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strmatch.c

/***********************************************************************
*                                                                      *
*               This software is part of the ast package               *
*           Copyright (c) 1985-2007 AT&T Knowledge Ventures            *
*                      and is licensed under the                       *
*                  Common Public License, Version 1.0                  *
*                      by AT&T Knowledge Ventures                      *
*                                                                      *
*                A copy of the License is available at                 *
*            http://www.opensource.org/licenses/cpl1.0.txt             *
*         (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9)         *
*                                                                      *
*              Information and Software Systems Research               *
*                            AT&T Research                             *
*                           Florham Park NJ                            *
*                                                                      *
*                 Glenn Fowler <gsf@research.att.com>                  *
*                  David Korn <dgk@research.att.com>                   *
*                   Phong Vo <kpv@research.att.com>                    *
*                                                                      *
***********************************************************************/
#pragma prototyped

/*
 * D. G. Korn
 * G. S. Fowler
 * AT&T Research
 *
 * match shell file patterns
 * this interface is a wrapper on regex
 *
 *    sh pattern  egrep RE    description
 *    ----------  --------    -----------
 *    *           .*          0 or more chars
 *    ?           .           any single char
 *    [.]         [.]         char class
 *    [!.]        [^.]        negated char class
 *    [[:.:]]           [[:.:]]           ctype class
 *    [[=.=]]           [[=.=]]           equivalence class
 *    [[...]]           [[...]]           collation element
 *    *(.)        (.)*        0 or more of
 *    +(.)        (.)+        1 or more of
 *    ?(.)        (.)?        0 or 1 of
 *    (.)         (.)         1 of
 *    @(.)        (.)         1 of
 *    a|b         a|b         a or b
 *    \#                      () subgroup back reference [1-9]
 *    a&b                     a and b
 *    !(.)                    none of
 *
 * \ used to escape metacharacters
 *
 *    *, ?, (, |, &, ), [, \ must be \'d outside of [...]
 *    only ] must be \'d inside [...]
 *
 */

#include <ast.h>
#include <regex.h>

static struct State_s
{
      regmatch_t* match;
      int         nmatch;
} matchstate;

/*
 * subgroup match
 * 0 returned if no match
 * otherwise number of subgroups matched returned
 * match group begin offsets are even elements of sub
 * match group end offsets are odd elements of sub
 * the matched string is from s+sub[0] up to but not
 * including s+sub[1]
 */

int
strgrpmatch(const char* b, const char* p, int* sub, int n, register int flags)
{
      register regex_t* re;
      register int*           end;
      register int            i;
      register regflags_t     reflags;

      /*
       * 0 and empty patterns are special
       */

      if (!p || !b)
      {
            if (!p && !b)
                  regcache(NiL, 0, NiL);
            return 0;
      }
      if (!*p)
            return *b == 0;

      /*
       * convert flags
       */

      if (flags & REG_ADVANCE)
            reflags = flags & ~REG_ADVANCE;
      else
      {
            reflags = REG_SHELL|REG_AUGMENTED;
            if (!(flags & STR_MAXIMAL))
                  reflags |= REG_MINIMAL;
            if (flags & STR_GROUP)
                  reflags |= REG_SHELL_GROUP;
            if (flags & STR_LEFT)
                  reflags |= REG_LEFT;
            if (flags & STR_RIGHT)
                  reflags |= REG_RIGHT;
            if (flags & STR_ICASE)
                  reflags |= REG_ICASE;
      }
      if (!sub || n <= 0)
            reflags |= REG_NOSUB;
      if (!(re = regcache(p, reflags, NiL)))
            return 0;
      if (n > matchstate.nmatch)
      {
            if (!(matchstate.match = newof(matchstate.match, regmatch_t, n, 0)))
                  return 0;
            matchstate.nmatch = n;
      }
      if (regexec(re, b, n, matchstate.match, reflags & ~(REG_MINIMAL|REG_SHELL_GROUP|REG_LEFT|REG_RIGHT|REG_ICASE)))
            return 0;
      if (!sub || n <= 0)
            return 1;
      i = re->re_nsub;
      end = sub + n * 2;
      for (n = 0; sub < end && n <= i; n++)
      {
            *sub++ = matchstate.match[n].rm_so;
            *sub++ = matchstate.match[n].rm_eo;
      }
      return i + 1;
}

/*
 * compare the string s with the shell pattern p
 * returns 1 for match 0 otherwise
 */

int
strmatch(const char* s, const char* p)
{
      return strgrpmatch(s, p, NiL, 0, STR_MAXIMAL|STR_LEFT|STR_RIGHT);
}

/*
 * leading substring match
 * first char after end of substring returned
 * 0 returned if no match
 *
 * OBSOLETE: use strgrpmatch()
 */

char*
strsubmatch(const char* s, const char* p, int flags)
{
      int   match[2];

      return strgrpmatch(s, p, match, 1, (flags ? STR_MAXIMAL : 0)|STR_LEFT) ? (char*)s + match[1] : (char*)0;
}

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