gnu/dist/groff/src/libs/libgroff/unicode.cpp

   1 /*      $NetBSD$        */
   2
   3 // -*- C++ -*-
   4 /* Copyright (C) 2002
   5    Free Software Foundation, Inc.
   6      Written by Werner Lemberg <wl@gnu.org>
   7
   8 This file is part of groff.
   9
  10 groff is free software; you can redistribute it and/or modify it under
  11 the terms of the GNU General Public License as published by the Free
  12 Software Foundation; either version 2, or (at your option) any later
  13 version.
  14
  15 groff is distributed in the hope that it will be useful, but WITHOUT ANY
  16 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18 for more details.
  19
  20 You should have received a copy of the GNU General Public License along
  21 with groff; see the file COPYING.  If not, write to the Free Software
  22 Foundation, 51 Franklin St - Fifth Floor, Boston, MA 02110-1301, USA. */
  23
  24 #include "lib.h"
  25 #include "cset.h"
  26 #include "stringclass.h"
  27
  28 #include "unicode.h"
  29
  30 const char *check_unicode_name(const char *u)
  31 {
  32   if (*u != 'u')
  33     return 0;
  34   const char *p = ++u;
  35   for (;;) {
  36     int val = 0;
  37     const char *start = p;
  38     for (;;) {
  39       // only uppercase hex digits allowed
  40       if (!csxdigit(*p))
  41         return 0;
  42       if (csdigit(*p))
  43         val = val*0x10 + (*p-'0');
  44       else if (csupper(*p))
  45         val = val*0x10 + (*p-'A'+10);
  46       else
  47         return 0;
  48       // biggest Unicode value is U+10FFFF
  49       if (val > 0x10FFFF)
  50         return 0;
  51       p++;
  52       if (*p == '\0' || *p == '_')
  53         break;
  54     }
  55     // surrogates not allowed
  56     if ((val >= 0xD800 && val <= 0xDBFF) || (val >= 0xDC00 && val <= 0xDFFF))
  57       return 0;
  58     if (val > 0xFFFF) {
  59       if (*start == '0')        // no leading zeros allowed if > 0xFFFF
  60         return 0;
  61     }
  62     else if (p - start != 4)    // otherwise, check for exactly 4 hex digits
  63       return 0;
  64     if (*p == '\0')
  65       break;
  66     p++;
  67   }
  68   return u;
  69 }