summaryrefslogtreecommitdiff
path: root/lisp/master.el
blob: 07e9ee5abc0c1916cab031063ad379df0d6a552c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
;;; master.el --- make a buffer the master over another buffer

;; Copyright (C) 1999-2017 Free Software Foundation, Inc.

;; Author: Alex Schroeder <alex@gnu.org>
;; Maintainer: Alex Schroeder <alex@gnu.org>
;; Version: 1.0.2
;; Keywords: comm

;; This file is part of GNU Emacs.

;; GNU Emacs 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 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs 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.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; master-mode is a minor mode which enables you to scroll another
;; buffer (the slave) without leaving your current buffer (the master).

;; It can be used by sql.el, for example: The SQL buffer is the master
;; and its SQLi buffer is the slave.  This allows you to scroll the SQLi
;; buffer containing the output from the SQL buffer containing the
;; commands.
;;
;; This is how to use sql.el and master.el together: The variable
;; sql-buffer contains the slave buffer.  It is a local variable in the
;; SQL buffer.
;;
;; (add-hook 'sql-mode-hook
;;	   (function (lambda ()
;;		       (master-mode t)
;;		       (master-set-slave sql-buffer))))
;; (add-hook 'sql-set-sqli-hook
;;	   (function (lambda ()
;;		       (master-set-slave sql-buffer))))

;;; Thanks to all the people who helped me out:
;;
;; Rob Riepel <networking.stanford.edu>

;;; History:
;;

;;; Code:

;; Unused.
;;; (defgroup master nil
;;;   "Support for master/slave relationships between buffers."
;;;   :version "22.1"
;;;   :group 'convenience)

;; Variables that don't need initialization.

(defvar master-of nil
  "Slave buffer of the current buffer.  See `master-mode'.
You can set this variable using `master-set-slave'.")

(defvar master-set-slave-hook nil
  "Hook run after the slave is changed using \\[master-set-slave].")

;;; Define master mode.

;;;###autoload
(define-minor-mode master-mode
  "Toggle Master mode.
With a prefix argument ARG, enable Master mode if ARG is
positive, and disable it otherwise.  If called from Lisp, enable
the mode if ARG is omitted or nil.

When Master mode is enabled, you can scroll the slave buffer
using the following commands:

\\{master-mode-map}

The slave buffer is stored in the buffer-local variable `master-of'.
You can set this variable using `master-set-slave'.  You can show
yourself the value of `master-of' by calling `master-show-slave'."
  ;; Not global, so no effect.
;;;  :group 'master
  :keymap
  '(("\C-c\C-n" . master-says-scroll-up)
    ("\C-c\C-p" . master-says-scroll-down)
    ("\C-c<" . master-says-beginning-of-buffer)
    ("\C-c>" . master-says-end-of-buffer)
    ("\C-c\C-l" . master-says-recenter)))

;; Initialize Master mode by setting a slave buffer.

(defun master-set-slave (buffer)
  "Makes BUFFER the slave of the current buffer.
Use \\[master-mode] to toggle control of the slave buffer."
  (interactive "bSlave: ")
  (make-local-variable 'master-of)
  (setq master-of buffer)
  (run-hooks 'master-set-slave-hook))

(defun master-show-slave ()
  "Displays a message with the name of the slave buffer."
  (interactive)
  (message "This buffer is the master of %s.  Master-mode is %S."
	   (or master-of "none")
	   master-mode))



;;; Functions that the master buffer can call for the slave buffer.

(defun master-says-scroll-up (&optional arg)
  "Display and scroll the slave buffer up.
See `scroll-up'."
  (interactive)
  (master-says 'scroll-up arg))

(defun master-says-scroll-down (&optional arg)
  "Display and scroll the slave buffer down.
See `scroll-down'."
  (interactive)
  (master-says 'scroll-down arg))

(defun master-says-beginning-of-buffer (&optional arg)
  "Display and move to the beginning of the slave buffer.
See `beginning-of-buffer'."
  (interactive)
  (master-says 'beginning-of-buffer arg))

(defun master-says-end-of-buffer (&optional arg)
  "Display and move to the end of the slave buffer.
See `end-of-buffer'."
  (interactive)
  (master-says 'end-of-buffer arg))

(defun master-says-recenter (&optional arg)
  "Recenter the slave buffer.
See `recenter'."
  (interactive)
  (master-says 'recenter arg))

;; The master function doing the stuff.

(defun master-says (&optional command arg)
  "Display slave buffer and execute COMMAND with ARG in its window."
  (interactive)
  (if (null (buffer-live-p (get-buffer master-of)))
      (error "Slave buffer has disappeared")
    (let ((window  (selected-window)))
      (if (not (eq (window-buffer window) (get-buffer master-of)))
	  (switch-to-buffer-other-window master-of))
      (if command (condition-case nil (apply command arg) (error nil)))
      (select-window window))))

(provide 'master)

;;; master.el ends here