bug#8463: 24.0.50; [PATCH] Direct Edit in *Occur* Buffer

[Leo]

I have extended the occur feature in Emacs to allow direct editing in
the *Occur* buffer by propagating the changes to the original buffers.

With the attached preliminary patch, one can press `C-x C-q' or `C-c
C-c' to enter occur-edit-mode and start editing. Pressing `C-x C-q' or
`C-c C-c' again finishes the edit.

Comments are highly welcomed. Thanks in advance.

Leo

=== modified file 'lisp/replace.el'
--- lisp/replace.el     2011-04-08 03:05:58 +0000
+++ lisp/replace.el     2011-04-10 08:02:15 +0000
@@ -761,7 +761,8 @@
   (let ((map (make-sparse-keymap)))
     ;; We use this alternative name, so we can use \\[occur-mode-mouse-goto].
     (define-key map [mouse-2] 'occur-mode-mouse-goto)
-    (define-key map "\C-c\C-c" 'occur-mode-goto-occurrence)
+    (define-key map "\C-c\C-c" 'occur-edit-mode)
+    (define-key map "\C-x\C-q" 'occur-edit-mode)
     (define-key map "\C-m" 'occur-mode-goto-occurrence)
     (define-key map "o" 'occur-mode-goto-occurrence-other-window)
     (define-key map "\C-o" 'occur-mode-display-occurrence)
@@ -815,6 +816,18 @@
     map)
   "Keymap for `occur-mode'.")
 
+(defvar occur-edit-mode-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map [mouse-2] 'occur-mode-mouse-goto)
+    (define-key map "\C-c\C-c" 'occur-edit-mode-finish)
+    (define-key map "\C-x\C-q" 'occur-edit-mode-finish)
+    (define-key map "\C-m" 'occur-mode-goto-occurrence)
+    (define-key map "\C-o" 'occur-mode-display-occurrence)
+    (define-key map "\M-n" 'occur-next)
+    (define-key map "\M-p" 'occur-prev)
+    (define-key map "\C-c\C-f" 'next-error-follow-minor-mode)
+    map))
+
 (defvar occur-revert-arguments nil
   "Arguments to pass to `occur-1' to revert an Occur mode buffer.
 See `occur-revert-function'.")
@@ -849,6 +862,59 @@
   (add-hook 'change-major-mode-hook 'font-lock-defontify nil t)
   (setq next-error-function 'occur-next-error))
 
+(defun occur-edit-mode ()
+  (interactive)
+  (setq buffer-read-only nil)
+  (use-local-map occur-edit-mode-map)
+  (setq major-mode 'occur-edit-mode
+       mode-name "Occur-Edit")
+  (add-hook 'after-change-functions 'occur-after-change-function nil t)
+  (force-mode-line-update))
+
+(defvar occur-edit-modified-buffers nil)
+(make-variable-buffer-local 'occur-edit-modified-buffers)
+
+(defun occur-edit-mode-finish ()
+  (interactive)
+  (mapc (lambda (buf)
+         (and (buffer-file-name buf)
+              (with-current-buffer buf
+                (save-buffer))))
+       occur-edit-modified-buffers)
+  (setq buffer-read-only t)
+  (kill-local-variable 'occur-edit-modified-buffers)
+  (remove-hook 'after-change-functions 'occur-after-change-function t)
+  (set-buffer-modified-p nil)
+  (use-local-map occur-mode-map)
+  (setq major-mode 'occur-mode
+       mode-name "Occur"))
+
+(defun occur-after-change-function (beg end length)
+  (let* ((m (get-text-property (point) 'occur-target))
+        (buf (marker-buffer m))
+        (col (current-column)))
+    (when (and (markerp m) (buffer-live-p buf))
+      (let ((line (- (line-number-at-pos)
+                    (line-number-at-pos (window-start))))
+           (readonly (with-current-buffer buf buffer-read-only))
+           (win (or (get-buffer-window buf)
+                    (display-buffer buf t)))
+           (text (save-excursion
+                   (forward-line 0)
+                   (search-forward ":" nil t)
+                   (setq col (- col (current-column)))
+                   (buffer-substring-no-properties (point) 
(line-end-position)))))
+       (and (not readonly)
+            (add-to-list 'occur-edit-modified-buffers buf))
+       (with-selected-window win
+         (goto-char m)
+         (recenter line)
+         (if readonly
+             (message "Buffer `%s' is read only." buf)
+           (delete-region (line-beginning-position) (line-end-position))
+           (insert text))
+         (move-to-column col))))))
+
 (defun occur-revert-function (ignore1 ignore2)
   "Handle `revert-buffer' for Occur mode buffers."
   (apply 'occur-1 (append occur-revert-arguments (list (buffer-name)))))
@@ -1273,6 +1339,7 @@
                                      `(font-lock-face prefix-face))
                                    `(occur-prefix t mouse-face (highlight)
                                                   occur-target ,marker 
follow-link t
+                                                  read-only t
                                                   help-echo "mouse-2: go to 
this occurrence"))))
                           (match-str
                            ;; We don't put `mouse-face' on the newline,
@@ -1333,13 +1400,15 @@
                (goto-char headerpt)
                (let ((beg (point))
                      end)
-                 (insert (format "%d match%s%s in buffer: %s\n"
-                                 matches (if (= matches 1) "" "es")
-                                 ;; Don't display regexp for multi-buffer.
-                                 (if (> (length buffers) 1)
-                                     "" (format " for \"%s\""
-                                                (query-replace-descr regexp)))
-                                 (buffer-name buf)))
+                 (insert (propertize
+                          (format "%d match%s%s in buffer: %s\n"
+                                  matches (if (= matches 1) "" "es")
+                                  ;; Don't display regexp for multi-buffer.
+                                  (if (> (length buffers) 1)
+                                      "" (format " for \"%s\""
+                                                 (query-replace-descr regexp)))
+                                  (buffer-name buf))
+                          'read-only t))
                  (setq end (point))
                  (add-text-properties beg end
                                       (append