How can I get Emacs to ShiftTab t开发者_StackOverflow社区o move the selected text to the left by 4 spaces?
To do that, I use the command indent-rigidly
, bound to C-x TAB
. Give it the argument -4 to move the selected region to the left by four spaces: C-u -4 C-x TAB
.
http://www.gnu.org/s/emacs/manual/html_node/elisp/Region-Indent.html
This removes 4 spaces from the front of the current line (provided the spaces exist).
(global-set-key (kbd "<S-tab>") 'un-indent-by-removing-4-spaces)
(defun un-indent-by-removing-4-spaces ()
"remove 4 spaces from beginning of of line"
(interactive)
(save-excursion
(save-match-data
(beginning-of-line)
;; get rid of tabs at beginning of line
(when (looking-at "^\\s-+")
(untabify (match-beginning 0) (match-end 0)))
(when (looking-at "^ ")
(replace-match "")))))
If your variable tab-width
happens to be 4 (and that's what you want to "undo"), then you can replace the (looking-at "^ ")
with something more general like (concat "^" (make-string tab-width ?\ ))
.
Also, the code will convert the tabs at the front of the line to spaces using untabify.
I made some functions for tabbing a region over by four spaces left or right depending on if you use tab or shift+tab:
(defun indent-region-custom(numSpaces)
(progn
; default to start and end of current line
(setq regionStart (line-beginning-position))
(setq regionEnd (line-end-position))
; if there's a selection, use that instead of the current line
(when (use-region-p)
(setq regionStart (region-beginning))
(setq regionEnd (region-end))
)
(save-excursion ; restore the position afterwards
(goto-char regionStart) ; go to the start of region
(setq start (line-beginning-position)) ; save the start of the line
(goto-char regionEnd) ; go to the end of region
(setq end (line-end-position)) ; save the end of the line
(indent-rigidly start end numSpaces) ; indent between start and end
(setq deactivate-mark nil) ; restore the selected region
)
)
)
(defun untab-region (N)
(interactive "p")
(indent-region-custom -4)
)
(defun tab-region (N)
(interactive "p")
(if (active-minibuffer-window)
(minibuffer-complete) ; tab is pressed in minibuffer window -> do completion
; else
(if (string= (buffer-name) "*shell*")
(comint-dynamic-complete) ; in a shell, use tab completion
; else
(if (use-region-p) ; tab is pressed is any other buffer -> execute with space insertion
(indent-region-custom 4) ; region was selected, call indent-region-custom
(insert " ") ; else insert four spaces as expected
)))
)
(global-set-key (kbd "<backtab>") 'untab-region)
(global-set-key (kbd "<tab>") 'tab-region)
Edit: Added Maven's code to check if in minibuffer, as well as for tab completion in specific buffers (shell, for example).
I have improved upon Stanley Bak's answer. For me, this global key binding was messing up minibuffer completion.
So I have included a case for minibuffer as well.
Edit : Renaming indent-region
-> indent-region-custom
.
indent-region
is clashing with existing command and gives error for indent on save (hook for before save) and some other key combinations.
(defun indent-region-custom(numSpaces)
(progn
;; default to start and end of current line
(setq regionStart (line-beginning-position))
(setq regionEnd (line-end-position))
;; if there's a selection, use that instead of the current line
(when (use-region-p)
(setq regionStart (region-beginning))
(setq regionEnd (region-end))
)
(save-excursion ; restore the position afterwards
(goto-char regionStart) ; go to the start of region
(setq start (line-beginning-position)) ; save the start of the line
(goto-char regionEnd) ; go to the end of region
(setq end (line-end-position)) ; save the end of the line
(indent-rigidly start end numSpaces) ; indent between start and end
(setq deactivate-mark nil) ; restore the selected region
)
)
)
(defun untab-region (N)
(interactive "p")
(indent-region-custom -4)
)
(defun tab-region (N)
(interactive "p")
(if (active-minibuffer-window)
(minibuffer-complete) ; tab is pressed in minibuffer window -> do completion
(if (use-region-p) ; tab is pressed is any other buffer -> execute with space insertion
(indent-region-custom 4) ; region was selected, call indent-region-custom
(insert " ") ; else insert four spaces as expected
)
)
)
(global-set-key (kbd "<backtab>") 'untab-region)
(global-set-key (kbd "<tab>") 'tab-region)
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