stupid-indent-mode.el

;;; stupid-indent-mode.el --- Plain stupid indentation minor mode

;; Copyright (C) 2013  Mihai Bazon

;; Author: Mihai Bazon <[email protected]>
;; Keywords:

;; This program 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.

;; This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; Dumb indentation mode is appropriate for editing buffers that Emacs
;; does not fully understand syntactically, such as HTML/PHP
;; (typically involving multiple languages with different indentation
;; rules in the same buffer).  The default indentation level is 2
;; (customize `stupid-indent-level').
;;
;; Key bindings:
;;
;; TAB       -- indent current line by the value of `stupid-indent-level'
;; S-TAB     -- outdent current line
;; C-c TAB   -- indent region
;; C-c S-TAB -- outdent region
;; RET       -- newline and indent
;; C-c C-TAB -- indent according to mode

;;; Code:

(defcustom stupid-indent-level 2
  "Indentation level for stupid-indent-mode")

(defun %stupid-force-indent-line ()
  (let (col)
    (save-excursion
     (back-to-indentation)
     (setq col (+ (current-column) stupid-indent-level))
     (indent-line-to col))
    (when (< (current-column) col)
      (back-to-indentation))))

(defun stupid-indent-line ()
  (interactive)
  (let ((bt (save-excursion
             (back-to-indentation)
             (current-column))))
    (cond
      ((< (current-column) bt)
       (back-to-indentation))
      ((looking-at "\\s-*\n")
       (let ((col (save-excursion
                   (previous-line)
                   (back-to-indentation)
                   (current-column))))
         (if (< (current-column) col)
             (indent-line-to col)
             (%stupid-force-indent-line))))
      (t
       (%stupid-force-indent-line)))))

(defun stupid-outdent-line ()
  (interactive)
  (let (col)
    (save-excursion
     (back-to-indentation)
     (setq col (- (current-column) stupid-indent-level))
     (when (>= col 0)
       (indent-line-to col)))))

(defun stupid-indent-region (start stop)
  (interactive "r")
  (setq stop (copy-marker stop))
  (goto-char start)
  (while (< (point) stop)
    (unless (and (bolp) (eolp))
      (%stupid-force-indent-line))
    (forward-line 1)))

(defun stupid-outdent-region (start stop)
  (interactive "r")
  (setq stop (copy-marker stop))
  (goto-char start)
  (while (< (point) stop)
    (unless (and (bolp) (eolp))
      (stupid-outdent-line))
    (forward-line 1)))

(defun stupid-indent ()
  (interactive)
  (if (use-region-p)
      (save-excursion
       (stupid-indent-region (region-beginning) (region-end))
       (setq deactivate-mark nil))
      (stupid-indent-line)))

(defun stupid-outdent ()
  (interactive)
  (if (use-region-p)
      (save-excursion
       (stupid-outdent-region (region-beginning) (region-end))
       (setq deactivate-mark nil))
      (stupid-outdent-line)))

(defun stupid-indent-newline ()
  (interactive)
  (when (< (point)
           (save-excursion
            (back-to-indentation)
            (point)))
    (back-to-indentation))
  (let ((col (save-excursion
              (back-to-indentation)
              (current-column))))
    (newline)
    (indent-to-column col)))

(define-minor-mode stupid-indent-mode
  "Stupid indent mode is just plain stupid."
  :init-value nil
  :lighter "/SI"
  :global nil
  :keymap `(
            (,(kbd "<tab>") . stupid-indent)
            (,(kbd "<backtab>") . stupid-outdent)
            (,(kbd "C-c <tab>") . stupid-indent-region)
            (,(kbd "C-c <backtab>") . stupid-outdent-region)
            (,(kbd "<return>") . stupid-indent-newline)
            (,(kbd "C-c C-<tab>") . indent-according-to-mode)
            )
  (when stupid-indent-mode
    (add-hook 'write-contents-functions
              'delete-trailing-whitespace)))

(provide 'stupid-indent-mode)
;;; stupid-indent-mode.el ends here

Updated so that if the caret is within indentation (whitespace before first non-whitespace character) then stupid-indent-line will just do a beginning-of-line-text, which seems to be what I'd expect most of the time (i.e. assume the line is already correctly indented).

Minor update: RET while the cursor is on some line within the indentation (before position of beginning-of-line-text) will not increase indentation as it used to do. Feels the right thing here.

Also, I should probably move it into a repository.. will do that the next time I update it.

I've tried this plugin and it works great, thanks!
The only minor issue I'm having is when I open a file and try to indent for the first time I get message:
The mark is not set now, so there is no region and indent fails.
The message disappears when I select and deselect something and try indenting again.

Please tag releases so that this appears in MELPA Stable.

Thanks!

It seems, its broken. Dont work on Emacs 24.5.1 on windows.

Edit: Nevermind, i need to put (require 'stupid-indent-mode) in my .emacs-file.

For terminal users, keybindings TAB and RET instead of <tab> and <return> are required.