wildmat.c

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/*** wildmat.c.orig     Wed Dec  3 11:46:31 1997 */
/*  $Revision: 1.1 $
**
**  Do shell-style pattern matching for ?, \, [], and * characters.
**  Might not be robust in face of malformed patterns; e.g., "foo[a-"
**  could cause a segmentation violation.  It is 8bit clean.
**
**  Written by Rich $alz, mirror!rs, Wed Nov 26 19:03:17 EST 1986.
**  Rich $alz is now <rsalz@osf.org>.
**  April, 1991:  Replaced mutually-recursive calls with in-line code
**  for the star character.
**
**  Special thanks to Lars Mathiesen <thorinn@diku.dk> for the ABORT code.
**  This can greatly speed up failing wildcard patterns.  For example:
**      pattern: -*-*-*-*-*-*-12-*-*-*-m-*-*-*
**      text 1:  -adobe-courier-bold-o-normal--12-120-75-75-m-70-iso8859-1
**      text 2:  -adobe-courier-bold-o-normal--12-120-75-75-X-70-iso8859-1
**  Text 1 matches with 51 calls, while text 2 fails with 54 calls.  Without
**  the ABORT code, it takes 22310 calls to fail.  Ugh.  The following
**  explanation is from Lars:
**  The precondition that must be fulfilled is that DoMatch will consume
**  at least one character in text.  This is true if *p is neither '*' nor
**  '\0'.)  The last return has ABORT instead of FALSE to avoid quadratic
**  behaviour in cases like pattern "*a*b*c*d" with text "abcxxxxx".  With
**  FALSE, each star-loop has to run to the end of the text; with ABORT
**  only the last one does.
**
**  Once the control of one instance of DoMatch enters the star-loop, that
**  instance will return either TRUE or ABORT, and any calling instance
**  will therefore return immediately after (without calling recursively
**  again).  In effect, only one star-loop is ever active.  It would be
**  possible to modify the code to maintain this context explicitly,
**  eliminating all recursive calls at the cost of some complication and
**  loss of clarity (and the ABORT stuff seems to be unclear enough by
**  itself).  I think it would be unwise to try to get this into a
**  released version unless you have a good test data base to try it out
**  on.
*/
 
#define TRUE   1
#define FALSE  0
#define ABORT -1
 
/* What character marks an inverted character class? */
#define NEGATE_CLASS '^'
/* Is "*" a common pattern? */
#define OPTIMIZE_JUST_STAR
/* Do tar(1) matching rules, which ignore a trailing slash? */
#undef MATCH_TAR_PATTERN
 
/*
**  Match text and p, return TRUE, FALSE, or ABORT.
*/
static int DoMatch(register char *text, register char *p)
{
  register int  last;
  register int  matched;
  register int  reverse;
 
  for (; *p; text++, p++) {
    if (*text == '\0' && *p != '*')
      return ABORT;
    switch (*p) {
      case '\\':                       /* Literal match with following character. */
        p++;
      case '?':                        /* Match anything. */
       continue;
      case '*':                        /* Consecutive stars act just like one. */
        while (*++p == '*')
          continue;
        if (*p == '\0') return TRUE;   /* Trailing star matches everything. */
         while (*text)
           if ((matched = DoMatch(text++, p)) != FALSE) return matched;
         return ABORT;
       case '[':
         reverse = p[1] == NEGATE_CLASS ? TRUE : FALSE;
         if (reverse) p++;             /* Inverted character class. */
         matched = FALSE;
         if (p[1] == ']' || p[1] == '-')
           if (*++p == *text) matched = TRUE;
         for (last = *p; *++p && *p != ']'; last = *p) /* This next line requires a good C compiler. */
           if (*p == '-' && p[1] != ']' ? *text <= *++p && *text >= last : *text == *p)
             matched = TRUE;
         if (matched == reverse) return FALSE;
         continue;
       default:                        /* FALLTHROUGH */
         if (*text != *p) return FALSE;
         continue;
    }
  }
 
#ifdef  MATCH_TAR_PATTERN
  if (*text == '/')
    return TRUE;
#endif  /* MATCH_TAR_ATTERN */
  return *text == '\0';
}
 
/*
**  User-level routine.  Returns TRUE or FALSE.
*/
int wildmat(char *text,char *p)
{
#ifdef  OPTIMIZE_JUST_STAR
  if (p[0] == '*' && p[1] == '\0')
    return TRUE;
#endif  /* OPTIMIZE_JUST_STAR */
  return DoMatch(text, p) == TRUE;
}