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[emacs.git] / lisp / master.el
blob115823e3087a6b86a384f5b4b393f391bc966aa5
1 ;;; master.el --- make a buffer the master over another buffer
3 ;; Copyright (C) 1999, 2000, 2001 Alexander Schroeder
5 ;; Author: Alex Schroeder <alex@gnu.org>
6 ;; Maintainer: Alex Schroeder <alex@gnu.org>
7 ;; Version: 1.0.2
8 ;; Keywords: comm
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software; you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation; either version 2, or (at your option)
15 ;; any later version.
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs; see the file COPYING. If not, write to the
24 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
25 ;; Boston, MA 02111-1307, USA.
27 ;;; Commentary:
29 ;; master-mode is a minor mode which enables you to scroll another
30 ;; buffer (the slave) without leaving your current buffer (the master).
32 ;; It can be used by sql.el, for example: The SQL buffer is the master
33 ;; and its SQLi buffer is the slave. This allows you to scroll the SQLi
34 ;; buffer containing the output from the SQL buffer containing the
35 ;; commands.
37 ;; This is how to use sql.el and master.el together: The variable
38 ;; sql-buffer contains the slave buffer. It is a local variable in the
39 ;; SQL buffer.
41 ;; (add-hook 'sql-mode-hook
42 ;; (function (lambda ()
43 ;; (master-mode t)
44 ;; (master-set-slave sql-buffer))))
45 ;; (add-hook 'sql-set-sqli-hook
46 ;; (function (lambda ()
47 ;; (master-set-slave sql-buffer))))
49 ;;; Thanks to all the people who helped me out:
51 ;; Rob Riepel <networking.stanford.edu>
53 ;;; History:
54 ;;
56 ;;; Code:
58 (require 'easy-mmode)
60 ;; Variables that don't need initialization.
62 (defvar master-of nil
63 "Slave buffer of the current buffer. See `master-mode'.
64 You can set this variable using `master-set-slave'.")
66 (defvar master-set-slave-hook nil
67 "Hook run after the slave is changed using \\[master-set-slave].")
69 ;;; Define master mode.
71 ;;;###autoload
72 (define-minor-mode master-mode
73 "Toggle Master mode.
74 With no argument, this command toggles the mode.
75 Non-null prefix argument turns on the mode.
76 Null prefix argument turns off the mode.
78 When Master mode is enabled, you can scroll the slave buffer using the
79 following commands:
81 \\{master-mode-map}
83 The slave buffer is stored in the buffer-local variable `master-of'.
84 You can set this variable using `master-set-slave'. You can show
85 yourself the value of `master-of' by calling `master-show-slave'."
86 ;; The initial value.
87 nil
88 ;; The indicator for the mode line.
89 nil
90 ;; The minor mode bindings.
91 '(("\C-c\C-n" . master-says-scroll-up)
92 ("\C-c\C-p" . master-says-scroll-down)
93 ("\C-c<" . master-says-beginning-of-buffer)
94 ("\C-c>" . master-says-end-of-buffer)
95 ("\C-c\C-l" . master-says-recenter)))
97 ;; Initialize Master mode by setting a slave buffer.
99 (defun master-set-slave (buffer)
100 "Makes BUFFER the slave of the current buffer.
101 Use \\[master-mode] to toggle control of the slave buffer."
102 (interactive "bSlave: ")
103 (make-local-variable 'master-of)
104 (setq master-of buffer)
105 (run-hooks 'master-set-slave-hook))
107 (defun master-show-slave ()
108 "Displays a message with the name of the slave buffer."
109 (interactive)
110 (message "This buffer is the master of %s. Master-mode is %S."
111 (or master-of "none")
112 master-mode))
116 ;;; Functions that the master buffer can call for the slave buffer.
118 (defun master-says-scroll-up (&optional arg)
119 "Display and scroll the slave buffer up.
120 See `scroll-up'."
121 (interactive)
122 (master-says 'scroll-up arg))
124 (defun master-says-scroll-down (&optional arg)
125 "Display and scroll the slave buffer down.
126 See `scroll-down'."
127 (interactive)
128 (master-says 'scroll-down arg))
130 (defun master-says-beginning-of-buffer (&optional arg)
131 "Display and move to the beginning of the slave buffer.
132 See `beginning-of-buffer'."
133 (interactive)
134 (master-says 'beginning-of-buffer arg))
136 (defun master-says-end-of-buffer (&optional arg)
137 "Display and move to the end of the slave buffer.
138 See `end-of-buffer'."
139 (interactive)
140 (master-says 'end-of-buffer arg))
142 (defun master-says-recenter (&optional arg)
143 "Recenter the slave buffer.
144 See `recenter'."
145 (interactive)
146 (master-says 'recenter arg))
148 ;; The master function doing the stuff.
150 (defun master-says (&optional command arg)
151 "Display slave buffer and execute COMMAND with ARG in its window."
152 (interactive)
153 (if (null (buffer-live-p (get-buffer master-of)))
154 (error "Slave buffer has disappeared")
155 (let ((window (selected-window)))
156 (if (not (eq (window-buffer window) (get-buffer master-of)))
157 (switch-to-buffer-other-window master-of))
158 (if command (condition-case nil (apply command arg) (error nil)))
159 (select-window window))))
161 (provide 'master)
163 ;;; master.el ends here