kc3-lang/gnulib/lib/mbspcasecmp.c

• Show log

  Commit

• Hash : b9be00f4
  Author :
  Date : 2023-08-26T23:19:10
  

  Tune single-byte code involving tolower
  
  * lib/mbmemcasecmp.c (mbmemcasecmp):
  * lib/mbscasecmp.c (mbscasecmp):
  * lib/mbscasestr.c (mbscasestr):
  * lib/mbsncasecmp.c (mbsncasecmp):
  * lib/mbspcasecmp.c (mbspcasecmp):
  Avoid some unnecessary calls to tolower.  For example, if the two
  single-byte characters are equal before downcasing there is no
  need to call tolower on either character.
  

Download

• lib/mbspcasecmp.c

• /* Case-insensitive string comparison function.
     Copyright (C) 1998-1999, 2005-2008, 2010-2023 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 <ctype.h>
  
  #include "mbuiterf.h"
  
  /* Compare the initial segment of the character string STRING consisting of
     at most mbslen (PREFIX) characters with the character string PREFIX,
     ignoring case.  If the two match, return a pointer to the first byte
     after this prefix in STRING.  Otherwise, return NULL.
     Note: This function may, in multibyte locales, return non-NULL if STRING
     is of smaller length than PREFIX!  */
  char *
  mbspcasecmp (const char *string, const char *prefix)
  {
    /* This is essentially the same as
         mbsncasecmp (string, prefix, mbslen (prefix))
       just with small optimizations.  */
    if (string == prefix)
      return (char *) (string + strlen (string));
  
    const char *iter1 = string;
    const char *iter2 = prefix;
  
    /* Be careful not to look at the entire extent of STRING or PREFIX until
       needed.  This is useful because when two strings differ, the difference is
       most often already in the very few first characters.  */
    if (MB_CUR_MAX > 1)
      {
        mbuif_state_t state1;
        mbuif_init (state1);
  
        mbuif_state_t state2;
        mbuif_init (state2);
  
        while (mbuif_avail (state1, iter1) && mbuif_avail (state2, iter2))
          {
            mbchar_t cur1 = mbuif_next (state1, iter1);
            mbchar_t cur2 = mbuif_next (state2, iter2);
            int cmp = mb_casecmp (cur1, cur2);
  
            if (cmp != 0)
              return NULL;
  
            iter1 += mb_len (cur1);
            iter2 += mb_len (cur2);
          }
        if (!mbuif_avail (state2, iter2))
          /* PREFIX equals STRING or is terminated before STRING.  */
          return (char *) iter1;
        else
          /* STRING terminated before PREFIX.  */
          return NULL;
      }
    else
      for (;; iter1++, iter2++)
        {
          unsigned char c2 = *iter2;
  
          if (c2 == '\0')
            /* PREFIX equals STRING or is terminated before STRING.  */
            return (char *) iter1;
  
          unsigned char c1 = *iter1;
  
          if (c1 != c2)
            {
              c1 = tolower (c1);
              if (c1 != c2 && c1 != tolower (c2))
                /* STRING and PREFIX disagree,
                   or STRING terminated before PREFIX.  */
                return NULL;
            }
        }
  }
  

Download