or M-p and
M-n. According to settings, a behavior of completion by TAB
will be changed as a behavior of completion by RET. See ac-dwim for more details.
There are other ways to select candidates. M-1 to select
candidate 1, M-2 to select candidate 2, and so on.
auto-complete-mode has two types of help functionalities
called Quick Help and Buffer Help. They are different
in a point of displaying. Quick help will appear at the side of
completion menu, so you can easily see that, but there is a problem if
there is no space to display the help. Quick help will be shown
automatically. To use quick help, you need to set ac-use-quick-help to
t. Delay time to show quick help is given by ac-quick-help-delay.
On the other side, buffer help will not be shown without any
instructions from users. Buffer help literally displays help in a buffer
in another window. It costs more to see than quick help, but it has more
readability. To show buffer help, press C-? or
f1. By pressing C-M-v or C-M-S-v
after showing buffer help, you can scroll forward or backward through
the help buffer. Other commands will be fallbacked and buffer help will
be closed.
Completion will be started by inserting characters. After completion is started, operations in the following table will be enabled temporarily. After completion is finished, these operations will be disabled.
| Key | Command | Description |
|---|---|---|
TAB, C-i |
ac-expand |
Completion by TAB |
RET, C-m |
ac-complete |
Completion by RET |
down, M-n |
ac-next |
Select next candidate |
up, M-p |
ac-previous |
Select previous candidate |
C-?, f1 |
ac-help |
Show buffer help |
To stop completion, simply use C-g.
auto-complete
commandBasically there is an assumption that auto-complete-mode
will be started automatically, but there is also exception. For example,
that is a case that an user wants to complete without inserting any
character or a case not to start auto-complete-mode
automatically by settings. A command called auto-complete
is useful in such cases, which is used with key binding in general. The
following code changes a default completion command to more advanced
feature that auto-complete-mode provides.
(define-key ac-mode-map (kbd "M-TAB") 'auto-complete)So, as of auto-complete command, it is a little
different from an original automatic completion.
Case that only one candidate remains
Complete immediately without showing completion menu.
Case that no candidates remains
Attempt to complete with fuzzy matching. See Completion by Fuzzy Matching for more details.
Otherwise
Otherwise start completion with/without expanding a whole common part
and showing completion menu. See also ac-show-menu-immediately-on-auto-complete
and ac-expand-on-auto-complete.
In a case that there are no candidates by auto-complete
command or the case where ac-fuzzy-complete command is
executed, auto-complete-mode attempts to complete with
fuzzy matching instead of the usual exact matching. Parameters of fuzzy
matching have already been optimized for use, so users don’t need to
change them. However if you want to know the internals, see
fuzzy.el. Using completion by fuzzy matching, typos will be
fixed as a series of completion. For instance, input “messaeg” in a
buffer, and then do M-x auto-complete or
M-x ac-fuzzy-complete. The cursor color will be changed to
red if completion has been successful, and then you can continue to
complete, regarding “messaeg” as “message”. It is not a bad idea to bind
auto-complete command to some key to handle such cases.
You can start filtering by C-s(You need to set
ac-use-menu-map to t). The cursor color will
change to blue. Then input characters to filter. It is possible to do
completion by TAB or select candidates, which changes the cursor color
to original so that telling filtering completion candidates has done.
The filtering string will be restored when C-s again. To
delete the filter string, press DEL or C-h.
Other general operations is not allowed there.
It is difficult what key auto-complete command is bound
to. It should be bound to a key which is easy to press as much as
possible because completion operation is often happened. However, it is
a major problem that there is no empty key to press easily.
auto-complete-mode provides a feature called Trigger
Key that handles such the problem. Using trigger key, you can use
an arbitrary key temporarily if necessary. The following code uses
TAB as trigger key.
(ac-set-trigger-key "TAB")Trigger key will be enabled after inserting characters. Otherwise it
is dealt as an usual command (TAB will be indent). Generally, trigger
key is used with ac-auto-start being nil.
(setq ac-auto-start nil)As of ac-auto-start, see Not to complete automatically
or ac-auto-start for more
details.
auto-complete-mode analyzes completion operations one by
one and reduces overheads of completion as much as possible. For
example, having a candidate “foobar” been completed few times,
auto-complete-mode arranges it to top of the candidates
next time and make a situation that allows users to complete the word
with one time TAB or few times TAB. It is called comphist
internally, and you can use it by setting ac-use-comphist
to t. It is enabled by default. Collection operations data
will be stored in user-emacs-directory or
~/.emacs.d/ with a name ac-comphist.dat.
auto-complete-mode collects two types of data to
accomplish accurate candidate suggestion.
Simply saying, it collects not only a completion count but also a
position of completion. A completion candidate will be scored with the
count and the point. If you complete find-file with a word
f few times, in next time find-file will be arranged to top
of candidates. However it is too simple. Actually find-file
with find- will not have the same score, because a distance
between f and find- will reduce a weight of
scoring. It means that if you often complete find-library
after find-, find-library will get high score
than find-file at that position. So
auto-complete-mode can guess find-file will be
top after f and find-library will be top after
find- as it seems to learn from users’ operations.
Dictionary is a simple list of string. There is three types of
dictionary: user defined dictionary, major mode dictionary, and
extension dictionary. You need to add ac-source-dictionary
to ac-sources (default). See Source
for more details.
User defined dictionary is composed of a list of string specified
ac-user-dictionary and dictionary files specified by
ac-user-dictionary-files. Dictionary file is a word list
separated with newline. User defined dictionary is shared with all
buffers. Here is example adding your mail address to dictionary.
(add-to-list 'ac-user-dictionary "foobar@example.com")Setting will be applied immediately. Try to input “foo” in a buffer.
You may see foobar@example.com as a completion candidate.
This setting will be cleared if Emacs will quit. You need to write the
following code to keep setting in next Emacs launching.
(setq ac-user-dictionary '("foobar@example.com" "hogehoge@example.com"))There is more easy way to add word to dictionary. Files specified by
ac-user-dictionary-files will be treated as dictionary
files. By default, ~/.dict will be a dictionary file, so
edit ~/.dict like:
foobar@example.com
hogehoge@example.comAs we said, words are separated with newline. They are not applied
immediately, because auto-complete-mode uses cache not to
load every time from a dictionary file. It may be high cost. To clear
cache, do M-x ac-clear-dictionary-cache. After that,
dictionary files will be load absolutely.
No need to say perhaps, you can use other files as dictionary file by
adding to ac-user-dictionary-files.
You can use other dictionaries for every major-modes and extensions.
A dictionary will loaded from a directory specified with
ac-dictionary-directories.
ac-dictionary-directories may be the following setting if
you followed Installation instructions.
(add-to-list 'ac-dictionary-directories "~/.emacs.d/ac-dict")A dictionary named c++-mode for specific major-mode and
a dictionary named txt for specific extension will be
stored in the directory. For instance, you complete in a buffer named
a.cpp with dictionary completion, following the setting
above, ~/.emacs.d/ac-dict/c++-mode and
~/.emacs.d/ac-dict/cpp will be loaded as dictionary file.
You can edit the dictionary files and make a new one. In addition, you
can add a new dictionary file to a directory that has same
configuration.
As same as user defined dictionary, after editing and adding
dictionary, you should do M-x ac-clear-dictionary-cache to
apply changes.
Source is a concept that ensures the extensibility of
auto-complete-mode. Simply saying, source is a description
of:
Anybody who knows a little Emacs Lisp can define a source easily. See Extend for how to define a source. Here we will explain how to use built-in sources.
Usually a source name starts with ac-source-. So you can
list sources with apropos
(M-x apropos RET ^ac-source-). You may see
ac-source-filename and ac-source-dictionary
which are entities of sources.
If you wrote (ac-config-default) in your
.emacs.d/init.el, it is rare to change a source setting
because it is already optimized to use. Here is a short explanation
about source however. Sources will be used by setting
ac-sources to a list of sources. You can see the setting by
evaluating ac-sources in *scratch* buffer:
;; Formatted
(ac-source-filename
ac-source-functions
ac-source-yasnippet
ac-source-variables
ac-source-symbols
ac-source-features
ac-source-abbrev
ac-source-words-in-same-mode-buffers
ac-source-dictionary)As you see, ac-sources in *scratch* buffer has six
sources. We explain each source for detail, you can guess meanings of
sources. It is worth to remember that ac-sources is a
buffer local variable, which means each ac-sources for
buffers will be different.
Here is an example. Imagine you are at the *scratch* buffer. As we
said, this buffer has many sources. Some people think there are too
many. So try to change ac-sources to reduce functionality.
It is easy to change. Just evaluate the following code in the *scratch*
buffer or with M-::
(setq ac-sources '(ac-source-symbols ac-source-words-in-same-mode-buffers))This example changes ac-source setting and enable only
symbol completion and word completion among same major modes. Then, how
can we enable this setting in next Emacs launching? We can change
settings by adding a hook which is called when *scratch* buffer is
created.
(defun my-ac-emacs-lisp-mode ()
(setq ac-sources '(ac-source-symbols ac-source-words-in-same-mode-buffers)))
(add-hook 'emacs-lisp-mode-hook 'my-ac-emacs-lisp-mode)If the code (ac-config-default) is written in
.emacs.d/init.el, the code above may not work correctly.
This is because (ac-config-default) will overwrite the
setting. In such case, you can redefine a function which is used in
(ac-config-default). The function name is
ac-emacs-lisp-mode-setup in emacs-lisp-mode.
See auto-complete-config.el for more details.
(defun ac-emacs-lisp-mode-setup ()
(setq ac-sources '(ac-source-symbols ac-source-words-in-same-mode-buffers)))So, now you know how to change sources in a specific major mode. Summary is:
ac-sourcesc++-mode-hook, ruby-mode-hook, and
python-mode-hook, etc)By the way, how can we change a setting for all buffers? We use
setq-default to change ac-sources instead of
setq in such case. Then the default value of
ac-sources will be changed to the value you specified.
(setq-default ac-sources '(ac-source-words-in-all-buffer))There are other ways to do that. (ac-config-default)
changes the default value of ac-sources by registering a
hook for auto-complete-mode. The registered function is
ac-common-setup that adds ac-source-filename
to the first of ac-sources by default. So all
auto-complete-mode enabled buffer will have
ac-source-filename at the first of ac-sources.
A reason why adding to the first is relating to Omni Completion. Anyway you don’t care about
it here. So if you want to change ac-sources of all buffer,
you can redefine ac-common-setup function to do that.
;; Add ac-source-dictionary to ac-sources of all buffer
(defun ac-common-setup ()
(setq ac-sources (append ac-sources '(ac-source-dictionary))))Here are defined sources in auto-complete.el and
auto-complete-config.el.
ac-source-abbrevA source for Emacs abbreviation function. See
info emacs Abbrevs about abbreviation function.
ac-source-css-propertyA source for CSS property.
ac-source-dictionaryA source for dictionary. See Completion by Dictionary about dictionary.
ac-source-eclimA source for Emacs-eclim.
ac-source-featuresA source for completing features which are available with
(require '.
ac-source-filenameA source for completing file name. Completion will be started after
inserting /.
ac-source-files-in-current-dirA source for completing files in a current directory. It may be
useful with eshell.
ac-source-functionsA source for completing Emacs Lisp functions. It is available only
after (.
ac-source-ghc-modA source for ghc-mod.
ac-source-gtagsA source for completing tags of Global.
ac-source-imenuA source for completing imenu nodes. See
info emacs imenu for details.
ac-source-semanticA source for Semantic. It can be used for completing member name for C/C++.
ac-source-slimeA source for SLIME.
ac-source-semantic-rawUnlike ac-source-semantic, this source is for completing
symbols in a raw namespace.
ac-source-symbolsA source for completing Emacs Lisp symbols.
ac-source-variablesA source for completing Emacs Lisp symbols.
ac-source-words-in-all-bufferA source for completing words in all buffer. Unlikely ac-source-words-in-same-mode-buffers,
it doesn’t regard major-mode.
ac-source-words-in-bufferA source for completing words in a current buffer.
ac-source-words-in-same-mode-buffersA source for completing words which are collected over buffers whom
major-mode is same to of a current buffer. For example, words will
shared among a.cpp and b.cpp, but not shared
among a.pl and b.cpp because they are
different major-mode buffers. Usually this source is more useful than ac-source-words-in-all-buffer.
ac-source-yasnippetA source for Yasnippet to complete and expand snippets.
If you are being annoyed with displaying completion menu, you can
disable automatic starting completion by setting
ac-auto-start to nil.
(setq ac-auto-start nil)You need to bind some key to auto-complete command
(because you need to complete anyway). For example, bind to
ac-mode-map, which is a key map for
auto-complete-mode enabled buffer:
(define-key ac-mode-map (kbd "M-TAB") 'auto-complete)Or bind to global key map.
(global-set-key "\M-/" 'auto-complete)In addition, if you allow to start completion automatically but also
want to be silent as much as possible, you can do it by setting
ac-auto-start to an prefix length integer. For example, if
you want to start completion automatically when you has inserted 4 or
more characters, just set ac-auto-start to 4:
(setq ac-auto-start 4)Setting ac-auto-start to large number will result in
good for performance. Lesser ac-auto-start, more high cost
to produce completion candidates, because there will be so many
candidates necessarily. If you feel auto-complete-mode is
stalling, change ac-auto-start to a larger number or
nil.
See ac-auto-start for more
details.
And consider to use Trigger Key.
There is another approach to solve the annoying problem is that not
to show completion menu automatically. Not to show completion menu
automatically, set ac-auto-show-menu to
nil.
(setq ac-auto-show-menu nil)When you select or filter candidates, completion menu will be shown.
In other way, you can delay showing completion menu by setting
ac-auto-show-menu to seconds in real number.
;; Show 0.8 second later
(setq ac-auto-show-menu 0.8)This interface has both good points of completely automatic completion and completely non-automatic completion. This may be default in the future.
You can stop completion by pressing C-g. However you
won’t press C-g while defining a macro. In such case, it is
a good idea to bind some key to ac-completing-map.
(define-key ac-completing-map "\M-/" 'ac-stop)Now you can stop completion by pressing M-/.
As we described above, there is many behaviors in TAB. You need to use TAB and RET properly, but there is a simple interface that bind RET to original and TAB to finish completion:
(define-key ac-completing-map "\t" 'ac-complete)
(define-key ac-completing-map "\r" nil)By evaluating the following code, you can select candidates with C-n/C-p, but it might be annoying sometimes.
;; Bad config
(define-key ac-completing-map "\C-n" 'ac-next)
(define-key ac-completing-map "\C-p" 'ac-previous)In this case, it is better that selecting candidates is enabled only
when completion menu is displayed so that the key input will not be
taken as much as possible. ac-menu-map is a keymap for
completion on completion menu which is enabled when
ac-use-menu-map is t.
(setq ac-use-menu-map t)
;; Default settings
(define-key ac-menu-map "\C-n" 'ac-next)
(define-key ac-menu-map "\C-p" 'ac-previous)See ac-use-menu-map and
ac-menu-map for more
details.
A tooltip help that is shown when completing is called quick help. You can disable it if you don’t want to use it:
(setq ac-use-quick-help nil)Set ac-menu-height to number of lines.
;; 20 lines
(setq ac-menu-height 20)auto-complete-mode automatically for specific modesauto-complete-mode won’t be enabled automatically for
modes that are not in ac-modes. So you need to set if
necessary:
(add-to-list 'ac-modes 'brandnew-mode)There is three ways to distinguish upper case and lower case.
;; Just ignore case
(setq ac-ignore-case t)
;; Ignore case if completion target string doesn't include upper characters
(setq ac-ignore-case 'smart)
;; Distinguish case
(setq ac-ignore-case nil)Default is smart.
Set ac-stop-words to words that stops completion
automatically. In ruby, some people want to stop completion
automatically after inserting “end”:
(add-hook 'ruby-mode-hook
(lambda ()
(make-local-variable 'ac-stop-words)
(add-to-list 'ac-stop-words "end")))Note that ac-stop-words is not a buffer local variable,
so you need to make it buffer local with
make-local-variable if it is buffer specific setting.
Colors settings are following:
| Face | Description |
|---|---|
ac-completion-face |
Foreground color of inline completion |
ac-candidate-face |
Color of completion menu |
ac-selection-face |
Selection color of completion menu |
To change face background color, use
set-face-background. To change face foreground color, use
set-face-foreground. To set underline, use
set-face-underline.
;; Examples
(set-face-background 'ac-candidate-face "lightgray")
(set-face-underline 'ac-candidate-face "darkgray")
(set-face-background 'ac-selection-face "steelblue")Read Source first if you don’t familiar with
sources. To change default of sources, use
setq-default:
(setq-default ac-sources '(ac-source-words-in-all-buffer))For example, you may want to use specific sources for C++ buffers. To
do that, register a hook by add-hook and change
ac-sources properly:
(add-hook 'c++-mode (lambda () (add-to-list 'ac-sources 'ac-source-semantic)))You can start completion with specific source. For example, if you
want to complete file name, do M-x ac-complete-filename at
point. Or if you want to complete C/C++ member name, do
M-x ac-complete-semantic at point. Usually, you may bind
them to some key like:
;; Complete member name by C-c . for C++ mode.
(add-hook 'c++-mode-hook
(lambda ()
(local-set-key (kbd "C-c .") 'ac-complete-semantic)))
;; Complete file name by C-c /
(global-set-key (kbd "C-c /") 'ac-complete-filename)Generally, such commands will be automatically available when sources
are defined. Assume that a source named ac-source-foobar is
being defined for example, a command called
ac-complete-foobar will be also defined automatically. See
also Builtin Sources for available
commands.
If you want to use multiple sources for a command, you need to define a command for it like:
(defun semantic-and-gtags-complete ()
(interactive)
(auto-complete '(ac-source-semantic ac-source-gtags)))auto-complete function can take an alternative of
ac-sources.
Use ac-persist-help instead of ac-help,
which is bound to M-<f1> and C-M-?.
ac-last-help command shows a lastly completed candidate
help in a ac-help (buffer help) form. If you give an
argument by C-u or just call
ac-last-persist-help, its help buffer will not disappear
automatically.
ac-last-quick-help command show a lastly completed
candidate help in a ac-quick-help (quick help) form. It is
useful if you want to see a function documentation, for example.
You may bind keys to these command like:
(define-key ac-mode-map (kbd "C-c h") 'ac-last-quick-help)
(define-key ac-mode-map (kbd "C-c H") 'ac-last-help)If pos-tip.el
is installed, auto-complete-mode uses its native rendering
engine for displaying quick help instead of legacy one.
See ac-slime page.
See ENSIME page.
Any configuration item will be set in .emacs.d/init.el
or with M-x customize-group RET auto-complete RET.
ac-delayDelay time to start completion in real number seconds. It is a trade-off of responsiveness and performance.
ac-auto-show-menuShow completion menu automatically if t specified.
t means always automatically showing completion menu.
nil means never showing completion menu. Real number means
delay time in seconds.
ac-show-menu-immediately-on-auto-completeWhether or not to show completion menu immediately on
auto-complete command. If inline completion has already
been showed, this configuration will be ignored.
ac-expand-on-auto-completeWhether or not to expand a common part of whole candidates.
ac-disable-facesSpecify a list of face symbols for disabling auto completion. Auto completion will not be started if a face text property at a point is included in the list.
ac-stop-flymake-on-completingWhether or not to stop Flymake on completion.
ac-use-fuzzyWhether or not to use fuzzy matching.
ac-fuzzy-cursor-colorChange cursor color to specified color when Completion by Fuzzy Matching is
started. nil means never changed. Available colors can be
seen with M-x list-colors-display.
ac-use-comphistWhether or not to use Candidate
Suggestion. nil means never using it and get
performance better maybe.
ac-comphist-thresholdSpecify a percentage of limiting lower scored candidates. 100% for whole scores.
ac-comphist-fileSpecify a file stores data of Candidate Suggestion.
ac-use-quick-helpWhether or not to use quick help.
ac-quick-help-delayDelay time to show quick help in real number seconds.
ac-menu-heightSpecify an integer of lines of completion menu.
ac-quick-help-heightSpecify an integer of lines of quick help.
ac-quick-help-prefer-pos-tipWhether or not auto-complete prefers native tooltip with pos-tip than overlap popup for displaying quick help. If non-nil, you also need to install pos-tip.el so that displaying tooltip can work well.
ac-candidate-limitLimit a number of candidates. Specifying an integer, the value will
be a limit of candidates. nil means no limit.
ac-modesSpecify major modes as a list of symbols that will be enabled
automatically if global-auto-complete-mode is enabled.
ac-compatible-packages-regexpSpecify a regexp that identifies starting completion or not for that package.
ac-non-trigger-commandsSpecify commands as a list of symbols that does NOT starts completion automatically.
ac-trigger-commandsSpecify commands as a list of symbols that starts completion
automatically. self-insert-command is one of default.
ac-trigger-commands-on-completingSame as ac-trigger-commands expect
this will be used on completing.
ac-trigger-keySpecify a Trigger Key.
ac-auto-startSpecify how completion will be started. t means always
starting completion automatically. nil means never started
automatically. An integer means completion will not be started until the
value is more than a length of the completion target string.
ac-stop-wordsSpecify a list of strings that stops completion.
ac-use-dictionary-as-stop-wordsSpecify whether auto-complete uses dictionaries as stop words.
ac-ignore-caseSpecify how distinguish case. t means always ignoring
case. nil means never ignoring case. smart in
symbol means ignoring case only when the completion target string
doesn’t include upper characters.
ac-dwim“Do What I Mean” function. t means:
ac-use-menu-mapSpecify a special keymap (ac-menu-map) should be enabled
when completion menu is displayed. ac-menu-map will be
enabled when it is t and satisfy one of the following
conditions:
ac-auto-start and ac-auto-show-menu are
not nil, and completion menu is displayed after starting
completionauto-complete
commandac-isearch commandac-use-overriding-local-mapUse only when operations is not affected. Internally it uses
overriding-local-map, which is too powerful to use with
keeping orthogonality. So don’t use as much as possible.
ac-completion-faceFace of inline completion.
ac-candidate-faceFace of completion menu background.
ac-selection-faceFace of completion menu selection.
global-auto-complete-modeWhether or not to use auto-complete-mode globally. It is
t in general.
ac-user-dictionarySpecify a dictionary as a list of string for Completion by Dictionary.
ac-user-dictionary-filesSpecify a dictionary files as a list of string for Completion by Dictionary.
ac-dictionary-directoriesSpecify a dictionary directories as a list of string for Completion by Dictionary.
ac-sourcesSpecify sources as a list of Source. This is a buffer local variable.
ac-completing-mapKeymap for completion.
ac-menu-mapKeymap for completion on completion menu. See also ac-use-menu-map.
ac-mode-mapKeymap for auto-complete-mode enabled buffers.
A meaning to extend auto-complete-mode is just defining
a Source. This section describe how to define a
source.
Source basically takes a form of the following:
(defvar ac-source-mysource1
'((prop . value)
...))As you see, source is just an associate list. You can define a source by combining pairs of defined property and its value.
The most important property for source is candidates property. This property
describes how to generate completion candidates by giving a function, an
expression, or a variable. A result of evaluation should be a list of
strings. Here is an example to generate candidates “Foo”, “Bar”, and
“Baz”:
(defvar ac-source-mysource1
'((candidates . (list "Foo" "Bar" "Baz"))))Then add this source to ac-sources and use:
(setq ac-sources '(ac-source-mysource1))It is successful if you have “Bar” and “Baz” by inserting “B”. The
example above has an expression (list ...) in
candidates property. The expression specified there will
not be byte-compiled, so you should not use an expression unless it is
too simple, because it has a bad affection on performance. You should
use a function instead maybe:
(defun mysource1-candidates ()
'("Foo" "Bar" "Baz"))
(defvar ac-source-mysource1
'((candidates . mysource1-candidates)))The function specified in candidates property will be
called without any arguments on every time candidates updated. There is
another way: a variable.
You may want to initialize a source at first time to complete. Use
init property in these cases. As same as
candidates property, specify a function without any
parameters or an expression. Here is an example:
(defvar mysource2-cache nil)
(defun mysource2-init ()
(setq mysource2-cache '("Huge" "Processing" "Is" "Done" "Here")))
(defvar ac-source-mysource2
'((init . mysource2-init)
(candidates . mysource2-cache)))In this example, mysource2-init function does huge
processing, and stores the result into mysource2-cache
variable. Then specifying the variable in candidates
property, this source prevents huge processing on every time update
completions. There are possible usage:
requireCaching strategy is important for auto-complete-mode.
There are two major ways: init property and
cache property that is described in this section.
Specifying cache property in source definition, a result of
evaluation of candidates property will be cached and reused
the result as the result of evaluation of candidates
property next time.
Rewrite the example in previous section by using cache
property.
(defun mysource2-candidates ()
'("Huge" "Processing" "Is" "Done" "Here"))
(defvar ac-source-mysource2
'((candidates . mysource2-candidates)
(cache)))There is no performance problem because this source has
cache property even if candidates property
will do huge processing.
It is possible to keep among more wider scope than init
property and cache property. It may be useful for
remembering all function names which is rarely changed. In these cases,
how can we clear cache property not at the expense of performance? This
is true time use that functionality.
Use ac-clear-variable-after-save to clear cache every
time a buffer saved. Here is an example:
(defvar mysource3-cache nil)
(ac-clear-variable-after-save 'mysource3-cache)
(defun mysource3-candidates ()
(or mysource3-cache
(setq mysource3-cache (list (format "Time %s" (current-time-string))))))
(defvar ac-source-mysource3
'((candidates . mysource3-candidates)))Add this source to ac-sources and complete with “Time”.
You may see a time when completion has been started. After that, you
also see the same time, because mysource3-candidates
returns the cache as much as possible. Then, save the buffer once and
complete with “Time” again. In this time, you may find a new time. An
essence of this source is to use
ac-clear-variable-after-save to manage a variable for
cache.
It is also possible to clear cache periodically. Use
ac-clear-variable-every-minute to do that. A way to use is
same to ac-clear-variable-after-save except its cache will
be cleared every minutes. A builtin source
ac-source-functions uses this functionality.
Completion by RET will evaluate a
function or an expression specified in action property. A
builtin sources ac-source-abbrev and
ac-source-yasnippet use this property.
Omni Completion is a type of completion which regards of a
context of editing. A file name completion which completes with slashed
detected and a member name completion in C/C++ with dots detected are
omni completions. To make a source support for omni completion, use
prefix property. A result of evaluation of
prefix property must be a beginning point of completion
target string. Retuning nil means the source is disabled
within the context.
Consider a source that completes mail addresses only after “To:”. First of all, define a mail address completion source as same as above.
(defvar ac-source-to-mailaddr
'((candidates . (list "foo1@example.com"
"foo2@example.com"
"foo3@example.com"))))
(setq ac-sources '(ac-source-to-mailaddr))Then enable completions only after “To:” by using prefix
property. prefix property must be one of:
Specifying a regexp, auto-complete-mode thinks of a
point of start of group 1 or group 0 as a beginning point of completion
target string by doing re-search-backward1
with the regexp. If you want to do more complicated, use a function or
an expression instead. The beginning point that is evaluated here will
be stored into ac-point. In above
example, regexp is enough.
^To: \(.*\)A reason why capturing group 1 is skipping “To:”. By adding this into the source definition, the source looks like:
(defvar ac-source-to-mailaddr
'((candidates . (list "foo1@example.com"
"foo2@example.com"
"foo3@example.com"))
(prefix . "^To: \\(.*\\)")))Add this source to ac-sources and then type “To:”. You
will be able to complete mail addresses.
ac-define-sourceYou may use an utility macro called ac-define-source
which defines a source and a command.
(ac-define-source mysource3
'((candidates . (list "Foo" "Bar" "Baz"))))This expression will be expanded like:
(defvar ac-source-mysource3
'((candidates . (list "Foo" "Bar" "Baz"))))
(defun ac-complete-mysource3 ()
(interactive)
(auto-complete '(ac-source-mysource3)))A source will be defined as usual and in addition a command that
completes with the source will be defined. Calling
auto-complete without arguments will use
ac-sources as default sources and with arguments will use
the arguments as default sources. Considering compatibility, it is
difficult to answer which you should use defvar and
ac-define-source. Builtin sources are defined with
ac-define-sources, so you can use them alone by binding
some key to these commands such like ac-complete-filename.
See also Completion with
specific source.
initSpecify a function or an expression that is evaluated only once when completion is started.
candidatesSpecify a function, an expression, or a variable to calculate
candidates. Candidates should be a list of string. If cache property is enabled, this
property will be ignored twice or later.
prefixSpecify a regexp, a function, or an expression to find a point of
completion target string for Omni
Completion. This source will be ignored when nil
returned. If a regexp is specified, a start point of group 1 or group 2
will be used as a value.
requiresSpecify a required number of characters of completion target string.
If nothing is specified, auto-complete-mode uses ac-auto-start instead.
actionSpecify a function or an expression that is executed on Completion by RET.
limitSpecify a limit of candidates. It overrides
ac-candidate-limit partially.
symbolSpecify a symbol of candidate meaning in one character string. The symbol will be any character, but you should follow the rule:
| Symbol | Meaning |
|---|---|
s |
Symbol |
f |
Function, Method |
v |
Variable |
c |
Constant |
a |
Abbreviation |
d |
Dictionary |
summarySpecify a summary of candidate in string. It should be used for summarizing the candidate in short string.
cacheUse Cache.
requireSpecify an integer or nil. This source will be ignored
when the integer value is lager than a length of completion target
string. nil means nothing ignored.
candidate-faceSpecify a face of candidate. It overrides ac-candidate-face
partially.
selection-faceSpecify a face of selection. It overrides ac-selection-face
partially.
dependsSpecify a list of features (which are required) that the
source is depending.
availableSpecify a function or an expression that describe the source is available or not.
documentSpecify a function or an expression that returns documentation of the candidate.
Here is a list of often used variables.
ac-bufferA buffer where completion started.
ac-pointA start point of completion target string.
ac-prefixA string of completion target.
ac-limitA limit of candidates. Its value may be one of ac-candidate-limit and limit property.
ac-candidatesA list of candidates.
To keep much responsibility is very important for
auto-complete-mode. However it is well known fact that a
performance is a trade off of functionalities. List up options related
to the performance.
ac-auto-startFor a larger number, it reduces a cost of generating completion
candidates. Or you can remove the cost by setting nil and
you can use when you truly need. See Not to complete automatically
for more details.
ac-delayFor a larger number, it reduces a cost of starting completion.
ac-auto-show-menuFor a larger number, it reduces a displaying cost of completion menu.
ac-use-comphistSetting ac-use-comphist
to nil to disable Candidate
Suggestion, it reduces a cost of suggestion.
ac-candidate-limitFor a property number, it reduces much computation of generating candidates.
There is two major cases.
auto-complete-mode tries to reduce a cost of computation
of columns to show completion menu correctly by using a optimized
function at the expense of accuracy. However, it probably causes a menu
to be disrupted. Not to use the optimized function, evaluate the
following code:
(setq popup-use-optimized-column-computation nil)There is a problem when render IPA font with Xft in Ubuntu 9.10. Use VL gothic, which renders more suitably. Or disable Xft, then it can render correctly.
We don’t good answers now, but you may shot the troubles by changing
font size with set-face-font. For instance, completion menu
may be disrupted when displaying the menu including Japanese in NTEmacs.
In such case, it is worth to try to evaluate the following code to fix
it:
(set-face-font 'ac-candidate-face "MS Gothic 11")
(set-face-font 'ac-selection-face "MS Gothic 11")flyspell-mode enabledA way of delaying processes of flyspell-mode disables
auto completion. You can avoid this problem by
M-x ac-flyspell-workaround. You can write the following
code into your ~/.emacs.d/init.el.
(ac-flyspell-workaround)linum-mode tries
to display the line numbers even for the comletion menulinum-mode tries to add the line numbers even for the comletion menu.
To stop that annoying behavior, do M-x ac-linum-workaround
or add the following code into your ~/.emacs.d/init.el.
(ac-linum-workaround)Visit Auto-Complete Issue Tracker and create a new issue.
Strictly re-search-backward with the added
adding \= at the end↩︎