rm_/lib/mbschr.c

/* Searching a string for a character.
   Copyright (C) 2007-2022 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2007.

   This file is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation, either version 3 of the
   License, or (at your option) any later version.

   This file is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include <string.h>

#include "mbuiter.h"

/* Locate the first single-byte character C in the character string STRING,
   and return a pointer to it.  Return NULL if C is not found in STRING.  */
char *
mbschr (const char *string, int c)
{
  if (MB_CUR_MAX > 1
      /* Optimization: We know that ASCII characters < 0x30 don't occur as
         part of multibyte characters longer than 1 byte.  Hence, if c < 0x30,
         the faster unibyte loop can be used.  */
      && (unsigned char) c >= 0x30)
    {
      mbui_iterator_t iter;

      for (mbui_init (iter, string);; mbui_advance (iter))
        {
          if (!mbui_avail (iter))
            goto notfound;
          if (mb_len (mbui_cur (iter)) == 1
              && (unsigned char) * mbui_cur_ptr (iter) == (unsigned char) c)
            break;
        }
      return (char *) mbui_cur_ptr (iter);
     notfound:
      return NULL;
    }
  else
    return strchr (string, c);
}