X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/7c6317a0498b6690ea668909ac012cb45e6f809b..99fe98d37a39d26f5dea424926d0e0a082655fe5:/lisp/simple.el

diff --git a/lisp/simple.el b/lisp/simple.el
index 37f6d5000e..51c9100d2c 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -602,7 +602,7 @@ buffer if the variable `delete-trailing-lines' is non-nil."
                    (list nil nil))))
   (save-match-data
     (save-excursion
-      (let ((end-marker (copy-marker (or end (point-max)))))
+      (let ((end-marker (and end (copy-marker end))))
         (goto-char (or start (point-min)))
         (with-syntax-table (make-syntax-table (syntax-table))
           ;; Don't delete formfeeds, even if they are considered whitespace.
@@ -611,15 +611,14 @@ buffer if the variable `delete-trailing-lines' is non-nil."
           (modify-syntax-entry ?\n "_")
           (while (re-search-forward "\\s-+$" end-marker t)
             (delete-region (match-beginning 0) (match-end 0))))
-        ;; Delete trailing empty lines.
-        (goto-char end-marker)
-        (when (and (not end)
-		   delete-trailing-lines
-                   ;; Really the end of buffer.
-		   (= (point-max) (1+ (buffer-size)))
-                   (<= (skip-chars-backward "\n") -2))
-          (delete-region (1+ (point)) end-marker))
-        (set-marker end-marker nil))))
+        (if end
+            (set-marker end-marker nil)
+          ;; Delete trailing empty lines.
+          (and delete-trailing-lines
+               ;; Really the end of buffer.
+               (= (goto-char (point-max)) (1+ (buffer-size)))
+               (<= (skip-chars-backward "\n") -2)
+               (delete-region (1+ (point)) (point-max)))))))
   ;; Return nil for the benefit of `write-file-functions'.
   nil)
 
@@ -2959,6 +2958,41 @@ behavior."
   (undo-auto--boundary-ensure-timer))
 ;; End auto-boundary section
 
+(defun undo-amalgamate-change-group (handle)
+  "Amalgamate changes in change-group since HANDLE.
+Remove all undo boundaries between the state of HANDLE and now.
+HANDLE is as returned by `prepare-change-group'."
+  (dolist (elt handle)
+    (with-current-buffer (car elt)
+      (setq elt (cdr elt))
+      (when (consp buffer-undo-list)
+        (let ((old-car (car-safe elt))
+              (old-cdr (cdr-safe elt)))
+          (unwind-protect
+              (progn
+                ;; Temporarily truncate the undo log at ELT.
+                (when (consp elt)
+                  (setcar elt t) (setcdr elt nil))
+                (when
+                    (or (null elt)        ;The undo-log was empty.
+                        ;; `elt' is still in the log: normal case.
+                        (eq elt (last buffer-undo-list))
+                        ;; `elt' is not in the log any more, but that's because
+                        ;; the log is "all new", so we should remove all
+                        ;; boundaries from it.
+                        (not (eq (last buffer-undo-list) (last old-cdr))))
+                  (cl-callf (lambda (x) (delq nil x))
+                      (if (car buffer-undo-list)
+                          buffer-undo-list
+                        ;; Preserve the undo-boundaries at either ends of the
+                        ;; change-groups.
+                        (cdr buffer-undo-list)))))
+            ;; Reset the modified cons cell ELT to its original content.
+            (when (consp elt)
+              (setcar elt old-car)
+              (setcdr elt old-cdr))))))))
+
+
 (defcustom undo-ask-before-discard nil
   "If non-nil ask about discarding undo info for the current command.
 Normally, Emacs discards the undo info for the current command if
@@ -3236,11 +3270,11 @@ Noninteractive callers can specify coding systems by binding
 
 The optional second argument OUTPUT-BUFFER, if non-nil,
 says to put the output in some other buffer.
-If OUTPUT-BUFFER is a buffer or buffer name, put the output there.
-If OUTPUT-BUFFER is not a buffer and not nil,
-insert output in current buffer.  (This cannot be done asynchronously.)
-In either case, the buffer is first erased, and the output is
-inserted after point (leaving mark after it).
+If OUTPUT-BUFFER is a buffer or buffer name, erase that buffer
+and insert the output there.
+If OUTPUT-BUFFER is not a buffer and not nil, insert the output
+in current buffer after point leaving mark after it.
+This cannot be done asynchronously.
 
 If the command terminates without error, but generates output,
 and you did not specify \"insert it in the current buffer\",
@@ -3329,6 +3363,8 @@ the use of a shell (with its need to quote arguments)."
 				     (current-buffer)))))
 	;; Output goes in a separate buffer.
 	;; Preserve the match data in case called from a program.
+        ;; FIXME: It'd be ridiculous for an Elisp function to call
+        ;; shell-command and assume that it won't mess the match-data!
 	(save-match-data
 	  (if (string-match "[ \t]*&[ \t]*\\'" command)
 	      ;; Command ending with ampersand means asynchronous.
@@ -3505,10 +3541,10 @@ Command Output*' is deleted.
 
 Optional fourth arg OUTPUT-BUFFER specifies where to put the
 command's output.  If the value is a buffer or buffer name,
-put the output there.  If the value is nil, use the buffer
-`*Shell Command Output*'.  Any other value, excluding nil,
-means to insert the output in the current buffer.  In either case,
-the output is inserted after point (leaving mark after it).
+erase that buffer and insert the output there.
+If the value is nil, use the buffer `*Shell Command Output*'.
+Any other non-nil value means to insert the output in the
+current buffer after START.
 
 Optional fifth arg REPLACE, if non-nil, means to insert the
 output in place of text from START to END, putting point and mark