lib/mbschr.c

   1 /* Searching a string for a character.
   2    Copyright (C) 2007-2020 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2007.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 /* Specification.  */
  21 #include <string.h>
  22
  23 #include "mbuiter.h"
  24
  25 /* Locate the first single-byte character C in the character string STRING,
  26    and return a pointer to it.  Return NULL if C is not found in STRING.  */
  27 char *
  28 mbschr (const char *string, int c)
  29 {
  30   if (MB_CUR_MAX > 1
  31       /* Optimization: We know that ASCII characters < 0x30 don't occur as
  32          part of multibyte characters longer than 1 byte.  Hence, if c < 0x30,
  33          the faster unibyte loop can be used.  */
  34       && (unsigned char) c >= 0x30)
  35     {
  36       mbui_iterator_t iter;
  37
  38       for (mbui_init (iter, string);; mbui_advance (iter))
  39         {
  40           if (!mbui_avail (iter))
  41             goto notfound;
  42           if (mb_len (mbui_cur (iter)) == 1
  43               && (unsigned char) * mbui_cur_ptr (iter) == (unsigned char) c)
  44             break;
  45         }
  46       return (char *) mbui_cur_ptr (iter);
  47      notfound:
  48       return NULL;
  49     }
  50   else
  51     return strchr (string, c);
  52 }