(diff-unified->context): Use the new `apply' undo entry kind

if applicable, so as to save undo-log space.

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 668cda526f9a3e97cda35f5173cddde05a151cec..dc71e83d69d248749340231a9f42c5ca39e9da16 100644 (file)
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,8 @@
 2007-07-22  Stefan Monnier  <monnier@iro.umontreal.ca>
 
+       * diff-mode.el (diff-unified->context): Use the new `apply' undo entry
+       if applicable, so as to save undo-log space.
+
        * diff-mode.el (diff-find-file-name): Add arg `batch'.
 
        * diff-mode.el (diff-beginning-of-file-and-junk): New function.

diff --git a/lisp/diff-mode.el b/lisp/diff-mode.el
index ecd32f4c33166aee7f8234a89307fc64f4281b1c..3c0208d5b271ae0ca335fd311b241c3a26114776 100644 (file)
--- a/lisp/diff-mode.el
+++ b/lisp/diff-mode.el
@@ -701,7 +701,12 @@ else cover the whole bufer."
            (let ((line1 (match-string 4))
                  (lines1 (match-string 5))
                  (line2 (match-string 6))
-                 (lines2 (match-string 7)))
+                 (lines2 (match-string 7))
+                 ;; Variables to use the special undo function.
+                 (old-undo buffer-undo-list)
+                 (old-end (marker-position end))
+                 (start (match-beginning 0))
+                 (reversible t))
              (replace-match
               (concat "***************\n*** " line1 ","
                       (number-to-string (+ (string-to-number line1)
@@ -743,6 +748,14 @@ else cover the whole bufer."
                  (if (not (save-excursion (re-search-forward "^+" nil t)))
                      (delete-region (point) (point-max))
                    (let ((modif nil) (delete nil))
+                     (if (save-excursion (re-search-forward "^\\+.*\n-" nil t))
+                          ;; Normally, lines in a substitution come with
+                          ;; first the removals and then the additions, and
+                          ;; the context->unified function follows this
+                          ;; convention, of course.  Yet, other alternatives
+                          ;; are valid as well, but they preclude the use of
+                          ;; context->unified as an undo command.
+                         (setq reversible nil))
                      (while (not (eobp))
                        (case (char-after)
                          (?\s (insert " ") (setq modif nil) (backward-char 1))
@@ -761,7 +774,15 @@ else cover the whole bufer."
                          (forward-line 1)
                          (when delete
                            (delete-region last-pt (point))
-                           (setq delete nil)))))))))))))))
+                           (setq delete nil)))))))
+               (unless (or (not reversible) (eq buffer-undo-list t))
+                  ;; Drop the many undo entries and replace them with
+                  ;; a single entry that uses diff-context->unified to do
+                  ;; the work.
+                 (setq buffer-undo-list
+                       (cons (list 'apply (- old-end end) start (point-max)
+                                   'diff-context->unified start (point-max))
+                             old-undo)))))))))))
 
 (defun diff-context->unified (start end &optional to-context)
   "Convert context diffs to unified diffs.