Emacs Shift-Tab to left shift the block

问题:

How can I get emacs to shift-tab to move the selected text to the left by 4 spaces?

回答1:

This removes 4 spaces from the front of the current line (provided the spaces exist).

(global-set-key (kbd "") '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.

回答2:

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

回答3:

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         (insert "    ") ; else insert four spaces as expected     ))) )  (global-set-key (kbd "") 'untab-region) (global-set-key (kbd "") 'tab-region) 

Edit: Added Maven's code to check if in minibuffer, as well as for tab completion in specific buffers (shell, for example).

回答4:

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 "") 'untab-region) (global-set-key (kbd "") 'tab-region) 

文章来源: Emacs Shift-Tab to left shift the block