;; Spanish minor mode - easy typing of Spanish accented characters

;; Copyright (C) 1999  Philip Dorrell
     
;;     This program 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 2
;;     of the License, or (at your option) any later version.
     
;;     This program 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.
     
;;     A copy of the GNU General Public License is included with the
;;     GNU Emacs distribution.

;; Email: pdorrell@.com      (add "pobox" after "@" and before ".com").
;; (The previous line is to confuse spambots trying to read this page.)
;; Web: www.1729.com

;; Standard GNU emacs contains two main functions that help with
;; editing accented non-English languages:

;; standard-european, which is used here, to display higher characters
;; as accented characters

;; iso-accents-mode, which allows one to use keys `'"^/~ as special
;; accent keys to compose accented characters

;; In Spanish, the following is almost true:
;; For every accented or non-ASCII character, there is one
;; corresponding ASCII character, and no ASCII character has more
;; than one corresponding non-ASCII character. The exceptions are
;; the raised a's and o's use with ordinal numbers.
;; spanish-minor-mode defines two toggle keys (here set to be F2 and F3).
;; F3 toggles a and o to the ordinal endings, F2 toggles all other
;; possibilities with characters AaEeIiNnOoUu!?
;; F2 and F3 toggle the characters preceding the cursor, i.e. the 
;; character just typed, so to type ¿ Como estás ?, type as follows:
;; ? F2 (space) C o m o (space) e s t a F2 s ?
;; It is also easy to add accents to text previously typed without
;; accents (move cursor position following character, use F2 or F3 to toggle).

;; To make this mode accessible, add the following lines (uncommented)
;; to your _emacs file or to "site-lisp/default.el":

;;(autoload 'spanish-minor-mode "spanish")
;;(global-set-key [?\M-\C-S] 'spanish-minor-mode)

;; Shift-Meta-Control S will then toggle spanish-minor-mode
;; (= Shift-Alt-Control S on Win 95/NT)
;-----------------------------------------------------------------
;; The next two functions are utility routines that help you to see
;; which character is which. They are not needed to make the
;; Spanish mode work.

(defun octal-digits (n)
  "Return NUMBER as a string of octal digits"
  (let ( (n1 n) (x 0) (digits nil) (len 0))
    (while (> n1 0)
      (setq n2 (/ n1 8))
      (setq digit (- n1 (* 8 n2)))
      (setq digits (cons digit digits))
      (setq x (+ (* x 10) digit))
      (setq len (1+ len))
      (setq n1 n2) )
    (setq string (make-string len 0))
    (dotimes (i len)
      (aset string i (+ ?0 (nth i digits))) )
    string) )

(defun show-char-codes ()
  "Show all characters and codes in a buffer"
  (interactive)
  (let ( (output (get-buffer-create "*characters*")) )
    (switch-to-buffer-other-window output)
    (delete-region (point-min) (point-max))
    (standard-display-european 1)
    (dotimes (i 32)
      (dotimes (j 8)
	(let ( (n (+ (* i 8) j)) )
	  (insert (octal-digits n) ": " n " ") ) )
      (insert "\n") ) ) )

;-----------------------------------------------------------------
(defun make-toggle-array (&rest strings)
  "Make a lookup array to toggle characters around the STRINGS"
  (let ( (toggle-array (make-vector 256 nil)) )
    (dolist (string strings)
      (let ( (len (length string)) j)
	(dotimes (i len)
	  (setq j (1+ i))
	  (if (>= j len) (setq j 0))
	  (aset toggle-array (aref string i) (aref string j)) ) ) )
    toggle-array) )

(defvar spanish-accents-toggler
  (make-toggle-array
   "a\341" "e\351" "i\355" "o\363" "u\372" "n\361"
   "A\301" "E\311" "I\315" "O\323" "U\332" "N\321"
   "!\241" "?\277" ) 
  "Array to toggle normal ASCII characters with most
common Spanish variants")

(defvar spanish-ordinal-toggler
  (make-toggle-array "a\252" "o\272")
  "Array to toggle normal ASCII characters with ordinal suffixes")

(defun toggle-character (toggle-array)
  "Toggle character just before cursor according to
toggle array"
  (let ( (ch (char-after (1- (point)))) new)
    (if ch
	(progn
	  (setq new (aref toggle-array ch))
	  (if new
	      (progn 
		(delete-backward-char 1)
		(insert (make-string 1 new)) )
	    (message 
	     (concat "No toggle value for character " (make-string 1 ch))) ) )
      (message "No character to toggle") ) ) )

(defun spanish-toggle-accent()
  "Toggle Spanish accent or other special character"
  (interactive)
  (toggle-character spanish-accents-toggler) )

(defun spanish-toggle-ordinal()
  "Toggle Spanish a or o to ordinal suffix"
  (interactive)
  (toggle-character spanish-ordinal-toggler) )

(defvar spanish-minor-mode nil
  "If NON-nil, F2 and F3 toggle Spanish accents and ordinals" )

(defvar spanish-minor-mode-keymap
  (make-sparse-keymap))

(if spanish-minor-mode-keymap
    (progn
      (define-key spanish-minor-mode-keymap [f2] 'spanish-toggle-accent)
      (define-key spanish-minor-mode-keymap [f3] 'spanish-toggle-ordinal) ) )

(if (not (assq 'spanish-minor-mode minor-mode-alist))
    (setq minor-mode-alist
	  (append minor-mode-alist '((spanish-minor-mode " Spanish"))) ) )

(if (not (assq 'spanish-minor-mode minor-mode-map-alist))
    (setq minor-mode-map-alist
	  (cons (cons 'spanish-minor-mode spanish-minor-mode-keymap)
		minor-mode-map-alist)))

(defun spanish-minor-mode()
  "Turn on F2 and F3 toggling of Spanish accents and ordinals"
  (interactive)
  (if spanish-minor-mode
      (progn
	(setq spanish-minor-mode nil)
	(standard-display-european -1) )
    (progn
      (setq spanish-minor-mode t)
      (standard-display-european +1) ) )
  (redraw-display) )