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From: Hrvoje Niksic <hniksic@iskon.hr>
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Subject: [patch] Caesar rotation using translate-region
Date: 06 Dec 1999 15:26:12 +0100
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I noticed that message.el avoids using translate-region for rotating,
in order to preserve text properties.  However, my tests show that, at
least under XEmacs, translate-region preserves the properties.  And
judging by the source, it seems to me that it should preserve them
under FSF Emacs at least as well as the hand-crafted version does.

Doing it with translate-region is much, much, and visibly faster.
Especially for larger regions.

So here is a patch:

1999-12-06  Hrvoje Niksic  <hniksic@iskon.hr>

	* message.el (message-caesar-region): Use translate-region.

--- lisp/message.el.orig	Mon Dec  6 15:21:48 1999
+++ lisp/message.el	Mon Dec  6 15:21:49 1999
@@ -1707,14 +1707,7 @@
 	      (/= (aref message-caesar-translation-table ?a) (+ ?a n)))
 	(setq message-caesar-translation-table
 	      (message-make-caesar-translation-table n)))
-    ;; Then we translate the region.  Do it this way to retain
-    ;; text properties.
-    (while (< b e)
-      (when (< (char-after b) 255)
-	(subst-char-in-region
-	 b (1+ b) (char-after b)
-	 (aref message-caesar-translation-table (char-after b))))
-      (incf b))))
+    (translate-region b e message-caesar-translation-table)))
 
 (defun message-make-caesar-translation-table (n)
   "Create a rot table with offset N."