/*

 * 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 _ANSI_ARGS_((regex_t *, CONST chr *, size_t, rm_detail_t *, size_t, regmatch_t [], int));

static int find _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *));

static int cfind _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *));

static int cfindloop _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *, struct dfa *, struct dfa *, chr **));

static VOID zapsubs _ANSI_ARGS_((regmatch_t *, size_t));

static VOID zapmem _ANSI_ARGS_((struct vars *, struct subre *));

static VOID subset _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int dissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int condissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int altdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int cdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int ccondissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int crevdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int cbrdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

static int caltdissect _ANSI_ARGS_((struct vars *, struct subre *, chr *, chr *));

/* === rege_dfa.c === */

static chr *longest _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *, int *));

static chr *shortest _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *, chr *, chr **, int *));

static chr *lastcold _ANSI_ARGS_((struct vars *, struct dfa *));

static struct dfa *newdfa _ANSI_ARGS_((struct vars *, struct cnfa *, struct colormap *, struct smalldfa *));

static VOID freedfa _ANSI_ARGS_((struct dfa *));

static unsigned hash _ANSI_ARGS_((unsigned *, int));

static struct sset *initialize _ANSI_ARGS_((struct vars *, struct dfa *, chr *));

static struct sset *miss _ANSI_ARGS_((struct vars *, struct dfa *, struct sset *, pcolor, chr *, chr *));

static int lacon _ANSI_ARGS_((struct vars *, struct cnfa *, chr *, pcolor));

static struct sset *getvacant _ANSI_ARGS_((struct vars *, struct dfa *, chr *, chr *));

static struct sset *pickss _ANSI_ARGS_((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(re, string, len, details, nmatch, pmatch, flags)

regex_t *re;

CONST chr *string;

size_t len;

rm_detail_t *details;

size_t nmatch;

regmatch_t pmatch[];

int flags;

{

	struct vars var;

	register struct vars *v = &var;

	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)

		return REG_INVARG;

	if (re->re_csize != sizeof(chr))

		return REG_MIXED;

	/* setup */

	v->re = re;

	v->g = (struct guts *)re->re_guts;

	if ((v->g->cflags&REG_EXPECT) && details == NULL)

		return REG_INVARG;

	if (v->g->info&REG_UIMPOSSIBLE)

		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)

			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);

			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);

	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(v, cnfa, cm)

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, (int *)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,

							(chr **)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(v, cnfa, cm)

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(v, cnfa, cm, d, s, coldp)

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, (int *)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, (chr **)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(p, n)

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(v, t)

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(v, sub, begin, end)

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);