code.delx.au - gnu-emacs/blob - lisp/language/tv-util.el

   1 ;;; tv-util.el --- support for Tai Viet                 -*- coding: utf-8 -*-
   2
   3 ;; Copyright (C) 2007
   4 ;;   National Institute of Advanced Industrial Science and Technology (AIST)
   5 ;;   Registration Number H13PRO009
   6
   7 ;; Keywords: multilingual, Tai Viet, i18n
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  24 ;; Boston, MA 02110-1301, USA.
  25
  26 ;;; Code
  27
  28 ;; Regexp matching with a sequence of Tai Viet characters.
  29 (defconst tai-viet-re
  30   (format "[\xaa80-\xaac2\xaadb-\xaadf-]+"))
  31
  32 ;; Char-table of information about glyph type of Tai Viet characters.
  33 (defconst tai-viet-glyph-info
  34   (let ((table (make-char-table nil))
  35         (specials '((right-overhang . "ꪊꪋꪌꪍꪏꪓꪖꪜꪞꪡꪤꪨ")
  36                     (left-overhang . "ꫂ")
  37                     (combining-vowel . "ꪴꪰꪲꪳꪷꪸꪾ")
  38                     (combining-tone . "꪿꫁")
  39                     (misc . "-"))))
  40     ;; Set all TaiViet characters to `t'.
  41     (set-char-table-range table (cons #xaa80 #xaac2) t)
  42     (set-char-table-range table (cons #xaadb #xaadf) t)
  43     ;; Overwrite it for special characters.
  44     (dolist (elt specials)
  45       (let ((category (car elt))
  46             (chars (cdr elt)))
  47         (dotimes (i (length chars))
  48           (aset table (aref chars i) category))))
  49     table))
  50
  51 (defun tai-viet-compose-string (from to string)
  52   "Compose Tai Viet characters in STRING between indices FROM and TO."
  53   (let* ((ch (aref string from))
  54          (info (aref tai-viet-glyph-info ch))
  55          prev-info)
  56     (if (eq info 'non-spacing)
  57         (compose-string string from (1+ from) (string ch ?\t)))
  58     (setq from (1+ from) prev-info info)
  59     (while (and (< from to)
  60                 (>= #xaa80 (setq ch (aref string from)))
  61                 (<= #xaaDF ch))
  62       (setq info (aref tai-viet-glyph-info ch))
  63       (if (and (eq info 'non-spacing)
  64                (eq prev-info 'non-spacing))
  65           (compose-string from (1+ from) (string ?\t ch)))
  66       (setq from (1+ from) prev-info info))
  67     (if (eq info 'right-overhang)
  68         (compose-string string (1- from) from (string ch ?\t)))
  69     from))
  70
  71 (defun tai-viet-compose-region (from to)
  72   "Compose Tai Viet characters in the region between FROM and TO."
  73   (decompose-region from to)
  74   (let ((normal-rule '(Br . Bl))
  75         (tone-rule '(tr . bl))
  76         (prev-viet nil)
  77         ch info pos components overhang)
  78     (while (< from to)
  79       (or ch
  80           (setq ch (char-after from)
  81                 info (aref tai-viet-glyph-info ch)))
  82       (setq from (1+ from))
  83       (if (not info)
  84           (setq prev-viet nil
  85                 ch nil)
  86         (if (memq info '(combining-vowel combining-tone))
  87             (progn
  88               ;; Display this as a spacing glyph.
  89               (compose-region (1- from) from (string ?\t ch))
  90               (setq prev-viet t
  91                     ch nil))
  92           (setq pos (1- from)
  93                 components ch
  94                 overhang (if (eq info 'right-overhang)
  95                              'right-overhang
  96                            (if (and (not prev-viet) (eq info 'left-overhang))
  97                                'left-overhang))
  98                 prev-viet t
  99                 ch nil)
 100           (if (and (< from to)
 101                    (setq ch (char-after from)
 102                          info (aref tai-viet-glyph-info ch)))
 103               (if (memq info '(combining-vowel combining-tone))
 104                   (progn
 105                     (setq components
 106                           (list components normal-rule ch)
 107                           from (1+ from)
 108                           ch nil)
 109                     (if (and (< from to)
 110                              (setq ch (char-after from)
 111                                    info (aref tai-viet-glyph-info ch))
 112                              (eq info 'combining-tone))
 113                         (setq components (nconc components
 114                                                 (list tone-rule ch))
 115                               from (1+ from)))
 116                     (if (eq overhang 'left-overhang)
 117                         (setq components (cons ?\t
 118                                                (cons normal-rule components)))
 119                       (if (and (eq overhang 'right-overhang)
 120                                (>= from to))
 121                           (setq components (nconc components
 122                                                   (list normal-rule ?\t)))))
 123                     (compose-region pos from components))
 124                 (if (eq overhang 'left-overhang)
 125                     (compose-region pos from (string ?\t components))))
 126             (if (eq overhang 'left-overhang)
 127                 (compose-region pos from (string ?\t components))
 128               (if (and (eq overhang 'right-overhang) (>= from to))
 129                   (compose-region pos from (string components ?\t))))))))
 130     from))
 131
 132
 133 ;;;###autoload
 134 (defun tai-viet-composition-function (from to font-object string)
 135   (if string
 136       (if (string-match tai-viet-re string from)
 137           (tai-viet-compose-string from (match-end 0) string))
 138     (goto-char from)
 139     (if (looking-at tai-viet-re)
 140         (tai-viet-compose-region from (match-end 0)))))
 141
 142 ;;
 143 (provide 'tai-viet-util)
 144
 145 ;; arch-tag: a45ac3fc-07d0-44d5-8841-2ebea7e11f5b