lisp/double.el

   1 ;;; double.el --- support for keyboard remapping with double clicking
   2
   3 ;; Copyright (C) 1994, 1997-1998, 2001-2011 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 3 of the License, or
  13 ;; (at your option) 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.  If not, see <http://www.gnu.org/licenses/>.
  22
  23 ;;; Commentary:
  24
  25 ;; This mode is intended for use with languages that adds a small
  26 ;; number of extra letters not available on the keyboard.
  27 ;;
  28 ;; Examples includes Scandinavian and German with an US keyboard.
  29 ;;
  30 ;; The idea is that certain keys are overloaded.  When you press it
  31 ;; once it will insert one string, and when you press it twice the
  32 ;; string will be replaced by another.  This can be used for mapping
  33 ;; keys on a US keyboard to generate characters according to the local
  34 ;; keyboard convention when pressed once, and according to US keyboard
  35 ;; convention when pressed twice.
  36 ;;
  37 ;; To use this mode, you must define the variable `double-map' and
  38 ;; then enable double mode with `M-x double-mode'.  Read the
  39 ;; documentation for both of them.
  40 ;;
  41 ;; The default mapping is for getting Danish/Norwegian keyboard layout
  42 ;; using ISO Latin 1 on a US keyboard.
  43 ;;
  44 ;; Important node: While I would like to hear comments, bug reports,
  45 ;; suggestions, please do @strong{not} expect me to put other mappings
  46 ;; than the default into this file.  There are billions and billions
  47 ;; of such mappings, and just supporting the most common would
  48 ;; increase the size of this nice small file manyfold.
  49
  50 ;;; Code:
  51
  52 (defgroup double nil
  53   "Remap keyboard, but get original by typing the same key twice."
  54   :group 'i18n)
  55
  56 (defcustom double-map
  57   '((?\; "\346" ";")
  58     (?\' "\370" "'")
  59     (?\[ "\345" "[")
  60     (?\: "\306" ":")
  61     (?\" "\330" "\"")
  62     (?\{ "\305" "{"))
  63   "Alist of key translations activated by double mode.
  64
  65 Each entry is a list with three elements:
  66 1. The key activating the translation.
  67 2. The string to be inserted when the key is pressed once.
  68 3. The string to be inserted when the key is pressed twice."
  69   :group 'double
  70   :type '(repeat (list (character :tag "Key")
  71                        (string :tag "Once")
  72                        (string :tag "Twice"))))
  73
  74 (defcustom double-prefix-only t
  75   "Non-nil means that Double mode mapping only works for prefix keys.
  76 That is, for any key `X' in `double-map', `X' alone will be mapped
  77 but not `C-u X' or `ESC X' since the X is not the prefix key."
  78   :group 'double
  79   :type 'boolean)
  80
  81 ;;; Read Event
  82
  83 (defvar double-last-event nil)
  84 ;; The last key that generated a double key event.
  85
  86 (defun double-read-event (prompt)
  87   ;; Read an event
  88   (if isearch-mode (isearch-update))
  89   (if prompt
  90       (prog2 (message "%s%c" prompt double-last-event)
  91           (read-event)
  92         (message ""))
  93     (read-event)))
  94
  95 (global-set-key [ignore] 'ignore)
  96
  97 (or (boundp 'isearch-mode-map)
  98     (load-library "isearch"))
  99
 100 (define-key isearch-mode-map [ignore]
 101   (function (lambda () (interactive) (isearch-update))))
 102
 103 (defun double-translate-key (prompt)
 104   ;; Translate input events using double map.
 105   (let ((key last-input-event))
 106     (cond (unread-command-events
 107            ;; Artificial event, ignore it.
 108            (vector key))
 109           ((and double-prefix-only
 110                 (> (length (this-command-keys)) 1))
 111            ;; This is not a prefix key, ignore it.
 112            (vector key))
 113           ((eq key 'magic-start)
 114            ;; End of generated event.  See if he will repeat it...
 115            (let ((new (double-read-event prompt))
 116                  (entry (assoc double-last-event double-map)))
 117              (force-window-update (selected-window))
 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 ;;; Mode
 140
 141 ;; This feature seemed useless and it confused describe-mode,
 142 ;; so I deleted it.
 143 ;; (defvar double-mode-name "Double")
 144 ;; ;; Name of current double mode.
 145 ;; (make-variable-buffer-local 'double-mode-name)
 146
 147 ;;;###autoload
 148 (define-minor-mode double-mode
 149   "Toggle special insertion on double keypresses (Double mode).
 150 With a prefix argument ARG, enable Double mode if ARG is
 151 positive, and disable it otherwise.  If called from Lisp, enable
 152 the mode if ARG is omitted or nil.
 153
 154 When Double mode is enabled, some keys will insert different
 155 strings when pressed twice.  See `double-map' for details."
 156   :lighter " Double"
 157   :link '(emacs-commentary-link "double")
 158   (kill-local-variable 'key-translation-map)
 159   (when double-mode
 160     ;; Set up key-translation-map as indicated by `double-map'.
 161     ;; XXX I don't think key-translation-map should be made local here. -- Lorentey
 162     (make-local-variable 'key-translation-map)
 163     (let ((map (make-sparse-keymap)))
 164       (set-keymap-parent map key-translation-map)
 165       (setq key-translation-map map)
 166       (dolist (entry (append double-map '((magic-start) (magic-end))))
 167         (define-key map
 168           (vector (nth 0 entry)) 'double-translate-key)))))
 169
 170 (provide 'double)
 171
 172 ;;; double.el ends here