Re: buffer-substring-filter

[Chong Yidong]

> In that case, could you make those two little changes, and then
> would someone please install it?

Here is the revised patch.


*** emacs/lisp/simple.el~       Thu Mar 17 06:46:12 2005
--- emacs/lisp/simple.el        Thu Mar 17 06:52:25 2005
***************
*** 2215,2220 ****
--- 2215,2256 ----
    (reset-this-command-lengths)
    (restore-overriding-map))
  
+ (defvar buffer-substring-filters nil
+   "List of filter functions for `filter-buffer-substring'.
+ Each function must accept a single argument, a string, and return
+ a string.  The buffer substring is passed to the first function
+ in the list, and the return value of each function is passed to
+ the next.  The return value of the last function is used as the
+ return value of `filter-buffer-substring'.
+
+ If this variable is nil, no filtering is performed.")
+
+ (defun filter-buffer-substring (beg end &optional delete)
+   "Return the buffer substring between BEG and END, after filtering.
+ The buffer substring is passed through each of the filter
+ functions in `buffer-substring-filters', and the value from the
+ last filter function is returned.  If `buffer-substring-filters'
+ is nil, the buffer substring is returned unaltered.
+
+ If DELETE is non-nil, the text between BEG and END is deleted
+ from the buffer.
+
+ Point is temporarily set to BEG before caling
+ `buffer-substring-filters', in case the functions need to know
+ where the text came from.
+
+ This function should be used instead of `buffer-substring' or
+ `delete-and-extract-region' when you want to allow filtering to
+ take place.  For example, major or minor modes can use
+ `buffer-substring-filters' to extract characters that are special
+ to a buffer, and should not be copied into other buffers."
+   (save-excursion
+     (goto-char beg)
+     (let ((string (if delete (delete-and-extract-region beg end)
+                     (buffer-substring beg end))))
+       (dolist (filter buffer-substring-filters string)
+         (setq string (funcall filter string))))))
+
  ;;;; Window system cut and paste hooks.

  (defvar interprogram-cut-function nil
***************
*** 2391,2397 ****
  text.  See `insert-for-yank'."
    (interactive "r")
    (condition-case nil
!       (let ((string (delete-and-extract-region beg end)))
        (when string                    ;STRING is nil if BEG = END
          ;; Add that string to the kill ring, one way or another.
          (if (eq last-command 'kill-region)
--- 2427,2433 ----
  text.  See `insert-for-yank'."
    (interactive "r")
    (condition-case nil
!       (let ((string (filter-buffer-substring beg end t)))
        (when string                    ;STRING is nil if BEG = END
          ;; Add that string to the kill ring, one way or another.
          (if (eq last-command 'kill-region)
***************
*** 2427,2434 ****
  system cut and paste."
    (interactive "r")
    (if (eq last-command 'kill-region)
!       (kill-append (buffer-substring beg end) (< end beg))
!     (kill-new (buffer-substring beg end)))
    (if transient-mark-mode
        (setq deactivate-mark t))
    nil)
--- 2463,2470 ----
  system cut and paste."
    (interactive "r")
    (if (eq last-command 'kill-region)
!       (kill-append (filter-buffer-substring beg end) (< end beg))
!     (kill-new (filter-buffer-substring beg end)))
    (if transient-mark-mode
        (setq deactivate-mark t))
    nil)