highlight-80+.el

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diff --git a/.emacs.d/site-lisp/highlight-80+.el b/.emacs.d/site-lisp/highlight-80+.el
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+;;; highlight-80+.el --- highlight characters beyond column 80
+;;
+;; Copyright (C) 2008 Nikolaj Schumacher
+;;
+;; Author: Nikolaj Schumacher <bugs * nschum de>
+;; Version: 1.0
+;; Keywords: faces
+;; URL: http://nschum.de/src/emacs/highlight-tabs/
+;; Compatibility: GNU Emacs 22.x
+;;
+;; This file is NOT part of GNU Emacs.
+;;
+;; This program is free software; you can redistribute it and/or
+;; modify it under the terms of the GNU General Public License
+;; as published by the Free Software Foundation; either version 2
+;; of the License, or (at your option) any later version.
+;;
+;; This program is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+;;
+;; You should have received a copy of the GNU General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+;;
+;;; Commentary:
+;;
+;; This mode highlights all characters that cross the 80 character line limit.
+;;
+;;; Change Log:
+;;
+;; 2008-08-11 (1.0)
+;;    Initial release.
+;;
+;;; Code:
+
+(defgroup highlight-80+ nil
+  "Highlight characters beyond column 80."
+  :group 'faces)
+
+(defcustom highlight-80+-columns 80
+  "*Number of columns to allow in lines."
+  :group 'highlight-80+
+  :type 'integer)
+
+(defface highlight-80+-line
+  nil
+  "*Face for showing lines with over `highlight-80+-columns'."
+  :group 'highlight-80+-line)
+
+(defface highlight-80+
+  '((((background dark)) (:background "blue"))
+    (((background light)) (:background "dark gray")))
+  "*Face for showing characters beyond column `highlight-80+-columns'."
+  :group 'highlight-80+-line)
+
+(defface highlight-80+-first
+  nil
+  "*Face for showing the first character beyond `highlight-80+-columns'."
+  :group 'highlight-80+-line)
+
+(defconst highlight-80+-keywords
+  `((highlight-80+-matcher (0 'highlight-80+-line prepend)
+                           (1 'highlight-80+ prepend)
+                           (2 'highlight-80+-first prepend))))
+
+(defsubst highlight-80+-format ()
+  (if (< tab-width 2)
+      "^\\(\\)\\([^\n]\\)\\{80,\\}$"
+    (concat (format "^\\(?:[^\t\n]\\{%d\\}\\|[^\t\n]\\{,%d\\}\t\\)\\{%d\\}"
+                    tab-width (- tab-width 1)
+                    (/ highlight-80+-columns tab-width))
+            (let ((remainder (mod highlight-80+-columns tab-width)))
+              (when remainder
+                (format "\\(?:[^\t\n]\\{%d\\}\\|\t\\)" remainder)))
+            "\\(\\(.\\).*\\)$")))
+
+(defvar highlight-80+-last-width 0)
+(make-variable-buffer-local 'highlight-80+-last-width)
+
+(defvar highlight-80+-last-keywords "")
+(make-variable-buffer-local 'highlight-80+-last-keywords)
+
+(defun highlight-80+-matcher (limit)
+  ;; Update search when `tab-width' has changed.
+  (unless (equal highlight-80+-last-width tab-width)
+    (setq highlight-80+-last-keywords (highlight-80+-format)
+          highlight-80+-last-width tab-width)
+    ;; The rest of the buffer can't be right, either.
+    (let ((font-lock-keywords))
+      (font-lock-fontify-buffer)))
+  ;; re-search-forward is C and much faster checking columns ourselves
+  (re-search-forward highlight-80+-last-keywords nil t))
+
+;;;###autoload
+(define-minor-mode highlight-80+-mode
+  "Highlight the portions of lines longer than 80 characters."
+  nil " 80+" nil
+  (if highlight-80+-mode
+      (font-lock-add-keywords nil highlight-80+-keywords t)
+    (font-lock-remove-keywords nil highlight-80+-keywords)
+    (kill-local-variable 'highlight-80+-last-keywords)
+    (kill-local-variable 'highlight-80+-last-width))
+  (font-lock-fontify-buffer))
+
+(provide 'highlight-80+)
+;;; highlight-80+.el ends here