string/strsep.c

   1 /* Copyright (C) 1992, 93, 96, 97, 98, 99, 2004 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <string.h>
  20
  21 #undef __strsep
  22 #undef strsep
  23
  24 char *
  25 __strsep (char **stringp, const char *delim)
  26 {
  27   char *begin, *end;
  28
  29   begin = *stringp;
  30   if (begin == NULL)
  31     return NULL;
  32
  33   /* A frequent case is when the delimiter string contains only one
  34      character.  Here we don't need to call the expensive `strpbrk'
  35      function and instead work using `strchr'.  */
  36   if (delim[0] == '\0' || delim[1] == '\0')
  37     {
  38       char ch = delim[0];
  39
  40       if (ch == '\0')
  41         end = NULL;
  42       else
  43         {
  44           if (*begin == ch)
  45             end = begin;
  46           else if (*begin == '\0')
  47             end = NULL;
  48           else
  49             end = strchr (begin + 1, ch);
  50         }
  51     }
  52   else
  53     /* Find the end of the token.  */
  54     end = strpbrk (begin, delim);
  55
  56   if (end)
  57     {
  58       /* Terminate the token and set *STRINGP past NUL character.  */
  59       *end++ = '\0';
  60       *stringp = end;
  61     }
  62   else
  63     /* No more delimiters; this is the last token.  */
  64     *stringp = NULL;
  65
  66   return begin;
  67 }
  68 weak_alias (__strsep, strsep)
  69 strong_alias (__strsep, __strsep_g)
  70 libc_hidden_def (__strsep_g)