Display-line-number.el (displaying row numbers in Emacs)

; Display-line-number.el --- line number mode for Emacs

; Copyright (c) 2004 Free Software Foundation, Inc.

; Author: chunye Wang
; Keywords: Tools

; This file is free software; you can redistribute it and/or modify
; It under the terms of the GNU General Public License as published
; 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
; Merchantability or fitness for a special purpose. See
; GNU General Public License for more details.

; You shoshould have written ed a copy of the GNU General Public License
; Along with GNU Emacs; see the file copying. If not, write
; The Free Software Foundation, inc., 59 temple place-Suite 330,
; Boston, MA 02111-1307, USA.

; Commentary:

; Installation:

; Put the display-line-number.el in your load-Path
; (Require 'display-line-number)
; M-X Display-line-number-Mode
; M-X Display-line-number-mode-on
; M-X Display-line-number-mode-off
; Code:

(Defvar display-line-number-mode Nil
"Non-nil if display-line-number-mode is active in the current buffer .")
(Make-variable-buffer-local 'display-line-number-mode)

(Defvar display-line-number-face 'font-lock-keyword-face)

(Defvar global-display-line-number-mode Nil
"Non-nil if display-line-number-mode is active in the all buffer .")

(Defvar display-line-number-format "% 5d"
"String suitable for 'format' that will generate a line number string.
'Format' will be called with this string and one other argument
Which will be an integer, the line number .")

(Defun display-line-number-mode (& optional Arg)
"Toggle display-line-number-mode.
With prefix argument, turn display-line-number-mode on If argument is positive.
When display-line-number-mode is enabled, a line number will appear at the left
Margin of each line ."
(Interactive "p ")
(If (null Arg) (setq Arg 0)
(Setq Arg (prefix-Numeric-value Arg )))
(Cond
(> Arg 0) (setq display-line-number-mode t ))
(= Arg 0) (setq display-line-number-Mode
(Not display-line-number-mode )))
(<Arg 0) (setq display-line-number-mode nil )))
(If display-line-number-Mode
(Display-line-number-mode-on)
(Display-line-number-mode-off )))

(Defun global-display-line-number-mode (& optional Arg)
"Toggle display-line-number-mode.
With prefix argument, turn display-line-number-mode on If argument is positive.
When display-line-number-mode is enabled, a line number will appear at the left
Margin of each line ."
(Interactive "p ")
(If (null Arg) (setq Arg 0)
(Setq Arg (prefix-Numeric-value Arg )))
(Cond
(> Arg 0) (setq global-display-line-number-mode t ))
(= Arg 0) (setq global-display-line-number-Mode
(Not global-display-line-number-mode )))
(<Arg 0) (setq global-display-line-number-mode nil )))
(If global-display-line-number-Mode
(Add-hook 'Find-file-hooks
'Display-line-number-mode-on)
(Remove-hook 'Find-file-hooks
'Display-line-number-mode-on ))
(Message "Global display line number mode is % s" (if global-display-line-number-mode "on" "off ")))

; (Global-display-line-number-mode (if global-display-line-number-mode 1 0 ))

(Defun display-line-number-mode-on ()
(Interactive)
(Setq display-line-number-mode t)
(DLN-undisplay)
(DLN-display)
(Make-local-variable 'after-change-functions)
(Make-local-variable 'window-scroll-functions)
(Make-local-variable 'window-configuration-change-hook)
(Add-to-list 'after-change-Functions
'Dln-after-change-function)
(Add-to-list 'window-configuration-change-hook
'Dln-window-configuration-change-function)
(Add-to-list 'window-scroll-Functions
'Dln-window-scroll-function ))

(Defun display-line-number-mode-off ()
(Interactive)
(DLN-undisplay)
(Setq after-change-functions (remq
'Dln-after-change-Function
After-change-Functions ))
(Setq window-configuration-change-hook (remq
'Dln-window-configuration-change-Function
Window-configuration-change-hook ))
(Setq window-scroll-functions (remq
'Dln-window-scroll-Function
Window-scroll-Functions )))

(Defun DLN-core (start end Str)
(Let (E (make-overlay start end )))
(Overlay-put e 'before-string (propertize STR 'face display-line-number-face ))
(Overlay-put e 'name' DLN-core )))

(Defun DLN-Display (& optional Arg)
(Interactive "p ")
; (Setq left-margin-width 5)
; (Set-window-margins (selected-window) 5 0)
(Let (line-number 1)
(START (window-start (selected-window )))
(End (window-end (selected-window) T ))
(N 0)
(Flag 0 ))
(Save-excursion
(Save-Restriction
(Widen)
(Goto-Char start)
(Beginning-of-line)
(Setq N (count-lines 1 (point )))
(While (= Flag 0)
(Setq N (1 + n ))
(DLN-core (line-beginning-position)
(Line-end-position)
(Format display-line-number-format n
))
(Forward-line 1)
(If (or (> = (point) end)
(> = (Point) (point-max ))
(Not (equal (point) (line-beginning-position ))))
(Setq flag 1 )))))))

(Defun DLN-undisplay ()
(Interactive)
(Save-excursion
(Save-Restriction
(Widen)
(Let (ES (overlays-in 1 (1 + (point-max )))))
(Mapc (lambda (E)
(If (eq (overlay-Get e'name) 'dln-core)
(Delete-overlay E )))
Es )))))

(Defun DLN-after-change-function (& optional start end length)
(DLN-undisplay)
(DLN-display ))

(Defun DLN-window-scroll-function (& optional win POS)
(DLN-undisplay)
(DLN-display ))

(Defun DLN-window-configuration-change-function (& optional win POS)
(DLN-undisplay)
(DLN-display ))

(Provide 'display-line-number)
; Display-line-number.el ends here