[PATCH] delete-trailing-whitespace on active region

[Deniz Dogan <deniz.a.m.dogan@gmail.com>]

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I have found myself in need of deleting trailing whitespace only in a
specific region from time to time.  Therefore, I wrote this patch
which changes the behavior of the command to act only on the region if
it is active.

So before I commit this, I'd like to check it with you guys.

Is this new behavior okay?  If so, is this patch okay?

--
Deniz Dogan

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=== modified file 'lisp/simple.el'
--- lisp/simple.el	2011-02-01 21:22:21 +0000
+++ lisp/simple.el	2011-02-09 18:15:31 +0000
@@ -614,22 +614,25 @@
     (if (looking-at "^[ \t]*\n\\'")
 	(delete-region (point) (point-max)))))
 
-(defun delete-trailing-whitespace ()
+(defun delete-trailing-whitespace (&optional start end)
   "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 \\[narrow-to-region] and friends.
-A formfeed is not considered whitespace by this function."
-  (interactive "*")
+A formfeed is not considered whitespace by this function.
+If the region is active, only delete whitespace within the region."
+  (interactive "*r")
   (save-match-data
     (save-excursion
-      (goto-char (point-min))
-      (while (re-search-forward "\\s-$" nil t)
-	(skip-syntax-backward "-" (save-excursion (forward-line 0) (point)))
-	;; Don't delete formfeeds, even if they are considered whitespace.
-	(save-match-data
-	  (if (looking-at ".*\f")
-	      (goto-char (match-end 0))))
-	(delete-region (point) (match-end 0))))))
+      (let ((start (or (and (region-active-p) start) (point-min)))
+            (end (or (and (region-active-p) end) (point-max))))
+        (goto-char start)
+        (while (re-search-forward "\\s-$" end t)
+          (skip-syntax-backward "-" (save-excursion (forward-line 0) (point)))
+          ;; Don't delete formfeeds, even if they are considered whitespace.
+          (save-match-data
+            (if (looking-at ".*\f")
+                (goto-char (match-end 0))))
+          (delete-region (point) (match-end 0)))))))
 
 (defun newline-and-indent ()
   "Insert a newline, then indent according to major mode.