src/casetab.c

   1 /* GNU Emacs routines to deal with case tables.
   2    Copyright (C) 1993, 1994 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Emacs.
   5
   6 GNU Emacs is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Emacs is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Emacs; see the file COPYING.  If not, write to
  18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 /* Written by Howard Gayle.  See chartab.c for details. */
  22
  23 #include <config.h>
  24 #include "lisp.h"
  25 #include "buffer.h"
  26
  27 Lisp_Object Qcase_table_p, Qcase_table;
  28 Lisp_Object Vascii_downcase_table, Vascii_upcase_table;
  29 Lisp_Object Vascii_canon_table, Vascii_eqv_table;
  30
  31 static void compute_trt_inverse ();
  32
  33 DEFUN ("case-table-p", Fcase_table_p, Scase_table_p, 1, 1, 0,
  34   "Return t iff OBJECT is a case table.\n\
  35 See `set-case-table' for more information on these data structures.")
  36   (object)
  37      Lisp_Object object;
  38 {
  39   Lisp_Object up, canon, eqv;
  40
  41   if (! CHAR_TABLE_P (object))
  42     return Qnil;
  43   if (! EQ (XCHAR_TABLE (object)->purpose, Qcase_table))
  44     return Qnil;
  45
  46   up = XCHAR_TABLE (object)->extras[0];
  47   canon = XCHAR_TABLE (object)->extras[1];
  48   eqv = XCHAR_TABLE (object)->extras[2];
  49
  50   return ((NILP (up) || CHAR_TABLE_P (up))
  51           && ((NILP (canon) && NILP (eqv))
  52               || (CHAR_TABLE_P (canon)
  53                   && (NILP (eqv) || CHAR_TABLE_P (eqv))))
  54           ? Qt : Qnil);
  55 }
  56
  57 static Lisp_Object
  58 check_case_table (obj)
  59      Lisp_Object obj;
  60 {
  61   register Lisp_Object tem;
  62
  63   while (tem = Fcase_table_p (obj), NILP (tem))
  64     obj = wrong_type_argument (Qcase_table_p, obj);
  65   return (obj);
  66 }
  67
  68 DEFUN ("current-case-table", Fcurrent_case_table, Scurrent_case_table, 0, 0, 0,
  69   "Return the case table of the current buffer.")
  70   ()
  71 {
  72   return current_buffer->downcase_table;
  73 }
  74
  75 DEFUN ("standard-case-table", Fstandard_case_table, Sstandard_case_table, 0, 0, 0,
  76   "Return the standard case table.\n\
  77 This is the one used for new buffers.")
  78   ()
  79 {
  80   return Vascii_downcase_table;
  81 }
  82
  83 static Lisp_Object set_case_table ();
  84
  85 DEFUN ("set-case-table", Fset_case_table, Sset_case_table, 1, 1, 0,
  86   "Select a new case table for the current buffer.\n\
  87 A case table is a char-table which maps characters\n\
  88 to their lower-case equivalents.  It also has three \"extra\" slots\n\
  89 which may be additional char-tables or nil.\n\
  90 These slots are called UPCASE, CANONICALIZE and EQUIVALENCES.\n\
  91 UPCASE maps each character to its upper-case equivalent;\n\
  92  if lower and upper case characters are in 1-1 correspondence,\n\
  93  you may use nil and the upcase table will be deduced from DOWNCASE.\n\
  94 CANONICALIZE maps each character to a canonical equivalent;\n\
  95  any two characters that are related by case-conversion have the same\n\
  96  canonical equivalent character; it may be nil, in which case it is\n\
  97  deduced from DOWNCASE and UPCASE.\n\
  98 EQUIVALENCES is a map that cyclicly permutes each equivalence class\n\
  99  (of characters with the same canonical equivalent); it may be nil,\n\
 100  in which case it is deduced from CANONICALIZE.")
 101   (table)
 102      Lisp_Object table;
 103 {
 104   return set_case_table (table, 0);
 105 }
 106
 107 DEFUN ("set-standard-case-table", Fset_standard_case_table, Sset_standard_case_table, 1, 1, 0,
 108   "Select a new standard case table for new buffers.\n\
 109 See `set-case-table' for more info on case tables.")
 110   (table)
 111      Lisp_Object table;
 112 {
 113   return set_case_table (table, 1);
 114 }
 115
 116 static Lisp_Object
 117 set_case_table (table, standard)
 118      Lisp_Object table;
 119      int standard;
 120 {
 121   Lisp_Object up, canon, eqv;
 122
 123   check_case_table (table);
 124
 125   up = XCHAR_TABLE (table)->extras[0];
 126   canon = XCHAR_TABLE (table)->extras[1];
 127   eqv = XCHAR_TABLE (table)->extras[2];
 128
 129   if (NILP (up))
 130     {
 131       up = Fmake_char_table (Qcase_table, Qnil);
 132       compute_trt_inverse (XCHAR_TABLE (table), XCHAR_TABLE (up));
 133       XCHAR_TABLE (table)->extras[0] = up;
 134     }
 135
 136   if (NILP (canon))
 137     {
 138       register int i;
 139       Lisp_Object *upvec = XCHAR_TABLE (up)->contents;
 140       Lisp_Object *downvec = XCHAR_TABLE (table)->contents;
 141
 142       canon = Fmake_char_table (Qcase_table, Qnil);
 143
 144       /* Set up the CANON vector; for each character,
 145          this sequence of upcasing and downcasing ought to
 146          get the "preferred" lowercase equivalent.  */
 147       for (i = 0; i < 256; i++)
 148         XCHAR_TABLE (canon)->contents[i] = downvec[upvec[downvec[i]]];
 149       XCHAR_TABLE (table)->extras[1] = canon;
 150     }
 151
 152   if (NILP (eqv))
 153     {
 154       eqv = Fmake_char_table (Qcase_table, Qnil);
 155       compute_trt_inverse (XCHAR_TABLE (canon), XCHAR_TABLE (eqv));
 156       XCHAR_TABLE (table)->extras[2] = eqv;
 157     }
 158
 159   if (standard)
 160     Vascii_downcase_table = table;
 161   else
 162     current_buffer->downcase_table = table;
 163
 164   return table;
 165 }
 166 \f
 167 /* Given a translate table TRT, store the inverse mapping into INVERSE.
 168    Since TRT is not one-to-one, INVERSE is not a simple mapping.
 169    Instead, it divides the space of characters into equivalence classes.
 170    All characters in a given class form one circular list, chained through
 171    the elements of INVERSE.  */
 172
 173 static void
 174 compute_trt_inverse (trt, inverse)
 175      struct Lisp_Char_Table *trt, *inverse;
 176 {
 177   register int i = 0400;
 178   register unsigned char c, q;
 179
 180   while (i--)
 181     inverse->contents[i] = i;
 182   i = 0400;
 183   while (i--)
 184     {
 185       if ((q = trt->contents[i]) != (unsigned char) i)
 186         {
 187           c = inverse->contents[q];
 188           inverse->contents[q] = i;
 189           inverse->contents[i] = c;
 190         }
 191     }
 192 }
 193 \f
 194 init_casetab_once ()
 195 {
 196   register int i;
 197   Lisp_Object down, up;
 198   Qcase_table = intern ("case-table");
 199   staticpro (&Qcase_table);
 200
 201   /* Intern this now in case it isn't already done.
 202      Setting this variable twice is harmless.
 203      But don't staticpro it here--that is done in alloc.c.  */
 204   Qchar_table_extra_slots = intern ("char-table-extra-slots");
 205
 206   /* Now we are ready to set up this property, so we can
 207      create char tables.  */
 208   Fput (Qcase_table, Qchar_table_extra_slots, make_number (3));
 209
 210   down = Fmake_char_table (Qcase_table, Qnil);
 211   Vascii_downcase_table = down;
 212
 213   for (i = 0; i < 256; i++)
 214     XCHAR_TABLE (down)->contents[i] = (i >= 'A' && i <= 'Z') ? i + 040 : i;
 215
 216   XCHAR_TABLE (down)->extras[1] = Fcopy_sequence (down);
 217
 218   up = Fmake_char_table (Qcase_table, Qnil);
 219   XCHAR_TABLE (down)->extras[0] = up;
 220
 221   for (i = 0; i < 256; i++)
 222     XCHAR_TABLE (up)->contents[i]
 223       = ((i >= 'A' && i <= 'Z')
 224          ? i + ('a' - 'A')
 225          : ((i >= 'a' && i <= 'z')
 226             ? i + ('A' - 'a')
 227             : i));
 228
 229   XCHAR_TABLE (down)->extras[2] = Fcopy_sequence (up);
 230 }
 231
 232 syms_of_casetab ()
 233 {
 234   Qcase_table_p = intern ("case-table-p");
 235   staticpro (&Qcase_table_p);
 236
 237   staticpro (&Vascii_downcase_table);
 238
 239   defsubr (&Scase_table_p);
 240   defsubr (&Scurrent_case_table);
 241   defsubr (&Sstandard_case_table);
 242   defsubr (&Sset_case_table);
 243   defsubr (&Sset_standard_case_table);
 244 }