(record_delete): Record pos before the deletion.

(Fprimitive_undo): Go back to recorded position.

1 files changed, 72 insertions, 51 deletions

diff --git a/src/undo.c b/src/undo.c
index 21f24b3c156..b966ab3e79b 100644
--- a/src/undo.c
+++ b/src/undo.c
@@ -89,6 +89,12 @@ record_delete (beg, length)
     XFASTINT (sbeg) = beg;
   XFASTINT (lbeg) = beg;
   XFASTINT (lend) = beg + length;
+
+  /* If point isn't at start of deleted range, record where it is.  */
+  if (PT != sbeg)
+    current_buffer->undo_list
+      = Fcons (make_number (PT), current_buffer->undo_list);
+
   current_buffer->undo_list
     = Fcons (Fcons (Fbuffer_substring (lbeg, lend), sbeg),
              current_buffer->undo_list);
@@ -258,66 +264,81 @@ Return what remains of the list.")
     {
       while (1)
         {
-          Lisp_Object next, car, cdr;
+          Lisp_Object next;
           next = Fcar (list);
           list = Fcdr (list);
+          /* Exit inner loop at undo boundary.  */
           if (NILP (next))
             break;
-          car = Fcar (next);
-          cdr = Fcdr (next);
-          if (EQ (car, Qt))
-            {
-              Lisp_Object high, low;
-              int mod_time;
-              high = Fcar (cdr);
-              low = Fcdr (cdr);
-              mod_time = (high << 16) + low;
-              /* If this records an obsolete save
-                 (not matching the actual disk file)
-                 then don't mark unmodified.  */
-              if (mod_time != current_buffer->modtime)
-                break;
-#ifdef CLASH_DETECTION
-              Funlock_buffer ();
-#endif /* CLASH_DETECTION */
-              Fset_buffer_modified_p (Qnil);
-            }
-          else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int)
-            {
-              Lisp_Object end;
-              if (XINT (car) < BEGV
-                  || XINT (cdr) > ZV)
-                error ("Changes to be undone are outside visible portion of buffer");
-              Fdelete_region (car, cdr);
-              Fgoto_char (car);
-            }
-          else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int)
+          /* Handle an integer by setting point to that value.  */
+          if (XTYPE (next) == Lisp_Int)
+            SET_PT (clip_to_bounds (BEGV, XINT (next), ZV));
+          else if (XTYPE (next) == Lisp_Cons)
             {
-              Lisp_Object membuf;
-              int pos = XINT (cdr);
-              membuf = car;
-              if (pos < 0)
+              Lisp_Object car, cdr;
+
+              car = Fcar (next);
+              cdr = Fcdr (next);
+              if (EQ (car, Qt))
                 {
-                  if (-pos < BEGV || -pos > ZV)
-                    error ("Changes to be undone are outside visible portion of buffer");
-                  SET_PT (-pos);
-                  Finsert (1, &membuf);
+                  /* Element (t high . low) records previous modtime.  */
+                  Lisp_Object high, low;
+                  int mod_time;
+
+                  high = Fcar (cdr);
+                  low = Fcdr (cdr);
+                  mod_time = (high << 16) + low;
+                  /* If this records an obsolete save
+                     (not matching the actual disk file)
+                     then don't mark unmodified.  */
+                  if (mod_time != current_buffer->modtime)
+                    break;
+    #ifdef CLASH_DETECTION
+                  Funlock_buffer ();
+    #endif /* CLASH_DETECTION */
+                  Fset_buffer_modified_p (Qnil);
                 }
-              else
+              else if (XTYPE (car) == Lisp_Int && XTYPE (cdr) == Lisp_Int)
                 {
-                  if (pos < BEGV || pos > ZV)
+                  /* Element (BEG . END) means range was inserted.  */
+                  Lisp_Object end;
+
+                  if (XINT (car) < BEGV
+                      || XINT (cdr) > ZV)
                     error ("Changes to be undone are outside visible portion of buffer");
-                  SET_PT (pos);
-
-                  /* Insert before markers so that if the mark is
-                     currently on the boundary of this deletion, it
-                     ends up on the other side of the now-undeleted
-                     text from point.  Since undo doesn't even keep
-                     track of the mark, this isn't really necessary,
-                     but it may lead to better behavior in certain
-                     situations.  */
-                  Finsert_before_markers (1, &membuf);
-                  SET_PT (pos);
+                  Fdelete_region (car, cdr);
+                  Fgoto_char (car);
+                }
+              else if (XTYPE (car) == Lisp_String && XTYPE (cdr) == Lisp_Int)
+                {
+                  /* Element (STRING . POS) means STRING was deleted.  */
+                  Lisp_Object membuf;
+                  int pos = XINT (cdr);
+
+                  membuf = car;
+                  if (pos < 0)
+                    {
+                      if (-pos < BEGV || -pos > ZV)
+                        error ("Changes to be undone are outside visible portion of buffer");
+                      SET_PT (-pos);
+                      Finsert (1, &membuf);
+                    }
+                  else
+                    {
+                      if (pos < BEGV || pos > ZV)
+                        error ("Changes to be undone are outside visible portion of buffer");
+                      SET_PT (pos);
+
+                      /* Insert before markers so that if the mark is
+                         currently on the boundary of this deletion, it
+                         ends up on the other side of the now-undeleted
+                         text from point.  Since undo doesn't even keep
+                         track of the mark, this isn't really necessary,
+                         but it may lead to better behavior in certain
+                         situations.  */
+                      Finsert_before_markers (1, &membuf);
+                      SET_PT (pos);
+                    }
                 }
             }
         }