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|
;;; company-tng.el --- company-mode configuration for single-button interaction
;; Copyright (C) 2017 Free Software Foundation, Inc.
;; Author: Nikita Leshenko
;; This file is part of GNU Emacs.
;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; company-tng (Tab and Go) allows you to perform completion using just TAB.
;; Pressing it will both select the next completion candidate in the list and
;; insert it into the buffer (or make it look like it's inserted, in fact).
;;
;; It cycles the candidates like `yank-pop' or `dabbrev-expand' or Vim:
;; Pressing TAB selects the first item in the completion menu and inserts it in
;; the buffer. Pressing TAB again selects the second item and replaces the
;; "inserted" item with the second one. This can continue as long as the user
;; wishes to cycle through the menu. You can also press S-TAB to select the
;; previous candidate, of course.
;;
;; The benefits are that you only have to use one shortcut key and there is no
;; need to confirm the entry.
;;
;; Usage:
;;
;; To apply the default configuration for company-tng call
;; `company-tng-configure-default' from your init script.
;;
;; You can also configure company-tng manually:
;;
;; Add `company-tng-frontend' to `company-frontends':
;;
;; (add-to-list 'company-frontends 'company-tng-frontend)
;;
;; We recommend to bind TAB to `company-select-next', S-TAB to
;; `company-select-previous', and unbind RET and other now-unnecessary
;; keys from `company-active-map':
;;
;; (define-key company-active-map (kbd "TAB") 'company-select-next)
;; (define-key company-active-map (kbd "<backtab>") 'company-select-previous)
;; (define-key company-active-map (kbd "RET") nil)
;;
;; Note that it's not necessary to rebind keys to use this frontend,
;; you can use the arrow keys or M-n/M-p to select and insert
;; candidates. You also need to decide which keys to unbind, depending
;; on whether you want them to do the Company action or the default
;; Emacs action (for example C-s or C-w).
;;
;; We recommend to disable `company-require-match' to allow free typing at any
;; point.
;;; Code:
(require 'company)
(require 'cl-lib)
(defvar-local company-tng--overlay nil)
;;;###autoload
(defun company-tng-frontend (command)
"When the user changes the selection at least once, this
frontend will display the candidate in the buffer as if it's
already there and any key outside of `company-active-map' will
confirm the selection and finish the completion."
(cl-case command
(show
(let ((ov (make-overlay (point) (point))))
(setq company-tng--overlay ov)
(overlay-put ov 'priority 2))
(advice-add 'company-select-next :before-until 'company-tng--allow-unselected)
(advice-add 'company-fill-propertize :filter-args 'company-tng--adjust-tooltip-highlight))
(update
(let ((ov company-tng--overlay)
(selected (nth company-selection company-candidates))
(prefix (length company-prefix)))
(move-overlay ov (- (point) prefix) (point))
(overlay-put ov
(if (= prefix 0) 'after-string 'display)
(and company-selection-changed selected))))
(hide
(when company-tng--overlay
(delete-overlay company-tng--overlay)
(kill-local-variable 'company-tng--overlay))
(advice-remove 'company-select-next 'company-tng--allow-unselected)
(advice-remove 'company-fill-propertize 'company-tng--adjust-tooltip-highlight))
(pre-command
(when (and company-selection-changed
(not (company--company-command-p (this-command-keys))))
(company--unread-this-command-keys)
(setq this-command 'company-complete-selection)
(advice-add 'company-call-backend :before-until 'company-tng--supress-post-completion)))))
;;;###autoload
(defun company-tng-configure-default ()
"Applies the default configuration to enable company-tng."
(setq company-require-match nil)
(setq company-frontends '(company-tng-frontend
company-pseudo-tooltip-frontend
company-echo-metadata-frontend))
(let ((keymap company-active-map))
(define-key keymap [return] nil)
(define-key keymap (kbd "RET") nil)
(define-key keymap [tab] 'company-select-next)
(define-key keymap (kbd "TAB") 'company-select-next)
(define-key keymap [backtab] 'company-select-previous)
(define-key keymap (kbd "S-TAB") 'company-select-previous)))
(defun company-tng--allow-unselected (&optional arg)
"Advice `company-select-next' to allow for an 'unselected'
state. Unselected means that no user interaction took place on the
completion candidates and it's marked by setting
`company-selection-changed' to nil. This advice will call the underlying
`company-select-next' unless we need to transition to or from an unselected
state.
Possible state transitions:
- (arg > 0) unselected -> first candidate selected
- (arg < 0) first candidate selected -> unselected
- (arg < 0 wrap-round) unselected -> last candidate selected
- (arg < 0 no wrap-round) unselected -> unselected
There is no need to advice `company-select-previous' because it calls
`company-select-next' internally."
(cond
;; Selecting next
((or (not arg) (> arg 0))
(unless company-selection-changed
(company-set-selection (1- (or arg 1)) 'force-update)
t))
;; Selecting previous
((< arg 0)
(when (and company-selection-changed
(< (+ company-selection arg) 0))
(company-set-selection 0)
(setq company-selection-changed nil)
(company-call-frontends 'update)
t)
)))
(defun company-tng--adjust-tooltip-highlight (args)
"Prevent the tooltip from highlighting the current selection if it wasn't
made explicitly (i.e. `company-selection-changed' is true)"
(unless company-selection-changed
;; The 4th arg of `company-fill-propertize' is selected
(setf (nth 3 args) nil))
args)
(defun company-tng--supress-post-completion (command &rest args)
"Installed as a :before-until advice on `company-call-backend' and
prevents the 'post-completion command from being delivered to the backend
for the next iteration. post-completion do things like expand snippets
which are undesirable because completions are implicit in company-tng and
visible side-effects after the completion are surprising."
(when (eq command 'post-completion)
(advice-remove 'company-call-backend 'company-tng--supress-post-completion)
t))
(provide 'company-tng)
;;; company-tng.el ends here
|
