regexec.c Go to the documentation of this file. /* * re_*exec and friends - match REs * * Copyright (c) 1998, 1999 Henry Spencer. All rights reserved. * * Development of this software was funded, in part, by Cray Research Inc., * UUNET Communications Services Inc., Sun Microsystems Inc., and Scriptics * Corporation, none of whom are responsible for the results. The author * thanks all of them. * * Redistribution and use in source and binary forms -- with or without * modification -- are permitted for any purpose, provided that * redistributions in source form retain this entire copyright notice and * indicate the origin and nature of any modifications. * * I'd appreciate being given credit for this package in the documentation of * software which uses it, but that is not a requirement. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL * HENRY SPENCER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "regguts.h" /* * Lazy-DFA representation. */ struct arcp { /* "pointer" to an outarc */ struct sset *ss; color co; }; struct sset { /* state set */ unsigned *states; /* pointer to bitvector */ unsigned hash; /* hash of bitvector */ #define HASH(bv, nw) (((nw) == 1) ? *(bv) : hash(bv, nw)) #define HIT(h,bv,ss,nw) ((ss)->hash == (h) && ((nw) == 1 || \ memcmp(VS(bv), VS((ss)->states), (nw)*sizeof(unsigned)) == 0)) int flags; #define STARTER 01 /* the initial state set */ #define POSTSTATE 02 /* includes the goal state */ #define LOCKED 04 /* locked in cache */ #define NOPROGRESS 010 /* zero-progress state set */ struct arcp ins; /* chain of inarcs pointing here */ chr *lastseen; /* last entered on arrival here */ struct sset **outs; /* outarc vector indexed by color */ struct arcp *inchain; /* chain-pointer vector for outarcs */ }; struct dfa { int nssets; /* size of cache */ int nssused; /* how many entries occupied yet */ int nstates; /* number of states */ int ncolors; /* length of outarc and inchain vectors */ int wordsper; /* length of state-set bitvectors */ struct sset *ssets; /* state-set cache */ unsigned *statesarea; /* bitvector storage */ unsigned *work; /* pointer to work area within statesarea */ struct sset **outsarea; /* outarc-vector storage */ struct arcp *incarea; /* inchain storage */ struct cnfa *cnfa; struct colormap *cm; chr *lastpost; /* location of last cache-flushed success */ chr *lastnopr; /* location of last cache-flushed NOPROGRESS */ struct sset *search; /* replacement-search-pointer memory */ int cptsmalloced; /* were the areas individually malloced? */ char *mallocarea; /* self, or master malloced area, or NULL */ }; #define WORK 1 /* number of work bitvectors needed */ /* * Setup for non-malloc allocation for small cases. */ #define FEWSTATES 20 /* must be less than UBITS */ #define FEWCOLORS 15 struct smalldfa { struct dfa dfa; struct sset ssets[FEWSTATES*2]; unsigned statesarea[FEWSTATES*2 + WORK]; struct sset *outsarea[FEWSTATES*2 * FEWCOLORS]; struct arcp incarea[FEWSTATES*2 * FEWCOLORS]; }; #define DOMALLOC ((struct smalldfa *)NULL) /* force malloc */ /* * Internal variables, bundled for easy passing around. */ struct vars { regex_t *re; struct guts *g; int eflags; /* copies of arguments */ size_t nmatch; regmatch_t *pmatch; rm_detail_t *details; chr *start; /* start of string */ chr *stop; /* just past end of string */ int err; /* error code if any (0 none) */ regoff_t *mem; /* memory vector for backtracking */ struct smalldfa dfa1; struct smalldfa dfa2; }; #define VISERR(vv) ((vv)->err != 0) /* have we seen an error yet? */ #define ISERR() VISERR(v) #define VERR(vv,e) (((vv)->err) ? (vv)->err : ((vv)->err = (e))) #define ERR(e) VERR(v, e) /* record an error */ #define NOERR() {if (ISERR()) return v->err;} /* if error seen, return it */ #define OFF(p) ((p) - v->start) #define LOFF(p) ((long)OFF(p))  /* * forward declarations */ /* =====^!^===== begin forwards =====^!^===== */ /* automatically gathered by fwd; do not hand-edit */ /* === regexec.c === */ int exec(regex_t *, CONST chr *, size_t, rm_detail_t *, size_t, regmatch_t [], int); static int find(struct vars *, struct cnfa *, struct colormap *); static int cfind(struct vars *, struct cnfa *, struct colormap *); static int cfindloop(struct vars *, struct cnfa *, struct colormap *, struct dfa *, struct dfa *, chr **); static VOID zapsubs(regmatch_t *, size_t); static VOID zapmem(struct vars *, struct subre *); static VOID subset(struct vars *, struct subre *, chr *, chr *); static int dissect(struct vars *, struct subre *, chr *, chr *); static int condissect(struct vars *, struct subre *, chr *, chr *); static int altdissect(struct vars *, struct subre *, chr *, chr *); static int cdissect(struct vars *, struct subre *, chr *, chr *); static int ccondissect(struct vars *, struct subre *, chr *, chr *); static int crevdissect(struct vars *, struct subre *, chr *, chr *); static int cbrdissect(struct vars *, struct subre *, chr *, chr *); static int caltdissect(struct vars *, struct subre *, chr *, chr *); /* === rege_dfa.c === */ static chr *longest(struct vars *, struct dfa *, chr *, chr *, int *); static chr *shortest(struct vars *, struct dfa *, chr *, chr *, chr *, chr **, int *); static chr *lastcold(struct vars *, struct dfa *); static struct dfa *newdfa(struct vars *, struct cnfa *, struct colormap *, struct smalldfa *); static VOID freedfa(struct dfa *); static unsigned hash(unsigned *, int); static struct sset *initialize(struct vars *, struct dfa *, chr *); static struct sset *miss(struct vars *, struct dfa *, struct sset *, pcolor, chr *, chr *); static int lacon(struct vars *, struct cnfa *, chr *, pcolor); static struct sset *getvacant(struct vars *, struct dfa *, chr *, chr *); static struct sset *pickss(struct vars *, struct dfa *, chr *, chr *); /* automatically gathered by fwd; do not hand-edit */ /* =====^!^===== end forwards =====^!^===== */  /* - exec - match regular expression ^ int exec(regex_t *, CONST chr *, size_t, rm_detail_t *, ^ size_t, regmatch_t [], int); */ int exec( regex_t *re, CONST chr *string, size_t len, rm_detail_t *details, size_t nmatch, regmatch_t pmatch[], int flags) { AllocVars(v); int st; size_t n; int backref; #define LOCALMAT 20 regmatch_t mat[LOCALMAT]; #define LOCALMEM 40 regoff_t mem[LOCALMEM]; /* * Sanity checks. */ if (re == NULL || string == NULL || re->re_magic != REMAGIC) { FreeVars(v); return REG_INVARG; } if (re->re_csize != sizeof(chr)) { FreeVars(v); return REG_MIXED; } /* * Setup. */ v->re = re; v->g = (struct guts *)re->re_guts; if ((v->g->cflags&REG_EXPECT) && details == NULL) { FreeVars(v); return REG_INVARG; } if (v->g->info&REG_UIMPOSSIBLE) { FreeVars(v); return REG_NOMATCH; } backref = (v->g->info&REG_UBACKREF) ? 1 : 0; v->eflags = flags; if (v->g->cflags&REG_NOSUB) { nmatch = 0; /* override client */ } v->nmatch = nmatch; if (backref) { /* * Need work area. */ if (v->g->nsub + 1 <= LOCALMAT) { v->pmatch = mat; } else { v->pmatch = (regmatch_t *) MALLOC((v->g->nsub + 1) * sizeof(regmatch_t)); } if (v->pmatch == NULL) { FreeVars(v); return REG_ESPACE; } v->nmatch = v->g->nsub + 1; } else { v->pmatch = pmatch; } v->details = details; v->start = (chr *)string; v->stop = (chr *)string + len; v->err = 0; if (backref) { /* * Need retry memory. */ assert(v->g->ntree >= 0); n = (size_t)v->g->ntree; if (n <= LOCALMEM) { v->mem = mem; } else { v->mem = (regoff_t *) MALLOC(n*sizeof(regoff_t)); } if (v->mem == NULL) { if (v->pmatch != pmatch && v->pmatch != mat) { FREE(v->pmatch); } FreeVars(v); return REG_ESPACE; } } else { v->mem = NULL; } /* * Do it. */ assert(v->g->tree != NULL); if (backref) { st = cfind(v, &v->g->tree->cnfa, &v->g->cmap); } else { st = find(v, &v->g->tree->cnfa, &v->g->cmap); } /* * Copy (portion of) match vector over if necessary. */ if (st == REG_OKAY && v->pmatch != pmatch && nmatch > 0) { zapsubs(pmatch, nmatch); n = (nmatch < v->nmatch) ? nmatch : v->nmatch; memcpy(VS(pmatch), VS(v->pmatch), n*sizeof(regmatch_t)); } /* * Clean up. */ if (v->pmatch != pmatch && v->pmatch != mat) { FREE(v->pmatch); } if (v->mem != NULL && v->mem != mem) { FREE(v->mem); } FreeVars(v); return st; }  /* - find - find a match for the main NFA (no-complications case) ^ static int find(struct vars *, struct cnfa *, struct colormap *); */ static int find( struct vars *v, struct cnfa *cnfa, struct colormap *cm) { struct dfa *s; struct dfa *d; chr *begin; chr *end = NULL; chr *cold; chr *open; /* Open and close of range of possible * starts */ chr *close; int hitend; int shorter = (v->g->tree->flags&SHORTER) ? 1 : 0; /* * First, a shot with the search RE. */ s = newdfa(v, &v->g->search, cm, &v->dfa1); assert(!(ISERR() && s != NULL)); NOERR(); MDEBUG(("\nsearch at %ld\n", LOFF(v->start))); cold = NULL; close = shortest(v, s, v->start, v->start, v->stop, &cold, NULL); freedfa(s); NOERR(); if (v->g->cflags&REG_EXPECT) { assert(v->details != NULL); if (cold != NULL) { v->details->rm_extend.rm_so = OFF(cold); } else { v->details->rm_extend.rm_so = OFF(v->stop); } v->details->rm_extend.rm_eo = OFF(v->stop); /* unknown */ } if (close == NULL) { /* not found */ return REG_NOMATCH; } if (v->nmatch == 0) { /* found, don't need exact location */ return REG_OKAY; } /* * Find starting point and match. */ assert(cold != NULL); open = cold; cold = NULL; MDEBUG(("between %ld and %ld\n", LOFF(open), LOFF(close))); d = newdfa(v, cnfa, cm, &v->dfa1); assert(!(ISERR() && d != NULL)); NOERR(); for (begin = open; begin <= close; begin++) { MDEBUG(("\nfind trying at %ld\n", LOFF(begin))); if (shorter) { end = shortest(v, d, begin, begin, v->stop, NULL, &hitend); } else { end = longest(v, d, begin, v->stop, &hitend); } NOERR(); if (hitend && cold == NULL) { cold = begin; } if (end != NULL) { break; /* NOTE BREAK OUT */ } } assert(end != NULL); /* search RE succeeded so loop should */ freedfa(d); /* * And pin down details. */ assert(v->nmatch > 0); v->pmatch[0].rm_so = OFF(begin); v->pmatch[0].rm_eo = OFF(end); if (v->g->cflags&REG_EXPECT) { if (cold != NULL) { v->details->rm_extend.rm_so = OFF(cold); } else { v->details->rm_extend.rm_so = OFF(v->stop); } v->details->rm_extend.rm_eo = OFF(v->stop); /* unknown */ } if (v->nmatch == 1) { /* no need for submatches */ return REG_OKAY; } /* * Submatches. */ zapsubs(v->pmatch, v->nmatch); return dissect(v, v->g->tree, begin, end); }  /* - cfind - find a match for the main NFA (with complications) ^ static int cfind(struct vars *, struct cnfa *, struct colormap *); */ static int cfind( struct vars *v, struct cnfa *cnfa, struct colormap *cm) { struct dfa *s; struct dfa *d; chr *cold = NULL; /* silence gcc 4 warning */ int ret; s = newdfa(v, &v->g->search, cm, &v->dfa1); NOERR(); d = newdfa(v, cnfa, cm, &v->dfa2); if (ISERR()) { assert(d == NULL); freedfa(s); return v->err; } ret = cfindloop(v, cnfa, cm, d, s, &cold); freedfa(d); freedfa(s); NOERR(); if (v->g->cflags&REG_EXPECT) { assert(v->details != NULL); if (cold != NULL) { v->details->rm_extend.rm_so = OFF(cold); } else { v->details->rm_extend.rm_so = OFF(v->stop); } v->details->rm_extend.rm_eo = OFF(v->stop); /* unknown */ } return ret; }  /* - cfindloop - the heart of cfind ^ static int cfindloop(struct vars *, struct cnfa *, struct colormap *, ^ struct dfa *, struct dfa *, chr **); */ static int cfindloop( struct vars *v, struct cnfa *cnfa, struct colormap *cm, struct dfa *d, struct dfa *s, chr **coldp) /* where to put coldstart pointer */ { chr *begin; chr *end; chr *cold; chr *open; /* Open and close of range of possible * starts */ chr *close; chr *estart; chr *estop; int er; int shorter = v->g->tree->flags&SHORTER; int hitend; assert(d != NULL && s != NULL); cold = NULL; close = v->start; do { MDEBUG(("\ncsearch at %ld\n", LOFF(close))); close = shortest(v, s, close, close, v->stop, &cold, NULL); if (close == NULL) { break; /* NOTE BREAK */ } assert(cold != NULL); open = cold; cold = NULL; MDEBUG(("cbetween %ld and %ld\n", LOFF(open), LOFF(close))); for (begin = open; begin <= close; begin++) { MDEBUG(("\ncfind trying at %ld\n", LOFF(begin))); estart = begin; estop = v->stop; for (;;) { if (shorter) { end = shortest(v, d, begin, estart, estop, NULL, &hitend); } else { end = longest(v, d, begin, estop, &hitend); } if (hitend && cold == NULL) { cold = begin; } if (end == NULL) { break; /* NOTE BREAK OUT */ } MDEBUG(("tentative end %ld\n", LOFF(end))); zapsubs(v->pmatch, v->nmatch); zapmem(v, v->g->tree); er = cdissect(v, v->g->tree, begin, end); if (er == REG_OKAY) { if (v->nmatch > 0) { v->pmatch[0].rm_so = OFF(begin); v->pmatch[0].rm_eo = OFF(end); } *coldp = cold; return REG_OKAY; } if (er != REG_NOMATCH) { ERR(er); return er; } if ((shorter) ? end == estop : end == begin) { /* * No point in trying again. */ *coldp = cold; return REG_NOMATCH; } /* * Go around and try again */ if (shorter) { estart = end + 1; } else { estop = end - 1; } } } } while (close < v->stop); *coldp = cold; return REG_NOMATCH; }  /* - zapsubs - initialize the subexpression matches to "no match" ^ static VOID zapsubs(regmatch_t *, size_t); */ static void zapsubs( regmatch_t *p, size_t n) { size_t i; for (i = n-1; i > 0; i--) { p[i].rm_so = -1; p[i].rm_eo = -1; } }  /* - zapmem - initialize the retry memory of a subtree to zeros ^ static VOID zapmem(struct vars *, struct subre *); */ static void zapmem( struct vars *v, struct subre *t) { if (t == NULL) { return; } assert(v->mem != NULL); v->mem[t->retry] = 0; if (t->op == '(') { assert(t->subno > 0); v->pmatch[t->subno].rm_so = -1; v->pmatch[t->subno].rm_eo = -1; } if (t->left != NULL) { zapmem(v, t->left); } if (t->right != NULL) { zapmem(v, t->right); } }  /* - subset - set any subexpression relevant to a successful subre ^ static VOID subset(struct vars *, struct subre *, chr *, chr *); */ static void subset( struct vars *v, struct subre *sub, chr *begin, chr *end) { int n = sub->subno; assert(n > 0); if ((size_t)n >= v->nmatch) { return; } MDEBUG(("setting %d\n", n)); v->pmatch[n].rm_so = OFF(begin); v->pmatch[n].rm_eo = OFF(end); }  /* - dissect - determine subexpression matches (uncomplicated case) ^ static int dissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ dissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { assert(t != NULL); MDEBUG(("dissect %ld-%ld\n", LOFF(begin), LOFF(end))); switch (t->op) { case '=': /* terminal node */ assert(t->left == NULL && t->right == NULL); return REG_OKAY; /* no action, parent did the work */ break; case '|': /* alternation */ assert(t->left != NULL); return altdissect(v, t, begin, end); break; case 'b': /* back ref -- shouldn't be calling us! */ return REG_ASSERT; break; case '.': /* concatenation */ assert(t->left != NULL && t->right != NULL); return condissect(v, t, begin, end); break; case '(': /* capturing */ assert(t->left != NULL && t->right == NULL); assert(t->subno > 0); subset(v, t, begin, end); return dissect(v, t->left, begin, end); break; default: return REG_ASSERT; break; } }  /* - condissect - determine concatenation subexpression matches (uncomplicated) ^ static int condissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ condissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { struct dfa *d; struct dfa *d2; chr *mid; int i; int shorter = (t->left->flags&SHORTER) ? 1 : 0; chr *stop = (shorter) ? end : begin; assert(t->op == '.'); assert(t->left != NULL && t->left->cnfa.nstates > 0); assert(t->right != NULL && t->right->cnfa.nstates > 0); d = newdfa(v, &t->left->cnfa, &v->g->cmap, &v->dfa1); NOERR(); d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, &v->dfa2); if (ISERR()) { assert(d2 == NULL); freedfa(d); return v->err; } /* * Pick a tentative midpoint. */ if (shorter) { mid = shortest(v, d, begin, begin, end, NULL, NULL); } else { mid = longest(v, d, begin, end, NULL); } if (mid == NULL) { freedfa(d); freedfa(d2); return REG_ASSERT; } MDEBUG(("tentative midpoint %ld\n", LOFF(mid))); /* * Iterate until satisfaction or failure. */ while (longest(v, d2, mid, end, NULL) != end) { /* * That midpoint didn't work, find a new one. */ if (mid == stop) { /* * All possibilities exhausted! */ MDEBUG(("no midpoint!\n")); freedfa(d); freedfa(d2); return REG_ASSERT; } if (shorter) { mid = shortest(v, d, begin, mid+1, end, NULL, NULL); } else { mid = longest(v, d, begin, mid-1, NULL); } if (mid == NULL) { /* * Failed to find a new one! */ MDEBUG(("failed midpoint!\n")); freedfa(d); freedfa(d2); return REG_ASSERT; } MDEBUG(("new midpoint %ld\n", LOFF(mid))); } /* * Satisfaction. */ MDEBUG(("successful\n")); freedfa(d); freedfa(d2); i = dissect(v, t->left, begin, mid); if (i != REG_OKAY) { return i; } return dissect(v, t->right, mid, end); }  /* - altdissect - determine alternative subexpression matches (uncomplicated) ^ static int altdissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ altdissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { struct dfa *d; int i; assert(t != NULL); assert(t->op == '|'); for (i = 0; t != NULL; t = t->right, i++) { MDEBUG(("trying %dth\n", i)); assert(t->left != NULL && t->left->cnfa.nstates > 0); d = newdfa(v, &t->left->cnfa, &v->g->cmap, &v->dfa1); if (ISERR()) { return v->err; } if (longest(v, d, begin, end, NULL) == end) { MDEBUG(("success\n")); freedfa(d); return dissect(v, t->left, begin, end); } freedfa(d); } return REG_ASSERT; /* none of them matched?!? */ }  /* - cdissect - determine subexpression matches (with complications) * The retry memory stores the offset of the trial midpoint from begin, plus 1 * so that 0 uniquely means "clean slate". ^ static int cdissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ cdissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { int er; assert(t != NULL); MDEBUG(("cdissect %ld-%ld %c\n", LOFF(begin), LOFF(end), t->op)); switch (t->op) { case '=': /* terminal node */ assert(t->left == NULL && t->right == NULL); return REG_OKAY; /* no action, parent did the work */ break; case '|': /* alternation */ assert(t->left != NULL); return caltdissect(v, t, begin, end); break; case 'b': /* back ref -- shouldn't be calling us! */ assert(t->left == NULL && t->right == NULL); return cbrdissect(v, t, begin, end); break; case '.': /* concatenation */ assert(t->left != NULL && t->right != NULL); return ccondissect(v, t, begin, end); break; case '(': /* capturing */ assert(t->left != NULL && t->right == NULL); assert(t->subno > 0); er = cdissect(v, t->left, begin, end); if (er == REG_OKAY) { subset(v, t, begin, end); } return er; break; default: return REG_ASSERT; break; } }  /* - ccondissect - concatenation subexpression matches (with complications) * The retry memory stores the offset of the trial midpoint from begin, plus 1 * so that 0 uniquely means "clean slate". ^ static int ccondissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ ccondissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { struct dfa *d; struct dfa *d2; chr *mid; int er; assert(t->op == '.'); assert(t->left != NULL && t->left->cnfa.nstates > 0); assert(t->right != NULL && t->right->cnfa.nstates > 0); if (t->left->flags&SHORTER) { /* reverse scan */ return crevdissect(v, t, begin, end); } d = newdfa(v, &t->left->cnfa, &v->g->cmap, DOMALLOC); if (ISERR()) { return v->err; } d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, DOMALLOC); if (ISERR()) { freedfa(d); return v->err; } MDEBUG(("cconcat %d\n", t->retry)); /* * Pick a tentative midpoint. */ if (v->mem[t->retry] == 0) { mid = longest(v, d, begin, end, NULL); if (mid == NULL) { freedfa(d); freedfa(d2); return REG_NOMATCH; } MDEBUG(("tentative midpoint %ld\n", LOFF(mid))); v->mem[t->retry] = (mid - begin) + 1; } else { mid = begin + (v->mem[t->retry] - 1); MDEBUG(("working midpoint %ld\n", LOFF(mid))); } /* * Iterate until satisfaction or failure. */ for (;;) { /* * Try this midpoint on for size. */ er = cdissect(v, t->left, begin, mid); if ((er == REG_OKAY) && (longest(v, d2, mid, end, NULL) == end) && (er = cdissect(v, t->right, mid, end)) == REG_OKAY) { break; /* NOTE BREAK OUT */ } if ((er != REG_OKAY) && (er != REG_NOMATCH)) { freedfa(d); freedfa(d2); return er; } /* * That midpoint didn't work, find a new one. */ if (mid == begin) { /* * All possibilities exhausted. */ MDEBUG(("%d no midpoint\n", t->retry)); freedfa(d); freedfa(d2); return REG_NOMATCH; } mid = longest(v, d, begin, mid-1, NULL); if (mid == NULL) { /* * Failed to find a new one. */ MDEBUG(("%d failed midpoint\n", t->retry)); freedfa(d); freedfa(d2); return REG_NOMATCH; } MDEBUG(("%d: new midpoint %ld\n", t->retry, LOFF(mid))); v->mem[t->retry] = (mid - begin) + 1; zapmem(v, t->left); zapmem(v, t->right); } /* * Satisfaction. */ MDEBUG(("successful\n")); freedfa(d); freedfa(d2); return REG_OKAY; }  /* - crevdissect - determine backref shortest-first subexpression matches * The retry memory stores the offset of the trial midpoint from begin, plus 1 * so that 0 uniquely means "clean slate". ^ static int crevdissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ crevdissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { struct dfa *d; struct dfa *d2; chr *mid; int er; assert(t->op == '.'); assert(t->left != NULL && t->left->cnfa.nstates > 0); assert(t->right != NULL && t->right->cnfa.nstates > 0); assert(t->left->flags&SHORTER); /* * Concatenation -- need to split the substring between parts. */ d = newdfa(v, &t->left->cnfa, &v->g->cmap, DOMALLOC); if (ISERR()) { return v->err; } d2 = newdfa(v, &t->right->cnfa, &v->g->cmap, DOMALLOC); if (ISERR()) { freedfa(d); return v->err; } MDEBUG(("crev %d\n", t->retry)); /* * Pick a tentative midpoint. */ if (v->mem[t->retry] == 0) { mid = shortest(v, d, begin, begin, end, NULL, NULL); if (mid == NULL) { freedfa(d); freedfa(d2); return REG_NOMATCH; } MDEBUG(("tentative midpoint %ld\n", LOFF(mid))); v->mem[t->retry] = (mid - begin) + 1; } else { mid = begin + (v->mem[t->retry] - 1); MDEBUG(("working midpoint %ld\n", LOFF(mid))); } /* * Iterate until satisfaction or failure. */ for (;;) { /* * Try this midpoint on for size. */ er = cdissect(v, t->left, begin, mid); if ((er == REG_OKAY) && (longest(v, d2, mid, end, NULL) == end) && (er = cdissect(v, t->right, mid, end)) == REG_OKAY) { break; /* NOTE BREAK OUT */ } if (er != REG_OKAY && er != REG_NOMATCH) { freedfa(d); freedfa(d2); return er; } /* * That midpoint didn't work, find a new one. */ if (mid == end) { /* * All possibilities exhausted. */ MDEBUG(("%d no midpoint\n", t->retry)); freedfa(d); freedfa(d2); return REG_NOMATCH; } mid = shortest(v, d, begin, mid+1, end, NULL, NULL); if (mid == NULL) { /* * Failed to find a new one. */ MDEBUG(("%d failed midpoint\n", t->retry)); freedfa(d); freedfa(d2); return REG_NOMATCH; } MDEBUG(("%d: new midpoint %ld\n", t->retry, LOFF(mid))); v->mem[t->retry] = (mid - begin) + 1; zapmem(v, t->left); zapmem(v, t->right); } /* * Satisfaction. */ MDEBUG(("successful\n")); freedfa(d); freedfa(d2); return REG_OKAY; }  /* - cbrdissect - determine backref subexpression matches ^ static int cbrdissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ cbrdissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { int i; int n = t->subno; size_t len; chr *paren; chr *p; chr *stop; int min = t->min; int max = t->max; assert(t != NULL); assert(t->op == 'b'); assert(n >= 0); assert((size_t)n < v->nmatch); MDEBUG(("cbackref n%d %d{%d-%d}\n", t->retry, n, min, max)); if (v->pmatch[n].rm_so == -1) { return REG_NOMATCH; } paren = v->start + v->pmatch[n].rm_so; len = v->pmatch[n].rm_eo - v->pmatch[n].rm_so; /* * No room to maneuver -- retries are pointless. */ if (v->mem[t->retry]) { return REG_NOMATCH; } v->mem[t->retry] = 1; /* * Special-case zero-length string. */ if (len == 0) { if (begin == end) { return REG_OKAY; } return REG_NOMATCH; } /* * And too-short string. */ assert(end >= begin); if ((size_t)(end - begin) < len) { return REG_NOMATCH; } stop = end - len; /* * Count occurrences. */ i = 0; for (p = begin; p <= stop && (i < max || max == INFINITY); p += len) { if ((*v->g->compare)(paren, p, len) != 0) { break; } i++; } MDEBUG(("cbackref found %d\n", i)); /* * And sort it out. */ if (p != end) { /* didn't consume all of it */ return REG_NOMATCH; } if (min <= i && (i <= max || max == INFINITY)) { return REG_OKAY; } return REG_NOMATCH; /* out of range */ }  /* - caltdissect - determine alternative subexpression matches (w. complications) ^ static int caltdissect(struct vars *, struct subre *, chr *, chr *); */ static int /* regexec return code */ caltdissect( struct vars *v, struct subre *t, chr *begin, /* beginning of relevant substring */ chr *end) /* end of same */ { struct dfa *d; int er; #define UNTRIED 0 /* not yet tried at all */ #define TRYING 1 /* top matched, trying submatches */ #define TRIED 2 /* top didn't match or submatches exhausted */ if (t == NULL) { return REG_NOMATCH; } assert(t->op == '|'); if (v->mem[t->retry] == TRIED) { return caltdissect(v, t->right, begin, end); } MDEBUG(("calt n%d\n", t->retry)); assert(t->left != NULL); if (v->mem[t->retry] == UNTRIED) { d = newdfa(v, &t->left->cnfa, &v->g->cmap, DOMALLOC); if (ISERR()) { return v->err; } if (longest(v, d, begin, end, NULL) != end) { freedfa(d); v->mem[t->retry] = TRIED; return caltdissect(v, t->right, begin, end); } freedfa(d); MDEBUG(("calt matched\n")); v->mem[t->retry] = TRYING; } er = cdissect(v, t->left, begin, end); if (er != REG_NOMATCH) { return er; } v->mem[t->retry] = TRIED; return caltdissect(v, t->right, begin, end); } #include "rege_dfa.c"  /* * Local Variables: * mode: c * c-basic-offset: 4 * fill-column: 78 * End: */

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