1  /* Internal header containing implementation of wcwidth() function.
       2     Copyright (C) 1996-2023 Free Software Foundation, Inc.
       3     This file is part of the GNU C Library.
       4  
       5     The GNU C Library is free software; you can redistribute it and/or
       6     modify it under the terms of the GNU Lesser General Public
       7     License as published by the Free Software Foundation; either
       8     version 2.1 of the License, or (at your option) any later version.
       9  
      10     The GNU C Library is distributed in the hope that it will be useful,
      11     but WITHOUT ANY WARRANTY; without even the implied warranty of
      12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
      13     Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public
      16     License along with the GNU C Library; if not, see
      17     <https://www.gnu.org/licenses/>.  */
      18  
      19  #include <wchar.h>
      20  #include <wctype.h>
      21  #include "../wctype/wchar-lookup.h"
      22  #include "../locale/localeinfo.h"
      23  
      24  /* Table containing width information.  */
      25  extern const char *__ctype32_width attribute_hidden;
      26  
      27  static __inline int
      28  internal_wcwidth (wchar_t wc)
      29  {
      30    unsigned char res;
      31  
      32    /* The tables have been prepared in such a way that
      33       1. wc == L'\0' yields res = 0,
      34       2. !iswprint (wc) implies res = '\xff'.  */
      35    res = wcwidth_table_lookup (_NL_CURRENT (LC_CTYPE, _NL_CTYPE_WIDTH), wc);
      36  
      37    return res == (unsigned char) '\xff' ? -1 : (int) res;
      38  }