Re: decode-coding-region

[Hrvoje Niksic <hniksic@srce.hr>]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Hrvoje Niksic <hniksic@srce.hr> writes:
> 
> > FYI, decode-coding-region and encode-coding-region also thrash the
> > extents under XEmacs.  If you need a workaround for that, please let
> > me know.
> 
> It would be nice to preserve the extents.

You might want to try something like this until we fix the primitives:

(defmacro gnus-xmas-preserve-extents (&rest body)
  (let ((extents (gensym "extents-")))
    `(let (,extents)
       (map-extents (lambda (extent ignored)
		      (push (list extent
				  (extent-start-position extent)
				  (extent-end-position extent))
			    ,extents)
		      (detach-extent extent)
		      nil)
		    buffer start end)
       ,@body
       (dolist (extent ,extents)
	 (set-extent-endpoints (first extent) (second extent) (third extent))))))

(defun gnus-xmas-decode-coding-region (start end coding-system &optional buffer)
  "Like decode-coding-region, but preserves extents."
  (gnus-xmas-preserve-extents
   (decode-coding-region start end coding-system buffer)))

(defun gnus-xmas-encode-coding-region (start end coding-system &optional buffer)
  "Like encode-coding-region, but preserves extents."
  (gnus-xmas-preserve-extents
   (encode-coding-region start end coding-system buffer)))

However, this will fail to work correctly when the decoding changes
the number of characters, because the extent indices will not be
preserved correctly.

-- 
Hrvoje Niksic <hniksic@srce.hr> | Student at FER Zagreb, Croatia
--------------------------------+--------------------------------
Thou Who might be our Father Who perhaps may be in Heaven...
                                                -- Roger Zelazny