stdlib/rpmatch.c

   1 /* rpmatch - determine whether string value is affirmation or negative
   2              response according to current locale's data
   3 Copyright (C) 1996 Free Software Foundation, Inc.
   4
   5 This file is part of the GNU C Library.
   6
   7 The GNU C Library is free software; you can redistribute it and/or
   8 modify it under the terms of the GNU Library General Public License as
   9 published by the Free Software Foundation; either version 2 of the
  10 License, or (at your option) any later version.
  11
  12 The GNU C Library is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15 Library General Public License for more details.
  16
  17 You should have received a copy of the GNU Library General Public
  18 License along with the GNU C Library; see the file COPYING.LIB.  If
  19 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #include <langinfo.h>
  23 #include <stdlib.h>
  24 #include <regex.h>
  25
  26
  27 int
  28 rpmatch (response)
  29      const char *response;
  30 {
  31   /* Match against one of the response patterns, compiling the pattern
  32      first if necessary.  */
  33   inline int try (const int tag, const int match, const int nomatch,
  34                   const char **lastp, regex_t *re)
  35     {
  36       const char *pattern = nl_langinfo (tag);
  37       if (pattern != *lastp)
  38         {
  39           /* The pattern has changed.  */
  40           if (*lastp)
  41             {
  42               /* Free the old compiled pattern.  */
  43               regfree (re);
  44               *lastp = NULL;
  45             }
  46           /* Compile the pattern and cache it for future runs.  */
  47           if (regcomp (re, pattern, REG_EXTENDED) != 0)
  48             return -1;
  49           *lastp = pattern;
  50         }
  51
  52       /* Try the pattern.  */
  53       return regexec (re, response, 0, NULL, 0) == 0 ? match : nomatch;
  54     }
  55
  56   /* We cache the response patterns and compiled regexps here.  */
  57   static const char *yesexpr, *noexpr;
  58   static regex_t yesre, nore;
  59
  60   return (try (YESEXPR, 1, 0, &yesexpr, &yesre) ?:
  61           try (NOEXPR, 0, -1, &noexpr, &nore));
  62 }