(decode-coding-inserted-region):

Set buffer-undo-list in a correct and optimal way.

1 files changed, 28 insertions, 5 deletions

diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index bec20a66df5..144bd0360ca 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -1878,13 +1878,27 @@ or a function symbol which, when called, returns such a cons cell."
 (defun decode-coding-inserted-region (from to filename
                                            &optional visit beg end replace)
   "Decode the region between FROM and TO as if it is read from file FILENAME.
+The idea is that the text between FROM and TO was just inserted somehow.
 Optional arguments VISIT, BEG, END, and REPLACE are the same as those
-of the function `insert-file-contents'."
+of the function `insert-file-contents'.
+Part of the job of this function is setting `buffer-undo-list' appropriately."
   (save-excursion
     (save-restriction
-      (narrow-to-region from to)
-      (goto-char (point-min))
-      (let ((coding coding-system-for-read))
+      (let ((coding coding-system-for-read)
+            undo-list-saved)
+        (if visit
+            ;; Temporarily turn off undo recording, if we're decoding the
+            ;; text of a visited file.
+            (setq buffer-undo-list t)
+          ;; Otherwise, if we can recognize the undo elt for the insertion,
+          ;; remove it and get ready to replace it later.
+          ;; In the mean time, turn off undo recording.
+          (let ((last (car buffer-undo-list))) 
+            (if (and (consp last) (eql (car last) from) (eql (cdr last) to))
+                (setq undo-list-saved (cdr buffer-undo-list)
+                      buffer-undo-list t))))
+        (narrow-to-region from to)
+        (goto-char (point-min))
         (or coding
             (setq coding (funcall set-auto-coding-function
                                   filename (- (point-max) (point-min)))))
@@ -1899,7 +1913,16 @@ of the function `insert-file-contents'."
           (setq coding nil))
         (if coding
             (decode-coding-region (point-min) (point-max) coding)
-          (setq last-coding-system-used coding))))))
+          (setq last-coding-system-used coding))
+        ;; If we're decoding the text of a visited file,
+        ;; the undo list should start out empty.
+        (if visit
+            (setq buffer-undo-list nil)
+          ;; If we decided to replace the undo entry for the insertion,
+          ;; do so now.
+          (if undo-list-saved
+              (setq buffer-undo-list
+                    (cons (cons from (point-max)) undo-list-saved))))))))
 
 (defun make-translation-table (&rest args)
   "Make a translation table from arguments.