lisp/master.el

   1 ;;; master.el --- make a buffer the master over another buffer
   2
   3 ;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
   4 ;;   Free Software Foundation, Inc.
   5
   6 ;; Author: Alex Schroeder <alex@gnu.org>
   7 ;; Maintainer: Alex Schroeder <alex@gnu.org>
   8 ;; Version: 1.0.2
   9 ;; Keywords: comm
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software; you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation; either version 3, or (at your option)
  16 ;; any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  25 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  26 ;; Boston, MA 02110-1301, USA.
  27
  28 ;;; Commentary:
  29
  30 ;; master-mode is a minor mode which enables you to scroll another
  31 ;; buffer (the slave) without leaving your current buffer (the master).
  32
  33 ;; It can be used by sql.el, for example: The SQL buffer is the master
  34 ;; and its SQLi buffer is the slave.  This allows you to scroll the SQLi
  35 ;; buffer containing the output from the SQL buffer containing the
  36 ;; commands.
  37 ;;
  38 ;; This is how to use sql.el and master.el together: The variable
  39 ;; sql-buffer contains the slave buffer.  It is a local variable in the
  40 ;; SQL buffer.
  41 ;;
  42 ;; (add-hook 'sql-mode-hook
  43 ;;         (function (lambda ()
  44 ;;                     (master-mode t)
  45 ;;                     (master-set-slave sql-buffer))))
  46 ;; (add-hook 'sql-set-sqli-hook
  47 ;;         (function (lambda ()
  48 ;;                     (master-set-slave sql-buffer))))
  49
  50 ;;; Thanks to all the people who helped me out:
  51 ;;
  52 ;; Rob Riepel <networking.stanford.edu>
  53
  54 ;;; History:
  55 ;;
  56
  57 ;;; Code:
  58
  59 (defgroup master nil
  60   "Support for master/slave relationships between buffers."
  61   :version "22.1"
  62   :group 'convenience)
  63
  64 ;; Variables that don't need initialization.
  65
  66 (defvar master-of nil
  67   "Slave buffer of the current buffer.  See `master-mode'.
  68 You can set this variable using `master-set-slave'.")
  69
  70 (defvar master-set-slave-hook nil
  71   "Hook run after the slave is changed using \\[master-set-slave].")
  72
  73 ;;; Define master mode.
  74
  75 ;;;###autoload
  76 (define-minor-mode master-mode
  77   "Toggle Master mode.
  78 With no argument, this command toggles the mode.
  79 Non-null prefix argument turns on the mode.
  80 Null prefix argument turns off the mode.
  81
  82 When Master mode is enabled, you can scroll the slave buffer using the
  83 following commands:
  84
  85 \\{master-mode-map}
  86
  87 The slave buffer is stored in the buffer-local variable `master-of'.
  88 You can set this variable using `master-set-slave'.  You can show
  89 yourself the value of `master-of' by calling `master-show-slave'."
  90   :group 'master
  91   :keymap
  92   '(("\C-c\C-n" . master-says-scroll-up)
  93     ("\C-c\C-p" . master-says-scroll-down)
  94     ("\C-c<" . master-says-beginning-of-buffer)
  95     ("\C-c>" . master-says-end-of-buffer)
  96     ("\C-c\C-l" . master-says-recenter)))
  97
  98 ;; Initialize Master mode by setting a slave buffer.
  99
 100 (defun master-set-slave (buffer)
 101   "Makes BUFFER the slave of the current buffer.
 102 Use \\[master-mode] to toggle control of the slave buffer."
 103   (interactive "bSlave: ")
 104   (make-local-variable 'master-of)
 105   (setq master-of buffer)
 106   (run-hooks 'master-set-slave-hook))
 107
 108 (defun master-show-slave ()
 109   "Displays a message with the name of the slave buffer."
 110   (interactive)
 111   (message "This buffer is the master of %s.  Master-mode is %S."
 112            (or master-of "none")
 113            master-mode))
 114
 115 \f
 116
 117 ;;; Functions that the master buffer can call for the slave buffer.
 118
 119 (defun master-says-scroll-up (&optional arg)
 120   "Display and scroll the slave buffer up.
 121 See `scroll-up'."
 122   (interactive)
 123   (master-says 'scroll-up arg))
 124
 125 (defun master-says-scroll-down (&optional arg)
 126   "Display and scroll the slave buffer down.
 127 See `scroll-down'."
 128   (interactive)
 129   (master-says 'scroll-down arg))
 130
 131 (defun master-says-beginning-of-buffer (&optional arg)
 132   "Display and move to the beginning of the slave buffer.
 133 See `beginning-of-buffer'."
 134   (interactive)
 135   (master-says 'beginning-of-buffer arg))
 136
 137 (defun master-says-end-of-buffer (&optional arg)
 138   "Display and move to the end of the slave buffer.
 139 See `end-of-buffer'."
 140   (interactive)
 141   (master-says 'end-of-buffer arg))
 142
 143 (defun master-says-recenter (&optional arg)
 144   "Recenter the slave buffer.
 145 See `recenter'."
 146   (interactive)
 147   (master-says 'recenter arg))
 148
 149 ;; The master function doing the stuff.
 150
 151 (defun master-says (&optional command arg)
 152   "Display slave buffer and execute COMMAND with ARG in its window."
 153   (interactive)
 154   (if (null (buffer-live-p (get-buffer master-of)))
 155       (error "Slave buffer has disappeared")
 156     (let ((window  (selected-window)))
 157       (if (not (eq (window-buffer window) (get-buffer master-of)))
 158           (switch-to-buffer-other-window master-of))
 159       (if command (condition-case nil (apply command arg) (error nil)))
 160       (select-window window))))
 161
 162 (provide 'master)
 163
 164 ;;; arch-tag: dca08daa-8127-45ae-b77e-b135160dce98
 165 ;;; master.el ends here