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Auto-completion layer

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1 Description

This layer provides auto-completion to Spacemacs.

The following completion engines are supported:

Snippets are supported via yasnippet and auto-yasnippet.

This layer also configures hippie-expand.

2 Install

To use this configuration layer, add it to your ~/.spacemacs. You will need to add auto-completion to the existing dotspacemacs-configuration-layers list in this file.

3 Configuration

3.1 Key bindings

You can customize the user experience of auto-completion with the following layer variables:

  1. auto-completion-return-key-behavior set the action to perform when the RET key is pressed, the possible values are:
    • complete completes with the current selection
    • nil does nothing
  2. auto-completion-tab-key-behavior set the action to perform when the TAB key is pressed, the possible values are:
    • complete completes with the current selection
    • cycle completes the common prefix and cycle between candidates
    • nil does nothing
  3. auto-completion-complete-with-key-sequence is a string of two characters denoting a key sequence that will perform a complete action if the sequence as been entered quickly enough. If its value is nil then the feature is disabled.
  4. auto-completion-complete-with-key-sequence-delay is the number of seconds to wait for the auto-completion key sequence to be entered. The default value is 0.1 seconds.

The default configuration of the layer is:

(setq-default dotspacemacs-configuration-layers '(
  (auto-completion :variables
                   auto-completion-return-key-behavior 'complete
                   auto-completion-tab-key-behavior 'cycle
                   auto-completion-complete-with-key-sequence nil
                   auto-completion-complete-with-key-sequence-delay 0.1
                   auto-completion-private-snippets-directory nil)

jk is a good candidate for auto-completion-complete-with-key-sequence if you don't use it already.

3.2 Snippets directories

The following directories are added by default:

  • ~/.emacs.d/elpa/yasnippet-xxxxx/snippets
  • ~/.emacs.d/layers/auto-completion/snippets
  • ~/.emacs.d/private/snippets (conditional to the value of auto-completion-private-snippets-directory)
  • ~/.spacemacs.d/snippets (conditional to the existence of ~/.spacemacs.d directory)

You can provide additional directories by setting the variable auto-completion-private-snippets-directory which can take a string in case of a single path or a list of paths. If its value is nil then the path ~/.emacs.d/private/snippets is used.

3.3 Show snippets in auto-completion popup

By default, snippets are not shown in the auto-completion popup. To show them in the popup, set the variable auto-completion-enable-snippets-in-popup to t.

(setq-default dotspacemacs-configuration-layers
              '((auto-completion :variables
                                 auto-completion-enable-snippets-in-popup t)))

3.4 Tooltips

To enable automatic docstring tooltips set auto-completion-enable-help-tooltip to t.

(setq-default dotspacemacs-configuration-layers
  '((auto-completion :variables
                    auto-completion-enable-help-tooltip t)))

To enable manual non-automatic invocation of docstring tooltips, set it to manual. The tooltip can be invoked manually by pressing M-h.

(setq-default dotspacemacs-configuration-layers
  '((auto-completion :variables
                    auto-completion-enable-help-tooltip 'manual)))

3.5 Sort results by usage

To enable sorting auto-completion results by their usage frequency set auto-completion-enable-sort-by-usage to t. This feature is provided by the company-statistics package when company is used. The variable has no effect when auto-complete is used.

(setq-default dotspacemacs-configuration-layers
  '((auto-completion :variables
                    auto-completion-enable-sort-by-usage t)))

3.6 Enable company or auto-complete globally

By default Spacemacs enables auto-completion explicitly for each supported major-mode, it means that company and auto-complete are not enabled globally, it allows more flexibility to choose an auto-completion engine for a given mode.

You may want to enable company globally to get auto-completion everywhere even in the modes which are not configured by Spacemacs. To do so, you just have to add (global-company-mode) in the dotspacemacs/user -config function of your dotfile.

Note that if you want to enable auto-complete globally you will have to disable company first, see the next section to do so.

3.7 Replacing company by auto-complete

You can disable company by adding it to the dotspacemacs-excluded-packages variable, then you are free to enable auto-complete globally.

3.8 Add auto-completion in a layer

Here is an example to add company auto-completion to python buffer:

3.8.1 In config.el

;; Define the buffer local company backend variable
(spacemacs|defvar-company-backends python-mode)

3.8.2 In packages.el

;; Add the relevant packages to the layer
(setq python-packages
    (company-anaconda :toggle (configuration-layer/package-usedp 'company))

;; Hook company to python-mode
(defun python/post-init-company ()
  (spacemacs|add-company-hook python-mode))

;; Add the backend to the major-mode specific backend list
(defun python/init-company-anaconda ()
  (use-package company-anaconda
    :defer t
    :init (push 'company-anaconda company-backends-python-mode)))

3.9 Completion back ends

Many spacemacs layers (e.g., python, html, haskell) configure company mode backends to provide mode-specific completion. These modes will include completion backends specified in the `spacemacs-default-company-backends` variable. The defaults should work well, but you can configure this variable in your .spacemacs file with (e.g.)

 '((auto-completion :variables
                    spacemacs-default-company-backends '(company-files company-capf))))

3.10 Improved faces

For nicer-looking faces, try adding the following to `custom-set-faces` in your dotspacemacs file.

   ((t (:inherit company-tooltip :weight bold :underline nil))))
   ((t (:inherit company-tooltip-selection :weight bold :underline nil)))))

4 Key Bindings

4.1 Company

Key Binding Description
C-d open minibuffer with documentation of thing at point in company dropdown
C-/ show candidates in Helm (for fuzzy searching)
C-M-/ filter the company dropdown menu
M-h show current candidate's documentation in a tooltip (requires auto-completion-enable-help-tooltip)

Vim Style:

Key Binding Description
C-j (vim style) go down in company dropdown menu
C-k (vim style) go up in company dropdown menu
C-l (vim style) complete selection

Emacs style:

Key Binding Description
C-f (emacs style) complete selection
C-n (emacs style) go down in company dropdown menu
C-p (emacs style) go up in company dropdown menu

4.2 Auto-complete

Key Binding Description
C-j select next candidate
C-k select previous candidate
TAB expand selection or select next candidate
S-TAB select previous candidate
return complete word, if word is already completed insert a carriage return

4.3 Yasnippet

Key Binding Description
M-/ Expand a snippet if text before point is a prefix of a snippet
SPC i s List all current yasnippets for inserting

4.4 Auto-yasnippet

Key Binding Description
SPC i S c create a snippet from an active region
SPC i S e Expand the snippet just created with SPC i y
SPC i S w Write the snippet inside private/snippets directory for future sessions

Author: Sylvain Benner

Created: 2016-10-03 Mon 00:56