lisp/international/kinsoku.el

   1 ;;; kinsoku.el --- `Kinsoku' processing funcs. -*- coding: iso-2022-7bit; -*-
   2
   3 ;; Copyright (C) 1995 Electrotechnical Laboratory, JAPAN.
   4 ;; Licensed to the Free Software Foundation.
   5
   6 ;; Keywords: mule, kinsoku
   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 ;; `Kinsoku' processing is to prohibit specific characters to be
  28 ;; placed at beginning of line or at end of line.  Characters not to
  29 ;; be placed at beginning and end of line have character category `>'
  30 ;; and `<' respectively.   This restriction is dissolved by making a
  31 ;; line longer or shorter.
  32 ;;
  33 ;; `Kinsoku' is a Japanese word which originally means ordering to
  34 ;; stay in one place, and is used for the text processing described
  35 ;; above in the context of text formatting.
  36
  37 ;;; Code:
  38
  39 (defvar kinsoku-limit 4
  40   "How many more columns we can make lines longer by `kinsoku' processing.
  41 The value 0 means there's no limitation.")
  42
  43 ;; Setting character category `>' for characters which should not be
  44 ;; placed at beginning of line.
  45 (let* ((kinsoku-bol
  46         (concat
  47          ;; ASCII
  48          "!)-_~}]:;',.?"
  49          ;; Latin JISX0201
  50          ;; Instead of putting Latin JISX0201 string directly, we
  51          ;; generate the string as below to avoid character
  52          ;; unification problem.
  53          (let* ((str1 "!)-_~}]:;',.?")
  54                 (len (length str1))
  55                 (idx 0)
  56                 (str2 "")
  57                 ch)
  58            (while (< idx len)
  59              (setq ch (make-char 'latin-jisx0201 (aref str1 idx))
  60                    str2 (concat str2 (char-to-string ch))
  61                    idx (1+ idx)))
  62            str2)
  63          ;; Katakana JISX0201
  64          "\e(I!#'()*+,-./0^_\e(B"
  65          ;; Japanese JISX0208
  66          "\e$B!"!#!$!%!&!'!(!)!*!+!,!-!.!/!0!1!2!3!4!5!6!7!8!9!:!;!<!=!>\e(B\
  67 \e$B!?!@!A!B!C!D!E!G!I!K!M!O!Q!S!U!W!Y![!k!l!m!n\e(B\
  68 \e$B$!$#$%$'$)$C$c$e$g$n%!%#%%%'%)%C%c%e%g%n%u%v\e(B"
  69          ;; Chinese GB2312
  70          "\e$A!"!##.#,!$!%!&!'!(!)!*!+!,!-!/!1#)!3!5!7!9!;!=\e(B\
  71 \e$A!?#;#:#?#!!@!A!B!C!c!d!e!f#/#\#"#_#~#|(e\e(B"
  72          ;; Chinese BIG5
  73          "\e$(0!"!#!$!%!&!'!(!)!*!+!,!-!.!/!0!1!2\e(B\
  74 \e$(0!3!4!5!6!7!8!9!:!;!<!=!?!A!C!E!G!I!K\e(B\
  75 \e$(0!M!O!Q!S!U!W!Y![!]!_!a!c!e!g!i!k!q\e(B\
  76 \e$(0"#"$"%"&"'"(")"*"+","2"3"4"j"k"l"x%7\e(B"))
  77        (len (length kinsoku-bol))
  78        (idx 0)
  79        ch)
  80   (while (< idx len)
  81     (setq ch (aref kinsoku-bol idx)
  82           idx (1+ idx))
  83     (modify-category-entry ch ?>)))
  84
  85 ;; Setting character category `<' for characters which should not be
  86 ;; placed at end of line.
  87 (let* ((kinsoku-eol
  88         (concat
  89          ;; ASCII
  90          "({[`"
  91          ;; Latin JISX0201
  92          ;; See the comment above.
  93          (let* ((str1 "({[`")
  94                 (len (length str1))
  95                 (idx 0)
  96                 (str2 "")
  97                 ch)
  98            (while (< idx len)
  99              (setq ch (make-char 'latin-jisx0201 (aref str1 idx))
 100                    str2 (concat str2 (char-to-string ch))
 101                    idx (1+ idx)))
 102            str2)
 103          ;; JISX0201 Katakana
 104          "\e(I"\e(B"
 105          ;; Japanese JISX0208
 106          "\e$B!F!H!J!L!N!P!R!T!V!X!Z!k!l!m!n!w!x\e(B\
 107 \e$A!.!0#"#(!2!4!6!8!:!<!>!c!d!e#@!f!l\e(B"
 108          ;; Chinese GB2312
 109          "\e$A(E(F(G(H(I(J(K(L(M(N(O(P(Q(R(S(T(U(V(W(X(Y(h\e(B\
 110 \e$(0!>!@!B!D!F!H!J!L!N!P!R!T!V!X!Z!\!^!`!b\e(B"
 111          ;; Chinese BIG5
 112          "\e$(0!d!f!h!j!k!q!p"i"j"k"n"x$u$v$w$x$y$z${\e(B\
 113 \e$(0$|$}$~%!%"%#%$%%%&%'%(%)%*%+%:\e(B"))
 114        (len (length kinsoku-eol))
 115        (idx 0)
 116        ch)
 117   (while (< idx len)
 118     (setq ch (aref kinsoku-eol idx)
 119           idx (1+ idx))
 120     (modify-category-entry ch ?<)))
 121
 122 ;; Try to resolve `kinsoku' restriction by making the current line longer.
 123 (defun kinsoku-longer ()
 124   (let ((pos-and-column (save-excursion
 125                           (forward-char 1)
 126                           (while (aref (char-category-set (following-char)) ?>)
 127                             (forward-char 1))
 128                           (cons (point) (current-column)))))
 129     (if (or (<= kinsoku-limit 0)
 130             (< (cdr pos-and-column) (+ (current-fill-column) kinsoku-limit)))
 131         (goto-char (car pos-and-column)))))
 132
 133 ;; Try to resolve `kinsoku' restriction by making the current line shorter.
 134 ;; The line can't be broken before the buffer position LINEBEG.
 135 (defun kinsoku-shorter (linebeg)
 136   (let ((pos (save-excursion
 137                (forward-char -1)
 138                (while (and (< linebeg (point))
 139                            (or (aref (char-category-set (preceding-char)) ?<)
 140                                (aref (char-category-set (following-char)) ?>)))
 141                  (forward-char -1))
 142                (point))))
 143     (if (< linebeg pos)
 144         (goto-char pos))))
 145
 146 ;;;###autoload
 147 (defun kinsoku (linebeg)
 148   "Go to a line breaking position near point by doing `kinsoku' processing.
 149 LINEBEG is a buffer position we can't break a line before.
 150
 151 `Kinsoku' processing is to prohibit specific characters to be placed
 152 at beginning of line or at end of line.  Characters not to be placed
 153 at beginning and end of line have character category `>' and `<'
 154 respectively.  This restriction is dissolved by making a line longer or
 155 shorter.
 156
 157 `Kinsoku' is a Japanese word which originally means ordering to stay
 158 in one place, and is used for the text processing described above in
 159 the context of text formatting."
 160   (if enable-kinsoku
 161       (if (or (and
 162                ;; The character after point can't be placed at beginning
 163                ;; of line.
 164                (aref (char-category-set (following-char)) ?>)
 165                ;; We at first try to dissolve this situation by making a
 166                ;; line longer.  If it fails, then try making a line
 167                ;; shorter.
 168                (not (kinsoku-longer)))
 169               ;; The character before point can't be placed at end of line.
 170               (aref (char-category-set (preceding-char)) ?<))
 171           (kinsoku-shorter linebeg))))
 172
 173 ;; kinsoku.el ends here