BSD 4_4_Lite2 development

[unix-history] / usr / src / contrib / rc-1.4 / match.c

/* match.c: pattern matching routines */

#include "rc.h"

static int rangematch(char *, char);

enum { RANGE_FAIL = -1, RANGE_ERROR = -2 };

/* match() matches a single pattern against a single string. */

extern bool match(char *p, char *m, char *s) {
       int i, j;
       if (m == NULL)
               return streq(p, s);
       i = 0;
       while (1) {
               if (p[i] == '\0')
                       return *s == '\0';
               else if (m[i]) {
                       switch (p[i++]) {
                       case '?':
                               if (*s++ == '\0')
                                       return FALSE;
                               break;
                       case '*':
                               while (p[i] == '*' && m[i] == 1)        /* collapse multiple stars */
                                       i++;
                               if (p[i] == '\0')       /* star at end of pattern? */
                                       return TRUE;
                               while (*s != '\0')
                                       if (match(p + i, m + i, s++))
                                               return TRUE;
                               return FALSE;
                       case '[':
                               if (*s == '\0')
                                       return FALSE;
                               switch (j = rangematch(p + i, *s)) {
                               default:
                                       i += j;
                                       break;
                               case RANGE_FAIL:
                                       return FALSE;
                               case RANGE_ERROR:
                                       if (*s != '[')
                                               return FALSE;
                               }
                               s++;
                               break;
                       default:
                               panic("bad metacharacter in match");
                               /* NOTREACHED */
                               return FALSE; /* hush up gcc -Wall */
                       }
               } else if (p[i++] != *s++)
                       return FALSE;
       }
}

/*
  From the ed(1) man pages (on ranges):

       The `-' is treated as an ordinary character if it occurs first
       (or first after an initial ^) or last in the string.

       The right square bracket does not terminate the enclosed string
       if it is the first character (after an initial `^', if any), in
       the bracketed string.

  rangematch() matches a single character against a class, and returns
  an integer offset to the end of the range on success, or -1 on
  failure.
*/

static int rangematch(char *p, char c) {
       char *orig = p;
       bool neg = (*p == '~');
       bool matched = FALSE;
       if (neg)
               p++;
       if (*p == ']') {
               p++;
               matched = (c == ']');
       }
       for (; *p != ']'; p++) {
               if (*p == '\0')
                       return RANGE_ERROR;     /* bad syntax */
               if (p[1] == '-' && p[2] != ']') { /* check for [..-..] but ignore [..-] */
                       if (c >= *p)
                               matched |= (c <= p[2]);
                       p += 2;
               } else {
                       matched |= (*p == c);
               }
       }
       if (matched ^ neg)
               return p - orig + 1; /* skip the right-bracket */
       else
               return RANGE_FAIL;
}