Logo Search packages:      
Sourcecode: pwlib version File versions  Download package

engine.c

/*
 * The matching engine and friends.  This file is #included by regexec.c
 * after suitable #defines of a variety of macros used herein, so that
 * different state representations can be used without duplicating masses
 * of code.
 */

#ifdef SNAMES
#define     matcher     smatcher
#define     fast  sfast
#define     slow  sslow
#define     dissect     sdissect
#define     backref     sbackref
#define     step  sstep
#define     print sprint
#define     at    sat
#define     match smat
#endif
#ifdef LNAMES
#define     matcher     lmatcher
#define     fast  lfast
#define     slow  lslow
#define     dissect     ldissect
#define     backref     lbackref
#define     step  lstep
#define     print lprint
#define     at    lat
#define     match lmat
#endif

/* another structure passed up and down to avoid zillions of parameters */
00032 struct match {
      struct re_guts *g;
      int eflags;
      regmatch_t *pmatch;     /* [nsub+1] (0 element unused) */
      char *offp;       /* offsets work from here */
      char *beginp;           /* start of string -- virtual NUL precedes */
      char *endp;       /* end of string -- virtual NUL here */
      char *coldp;            /* can be no match starting before here */
      char **lastpos;         /* [nplus+1] */
      STATEVARS;
      states st;        /* current states */
      states fresh;           /* states for a fresh start */
      states tmp;       /* temporary */
      states empty;           /* empty set of states */
};

#include "engine.ih"

#ifdef REDEBUG
#define     SP(t, s, c) print(m, t, s, c, stdout)
#define     AT(t, p1, p2, s1, s2)   at(m, t, p1, p2, s1, s2)
#define     NOTE(str)   { if (m->eflags&REG_TRACE) printf("=%s\n", (str)); }
#else
#define     SP(t, s, c) /* nothing */
#define     AT(t, p1, p2, s1, s2)   /* nothing */
#define     NOTE(s)     /* nothing */
#endif

/*
 - matcher - the actual matching engine
 == static int matcher(register struct re_guts *g, char *string, \
 ==   size_t nmatch, regmatch_t pmatch[], int eflags);
 */
static int              /* 0 success, REG_NOMATCH failure */
matcher(g, string, nmatch, pmatch, eflags)
register struct re_guts *g;
char *string;
size_t nmatch;
regmatch_t pmatch[];
int eflags;
{
      register char *endp;
      register int i;
      struct match mv;
      register struct match *m = &mv;
      register char *dp;
      const register sopno gf = g->firststate+1;      /* +1 for OEND */
      const register sopno gl = g->laststate;
      char *start;
      char *stop;

      /* simplify the situation where possible */
      if (g->cflags&REG_NOSUB)
            nmatch = 0;
      if (eflags&REG_STARTEND) {
            start = string + pmatch[0].rm_so;
            stop = string + pmatch[0].rm_eo;
      } else {
            start = string;
            stop = start + strlen(start);
      }
      if (stop < start)
            return(REG_INVARG);

      /* prescreening; this does wonders for this rather slow code */
      if (g->must != NULL) {
            for (dp = start; dp < stop; dp++)
                  if (*dp == g->must[0] && stop - dp >= g->mlen &&
                        memcmp(dp, g->must, (size_t)g->mlen) == 0)
                        break;
            if (dp == stop)         /* we didn't find g->must */
                  return(REG_NOMATCH);
      }

      /* match struct setup */
      m->g = g;
      m->eflags = eflags;
      m->pmatch = NULL;
      m->lastpos = NULL;
      m->offp = string;
      m->beginp = start;
      m->endp = stop;
      STATESETUP(m, 4);
      SETUP(m->st);
      SETUP(m->fresh);
      SETUP(m->tmp);
      SETUP(m->empty);
      CLEAR(m->empty);

      /* this loop does only one repetition except for backrefs */
      for (;;) {
            endp = fast(m, start, stop, gf, gl);
            if (endp == NULL) {           /* a miss */
                  STATETEARDOWN(m);
                  return(REG_NOMATCH);
            }
            if (nmatch == 0 && !g->backrefs)
                  break;            /* no further info needed */

            /* where? */
            assert(m->coldp != NULL);
            for (;;) {
                  NOTE("finding start");
                  endp = slow(m, m->coldp, stop, gf, gl);
                  if (endp != NULL)
                        break;
                  assert(m->coldp < m->endp);
                  m->coldp++;
            }
            if (nmatch == 1 && !g->backrefs)
                  break;            /* no further info needed */

            /* oh my, he wants the subexpressions... */
            if (m->pmatch == NULL)
                  m->pmatch = (regmatch_t *)malloc((m->g->nsub + 1) *
                                          sizeof(regmatch_t));
            if (m->pmatch == NULL) {
                  STATETEARDOWN(m);
                  return(REG_ESPACE);
            }
            for (i = 1; i <= m->g->nsub; i++)
                  m->pmatch[i].rm_so = m->pmatch[i].rm_eo = -1;
            if (!g->backrefs && !(m->eflags&REG_BACKR)) {
                  NOTE("dissecting");
                  dp = dissect(m, m->coldp, endp, gf, gl);
            } else {
                  if (g->nplus > 0 && m->lastpos == NULL)
                        m->lastpos = (char **)malloc((g->nplus+1) *
                                          sizeof(char *));
                  if (g->nplus > 0 && m->lastpos == NULL) {
                        free(m->pmatch);
                        STATETEARDOWN(m);
                        return(REG_ESPACE);
                  }
                  NOTE("backref dissect");
                  dp = backref(m, m->coldp, endp, gf, gl, (sopno)0);
            }
            if (dp != NULL)
                  break;

            /* uh-oh... we couldn't find a subexpression-level match */
            assert(g->backrefs);    /* must be back references doing it */
            assert(g->nplus == 0 || m->lastpos != NULL);
            for (;;) {
                  if (dp != NULL || endp <= m->coldp)
                        break;            /* defeat */
                  NOTE("backoff");
                  endp = slow(m, m->coldp, endp-1, gf, gl);
                  if (endp == NULL)
                        break;            /* defeat */
                  /* try it on a shorter possibility */
#ifndef NDEBUG
                  for (i = 1; i <= m->g->nsub; i++) {
                        assert(m->pmatch[i].rm_so == -1);
                        assert(m->pmatch[i].rm_eo == -1);
                  }
#endif
                  NOTE("backoff dissect");
                  dp = backref(m, m->coldp, endp, gf, gl, (sopno)0);
            }
            assert(dp == NULL || dp == endp);
            if (dp != NULL)         /* found a shorter one */
                  break;

            /* despite initial appearances, there is no match here */
            NOTE("false alarm");
            start = m->coldp + 1;   /* recycle starting later */
            assert(start <= stop);
      }

      /* fill in the details if requested */
      if (nmatch > 0) {
            pmatch[0].rm_so = m->coldp - m->offp;
            pmatch[0].rm_eo = endp - m->offp;
      }
      if (nmatch > 1) {
            assert(m->pmatch != NULL);
            for (i = 1; i < nmatch; i++)
                  if (i <= m->g->nsub)
                        pmatch[i] = m->pmatch[i];
                  else {
                        pmatch[i].rm_so = -1;
                        pmatch[i].rm_eo = -1;
                  }
      }

      if (m->pmatch != NULL)
            free((char *)m->pmatch);
      if (m->lastpos != NULL)
            free((char *)m->lastpos);
      STATETEARDOWN(m);
      return(0);
}

/*
 - dissect - figure out what matched what, no back references
 == static char *dissect(register struct match *m, char *start, \
 ==   char *stop, sopno startst, sopno stopst);
 */
static char *                 /* == stop (success) always */
dissect(m, start, stop, startst, stopst)
register struct match *m;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
      register int i;
      register sopno ss;      /* start sop of current subRE */
      register sopno es;      /* end sop of current subRE */
      register char *sp;      /* start of string matched by it */
      register char *stp;     /* string matched by it cannot pass here */
      register char *rest;    /* start of rest of string */
      register char *tail;    /* string unmatched by rest of RE */
      register sopno ssub;    /* start sop of subsubRE */
      register sopno esub;    /* end sop of subsubRE */
      register char *ssp;     /* start of string matched by subsubRE */
      register char *sep;     /* end of string matched by subsubRE */
      register char *oldssp;  /* previous ssp */
      register char *dp;

      AT("diss", start, stop, startst, stopst);
      sp = start;
      for (ss = startst; ss < stopst; ss = es) {
            /* identify end of subRE */
            es = ss;
            switch (OP(m->g->strip[es])) {
            case OPLUS_:
            case OQUEST_:
                  es += OPND(m->g->strip[es]);
                  break;
            case OCH_:
                  while (OP(m->g->strip[es]) != O_CH)
                        es += OPND(m->g->strip[es]);
                  break;
            }
            es++;

            /* figure out what it matched */
            switch (OP(m->g->strip[ss])) {
            case OEND:
                  assert(nope);
                  break;
            case OCHAR:
                  sp++;
                  break;
            case OBOL:
            case OEOL:
            case OBOW:
            case OEOW:
                  break;
            case OANY:
            case OANYOF:
                  sp++;
                  break;
            case OBACK_:
            case O_BACK:
                  assert(nope);
                  break;
            /* cases where length of match is hard to find */
            case OQUEST_:
                  stp = stop;
                  for (;;) {
                        /* how long could this one be? */
                        rest = slow(m, sp, stp, ss, es);
                        assert(rest != NULL);   /* it did match */
                        /* could the rest match the rest? */
                        tail = slow(m, rest, stop, es, stopst);
                        if (tail == stop)
                              break;            /* yes! */
                        /* no -- try a shorter match for this one */
                        stp = rest - 1;
                        assert(stp >= sp);      /* it did work */
                  }
                  ssub = ss + 1;
                  esub = es - 1;
                  /* did innards match? */
                  if (slow(m, sp, rest, ssub, esub) != NULL) {
                        dp = dissect(m, sp, rest, ssub, esub);
                        assert(dp == rest);
                  } else            /* no */
                        assert(sp == rest);
                  sp = rest;
                  break;
            case OPLUS_:
                  stp = stop;
                  for (;;) {
                        /* how long could this one be? */
                        rest = slow(m, sp, stp, ss, es);
                        assert(rest != NULL);   /* it did match */
                        /* could the rest match the rest? */
                        tail = slow(m, rest, stop, es, stopst);
                        if (tail == stop)
                              break;            /* yes! */
                        /* no -- try a shorter match for this one */
                        stp = rest - 1;
                        assert(stp >= sp);      /* it did work */
                  }
                  ssub = ss + 1;
                  esub = es - 1;
                  ssp = sp;
                  oldssp = ssp;
                  for (;;) {  /* find last match of innards */
                        sep = slow(m, ssp, rest, ssub, esub);
                        if (sep == NULL || sep == ssp)
                              break;      /* failed or matched null */
                        oldssp = ssp;     /* on to next try */
                        ssp = sep;
                  }
                  if (sep == NULL) {
                        /* last successful match */
                        sep = ssp;
                        ssp = oldssp;
                  }
                  assert(sep == rest);    /* must exhaust substring */
                  assert(slow(m, ssp, sep, ssub, esub) == rest);
                  dp = dissect(m, ssp, sep, ssub, esub);
                  assert(dp == sep);
                  sp = rest;
                  break;
            case OCH_:
                  stp = stop;
                  for (;;) {
                        /* how long could this one be? */
                        rest = slow(m, sp, stp, ss, es);
                        assert(rest != NULL);   /* it did match */
                        /* could the rest match the rest? */
                        tail = slow(m, rest, stop, es, stopst);
                        if (tail == stop)
                              break;            /* yes! */
                        /* no -- try a shorter match for this one */
                        stp = rest - 1;
                        assert(stp >= sp);      /* it did work */
                  }
                  ssub = ss + 1;
                  esub = ss + OPND(m->g->strip[ss]) - 1;
                  assert(OP(m->g->strip[esub]) == OOR1);
                  for (;;) {  /* find first matching branch */
                        if (slow(m, sp, rest, ssub, esub) == rest)
                              break;      /* it matched all of it */
                        /* that one missed, try next one */
                        assert(OP(m->g->strip[esub]) == OOR1);
                        esub++;
                        assert(OP(m->g->strip[esub]) == OOR2);
                        ssub = esub + 1;
                        esub += OPND(m->g->strip[esub]);
                        if (OP(m->g->strip[esub]) == OOR2)
                              esub--;
                        else
                              assert(OP(m->g->strip[esub]) == O_CH);
                  }
                  dp = dissect(m, sp, rest, ssub, esub);
                  assert(dp == rest);
                  sp = rest;
                  break;
            case O_PLUS:
            case O_QUEST:
            case OOR1:
            case OOR2:
            case O_CH:
                  assert(nope);
                  break;
            case OLPAREN:
                  i = OPND(m->g->strip[ss]);
                  assert(0 < i && i <= m->g->nsub);
                  m->pmatch[i].rm_so = sp - m->offp;
                  break;
            case ORPAREN:
                  i = OPND(m->g->strip[ss]);
                  assert(0 < i && i <= m->g->nsub);
                  m->pmatch[i].rm_eo = sp - m->offp;
                  break;
            default:          /* uh oh */
                  assert(nope);
                  break;
            }
      }

      assert(sp == stop);
      return(sp);
}

/*
 - backref - figure out what matched what, figuring in back references
 == static char *backref(register struct match *m, char *start, \
 ==   char *stop, sopno startst, sopno stopst, sopno lev);
 */
static char *                 /* == stop (success) or NULL (failure) */
backref(m, start, stop, startst, stopst, lev)
register struct match *m;
char *start;
char *stop;
sopno startst;
sopno stopst;
sopno lev;              /* PLUS nesting level */
{
      register int i;
      register sopno ss;      /* start sop of current subRE */
      register char *sp;      /* start of string matched by it */
      register sopno ssub;    /* start sop of subsubRE */
      register sopno esub;    /* end sop of subsubRE */
      register char *ssp;     /* start of string matched by subsubRE */
      register char *dp;
      register size_t len;
      register int hard;
      register sop s;
      register regoff_t offsave;
      register cset *cs;

      AT("back", start, stop, startst, stopst);
      sp = start;

      /* get as far as we can with easy stuff */
      hard = 0;
      for (ss = startst; !hard && ss < stopst; ss++)
            switch (OP(s = m->g->strip[ss])) {
            case OCHAR:
                  if (sp == stop || *sp++ != (char)OPND(s))
                        return(NULL);
                  break;
            case OANY:
                  if (sp == stop)
                        return(NULL);
                  sp++;
                  break;
            case OANYOF:
                  cs = &m->g->sets[OPND(s)];
                  if (sp == stop || !CHIN(cs, *sp++))
                        return(NULL);
                  break;
            case OBOL:
                  if ( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
                              (sp < m->endp && *(sp-1) == '\n' &&
                                    (m->g->cflags&REG_NEWLINE)) )
                        { /* yes */ }
                  else
                        return(NULL);
                  break;
            case OEOL:
                  if ( (sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
                              (sp < m->endp && *sp == '\n' &&
                                    (m->g->cflags&REG_NEWLINE)) )
                        { /* yes */ }
                  else
                        return(NULL);
                  break;
            case OBOW:
                  if (( (sp == m->beginp && !(m->eflags&REG_NOTBOL)) ||
                              (sp < m->endp && *(sp-1) == '\n' &&
                                    (m->g->cflags&REG_NEWLINE)) ||
                              (sp > m->beginp &&
                                          !ISWORD(*(sp-1))) ) &&
                              (sp < m->endp && ISWORD(*sp)) )
                        { /* yes */ }
                  else
                        return(NULL);
                  break;
            case OEOW:
                  if (( (sp == m->endp && !(m->eflags&REG_NOTEOL)) ||
                              (sp < m->endp && *sp == '\n' &&
                                    (m->g->cflags&REG_NEWLINE)) ||
                              (sp < m->endp && !ISWORD(*sp)) ) &&
                              (sp > m->beginp && ISWORD(*(sp-1))) )
                        { /* yes */ }
                  else
                        return(NULL);
                  break;
            case O_QUEST:
                  break;
            case OOR1:  /* matches null but needs to skip */
                  ss++;
                  s = m->g->strip[ss];
                  do {
                        assert(OP(s) == OOR2);
                        ss += OPND(s);
                  } while (OP(s = m->g->strip[ss]) != O_CH);
                  /* note that the ss++ gets us past the O_CH */
                  break;
            default:    /* have to make a choice */
                  hard = 1;
                  break;
            }
      if (!hard) {            /* that was it! */
            if (sp != stop)
                  return(NULL);
            return(sp);
      }
      ss--;             /* adjust for the for's final increment */

      /* the hard stuff */
      AT("hard", sp, stop, ss, stopst);
      s = m->g->strip[ss];
      switch (OP(s)) {
      case OBACK_:            /* the vilest depths */
            i = OPND(s);
            assert(0 < i && i <= m->g->nsub);
            if (m->pmatch[i].rm_eo == -1)
                  return(NULL);
            assert(m->pmatch[i].rm_so != -1);
            len = m->pmatch[i].rm_eo - m->pmatch[i].rm_so;
            assert(stop - m->beginp >= len);
            if (sp > stop - len)
                  return(NULL);     /* not enough left to match */
            ssp = m->offp + m->pmatch[i].rm_so;
            if (memcmp(sp, ssp, len) != 0)
                  return(NULL);
            while (m->g->strip[ss] != SOP(O_BACK, i))
                  ss++;
            return(backref(m, sp+len, stop, ss+1, stopst, lev));
            break;
      case OQUEST_:           /* to null or not */
            dp = backref(m, sp, stop, ss+1, stopst, lev);
            if (dp != NULL)
                  return(dp); /* not */
            return(backref(m, sp, stop, ss+OPND(s)+1, stopst, lev));
            break;
      case OPLUS_:
            assert(m->lastpos != NULL);
            assert(lev+1 <= m->g->nplus);
            m->lastpos[lev+1] = sp;
            return(backref(m, sp, stop, ss+1, stopst, lev+1));
            break;
      case O_PLUS:
            if (sp == m->lastpos[lev])    /* last pass matched null */
                  return(backref(m, sp, stop, ss+1, stopst, lev-1));
            /* try another pass */
            m->lastpos[lev] = sp;
            dp = backref(m, sp, stop, ss-OPND(s)+1, stopst, lev);
            if (dp == NULL)
                  return(backref(m, sp, stop, ss+1, stopst, lev-1));
            else
                  return(dp);
            break;
      case OCH_:        /* find the right one, if any */
            ssub = ss + 1;
            esub = ss + OPND(s) - 1;
            assert(OP(m->g->strip[esub]) == OOR1);
            for (;;) {  /* find first matching branch */
                  dp = backref(m, sp, stop, ssub, esub, lev);
                  if (dp != NULL)
                        return(dp);
                  /* that one missed, try next one */
                  if (OP(m->g->strip[esub]) == O_CH)
                        return(NULL);     /* there is none */
                  esub++;
                  assert(OP(m->g->strip[esub]) == OOR2);
                  ssub = esub + 1;
                  esub += OPND(m->g->strip[esub]);
                  if (OP(m->g->strip[esub]) == OOR2)
                        esub--;
                  else
                        assert(OP(m->g->strip[esub]) == O_CH);
            }
            break;
      case OLPAREN:           /* must undo assignment if rest fails */
            i = OPND(s);
            assert(0 < i && i <= m->g->nsub);
            offsave = m->pmatch[i].rm_so;
            m->pmatch[i].rm_so = sp - m->offp;
            dp = backref(m, sp, stop, ss+1, stopst, lev);
            if (dp != NULL)
                  return(dp);
            m->pmatch[i].rm_so = offsave;
            return(NULL);
            break;
      case ORPAREN:           /* must undo assignment if rest fails */
            i = OPND(s);
            assert(0 < i && i <= m->g->nsub);
            offsave = m->pmatch[i].rm_eo;
            m->pmatch[i].rm_eo = sp - m->offp;
            dp = backref(m, sp, stop, ss+1, stopst, lev);
            if (dp != NULL)
                  return(dp);
            m->pmatch[i].rm_eo = offsave;
            return(NULL);
            break;
      default:          /* uh oh */
            assert(nope);
            break;
      }

      /* "can't happen" */
      assert(nope);
      /* NOTREACHED */
      return((char *)NULL);   /* dummy */
}

/*
 - fast - step through the string at top speed
 == static char *fast(register struct match *m, char *start, \
 ==   char *stop, sopno startst, sopno stopst);
 */
static char *                 /* where tentative match ended, or NULL */
fast(m, start, stop, startst, stopst)
register struct match *m;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
      register states st = m->st;
      register states fresh = m->fresh;
      register states tmp = m->tmp;
      register char *p = start;
      register int c = (start == m->beginp) ? OUT : *(start-1);
      register int lastc;     /* previous c */
      register int flagch;
      register int i;
      register char *coldp;   /* last p after which no match was underway */

      CLEAR(st);
      SET1(st, startst);
      st = step(m->g, startst, stopst, st, NOTHING, st);
      ASSIGN(fresh, st);
      SP("start", st, *p);
      coldp = NULL;
      for (;;) {
            /* next character */
            lastc = c;
            c = (p == m->endp) ? OUT : *p;
            if (EQ(st, fresh))
                  coldp = p;

            /* is there an EOL and/or BOL between lastc and c? */
            flagch = '\0';
            i = 0;
            if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
                        (lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
                  flagch = BOL;
                  i = m->g->nbol;
            }
            if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
                        (c == OUT && !(m->eflags&REG_NOTEOL)) ) {
                  flagch = (flagch == BOL) ? BOLEOL : EOL;
                  i += m->g->neol;
            }
            if (i != 0) {
                  for (; i > 0; i--)
                        st = step(m->g, startst, stopst, st, flagch, st);
                  SP("boleol", st, c);
            }

            /* how about a word boundary? */
            if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
                              (c != OUT && ISWORD(c)) ) {
                  flagch = BOW;
            }
            if ( (lastc != OUT && ISWORD(lastc)) &&
                        (flagch == EOL || (c != OUT && !ISWORD(c))) ) {
                  flagch = EOW;
            }
            if (flagch == BOW || flagch == EOW) {
                  st = step(m->g, startst, stopst, st, flagch, st);
                  SP("boweow", st, c);
            }

            /* are we done? */
            if (ISSET(st, stopst) || p == stop)
                  break;            /* NOTE BREAK OUT */

            /* no, we must deal with this character */
            ASSIGN(tmp, st);
            ASSIGN(st, fresh);
            assert(c != OUT);
            st = step(m->g, startst, stopst, tmp, c, st);
            SP("aft", st, c);
            assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
            p++;
      }

      assert(coldp != NULL);
      m->coldp = coldp;
      if (ISSET(st, stopst))
            return(p+1);
      else
            return(NULL);
}

/*
 - slow - step through the string more deliberately
 == static char *slow(register struct match *m, char *start, \
 ==   char *stop, sopno startst, sopno stopst);
 */
static char *                 /* where it ended */
slow(m, start, stop, startst, stopst)
register struct match *m;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
      register states st = m->st;
      register states empty = m->empty;
      register states tmp = m->tmp;
      register char *p = start;
      register int c = (start == m->beginp) ? OUT : *(start-1);
      register int lastc;     /* previous c */
      register int flagch;
      register int i;
      register char *matchp;  /* last p at which a match ended */

      AT("slow", start, stop, startst, stopst);
      CLEAR(st);
      SET1(st, startst);
      SP("sstart", st, *p);
      st = step(m->g, startst, stopst, st, NOTHING, st);
      matchp = NULL;
      for (;;) {
            /* next character */
            lastc = c;
            c = (p == m->endp) ? OUT : *p;

            /* is there an EOL and/or BOL between lastc and c? */
            flagch = '\0';
            i = 0;
            if ( (lastc == '\n' && m->g->cflags&REG_NEWLINE) ||
                        (lastc == OUT && !(m->eflags&REG_NOTBOL)) ) {
                  flagch = BOL;
                  i = m->g->nbol;
            }
            if ( (c == '\n' && m->g->cflags&REG_NEWLINE) ||
                        (c == OUT && !(m->eflags&REG_NOTEOL)) ) {
                  flagch = (flagch == BOL) ? BOLEOL : EOL;
                  i += m->g->neol;
            }
            if (i != 0) {
                  for (; i > 0; i--)
                        st = step(m->g, startst, stopst, st, flagch, st);
                  SP("sboleol", st, c);
            }

            /* how about a word boundary? */
            if ( (flagch == BOL || (lastc != OUT && !ISWORD(lastc))) &&
                              (c != OUT && ISWORD(c)) ) {
                  flagch = BOW;
            }
            if ( (lastc != OUT && ISWORD(lastc)) &&
                        (flagch == EOL || (c != OUT && !ISWORD(c))) ) {
                  flagch = EOW;
            }
            if (flagch == BOW || flagch == EOW) {
                  st = step(m->g, startst, stopst, st, flagch, st);
                  SP("sboweow", st, c);
            }

            /* are we done? */
            if (ISSET(st, stopst))
                  matchp = p;
            if (EQ(st, empty) || p == stop)
                  break;            /* NOTE BREAK OUT */

            /* no, we must deal with this character */
            ASSIGN(tmp, st);
            ASSIGN(st, empty);
            assert(c != OUT);
            st = step(m->g, startst, stopst, tmp, c, st);
            SP("saft", st, c);
            assert(EQ(step(m->g, startst, stopst, st, NOTHING, st), st));
            p++;
      }

      return(matchp);
}


/*
 - step - map set of states reachable before char to set reachable after
 == static states step(register struct re_guts *g, sopno start, sopno stop, \
 ==   register states bef, int ch, register states aft);
 == #define BOL   (OUT+1)
 == #define EOL   (BOL+1)
 == #define BOLEOL      (BOL+2)
 == #define NOTHING     (BOL+3)
 == #define BOW   (BOL+4)
 == #define EOW   (BOL+5)
 == #define CODEMAX     (BOL+5)           // highest code used
 == #define NONCHAR(c)  ((c) > CHAR_MAX)
 == #define NNONCHAR    (CODEMAX-CHAR_MAX)
 */
static states
step(g, start, stop, bef, ch, aft)
register struct re_guts *g;
sopno start;                  /* start state within strip */
sopno stop;             /* state after stop state within strip */
register states bef;          /* states reachable before */
int ch;                       /* character or NONCHAR code */
register states aft;          /* states already known reachable after */
{
      register cset *cs;
      register sop s;
      register sopno pc;
      register onestate here;       /* note, macros know this name */
      register sopno look;
      register long i;

      for (pc = start, INIT(here, pc); pc != stop; pc++, INC(here)) {
            s = g->strip[pc];
            switch (OP(s)) {
            case OEND:
                  assert(pc == stop-1);
                  break;
            case OCHAR:
                  /* only characters can match */
                  assert(!NONCHAR(ch) || ch != (char)OPND(s));
                  if (ch == (char)OPND(s))
                        FWD(aft, bef, 1);
                  break;
            case OBOL:
                  if (ch == BOL || ch == BOLEOL)
                        FWD(aft, bef, 1);
                  break;
            case OEOL:
                  if (ch == EOL || ch == BOLEOL)
                        FWD(aft, bef, 1);
                  break;
            case OBOW:
                  if (ch == BOW)
                        FWD(aft, bef, 1);
                  break;
            case OEOW:
                  if (ch == EOW)
                        FWD(aft, bef, 1);
                  break;
            case OANY:
                  if (!NONCHAR(ch))
                        FWD(aft, bef, 1);
                  break;
            case OANYOF:
                  cs = &g->sets[OPND(s)];
                  if (!NONCHAR(ch) && CHIN(cs, ch))
                        FWD(aft, bef, 1);
                  break;
            case OBACK_:            /* ignored here */
            case O_BACK:
                  FWD(aft, aft, 1);
                  break;
            case OPLUS_:            /* forward, this is just an empty */
                  FWD(aft, aft, 1);
                  break;
            case O_PLUS:            /* both forward and back */
                  FWD(aft, aft, 1);
                  i = ISSETBACK(aft, OPND(s));
                  BACK(aft, aft, OPND(s));
                  if (!i && ISSETBACK(aft, OPND(s))) {
                        /* oho, must reconsider loop body */
                        pc -= OPND(s) + 1;
                        INIT(here, pc);
                  }
                  break;
            case OQUEST_:           /* two branches, both forward */
                  FWD(aft, aft, 1);
                  FWD(aft, aft, OPND(s));
                  break;
            case O_QUEST:           /* just an empty */
                  FWD(aft, aft, 1);
                  break;
            case OLPAREN:           /* not significant here */
            case ORPAREN:
                  FWD(aft, aft, 1);
                  break;
            case OCH_:        /* mark the first two branches */
                  FWD(aft, aft, 1);
                  assert(OP(g->strip[pc+OPND(s)]) == OOR2);
                  FWD(aft, aft, OPND(s));
                  break;
            case OOR1:        /* done a branch, find the O_CH */
                  if (ISSTATEIN(aft, here)) {
                        for (look = 1;
                                    OP(s = g->strip[pc+look]) != O_CH;
                                    look += OPND(s))
                              assert(OP(s) == OOR2);
                        FWD(aft, aft, look);
                  }
                  break;
            case OOR2:        /* propagate OCH_'s marking */
                  FWD(aft, aft, 1);
                  if (OP(g->strip[pc+OPND(s)]) != O_CH) {
                        assert(OP(g->strip[pc+OPND(s)]) == OOR2);
                        FWD(aft, aft, OPND(s));
                  }
                  break;
            case O_CH:        /* just empty */
                  FWD(aft, aft, 1);
                  break;
            default:          /* ooooops... */
                  assert(nope);
                  break;
            }
      }

      return(aft);
}

#ifdef REDEBUG
/*
 - print - print a set of states
 == #ifdef REDEBUG
 == static void print(struct match *m, char *caption, states st, \
 ==   int ch, FILE *d);
 == #endif
 */
static void
print(m, caption, st, ch, d)
struct match *m;
char *caption;
states st;
int ch;
FILE *d;
{
      register struct re_guts *g = m->g;
      register int i;
      register int first = 1;

      if (!(m->eflags&REG_TRACE))
            return;

      fprintf(d, "%s", caption);
      if (ch != '\0')
            fprintf(d, " %s", pchar(ch));
      for (i = 0; i < g->nstates; i++)
            if (ISSET(st, i)) {
                  fprintf(d, "%s%d", (first) ? "\t" : ", ", i);
                  first = 0;
            }
      fprintf(d, "\n");
}

/* 
 - at - print current situation
 == #ifdef REDEBUG
 == static void at(struct match *m, char *title, char *start, char *stop, \
 ==                                 sopno startst, sopno stopst);
 == #endif
 */
static void
at(m, title, start, stop, startst, stopst)
struct match *m;
char *title;
char *start;
char *stop;
sopno startst;
sopno stopst;
{
      if (!(m->eflags&REG_TRACE))
            return;

      printf("%s %s-", title, pchar(*start));
      printf("%s ", pchar(*stop));
      printf("%ld-%ld\n", (long)startst, (long)stopst);
}

#ifndef PCHARDONE
#define     PCHARDONE   /* never again */
/*
 - pchar - make a character printable
 == #ifdef REDEBUG
 == static char *pchar(int ch);
 == #endif
 *
 * Is this identical to regchar() over in debug.c?  Well, yes.  But a
 * duplicate here avoids having a debugging-capable regexec.o tied to
 * a matching debug.o, and this is convenient.  It all disappears in
 * the non-debug compilation anyway, so it doesn't matter much.
 */
static char *                 /* -> representation */
pchar(ch)
int ch;
{
      static char pbuf[10];

      if (isprint(ch) || ch == ' ')
            sprintf(pbuf, "%c", ch);
      else
            sprintf(pbuf, "\\%o", ch);
      return(pbuf);
}
#endif
#endif

#undef      matcher
#undef      fast
#undef      slow
#undef      dissect
#undef      backref
#undef      step
#undef      print
#undef      at
#undef      match

Generated by  Doxygen 1.6.0   Back to index