stdlib/rpmatch.c

   1 /* Determine whether string value is affirmation or negative response
   2    according to current locale's data.
   3    This file is part of the GNU C Library.
   4    Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <langinfo.h>
  22 #include <stdlib.h>
  23 #include <regex.h>
  24
  25
  26 int
  27 rpmatch (response)
  28      const char *response;
  29 {
  30   /* Match against one of the response patterns, compiling the pattern
  31      first if necessary.  */
  32   inline int try (const int tag, const int match, const int nomatch,
  33                   const char **lastp, regex_t *re)
  34     {
  35       const char *pattern = nl_langinfo (tag);
  36       if (pattern != *lastp)
  37         {
  38           /* The pattern has changed.  */
  39           if (*lastp)
  40             {
  41               /* Free the old compiled pattern.  */
  42               regfree (re);
  43               *lastp = NULL;
  44             }
  45           /* Compile the pattern and cache it for future runs.  */
  46           if (regcomp (re, pattern, REG_EXTENDED) != 0)
  47             return -1;
  48           *lastp = pattern;
  49         }
  50
  51       /* Try the pattern.  */
  52       return regexec (re, response, 0, NULL, 0) == 0 ? match : nomatch;
  53     }
  54
  55   /* We cache the response patterns and compiled regexps here.  */
  56   static const char *yesexpr, *noexpr;
  57   static regex_t yesre, nore;
  58
  59   return (try (YESEXPR, 1, 0, &yesexpr, &yesre) ?:
  60           try (NOEXPR, 0, -1, &noexpr, &nore));
  61 }