detect if line has only white space?

detect if line has only white space?

[Miguel Frasson]

Hello.

I would like to have a elisp function that detects if the current line
contains only white space. Some idea? 

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

Many thanks.

Miguel.

-- 
Miguel Vinicius Santini Frasson
http://www.math.leidenuniv.nl/~frasson

Re: detect if line has only white space?

[Phillip Lord]

>>>>> "Miguel" == Miguel Frasson <frasson@enquist.math.leidenuniv.nl> writes:

  Miguel> Hello.

  Miguel> I would like to have a elisp function that detects if the
  Miguel> current line contains only white space. Some idea?

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



(forward-word) will move past the end of the line. 

Or you get check whether a white space only regexp match is the same
length as the entire line. 

Others may have better suggestions.



Cheers

Phil

Re: detect if line has only white space?

[marc0]

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? 

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-x replace-regexp RET [ 	]*$ RET RET

-- 
marc0@autistici.org - 0x4E8899C2

Re: detect if line has only white space?

[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))))


 /\            ___
/___/\__|_|\_|__|___Gian Uberto Lauri_____________________
  //--\ | | \|  |   Integralista GNUslamico e fancazzista 
\/

Re: detect if line has only white space?

[LEE Sau Dan]

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

    marc0> Miguel Frasson on 10 Nov 2003 18:42:56 퍝 writes:
    >> I would like to have a elisp function that detects if the
    >> current line contains only white space. Some idea?

    marc0> matching the current line content with the regexp ^[ ]*$ ?

I've just checked and my Emacs (21.2.1) support the posix class syntax
in regex.  So, the above would be better written as:

        ^[[:space:]]*$


-- 
Lee Sau Dan                     李守敦(Big5)                    ~{@nJX6X~}(HZ) 

E-mail: danlee@informatik.uni-freiburg.de
Home page: http://www.informatik.uni-freiburg.de/~danlee

Re: detect if line has only white space?

[Johan Bockgård]

Miguel Frasson <frasson@enquist.math.leidenuniv.nl> writes:

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

,----[ C-h f delete-trailing-whitespace RET ]
| delete-trailing-whitespace is an interactive compiled Lisp function in `simple'.
| (delete-trailing-whitespace)
| 
| Delete all the trailing whitespace across the current buffer.
| All whitespace after the last non-whitespace character in a line is deleted.
| This respects narrowing, created by C-x n n and friends.
| A formfeed is not considered whitespace by this function.
`----

-- 
Johan Bockgård

Re: detect if line has only white space?

[François Fleuret]

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

delete-trailing-whitespace

Re: detect if line has only white space?

[jan]

Miguel Frasson <frasson@enquist.math.leidenuniv.nl> writes:

> I would like to have a elisp function that detects if the current
> line contains only white space. Some idea?

Probably not the best way to do it, but this is from my utils file

(defun line-empty-p ()
  "Returns non-nil if current line is empty."
  (save-excursion
    (end-of-line)
    (let ((eol (point)))
      (beginning-of-line)
      (not (re-search-forward "[^ \t]" eol t)))))

-- 
jan