emacs/modules/programming.el

;;; programming.el --- Module file for programming configuration.
;;
;; Copyright (C) 2017 Wojciech Kozlowski
;;
;; Author: Wojciech Kozlowski <wojciech.kozlowski@vivaldi.net>
;; Created: 28 Aug 2017
;;
;; This file is not part of GNU Emacs.
;;
;;; Commentary:
;;
;; This module sets up packages and configuration for editing source code in
;; all languages.
;;
;;; License: GPLv3

;;; Required packages:

(setq init-packages/programming-packages

      '(yasnippet)

      )

;; Configuration:

(defun init-packages/init-programming ()

  ;; --------------------------------------------------------------------------
  ;; Enable yasnippet.
  ;; --------------------------------------------------------------------------

  (use-package yasnippet
    :init
    (yas-global-mode 1))

  ;; --------------------------------------------------------------------------
  ;; Line numbers.
  ;;
  ;; Ideally, we could just use linum-format "%4d \u2502".  However, the
  ;; unicode character for the vertical line causes the screen to flicker on
  ;; some screens when typing or moving the cursor. Using `nlinum' does not
  ;; solve the problem.  A compromise is to instead use a whitespace character
  ;; of a different colour.
  ;;
  ;; Furthermore, since `linum' can struggle with large buffers, it is disabled
  ;; once the number of lines cannot fit into linum-format anymore.  `nlinum'
  ;; is meant to solve the problem, but it updates line numbers after a visible
  ;; pause if a line is inderted/deleted.
  ;; --------------------------------------------------------------------------

  (defun linum-format-func (line)
    (concat
     (propertize (format "%4d " line) 'face 'linum)
     (propertize " " 'face 'mode-line-inactive)))

  (setq-default linum-format 'linum-format-func)
  (add-hook 'prog-mode-hook '(lambda ()
                               (unless (> (count-lines (point-min) (point-max))
                                          9999)
                                 (linum-mode))))

  ;; --------------------------------------------------------------------------
  ;; Formatting settings.
  ;; --------------------------------------------------------------------------

  (setq-default c-default-style "linux")

  ;; --------------------------------------------------------------------------
  ;; Trailing whitespace.
  ;; --------------------------------------------------------------------------

  ;; The following setting of `show-trailing-whitespace' is incompatible with
  ;; fci-mode.  The only known workaround is to have whitespace mode on with
  ;; whitespace-style set such that only trailing whitespace is shown.  At the
  ;; moment, just rely on `ws-butler'.

  ;; (add-hook 'prog-mode-hook (lambda ()
  ;;                             (interactive)
  ;;                             (setq show-trailing-whitespace t)))

  ;; --------------------------------------------------------------------------
  ;; Automatically indent yanked text in programming mode.
  ;; --------------------------------------------------------------------------

  (defvar yank-indent-modes
    '(LaTeX-mode TeX-mode)
    "Modes in which to indent regions that are yanked (or yank-popped).
    Only modes that don't derive from `prog-mode' should be
    listed here.")

  (defvar yank-indent-blacklisted-modes
    '(python-mode slim-mode haml-mode)
    "Modes for which auto-indenting is suppressed.")

  (defvar yank-advised-indent-threshold 10000
    "Threshold (# chars) over which indentation does not
    automatically occur.")

  (defun yank-advised-indent-function (beg end)
    "Do indentation, as long as the region isn't too large."
    (if (<= (- end beg) yank-advised-indent-threshold)
        (indent-region beg end nil)))

  (defadvice yank (after yank-indent activate)
    "If current mode is one of 'yank-indent-modes,
    indent yanked text (with prefix arg don't indent)."
    (if (and (not (ad-get-arg 0))
             (not (member major-mode yank-indent-blacklisted-modes))
             (or (derived-mode-p 'prog-mode)
                 (member major-mode yank-indent-modes)))
        (let ((transient-mark-mode nil))
          (yank-advised-indent-function (region-beginning) (region-end)))))

  (defadvice yank-pop (after yank-pop-indent activate)
    "If current mode is one of `yank-indent-modes',
    indent yanked text (with prefix arg don't indent)."
    (when (and (not (ad-get-arg 0))
               (not (member major-mode yank-indent-blacklisted-modes))
               (or (derived-mode-p 'prog-mode)
                   (member major-mode yank-indent-modes)))
      (let ((transient-mark-mode nil))
        (yank-advised-indent-function (region-beginning) (region-end)))))

  )