config.phundrak.com/docs/emacs/packages/autocompletion.org

#+title: Emacs — Packages — Autocompletion
#+setupfile: ../../headers
#+property: header-args:emacs-lisp  :mkdirp yes :lexical t :exports code
#+property: header-args:emacs-lisp+ :tangle ~/.config/emacs/lisp/autocompletion.el
#+property: header-args:emacs-lisp+ :mkdirp yes :noweb no-export

* Autocompletion
** Code Autocompletion
Company is, in my opinion, the best autocompleting engine for Emacs,
and it is one of the most popular if not /the/ most popular.
#+begin_src emacs-lisp
(use-package company
  :straight (:build t)
  :defer t
  :hook (company-mode . evil-normalize-keymaps)
  :init (global-company-mode)
  :config
  (setq company-minimum-prefix-length     2
        company-toolsip-limit             14
        company-tooltip-align-annotations t
        company-require-match             'never
        company-global-modes              '(not erc-mode message-mode help-mode gud-mode)
        company-frontends
        '(company-pseudo-tooltip-frontend ; always show candidates in overlay tooltip
          company-echo-metadata-frontend) ; show selected candidate docs in echo area
        company-backends '(company-capf)
        company-auto-commit         nil
        company-auto-complete-chars nil
        company-dabbrev-other-buffers nil
        company-dabbrev-ignore-case nil
        company-dabbrev-downcase    nil))
#+end_src

This package is a backend for company. It emulates
~ac-source-dictionary~ by proposing text related to the current
major-mode.
#+begin_src emacs-lisp
(use-package company-dict
  :after company
  :straight (:build t)
  :config
  (setq company-dict-dir (expand-file-name "dicts" user-emacs-directory)))
#+end_src

On the other hand, ~company-box~ is a Company front-end which offers
colours, icons, documentation and so on. Very nice.

Declaring all the icons for the variable
~company-box-icons-all-the-icons~ is quite verbose in Elisp, so I do it
with an org-table.
#+name: company-box-icons
| Type          | Icon                     | Color  |
|---------------+--------------------------+--------|
| Unknown       | find_in_page             | purple |
| Text          | text_fields              | green  |
| Method        | functions                | red    |
| Function      | functions                | red    |
| Constructor   | functions                | red    |
| Field         | functions                | red    |
| Variable      | adjust                   | blue   |
| Class         | class                    | red    |
| Interface     | settings_input_component | red    |
| Module        | view_module              | red    |
| Property      | settings                 | red    |
| Unit          | straighten               | red    |
| Value         | filter_1                 | red    |
| Enum          | plus_one                 | red    |
| Keyword       | filter_center_focus      | red    |
| Snippet       | short_text               | red    |
| Color         | color_lens               | red    |
| File          | insert_drive_file        | red    |
| Reference     | collections_bookmark     | red    |
| Folder        | folder                   | red    |
| EnumMember    | people                   | red    |
| Constant      | pause_circle_filled      | red    |
| Struct        | streetview               | red    |
| Event         | event                    | red    |
| Operator      | control_point            | red    |
| TypeParameter | class                    | red    |
| Template      | short_text               | green  |
| ElispFunction | functions                | red    |
| ElispVariable | check_circle             | blue   |
| ElispFeature  | stars                    | orange |
| ElispFace     | format_paint             | pink   |

#+name: gen-company-box-icons
#+headers: :tangle no :noweb yes :exports none :cache yes
#+header: :wrap "src emacs-lisp :exports none :tangle no"
#+begin_src emacs-lisp :var table=company-box-icons
(mapconcat (lambda (row)
             (format "(%s . ,(all-the-icons-material \"%s\" :face 'all-the-icons-%s))"
                     (car row)
                     (cadr row)
                     (caddr row)))
           table
           "\n")
#+end_src

#+RESULTS[8ebf4bb3f7f354571a5d42cf58f8b9ba847ba028]: gen-company-box-icons
#+begin_src emacs-lisp :exports none :tangle no
(Unknown . ,(all-the-icons-material "find_in_page" :face 'all-the-icons-purple))
(Text . ,(all-the-icons-material "text_fields" :face 'all-the-icons-green))
(Method . ,(all-the-icons-material "functions" :face 'all-the-icons-red))
(Function . ,(all-the-icons-material "functions" :face 'all-the-icons-red))
(Constructor . ,(all-the-icons-material "functions" :face 'all-the-icons-red))
(Field . ,(all-the-icons-material "functions" :face 'all-the-icons-red))
(Variable . ,(all-the-icons-material "adjust" :face 'all-the-icons-blue))
(Class . ,(all-the-icons-material "class" :face 'all-the-icons-red))
(Interface . ,(all-the-icons-material "settings_input_component" :face 'all-the-icons-red))
(Module . ,(all-the-icons-material "view_module" :face 'all-the-icons-red))
(Property . ,(all-the-icons-material "settings" :face 'all-the-icons-red))
(Unit . ,(all-the-icons-material "straighten" :face 'all-the-icons-red))
(Value . ,(all-the-icons-material "filter_1" :face 'all-the-icons-red))
(Enum . ,(all-the-icons-material "plus_one" :face 'all-the-icons-red))
(Keyword . ,(all-the-icons-material "filter_center_focus" :face 'all-the-icons-red))
(Snippet . ,(all-the-icons-material "short_text" :face 'all-the-icons-red))
(Color . ,(all-the-icons-material "color_lens" :face 'all-the-icons-red))
(File . ,(all-the-icons-material "insert_drive_file" :face 'all-the-icons-red))
(Reference . ,(all-the-icons-material "collections_bookmark" :face 'all-the-icons-red))
(Folder . ,(all-the-icons-material "folder" :face 'all-the-icons-red))
(EnumMember . ,(all-the-icons-material "people" :face 'all-the-icons-red))
(Constant . ,(all-the-icons-material "pause_circle_filled" :face 'all-the-icons-red))
(Struct . ,(all-the-icons-material "streetview" :face 'all-the-icons-red))
(Event . ,(all-the-icons-material "event" :face 'all-the-icons-red))
(Operator . ,(all-the-icons-material "control_point" :face 'all-the-icons-red))
(TypeParameter . ,(all-the-icons-material "class" :face 'all-the-icons-red))
(Template . ,(all-the-icons-material "short_text" :face 'all-the-icons-green))
(ElispFunction . ,(all-the-icons-material "functions" :face 'all-the-icons-red))
(ElispVariable . ,(all-the-icons-material "check_circle" :face 'all-the-icons-blue))
(ElispFeature . ,(all-the-icons-material "stars" :face 'all-the-icons-orange))
(ElispFace . ,(all-the-icons-material "format_paint" :face 'all-the-icons-pink))
#+end_src

#+begin_src emacs-lisp
(use-package company-box
  :straight (:build t)
  :after (company all-the-icons)
  :config
  (setq company-box-show-single-candidate t
        company-box-backends-colors       nil
        company-box-max-candidates        50
        company-box-icons-alist           'company-box-icons-all-the-icons
        company-box-icons-all-the-icons
        (let ((all-the-icons-scale-factor 0.8))
          `(
            <<gen-company-box-icons()>>))))
#+end_src

** Ivy
My main menu package is =ivy= which I use as much as possible –I’ve
noticed =helm= can be slow, very slow in comparison to =ivy=, so I’ll use
the latter as much as possible. Actually, only =ivy= is installed for
now. I could have used =ido= too, but I find it to be a bit too
restricted in terms of features compared to =ivy=.
#+begin_src emacs-lisp
(use-package ivy
  :straight t
  :defer t
  :diminish
  :bind (("C-s" . swiper)
         :map ivy-minibuffer-map
         ("TAB" . ivy-alt-done)
         ("C-l" . ivy-alt-done)
         ("C-t" . ivy-next-line)
         ("C-s" . ivy-previous-line)
         ("C-u" . ivy-scroll-up-command)
         ("C-d" . ivy-scroll-down-command)
         :map ivy-switch-buffer-map
         ("C-t" . ivy-next-line)
         ("C-s" . ivy-previous-line)
         ("C-l" . ivy-done)
         ("C-d" . ivy-switch-buffer-kill)
         :map ivy-reverse-i-search-map
         ("C-t" . ivy-next-line)
         ("C-s" . ivy-previous-line)
         ("C-d" . ivy-reverse-i-search-kill))
  :config
  (ivy-mode 1)
  (setq ivy-wrap                        t
        ivy-height                      17
        ivy-sort-max-size               50000
        ivy-fixed-height-minibuffer     t
        ivy-read-action-functions       #'ivy-hydra-read-action
        ivy-read-action-format-function #'ivy-read-action-format-columns
        projectile-completion-system    'ivy
        ivy-on-del-error-function       #'ignore
        ivy-use-selectable-prompt       t))
#+end_src

There is also [[https://github.com/raxod502/prescient.el][~prescient.el~]] that offers some nice features when
coupled with ~ivy~, guess what was born out of it? ~ivy-prescient~, of
course!
#+begin_src emacs-lisp
(use-package ivy-prescient
  :after ivy
  :straight (:build t))
#+end_src

I warned you I’d use too much ~all-the-icons~, I did!
#+begin_src emacs-lisp
(use-package all-the-icons-ivy
  :straight (:build t)
  :after (ivy all-the-icons)
  :init (all-the-icons-ivy-setup)
  :hook (after-init . all-the-icons-ivy-setup))
(all-the-icons-ivy-setup)
#+end_src

A buffer popping at the bottom of the screen is nice and all, but have
you considered a floating buffer in the centre of your frame?
#+begin_src emacs-lisp
(use-package ivy-posframe
  :defer t
  :after (:any ivy helpful)
  :hook (ivy-mode . ivy-posframe-mode)
  :straight (:build t)
  :init
  (ivy-posframe-mode 1)
  :config
  (setq ivy-fixed-height-minibuffer nil
        ivy-posframe-border-width   10
        ivy-posframe-parameters
        `((min-width  . 90)
          (min-height . ,ivy-height))))
#+end_src

Something that can be missing sometimes in Ivy is the ability to
select multiple entries at once. For instance, when programming in
Java, LPS can offer you to automatically generate the methods ~equals~
and ~hashCode~ based on selected members, but with vanilla Ivy, you can
only select one. Not really useful. ~ivy-hydra~ is a package that offers
a Hydra interface when in Ivy which allows you to select multiple
choices among other things.
#+begin_src emacs-lisp
(use-package ivy-hydra
  :requires (ivy hydra)
  :after ivy
  :straight (:build t))
#+end_src

Finally, let’s make ~ivy~ richer:
#+begin_src emacs-lisp
(use-package ivy-rich
  :straight (:build t)
  :after ivy
  :init
  (ivy-rich-mode 1))
#+end_src

** Counsel
I could almost merge this chapter with the previous one since counsel
is a package that provides loads of completion functions for ivy. The
ones I find most useful are ~counsel-M-x~ and ~counsel-find-file~.
#+begin_src emacs-lisp
(use-package counsel
  :straight t
  :after recentf
  :after ivy
  :bind (("M-x"     . counsel-M-x)
         ("C-x b"   . counsel-ibuffer)
         ("C-x C-f" . counsel-find-file)
         :map minibuffer-local-map
         ("C-r" . 'counsel-minibuffer-history)))
#+end_src

** Yasnippet
Yasnippet allows you to insert some pre-made code by just typing a few
characters. It can even generate some string with Elisp expressions
and ask the user for some input in some precise places.
#+begin_src emacs-lisp
(use-package yasnippet
  :defer t
  :straight (:build t)
  :init
  (yas-global-mode)
  :hook ((prog-mode . yas-minor-mode)
         (text-mode . yas-minor-mode)))
#+end_src

Of course, yasnippet wouldn’t be as awesome as it is without pre-made
snippets.
#+begin_src emacs-lisp
(use-package yasnippet-snippets
  :defer t
  :after yasnippet
  :straight (:build t))
#+end_src

Similarly, yatemplate offers pre-made files rather than just strings.
That’s still yasnippet by the way.
#+begin_src emacs-lisp
(use-package yatemplate
  :defer t
  :after yasnippet
  :straight (:build t))
#+end_src

And finally, with ivy you can choose your snippets from a menu if
you’re not sure or if you don’t remember what your snippet is.
#+begin_src emacs-lisp
(use-package ivy-yasnippet
  :defer t
  :after (ivy yasnippet)
  :straight (:build t)
  :general
  (phundrak/leader-key
    :infix "i"
    :packages 'ivy-yasnippet
    "y" #'ivy-yasnippet))
#+end_src