lisp/international/kinsoku.el

   1 ;;; kinsoku.el --- `Kinsoku' processing funcs -*- coding: iso-2022-7bit; -*-
   2
   3 ;; Copyright (C) 1997, 2001-2014 Free Software Foundation, Inc.
   4 ;; Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   5 ;;   2005, 2006, 2007, 2008, 2009, 2010, 2011
   6 ;;   National Institute of Advanced Industrial Science and Technology (AIST)
   7 ;;   Registration Number H14PRO021
   8
   9 ;; Keywords: mule, kinsoku
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; `Kinsoku' processing is to prohibit specific characters to be
  29 ;; placed at beginning of line or at end of line.  Characters not to
  30 ;; be placed at beginning and end of line have character category `>'
  31 ;; and `<' respectively.   This restriction is dissolved by making a
  32 ;; line longer or shorter.
  33 ;;
  34 ;; `Kinsoku' is a Japanese word which originally means ordering to
  35 ;; stay in one place, and is used for the text processing described
  36 ;; above in the context of text formatting.
  37
  38 ;;; Code:
  39
  40 (defvar kinsoku-limit 4
  41   "How many more columns we can make lines longer by `kinsoku' processing.
  42 The value 0 means there's no limitation.")
  43
  44 ;; Setting character category `>' for characters which should not be
  45 ;; placed at beginning of line.
  46 (let* ((kinsoku-bol
  47         (concat
  48          ;; ASCII
  49          "!)-_~}]:;',.?"
  50          ;; Latin JISX0201
  51          ;; Instead of putting Latin JISX0201 string directly, we
  52          ;; generate the string as below to avoid character
  53          ;; unification problem.
  54          (let* ((str1 "!)-_~}]:;',.?")
  55                 (len (length str1))
  56                 (idx 0)
  57                 (str2 "")
  58                 ch)
  59            (while (< idx len)
  60              (setq ch (make-char 'latin-jisx0201 (aref str1 idx))
  61                    str2 (concat str2 (char-to-string ch))
  62                    idx (1+ idx)))
  63            str2)
  64          ;; Katakana JISX0201
  65          "\e(I!#'()*+,-./0^_\e(B"
  66          ;; Japanese JISX0208
  67          "\e$B!"!#!$!%!&!'!(!)!*!+!,!-!.!/!0!1!2!3!4!5!6!7!8!9!:!;!<!=!>\e(B\
  68 \e$B!?!@!A!B!C!D!E!G!I!K!M!O!Q!S!U!W!Y![!k!l!m!n\e(B\
  69 \e$B$!$#$%$'$)$C$c$e$g$n%!%#%%%'%)%C%c%e%g%n%u%v\e(B"
  70          ;; Chinese GB2312
  71          "\e$A!"!##.#,!$!%!&!'!(!)!*!+!,!-!/!1#)!3!5!7!9!;!=\e(B\
  72 \e$A!?#;#:#?#!!@!A!B!C!c!d!e!f#/#\#"#_#~#|(e\e(B"
  73          ;; Chinese BIG5
  74          "\e$(0!"!#!$!%!&!'!(!)!*!+!,!-!.!/!0!1!2\e(B\
  75 \e$(0!3!4!5!6!7!8!9!:!;!<!=!?!A!C!E!G!I!K\e(B\
  76 \e$(0!M!O!Q!S!U!W!Y![!]!_!a!c!e!g!i!k!q\e(B\
  77 \e$(0"#"$"%"&"'"(")"*"+","2"3"4"j"k"l"x%7\e(B"))
  78        (len (length kinsoku-bol))
  79        (idx 0)
  80        ch)
  81   (while (< idx len)
  82     (setq ch (aref kinsoku-bol idx)
  83           idx (1+ idx))
  84     (modify-category-entry ch ?>)))
  85
  86 ;; Setting character category `<' for characters which should not be
  87 ;; placed at end of line.
  88 (let* ((kinsoku-eol
  89         (concat
  90          ;; ASCII
  91          "({[`"
  92          ;; Latin JISX0201
  93          ;; See the comment above.
  94          (let* ((str1 "({[`")
  95                 (len (length str1))
  96                 (idx 0)
  97                 (str2 "")
  98                 ch)
  99            (while (< idx len)
 100              (setq ch (make-char 'latin-jisx0201 (aref str1 idx))
 101                    str2 (concat str2 (char-to-string ch))
 102                    idx (1+ idx)))
 103            str2)
 104          ;; JISX0201 Katakana
 105          "\e(I"\e(B"
 106          ;; Japanese JISX0208
 107          "\e$B!F!H!J!L!N!P!R!T!V!X!Z!k!l!m!n!w!x\e(B\
 108 \e$A!.!0#"#(!2!4!6!8!:!<!>!c!d!e#@!f!l\e(B"
 109          ;; Chinese GB2312
 110          "\e$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\
 111 \\e$(0!>!@!B!D!F!H!J!L!N!P!R!T!V!X!Z!\!^!`!b\e(B"
 112          ;; Chinese BIG5
 113          "\e$(0!d!f!h!j!k!q!p"i"j"k"n"x$u$v$w$x$y$z${\e(B\
 114 \e$(0$|$}$~%!%"%#%$%%%&%'%(%)%*%+%:\e(B"))
 115        (len (length kinsoku-eol))
 116        (idx 0)
 117        ch)
 118   (while (< idx len)
 119     (setq ch (aref kinsoku-eol idx)
 120           idx (1+ idx))
 121     (modify-category-entry ch ?<)))
 122
 123 ;; Try to resolve `kinsoku' restriction by making the current line longer.
 124 (defun kinsoku-longer ()
 125   (let ((pos-and-column
 126          (save-excursion
 127            (forward-char 1)
 128            (while (and (not (eolp))
 129                        (or (aref (char-category-set (following-char)) ?>)
 130                            ;; protect non-kinsoku words
 131                            (not (or (eq (preceding-char) ? )
 132                                     (aref (char-category-set (preceding-char))
 133                                           ?|)))))
 134              (forward-char 1))
 135            (cons (point) (current-column)))))
 136     (if (or (<= kinsoku-limit 0)
 137             (< (cdr pos-and-column) (+ (current-fill-column) kinsoku-limit)))
 138         (goto-char (car pos-and-column)))))
 139
 140 ;; Try to resolve `kinsoku' restriction by making the current line shorter.
 141 ;; The line can't be broken before the buffer position LINEBEG.
 142 (defun kinsoku-shorter (linebeg)
 143   (let ((pos (save-excursion
 144                (forward-char -1)
 145                (while (and
 146                        (< linebeg (point))
 147                        (or (aref (char-category-set (preceding-char)) ?<)
 148                            (aref (char-category-set (following-char)) ?>)
 149                            ;; protect non-kinsoku words
 150                            (not (or (eq (preceding-char) ? )
 151                                     (aref (char-category-set (preceding-char))
 152                                           ?|)))))
 153                  (forward-char -1))
 154                (point))))
 155     (if (< linebeg pos)
 156         (goto-char pos))))
 157
 158 ;;;###autoload
 159 (defun kinsoku (linebeg)
 160   "Go to a line breaking position near point by doing `kinsoku' processing.
 161 LINEBEG is a buffer position we can't break a line before.
 162
 163 `Kinsoku' processing is to prohibit specific characters to be placed
 164 at beginning of line or at end of line.  Characters not to be placed
 165 at beginning and end of line have character category `>' and `<'
 166 respectively.  This restriction is dissolved by making a line longer or
 167 shorter.
 168
 169 `Kinsoku' is a Japanese word which originally means ordering to stay
 170 in one place, and is used for the text processing described above in
 171 the context of text formatting."
 172   (if enable-kinsoku
 173       (if (or (and
 174                ;; The character after point can't be placed at beginning
 175                ;; of line.
 176                (aref (char-category-set (following-char)) ?>)
 177                ;; We at first try to dissolve this situation by making a
 178                ;; line longer.  If it fails, then try making a line
 179                ;; shorter.
 180                (not (kinsoku-longer)))
 181               ;; The character before point can't be placed at end of line.
 182               (aref (char-category-set (preceding-char)) ?<))
 183           (kinsoku-shorter linebeg))))
 184
 185 ;;; kinsoku.el ends here