Does anyone have an Emacs macro for indenting (and unindenting) blocks of text?

Question

Does anyone have an Emacs macro to indent (and unindenting) blocks of text?

And I mean "indentation" in the common sense, not in Emacspeak. In other words, I want to mark the area, press Cu 2, run this macro and add two spaces before each line in the region.

Or press Cu -2 before running the macro and remove two spaces from the beginning of each line in the region. Bonus points if he complains if the lines do not have enough spaces.

Answer 1

indent-rigidly (associated with Cx TAB) does what you want. This is in indent.el, which should be part of the standard emacs distribution.

Also, so that it complains / interrupts when there is not enough space somewhere, you can do something like this: (quick ugly cracking of source code with indentation)

(defun enough-whitespace-to-indent-p (start end arg) (save-excursion (goto-char end) (setq end (point-marker)) (goto-char start) (or (bolp) (forward-line 1)) (while (and (< (point) end) (>= (+ (current-indentation) arg) 0)) (forward-line 1)) (>= (point) end))) (defun indent-rigidly-and-be-picky (start end arg) (interactive "r\np") (if (or (plusp arg) (enough-whitespace-to-indent-p start end arg)) (indent-rigidly start end arg) (message "Not enough whitespace to unindent!"))) 

Answer 2

You can also use the world of rectangles . To insert two spaces:

 Cx rt SPC SPC RET 

Delete two spaces

 Cx rd 

provided that you define a rectangle to cover two spaces. Also, in addition to editing rectangles, a nice addition has also been added to the CUA package. The CUA package does not only cover rectangles, so if you just want a part of the rectangle, look at this description (full disclosure, link to my blog).

Answer 3

Use indent-rigidly default Cx TAB by default