Re: detect if line has only white space?

[GianUberto.Lauri@eng.it (Gian Uberto Lauri)]

>>>>> "m" == marc0  <marc0@autistici.org> writes:

m> Miguel Frasson on 10 Nov 2003 18:42:56 +0100 writes:
>> I would like to have a elisp function that detects if the current line
>> contains only white space. Some idea? 

m> matching the current line content with the regexp ^[ 	]*$   ?

>> Aditionally, I would like to remove all space at the end of the
>> lines at once (e-lisp code). How?

m> M-x replace-regexp RET [ 	]*$ RET RET

;; I have this little piece of code in my .emacs (i think it comes from this list!):

(defun remove-trailing-blanks (&optional ask)
  "Removes useless blanks from a buffer.
Removes trailing spaces and tabs from every line in the current buffer,
and trailing newlines from the end of the buffer, apart from one.
If ASK is non-nil, ask for confirmation."
  (if (and (not (zerop (buffer-size)))
	   (char-equal (char-after (buffer-size)) ?
)
	   (save-excursion
	     (save-restriction
	       (save-match-data
		 (widen)
		 (goto-char 0)
		 (or (search-forward "
" nil t)
		     (search-forward "
" nil t)
		     (re-search-forward "

\`" nil t)))))
	   (if ask
	       (y-or-n-p "Remove trailing spaces and newlines before saving? ")
	     (message "Removing trailing spaces and newlines...")
	     t))
      (save-excursion
	(save-restriction
	  (save-match-data
	    (widen)
	    (goto-char 0)
	    (while (re-search-forward "[ 	]+$" nil `move)
	      (replace-match ""))
	    (if (bolp)
		(progn
		  (skip-chars-backward "
")
		  (delete-region (1+ (point)) (point-max))))
	    )))))

;; that can be hooked to several modes:
;;; Remove trailing blanks and newlines before saving a text buffer.
(add-hook 'text-mode-hook 'install-remove-trailing-blanks-ask)

(add-hook 'emacs-lisp-mode-hook 'install-remove-trailing-blanks)
(add-hook 'c-mode-hook 'install-remove-trailing-blanks)
(add-hook 'c++-mode-hook 'install-remove-trailing-blanks)
(add-hook 'octave-mode-hook 'install-remove-trailing-blanks)
(add-hook 'jde-mode-hook 'install-remove-trailing-blanks)

(defun install-remove-trailing-blanks ()
  (add-hook 'write-contents-hooks 'remove-trailing-blanks))
(defun install-remove-trailing-blanks-ask ()
  (add-hook 'write-contents-hooks '(lambda () (remove-trailing-blanks t))))


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