1  /* Searching a string for a character.
       2     Copyright (C) 2007-2023 Free Software Foundation, Inc.
       3     Written by Bruno Haible <bruno@clisp.org>, 2007.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation, either version 3 of the
       8     License, or (at your option) any later version.
       9  
      10     This file 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 Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser 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 "mbuiterf.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        mbuif_state_t state;
      37        const char *iter;
      38        for (mbuif_init (state), iter = string;; )
      39          {
      40            if (!mbuif_avail (state, iter))
      41              goto notfound;
      42            mbchar_t cur = mbuif_next (state, iter);
      43            if (mb_len (cur) == 1 && (unsigned char) *iter == (unsigned char) c)
      44              break;
      45            iter += mb_len (cur);
      46          }
      47        return (char *) iter;
      48       notfound:
      49        return NULL;
      50      }
      51    else
      52      return strchr (string, c);
      53  }