lisp/master.el

   1 ;;; master.el --- make a buffer the master over another buffer
   2
   3 ;; Copyright (C) 1999, 2000, 2001  Alexander Schroeder
   4
   5 ;; Author: Alex Schroeder <alex@gnu.org>
   6 ;; Maintainer: Alex Schroeder <alex@gnu.org>
   7 ;; Version: 1.0.2
   8 ;; Keywords: comm
   9
  10 ;; This file is part of GNU Emacs.
  11
  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.
  16
  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.
  21
  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.
  26
  27 ;;; Commentary:
  28
  29 ;; master-mode is a minor mode which enables you to scroll another
  30 ;; buffer (the slave) without leaving your current buffer (the master).
  31
  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.
  36 ;;
  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.
  40 ;;
  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))))
  48
  49 ;;; Thanks to all the people who helped me out:
  50 ;;
  51 ;; Rob Riepel <networking.stanford.edu>
  52
  53 ;;; History:
  54 ;;
  55
  56 ;;; Code:
  57
  58 (require 'easy-mmode)
  59
  60 ;; Variables that don't need initialization.
  61
  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'.")
  65
  66 (defvar master-set-slave-hook nil
  67   "Hook run after the slave is changed using \\[master-set-slave].")
  68
  69 ;;; Define master mode.
  70
  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.
  77
  78 When Master mode is enabled, you can scroll the slave buffer using the
  79 following commands:
  80
  81 \\{master-mode-map}
  82
  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)))
  96
  97 ;; Initialize Master mode by setting a slave buffer.
  98
  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))
 106
 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))
 113
 114 \f
 115
 116 ;;; Functions that the master buffer can call for the slave buffer.
 117
 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))
 123
 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))
 129
 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))
 135
 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))
 141
 142 (defun master-says-recenter (&optional arg)
 143   "Recenter the slave buffer.
 144 See `recenter'."
 145   (interactive)
 146   (master-says 'recenter arg))
 147
 148 ;; The master function doing the stuff.
 149
 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))))
 160
 161 (provide 'master)
 162
 163 ;;; master.el ends here