lisp/double.el

   1 ;;; double.el --- Support for keyboard remapping with double clicking
   2
   3 ;; Copyright (C) 1994 Free Software Foundation, Inc.
   4
   5 ;; Author: Per Abrahamsen <abraham@dina.kvl.dk>
   6 ;; Keywords: i18n
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; This mode is intended for use with languages that adds a small
  28 ;; number of extra letters not available on the keyboard.
  29 ;;
  30 ;; Examples includes Scandinavian and German with an US keyboard.
  31 ;;
  32 ;; The idea is that certain keys are overloaded.  When you press it
  33 ;; once it will insert one string, and when you press it twice the
  34 ;; string will be replaced by another.  This can be used for mapping
  35 ;; keys on a US keyboard to generate characters according to the local
  36 ;; keyboard convention when pressed once, and according to US keyboard
  37 ;; convention when pressed twice.
  38 ;;
  39 ;; To use this mode, you must define the variable `double-map' and
  40 ;; then enable double mode with `M-x double-mode'.  Read the
  41 ;; documentation for both of them.
  42 ;;
  43 ;; The default mapping is for getting Danish/Norwegian keyboard layout
  44 ;; using ISO Latin 1 on a US keyboard.
  45 ;;
  46 ;; Important node: While I would like to hear comments, bug reports,
  47 ;; suggestions, please do @strong{not} expect me to put other mappings
  48 ;; than the default into this file.  There are billions and billions
  49 ;; of such mappings, and just supporting the most common would
  50 ;; increase the size of this nice small file manyfold.
  51
  52 ;;; ChangeLog:
  53
  54 ;; * 1994-06-21         Per Abrahamsen
  55 ;;      Added `double-prefix-only'.
  56 ;; * 1994-02-28         Per Abrahamsen
  57 ;;      Use 127 instead of 'delete to delete a character.
  58 ;; * 1994-02-03         Per Abrahamsen
  59 ;;      Created.
  60
  61 ;;; Code:
  62
  63 (defvar double-map
  64   '((?\; "\346" ";")
  65     (?\' "\370" "'")
  66     (?\[ "\345" "[")
  67     (?\: "\306" ":")
  68     (?\" "\330" "\"")
  69     (?\{ "\305" "{"))
  70   "Alist of key translations activated by double mode.
  71
  72 Each entry is a list with three elements:
  73 1. The key activating the translation.
  74 2. The string to be inserted when the key is pressed once.
  75 3. The string to be inserted when the key is pressed twice.")
  76
  77 (defvar double-prefix-only t
  78   "*Non-nil means that Double mode mapping only works for prefix keys.
  79 That is, for any key `X' in `double-map',  `X' alone will be mapped
  80 but not `C-u X' or `ESC X' since the X is not the prefix key.")
  81
  82 ;;; Read Event
  83
  84 (defvar double-last-event nil)
  85 ;; The last key that generated a double key event.
  86
  87 (defun double-read-event (prompt)
  88   ;; Read an event
  89   (if isearch-mode (isearch-update))
  90   (if prompt
  91       (prog2 (message "%s%c" prompt double-last-event)
  92           (read-event)
  93         (message ""))
  94     (read-event)))
  95
  96 (global-set-key [ignore] '(lambda () (interactive)))
  97
  98 (or (boundp 'isearch-mode-map)
  99     (load-library "isearch"))
 100
 101 (define-key isearch-mode-map [ignore]
 102   (function (lambda () (interactive) (isearch-update))))
 103
 104 (defun double-translate-key (prompt)
 105   ;; Translate input events using double map.
 106   (let ((key last-input-char))
 107     (cond (unread-command-events
 108            ;; Artificial event, ignore it.
 109            (vector key))
 110           ((and double-prefix-only
 111                 (> (length (this-command-keys)) 1))
 112            ;; This is not a prefix key, ignore it.
 113            (vector key))
 114           ((eq key 'magic-start)
 115            ;; End of generated event.  See if he will repeat it...
 116            (let ((new (double-read-event prompt))
 117                  (entry (assoc double-last-event double-map)))
 118              (if (eq new double-last-event)
 119                  (progn
 120                    (setq unread-command-events
 121                          (append (make-list (1- (length (nth 1 entry)))
 122                                             127)
 123                                  (nth 2 entry)
 124                                  '(magic-end)))
 125                    (vector 127))
 126                (setq unread-command-events (list new))
 127                [ignore])))
 128           ((eq key 'magic-end)
 129            ;; End of double event.  Ignore.
 130            [ignore])
 131           (t
 132            ;; New key.
 133            (let ((exp (nth 1 (assoc key double-map))))
 134              (setq double-last-event key)
 135              (setq unread-command-events
 136                    (append (substring exp 1) '(magic-start)))
 137              (vector (aref exp 0)))))))
 138
 139 ;;; Key Translation Map
 140
 141 (defvar default-key-translation-map
 142   (or key-translation-map (make-sparse-keymap))
 143   "Key translation you want to have effect, regardless of Double mode.
 144 This defaults to the value of `key-translation-map' when double was
 145 first loaded.")
 146
 147 (make-variable-buffer-local 'key-translation-map)
 148
 149 (defun double-setup ()
 150   ;; Setup key-translation-map as indicated by `double-map'.
 151   (setq key-translation-map (copy-keymap default-key-translation-map))
 152   (mapcar (function (lambda (entry)
 153             (define-key key-translation-map (vector (nth 0 entry))
 154                         'double-translate-key)))
 155           (append double-map '((magic-start) (magic-end)))))
 156
 157 ;;; Mode
 158
 159 (defvar double-mode nil)
 160 ;; Indicator for the double mode.
 161   (make-variable-buffer-local 'double-mode)
 162
 163 (or (assq 'double-mode minor-mode-alist)
 164     (setq minor-mode-alist
 165           (cons '(double-mode " Double") minor-mode-alist)))
 166
 167 ;; This feature seemed useless and it confused describe-mode,
 168 ;;  so I deleted it.
 169 ;;;(defvar double-mode-name "Double")
 170 ;;;;; Name of current double mode.
 171 ;;; (make-variable-buffer-local 'double-mode-name)
 172
 173 ;;;###autoload
 174 (defun double-mode (arg)
 175   "Toggle Double mode.
 176 With prefix arg, turn Double mode on iff arg is positive.
 177
 178 When Double mode is on, some keys will insert different strings
 179 when pressed twice.  See variable `double-map' for details."
 180   (interactive "P")
 181   (if (or (and (null arg) double-mode)
 182           (<= (prefix-numeric-value arg) 0))
 183       ;; Turn it off
 184       (if double-mode
 185           (progn
 186             (let ((double-map))
 187               (double-setup))
 188             (setq double-mode nil)
 189             (force-mode-line-update)))
 190     ;;Turn it on
 191     (if double-mode
 192         ()
 193       (double-setup)
 194       (setq double-mode t)
 195       (force-mode-line-update))))
 196
 197 (provide 'double)
 198
 199 ;;; double.el ends here
 200