1 ;;; master.el --- make a buffer the master over another buffer
3 ;; Copyright (C) 1999-2018 Free Software Foundation, Inc.
5 ;; Author: Alex Schroeder <alex@gnu.org>
6 ;; Maintainer: Alex Schroeder <alex@gnu.org>
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 3 of the License, or
15 ;; (at your option) 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. If not, see <https://www.gnu.org/licenses/>.
27 ;; master-mode is a minor mode which enables you to scroll another
28 ;; buffer (the slave) without leaving your current buffer (the master).
30 ;; It can be used by sql.el, for example: The SQL buffer is the master
31 ;; and its SQLi buffer is the slave. This allows you to scroll the SQLi
32 ;; buffer containing the output from the SQL buffer containing the
35 ;; This is how to use sql.el and master.el together: The variable
36 ;; sql-buffer contains the slave buffer. It is a local variable in the
39 ;; (add-hook 'sql-mode-hook
40 ;; (function (lambda ()
42 ;; (master-set-slave sql-buffer))))
43 ;; (add-hook 'sql-set-sqli-hook
44 ;; (function (lambda ()
45 ;; (master-set-slave sql-buffer))))
47 ;;; Thanks to all the people who helped me out:
49 ;; Rob Riepel <networking.stanford.edu>
57 ;;; (defgroup master nil
58 ;;; "Support for master/slave relationships between buffers."
60 ;;; :group 'convenience)
62 ;; Variables that don't need initialization.
65 "Slave buffer of the current buffer. See `master-mode'.
66 You can set this variable using `master-set-slave'.")
68 (defvar master-set-slave-hook nil
69 "Hook run after the slave is changed using \\[master-set-slave].")
71 ;;; Define master mode.
74 (define-minor-mode master-mode
77 When Master mode is enabled, you can scroll the slave buffer
78 using the following commands:
82 The slave buffer is stored in the buffer-local variable `master-of'.
83 You can set this variable using `master-set-slave'. You can show
84 yourself the value of `master-of' by calling `master-show-slave'."
85 ;; Not global, so no effect.
88 '(("\C-c\C-n" . master-says-scroll-up
)
89 ("\C-c\C-p" . master-says-scroll-down
)
90 ("\C-c<" . master-says-beginning-of-buffer
)
91 ("\C-c>" . master-says-end-of-buffer
)
92 ("\C-c\C-l" . master-says-recenter
)))
94 ;; Initialize Master mode by setting a slave buffer.
96 (defun master-set-slave (buffer)
97 "Makes BUFFER the slave of the current buffer.
98 Use \\[master-mode] to toggle control of the slave buffer."
99 (interactive "bSlave: ")
100 (make-local-variable 'master-of
)
101 (setq master-of buffer
)
102 (run-hooks 'master-set-slave-hook
))
104 (defun master-show-slave ()
105 "Displays a message with the name of the slave buffer."
107 (message "This buffer is the master of %s. Master-mode is %S."
108 (or master-of
"none")
113 ;;; Functions that the master buffer can call for the slave buffer.
115 (defun master-says-scroll-up (&optional arg
)
116 "Display and scroll the slave buffer up.
119 (master-says 'scroll-up arg
))
121 (defun master-says-scroll-down (&optional arg
)
122 "Display and scroll the slave buffer down.
125 (master-says 'scroll-down arg
))
127 (defun master-says-beginning-of-buffer (&optional arg
)
128 "Display and move to the beginning of the slave buffer.
129 See `beginning-of-buffer'."
131 (master-says 'beginning-of-buffer arg
))
133 (defun master-says-end-of-buffer (&optional arg
)
134 "Display and move to the end of the slave buffer.
135 See `end-of-buffer'."
137 (master-says 'end-of-buffer arg
))
139 (defun master-says-recenter (&optional arg
)
140 "Recenter the slave buffer.
143 (master-says 'recenter arg
))
145 ;; The master function doing the stuff.
147 (defun master-says (&optional command arg
)
148 "Display slave buffer and execute COMMAND with ARG in its window."
150 (if (null (buffer-live-p (get-buffer master-of
)))
151 (error "Slave buffer has disappeared")
152 (let ((window (selected-window)))
153 (if (not (eq (window-buffer window
) (get-buffer master-of
)))
154 (switch-to-buffer-other-window master-of
))
155 (if command
(condition-case nil
(apply command arg
) (error nil
)))
156 (select-window window
))))
160 ;;; master.el ends here