;;; dispret.el --- show end of line mode.

;; Copyright (C) 2002 by Taiki SUGAWARA <taiki.s@cityfujisawa.ne.jp>

;; Author: Taiki SUGAWARA <taiki.s@cityfujisawa.ne.jp>
;; Keywords: faces, editing

;; This file 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, or (at your option)
;; any later version.

;; This file 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 GNU Emacs; see the file COPYING.  If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Comments
;; 改行を表示してみるモード

;;; Todo
;; vline.el と共存できるようにしたい。

;;; Code:

(defvar dispret-overlay-table-size 200)
(defvar dispret-overlay-table (make-vector dispret-overlay-table-size nil))
(defvar dispret-eol-string "<")
(defvar dispret-eof-string "[EOF]")

(defvar dispret-mode nil)

(defun dispret-clear ()
  (mapcar (lambda (ovr)
	    (and ovr (delete-overlay ovr)))
	  dispret-overlay-table))
(defun dispret-show ()
  (let ((current (point))
	(i 0))
    (save-excursion
      (goto-char (window-start))
      (catch 'loop
	(while (and (< i (1- (window-height)))
		    (< i (length dispret-overlay-table)))
	  (end-of-line)
	  ;; カーソルがあったらそこは無視する
	  (unless (= (point) current)
	    (let ((ovr (aref dispret-overlay-table i)))
	      ;; overlay がなかったら準備する
	      (unless ovr
		(setq ovr (make-overlay 0 0))
		(overlay-put ovr 'rear-nonsticky t)
		(aset dispret-overlay-table i ovr))

	      (move-overlay ovr (point) (1+ (point)))
	      (overlay-put ovr 'before-string 
			   (if (eobp) 
			       dispret-eof-string
			     dispret-eol-string))))
	  (when (eobp)
	    (throw 'loop nil))
	  (setq i (1+ i))
	  (forward-line))))))

(defun dispret-on ()
  (interactive)
  (setq dispret-mode t)
  (make-local-hook 'post-command-hook)
  (make-local-hook 'pre-command-hook)
  (add-hook 'post-command-hook 'dispret-show nil t)
  (add-hook 'pre-command-hook 'dispret-clear nil t))

(defun dispret-off ()
  (interactive)
  (setq dispret-mode nil)
  (dispret-clear)
  (remove-hook 'post-command-hook 'dispret-show t)
  (remove-hook 'pre-command-hook 'dispret-clear t))

(add-to-list 'minor-mode-alist '(dispret-mode " DispRet"))

(provide 'dispret)

;;; dispret.el ends here