XEmacs 21.4.9 "Informed Management".

[chise/xemacs-chise.git.1] / lisp / files.el

diff --git a/lisp/files.el b/lisp/files.el
index 8116b07..4d9562d 100644 (file)
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -376,7 +376,8 @@ and ignores this variable."
       (let ((name (copy-sequence filename))
            (start 0))
        ;; leave ':' if part of drive specifier
       (let ((name (copy-sequence filename))
            (start 0))
        ;; leave ':' if part of drive specifier

-       (if (eq (aref name 1) ?:)
+       (if (and (> (length name) 1)
+                (eq (aref name 1) ?:))

            (setq start 2))
        ;; destructively replace invalid filename characters with !
        (while (string-match "[?*:<>|\"\000-\037]" name start)
            (setq start 2))
        ;; destructively replace invalid filename characters with !
        (while (string-match "[?*:<>|\"\000-\037]" name start)

@@ -2641,7 +2642,9 @@ which are the arguments that `revert-buffer' received.")
 (defvar revert-buffer-insert-file-contents-function nil
   "Function to use to insert contents when reverting this buffer.
 Gets two args, first the nominal file name to use,
 (defvar revert-buffer-insert-file-contents-function nil
   "Function to use to insert contents when reverting this buffer.
 Gets two args, first the nominal file name to use,

-and second, t if reading the auto-save file.")
+and second, t if reading the auto-save file.
+If the current buffer contents are to be discarded, the function must do
+so itself.")

 
 (defvar before-revert-hook nil
   "Normal hook for `revert-buffer' to run before reverting.
 
 (defvar before-revert-hook nil
   "Normal hook for `revert-buffer' to run before reverting.

@@ -2666,10 +2669,10 @@ This undoes all changes since the file was visited or saved.
 With a prefix argument, offer to revert from latest auto-save file, if
 that is more recent than the visited file.
 
 With a prefix argument, offer to revert from latest auto-save file, if
 that is more recent than the visited file.
 

-This command also works for special buffers that contain text which
-doesn't come from a file, but reflects some other data base instead:
-for example, Dired buffers and buffer-list buffers.  In these cases,
-it reconstructs the buffer contents from the appropriate data base.
+This command also refreshes certain special buffers that contain text
+which doesn't come from a file, but reflects some other data base
+instead: for example, Dired buffers and buffer-list buffers.  This is
+implemented by having the modes set `revert-buffer-function'.

 
 When called from Lisp, the first argument is IGNORE-AUTO; only offer
 to revert from the auto-save file when this is nil.  Note that the
 
 When called from Lisp, the first argument is IGNORE-AUTO; only offer
 to revert from the auto-save file when this is nil.  Note that the

@@ -2681,13 +2684,17 @@ Optional second argument NOCONFIRM means don't ask for confirmation at
 all.
 
 Optional third argument PRESERVE-MODES non-nil means don't alter
 all.
 
 Optional third argument PRESERVE-MODES non-nil means don't alter

-the files modes.  Normally we reinitialize them using `normal-mode'.
+the buffer's modes.  Otherwise, reinitialize them using `normal-mode'.

 
 If the value of `revert-buffer-function' is non-nil, it is called to
 do all the work for this command.  Otherwise, the hooks
 `before-revert-hook' and `after-revert-hook' are run at the beginning
 and the end, and if `revert-buffer-insert-file-contents-function' is
 
 If the value of `revert-buffer-function' is non-nil, it is called to
 do all the work for this command.  Otherwise, the hooks
 `before-revert-hook' and `after-revert-hook' are run at the beginning
 and the end, and if `revert-buffer-insert-file-contents-function' is

-non-nil, it is called instead of rereading visited file contents."
+non-nil, it is called instead of rereading visited file contents.
+
+If the buffer-modified flag is nil, and we are not reverting from an
+auto-save file, then compare the contents of the buffer and the file.
+Revert only if they differ."

 
   ;; I admit it's odd to reverse the sense of the prefix argument, but
   ;; there is a lot of code out there which assumes that the first
 
   ;; I admit it's odd to reverse the sense of the prefix argument, but
   ;; there is a lot of code out there which assumes that the first

@@ -2699,6 +2706,8 @@ non-nil, it is called instead of rereading visited file contents."
   (if revert-buffer-function
       (funcall revert-buffer-function ignore-auto noconfirm)
     (let* ((opoint (point))
   (if revert-buffer-function
       (funcall revert-buffer-function ignore-auto noconfirm)
     (let* ((opoint (point))

+          (newbuf nil)
+          (delay-prompt nil)

           (auto-save-p (and (not ignore-auto)
                              (recent-auto-save-p)
                             buffer-auto-save-file-name
           (auto-save-p (and (not ignore-auto)
                              (recent-auto-save-p)
                             buffer-auto-save-file-name

@@ -2716,58 +2725,111 @@ non-nil, it is called instead of rereading visited file contents."
                        (dolist (rx revert-without-query found)
                          (when (string-match rx file-name)
                            (setq found t)))))
                        (dolist (rx revert-without-query found)
                          (when (string-match rx file-name)
                            (setq found t)))))

+                ;; If we will call revert-buffer-internal, delay prompting
+                (and (not auto-save-p)
+                     (not (buffer-modified-p))
+                     (setq delay-prompt t))

                 (yes-or-no-p (format "Revert buffer from file %s? "
                                      file-name)))
             (run-hooks 'before-revert-hook)
                 (yes-or-no-p (format "Revert buffer from file %s? "
                                      file-name)))
             (run-hooks 'before-revert-hook)

-            ;; If file was backed up but has changed since,
-            ;; we should make another backup.
-            (and (not auto-save-p)
-                 (not (verify-visited-file-modtime (current-buffer)))
-                 (setq buffer-backed-up nil))
-            ;; Get rid of all undo records for this buffer.
-            (or (eq buffer-undo-list t)
-                (setq buffer-undo-list nil))
-            ;; Effectively copy the after-revert-hook status,
-            ;; since after-find-file will clobber it.
-            (let ((global-hook (default-value 'after-revert-hook))
-                  (local-hook-p (local-variable-p 'after-revert-hook
-                                                  (current-buffer)))
-                  (local-hook (and (local-variable-p 'after-revert-hook
-                                                     (current-buffer))
-                                   after-revert-hook)))
-              (let (buffer-read-only
-                    ;; Don't make undo records for the reversion.
-                    (buffer-undo-list t))
-                (if revert-buffer-insert-file-contents-function
-                    (funcall revert-buffer-insert-file-contents-function
-                             file-name auto-save-p)
-                  (if (not (file-exists-p file-name))
-                      (error "File %s no longer exists!" file-name))
-                  ;; Bind buffer-file-name to nil
-                  ;; so that we don't try to lock the file.
-                  (let ((buffer-file-name nil))
-                    (or auto-save-p
-                        (unlock-buffer)))
-                  (widen)
-                  (insert-file-contents file-name (not auto-save-p)
-                                        nil nil t)))
-              (goto-char (min opoint (point-max)))
-              ;; Recompute the truename in case changes in symlinks
-              ;; have changed the truename.
-              ;XEmacs: already done by insert-file-contents
-              ;;(setq buffer-file-truename
-                    ;;(abbreviate-file-name (file-truename buffer-file-name)))
-              (after-find-file nil nil t t preserve-modes)
-              ;; Run after-revert-hook as it was before we reverted.
-              (setq-default revert-buffer-internal-hook global-hook)
-              (if local-hook-p
-                  (progn
-                    (make-local-variable 'revert-buffer-internal-hook)
-                    (setq revert-buffer-internal-hook local-hook))
-                (kill-local-variable 'revert-buffer-internal-hook))
-              (run-hooks 'revert-buffer-internal-hook))
+            (cond ((or auto-save-p
+                       (buffer-modified-p)
+                       ;; Do we need to do expensive reversion?  Compare ...
+                       (and (setq newbuf (revert-buffer-internal
+                                          file-name))
+                            ;; ... and if different, prompt
+                            (or noconfirm
+                                (and delay-prompt
+                                     (yes-or-no-p 
+                                      (format "Revert buffer from file %s? "
+                                              file-name))))))
+                   ;; If file was backed up but has changed since,
+                   ;; we should make another backup.
+                   (and (not auto-save-p)
+                        (not (verify-visited-file-modtime (current-buffer)))
+                        (setq buffer-backed-up nil))
+                   ;; Get rid of all undo records for this buffer.
+                   (or (eq buffer-undo-list t)
+                       (setq buffer-undo-list nil))
+                   ;; Effectively copy the after-revert-hook status,
+                   ;; since after-find-file will clobber it.
+                   (let ((global-hook (default-value 'after-revert-hook))
+                         (local-hook-p (local-variable-p 'after-revert-hook
+                                                         (current-buffer)))
+                         (local-hook (and (local-variable-p 'after-revert-hook
+                                                            (current-buffer))
+                                          after-revert-hook)))
+                     (let (buffer-read-only
+                           ;; Don't make undo records for the reversion.
+                           (buffer-undo-list t))
+                       (if revert-buffer-insert-file-contents-function
+                           (funcall revert-buffer-insert-file-contents-function
+                                    file-name auto-save-p)
+                         (if (not (file-exists-p file-name))
+                             (error "File %s no longer exists!" file-name))
+                         ;; Bind buffer-file-name to nil
+                         ;; so that we don't try to lock the file.
+                         (let ((buffer-file-name nil))
+                           (or auto-save-p
+                               (unlock-buffer)))
+                         (widen)
+                         (insert-file-contents file-name (not auto-save-p)
+                                               nil nil t)))
+                     (goto-char (min opoint (point-max)))
+                     ;; Recompute the truename in case changes in symlinks
+                     ;; have changed the truename.
+                     ;;XEmacs: already done by insert-file-contents
+                     ;;(setq buffer-file-truename
+                     ;;(abbreviate-file-name (file-truename buffer-file-name)))
+                     (after-find-file nil nil t t preserve-modes)
+                     ;; Run after-revert-hook as it was before we reverted.
+                     (setq-default revert-buffer-internal-hook global-hook)
+                     (if local-hook-p
+                         (progn
+                           (make-local-variable 'revert-buffer-internal-hook)
+                           (setq revert-buffer-internal-hook local-hook))
+                       (kill-local-variable 'revert-buffer-internal-hook))
+                     (run-hooks 'revert-buffer-internal-hook)))
+                  ((null newbuf)
+                   ;; The resultant buffer is identical, alter
+                   ;; modtime, update mods and exit
+                   (set-visited-file-modtime)
+                   (after-find-file nil nil t t t))
+                  (t t))

             t)))))
 
             t)))))
 

+;; #### something like `revert-buffer-compare-with-file' is a better name
+;; #### why is the argument optional?
+(defun revert-buffer-internal (&optional file-name)
+  "Read contents of FILE-NAME into a buffer, and compare to current buffer.
+Return nil if identical, and the new buffer if different."
+
+  (let* ((newbuf (get-buffer-create " *revert*"))
+        bmin bmax)
+    (save-excursion
+      (set-buffer newbuf)
+      (let (buffer-read-only
+           (buffer-undo-list t)
+           after-change-function
+           after-change-functions
+           before-change-function
+           before-change-functions)
+       (if revert-buffer-insert-file-contents-function
+           (funcall revert-buffer-insert-file-contents-function
+                    file-name nil)
+         (if (not (file-exists-p file-name))
+             (error "File %s no longer exists!" file-name))
+         (widen)
+         (insert-file-contents file-name nil nil nil t)
+         (setq bmin (point-min)
+               bmax (point-max)))))
+    (if (not (and (eq bmin (point-min))
+                 (eq bmax (point-max))
+                 (eq (compare-buffer-substrings 
+                      newbuf bmin bmax (current-buffer) bmin bmax) 0)))
+       newbuf
+      (and (kill-buffer newbuf) nil))))
+

 (defun recover-file (file)
   "Visit file FILE, but get contents from its last auto-save file."
   ;; Actually putting the file name in the minibuffer should be used
 (defun recover-file (file)
   "Visit file FILE, but get contents from its last auto-save file."
   ;; Actually putting the file name in the minibuffer should be used