+
+(defun whitespace-trailing-regexp (limit)
+ "Match trailing spaces which do not contain the point at end of line."
+ (let ((status t))
+ (while (if (re-search-forward whitespace-trailing-regexp limit t)
+ (save-match-data
+ (= whitespace-point (match-end 1))) ;; loop if point at eol
+ (setq status nil))) ;; end of buffer
+ status))
+
+
+(defun whitespace-empty-at-bob-regexp (limit)
+ "Match spaces at beginning of buffer which do not contain the point at \
+beginning of buffer."
+ (let ((b (point))
+ r)
+ (cond
+ ;; at bob
+ ((= b 1)
+ (setq r (and (/= whitespace-point 1)
+ (looking-at whitespace-empty-at-bob-regexp)))
+ (if r
+ (set-marker whitespace-bob-marker (match-end 1))
+ (set-marker whitespace-bob-marker b)))
+ ;; inside bob empty region
+ ((<= limit whitespace-bob-marker)
+ (setq r (looking-at whitespace-empty-at-bob-regexp))
+ (if r
+ (when (< (match-end 1) limit)
+ (set-marker whitespace-bob-marker (match-end 1)))
+ (set-marker whitespace-bob-marker b)))
+ ;; intersection with end of bob empty region
+ ((<= b whitespace-bob-marker)
+ (setq r (looking-at whitespace-empty-at-bob-regexp))
+ (if r
+ (set-marker whitespace-bob-marker (match-end 1))
+ (set-marker whitespace-bob-marker b)))
+ ;; it is not inside bob empty region
+ (t
+ (setq r nil)))
+ ;; move to end of matching
+ (and r (goto-char (match-end 1)))
+ r))
+
+
+(defsubst whitespace-looking-back (regexp limit)
+ (save-excursion
+ (when (/= 0 (skip-chars-backward " \t\n" limit))
+ (unless (bolp)
+ (forward-line 1))
+ (looking-at regexp))))
+
+
+(defun whitespace-empty-at-eob-regexp (limit)
+ "Match spaces at end of buffer which do not contain the point at end of \
+buffer."
+ (let ((b (point))
+ (e (1+ (buffer-size)))
+ r)
+ (cond
+ ;; at eob
+ ((= limit e)
+ (when (/= whitespace-point e)
+ (goto-char limit)
+ (setq r (whitespace-looking-back whitespace-empty-at-eob-regexp b)))
+ (if r
+ (set-marker whitespace-eob-marker (match-beginning 1))
+ (set-marker whitespace-eob-marker limit)
+ (goto-char b))) ; return back to initial position
+ ;; inside eob empty region
+ ((>= b whitespace-eob-marker)
+ (goto-char limit)
+ (setq r (whitespace-looking-back whitespace-empty-at-eob-regexp b))
+ (if r
+ (when (> (match-beginning 1) b)
+ (set-marker whitespace-eob-marker (match-beginning 1)))
+ (set-marker whitespace-eob-marker limit)
+ (goto-char b))) ; return back to initial position
+ ;; intersection with beginning of eob empty region
+ ((>= limit whitespace-eob-marker)
+ (goto-char limit)
+ (setq r (whitespace-looking-back whitespace-empty-at-eob-regexp b))
+ (if r
+ (set-marker whitespace-eob-marker (match-beginning 1))
+ (set-marker whitespace-eob-marker limit)
+ (goto-char b))) ; return back to initial position
+ ;; it is not inside eob empty region
+ (t
+ (setq r nil)))
+ r))
+
+
+(defun whitespace-buffer-changed (beg end)
+ "Set `whitespace-buffer-changed' variable to t."
+ (setq whitespace-buffer-changed t))
+
+
+(defun whitespace-post-command-hook ()
+ "Save current point into `whitespace-point' variable.
+Also refontify when necessary."
+ (setq whitespace-point (point)) ; current point position
+ (let ((refontify
+ (or
+ ;; it is at end of line ...
+ (and (eolp)
+ ;; ... with trailing SPACE or TAB
+ (or (= (preceding-char) ?\ )
+ (= (preceding-char) ?\t)))
+ ;; it is at beginning of buffer (bob)
+ (= whitespace-point 1)
+ ;; the buffer was modified and ...
+ (and whitespace-buffer-changed
+ (or
+ ;; ... or inside bob whitespace region
+ (<= whitespace-point whitespace-bob-marker)
+ ;; ... or at bob whitespace region border
+ (and (= whitespace-point (1+ whitespace-bob-marker))
+ (= (preceding-char) ?\n))))
+ ;; it is at end of buffer (eob)
+ (= whitespace-point (1+ (buffer-size)))
+ ;; the buffer was modified and ...
+ (and whitespace-buffer-changed
+ (or
+ ;; ... or inside eob whitespace region
+ (>= whitespace-point whitespace-eob-marker)
+ ;; ... or at eob whitespace region border
+ (and (= whitespace-point (1- whitespace-eob-marker))
+ (= (following-char) ?\n)))))))
+ (when (or refontify (> whitespace-font-lock-refontify 0))
+ (setq whitespace-buffer-changed nil)
+ ;; adjust refontify counter
+ (setq whitespace-font-lock-refontify
+ (if refontify
+ 1
+ (1- whitespace-font-lock-refontify)))
+ ;; refontify
+ (jit-lock-refontify))))
+