+(eval-when-compile (require 'cl))
+
+(defcustom fill-flowed-display-column 'fill-column
+ "Column beyond which format=flowed lines are wrapped, when displayed.
+This can be a Lisp expression or an integer."
+ :version "22.1"
+ :group 'mime-display
+ :type '(choice (const :tag "Standard `fill-column'" fill-column)
+ (const :tag "Fit Window" (- (window-width) 5))
+ (sexp)
+ (integer)))
+
+(defcustom fill-flowed-encode-column 66
+ "Column beyond which format=flowed lines are wrapped, in outgoing messages.
+This can be a Lisp expression or an integer.
+RFC 2646 suggests 66 characters for readability."
+ :version "22.1"
+ :group 'mime-display
+ :type '(choice (const :tag "Standard fill-column" fill-column)
+ (const :tag "RFC 2646 default (66)" 66)
+ (sexp)
+ (integer)))
+
+;;;###autoload
+(defun fill-flowed-encode (&optional buffer)
+ (with-current-buffer (or buffer (current-buffer))
+ ;; No point in doing this unless hard newlines is used.
+ (when use-hard-newlines
+ (let ((start (point-min)) end)
+ ;; Go through each paragraph, filling it and adding SPC
+ ;; as the last character on each line.
+ (while (setq end (text-property-any start (point-max) 'hard 't))
+ (save-restriction
+ (narrow-to-region start end)
+ (let ((fill-column (eval fill-flowed-encode-column)))
+ (fill-flowed-fill-buffer))
+ (goto-char (point-min))
+ (while (re-search-forward "\n" nil t)
+ (replace-match " \n" t t))
+ (goto-char (setq start (1+ (point-max)))))))
+ t)))
+
+(defun fill-flowed-fill-buffer ()
+ (let ((prefix nil)
+ (prev-prefix nil)
+ (start (point-min)))
+ (goto-char (point-min))
+ (while (not (eobp))
+ (setq prefix (and (looking-at "[> ]+")
+ (match-string 0)))
+ (if (equal prefix prev-prefix)
+ (forward-line 1)
+ (save-restriction
+ (narrow-to-region start (point))
+ (let ((fill-prefix prev-prefix))
+ (fill-region (point-min) (point-max) t 'nosqueeze 'to-eop))
+ (goto-char (point-max)))
+ (setq prev-prefix prefix
+ start (point))))
+ (save-restriction
+ (narrow-to-region start (point))
+ (let ((fill-prefix prev-prefix))
+ (fill-region (point-min) (point-max) t 'nosqueeze 'to-eop)))))
+
+;;;###autoload
+(defun fill-flowed (&optional buffer delete-space)
+ (with-current-buffer (or (current-buffer) buffer)
+ (goto-char (point-min))
+ ;; Remove space stuffing.
+ (while (re-search-forward "^\\( \\|>+ $\\)" nil t)
+ (delete-char -1)
+ (forward-line 1))