/* $Copyright:	$
 * Copyright (c) 1984, 1985, 1986, 1987, 1988, 1989, 1990 
 * Sequent Computer Systems, Inc.   All rights reserved.
 *  
 * This software is furnished under a license and may be used
 * only in accordance with the terms of that license and with the
 * inclusion of the above copyright notice.   This software may not
 * be provided or otherwise made available to, or used by, any
 * other person.  No title to or ownership of the software is
 * hereby transferred.
*/

/*	Copyright (c) 1988 AT&T	*/
/*	  All Rights Reserved  	*/

/*	THIS IS UNPUBLISHED PROPRIETARY SOURCE CODE OF AT&T	*/
/*	The copyright notice above does not evidence any   	*/
/*	actual or intended publication of such source code.	*/

#ident	"$Header: reg_step.c 1.1 89/10/23 $@(#)libgen:reg_step.c 1.0 AT&T-UP"

#include <euc.h>
#include <pcode.h>
#include <ctype.h>
#include <stdlib.h>
#include "_wchar.h"
#include "_regexp.h"
#define ecmp(s1, s2, n)	(!strncmp(s1, s2, n))
#define Popwchar(p, l) mbtowc(&l, p, MULTI_BYTE_MAX)
char	*loc1, *loc2, *locs;
char	*braslist[NBRA];
char	*braelist[NBRA];
static char _bittab[] = { 1, 2, 4, 8, 16, 32, 64, 128 };
static void getrnge();
static int cclass();
int strncmp();
static int	low;
static int	size;
static int _advance();

int step(p1, p2)
register char *p1, *p2; 
{
	register c;
	wchar_t cl;
	int n;

	/* check if match is restricted to beginning of string */
	if(*p2++) { 
		loc1 = p1;
		return(_advance(p1, p2));
	}
	if(*p2 == CCHR) {
	/* fast check for first character */
		c = p2[1];
		do {
			if(*p1 != c) 
				continue;
			if(_advance(p1, p2)) {
				loc1 = p1;
				return(1);
			}
		} while(*p1++);
	} else if(multibyte)
		do {
			if(_advance(p1, p2)) {
				loc1 = p1;
				return(1);
			}
			n = Popwchar(p1, cl);
			if(n < 0)
				/* skip past illegal multibyte characters */
				p1++;
			else
				p1 += n;
		} while(n);
	else
		/* regular algorithm */
		do {
			if(_advance(p1, p2)) {
				loc1 = p1;
				return(1);
			}
		} while(*p1++);
	return(0);
}

advance(lp, ep)
register char *lp, *ep;
{
	/* ignore flag to see if expression is anchored */
	return(_advance(lp, ++ep));
}

static int _advance(lp, ep)
register char *lp, *ep;
{
	char *rp;
	register char *curlp;
	register wchar_t c, d;
	register int n;
	wchar_t cl;
	int neg;
	char *bbeg;
	int ct;

	while(1) {
		neg = 0;
		switch(*ep++) {
		
		case CCHR:
			if(*ep++ == *lp++)
				continue;
			return(0);

		case MCCHR:
			ep += Popwchar(ep, cl);
			c = cl;
			if((n = Popwchar(lp, cl)) <= 0 || c !=  cl)
				return(0);
			lp += n;
			continue;
	
		case CDOT:
			/* 
			 * do not match illegal multibyte characters 
			 * or null 
			 */
			if((n = Popwchar(lp, cl)) > 0) {
				lp +=n;
				continue;
			}
			return(0);
	
		case CDOL:
			if(*lp == 0)
				continue;
			return(0);
	
		case CCEOF:
			loc2 = lp;
			return(1);
	
		case CCL: 
			c = (unsigned char)*lp++;
			if(ISTHERE(c)) {
				ep += 32;
				continue;
			}
			return(0);
		
		case NMCCL:
			neg = 1;
			/* fall through */
		
		case MCCL:
			rp = lp;
			if(cclass(ep, &rp, neg) != 1)
				return(0);
			ep += *(ep + 32) + 32;
			lp = rp;
			continue;
			
		case CBRA:
			braslist[*ep++] = lp;
			continue;
	
		case CKET:
			braelist[*ep++] = lp;
			continue;
		
		case MCCHR | RNGE:
			ep += Popwchar(ep, cl);
			c = cl;
			getrnge(ep);
			while(low--) {
				if((n = Popwchar(lp, cl)) <= 0 || cl != c)
					return(0);
				lp += n;
			}
			curlp = lp;
			while(size--) {
				if((n = Popwchar(lp, cl)) <= 0 || cl != c)
					break;
				lp += n;
			}
			if(size < 0)
				n = Popwchar(lp, cl);
			if(n == -1)
				return(0);
			lp += (n ? n : 1);
			ep += 2;
			goto mstar;
				
		case CCHR | RNGE:
			c = *ep++;
			getrnge(ep);
			while(low--)
				if(*lp++ != c)
					return(0);
			curlp = lp;
			while(size--) 
				if(*lp++ != c)
					break;
			if(size < 0)
				lp++;
			ep += 2;
			goto star;
	
		case CDOT | RNGE:
			getrnge(ep);
			while(low--) {
				if((n = Popwchar(lp, cl)) <= 0)
					return(0);
				lp += n;
			}
			curlp = lp;
			while(size--) {
				if((n = Popwchar(lp, cl)) <= 0) 
					break;
				lp += n;
			}
			if(size < 0)
				n = Popwchar(lp, cl);
			if(n == -1)
				return(0);
			lp += (n ? n : 1);
			ep += 2;
			goto mstar;
		
		case NMCCL | RNGE:
			neg = 1;
			/* fall through */
		
		case MCCL | RNGE:
			getrnge(ep + *(ep + 32) + 32);
			rp = lp;
			while(low--) {
				if(cclass(ep, &rp, neg) != 1)
					return(0);
			}
			curlp = rp;
			while(size-- &&	(c=(cclass(ep, &rp, neg))) == 1);
			if(c == -1)
				return(0);
			lp = rp;
			if(size < 0) {
				if((n = Popwchar(lp, cl)) == -1)
					return(0);
				lp += (n ? n : 1);
			}
			ep += *(ep + 32) + 34;
			goto mstar;
		
		case CCL | RNGE:
			getrnge(ep + 32);
			while(low--) {
				c = (unsigned char)*lp++;
				if(!ISTHERE(c))
					return(0);
			}
			curlp = lp;
			while(size--) {
				c = (unsigned char)*lp++;
				if(!ISTHERE(c))
					break;
			}
			if(size < 0)
				lp++;
			ep += 34;		/* 32 + 2 */
			goto star;
	
		case CBACK:
			bbeg = braslist[*ep];
			ct = braelist[*ep++] - bbeg;
	
			if(ecmp(bbeg, lp, ct)) {
				lp += ct;
				continue;
			}
			return(0);
	
		case CBACK | STAR:
			bbeg = braslist[*ep];
			ct = braelist[*ep++] - bbeg;
			curlp = lp;
			while(ecmp(bbeg, lp, ct))
				lp += ct;
	
			while(lp >= curlp) {
				if(_advance(lp, ep))	
					return(1);
				lp -= ct;
			}
			return(0);
	
		case CDOT | STAR:
			curlp = lp;
			if(!multibyte)
				while(*lp++);
			else {
				while((n = Popwchar(lp, cl)) > 0)
					lp += n;
				if(n == -1)
					return(0);
				if(n == 0)
					lp++;
			}
			goto mstar;
	
		case CCHR | STAR:
			curlp = lp;
			while(*lp++ == *ep);
			ep++;
			goto star;
	
		case MCCHR | STAR:
			curlp = lp;
			ep += Popwchar(ep, cl);
			c = cl;
			while((n = Popwchar(lp, cl))  > 0 && cl == c)
				lp += n;
			if(n == -1)
				return(0);
			lp += (n ? n : 1);
			goto mstar;
		
		case NMCCL | STAR:
			neg = 1;
			/* fall through */
		
		case MCCL | STAR:
			curlp = rp = lp;
			while((d = cclass(ep, &rp, neg)) == 1);
			if(d == -1)
				return(0);
			lp = rp;
			ep += *(ep + 32) + 32;
			goto mstar;
		
		case CCL | STAR:
			curlp = lp;
			do {
				c = (unsigned char)*lp++;
			} while(ISTHERE(c));
			ep += 32;
			goto star;
	
		default: 
			return(0);
		}
	}

mstar:
	if(multibyte) {
		do {
			register char *p1, *p2;
			lp--;
			p1 = lp - eucw2;
			p2 = lp - eucw3;
			/* check if previous character is from
		       	 * supplementary code sets 1, 2, or 3 and
			 * back up appropriate number of bytes
			 */
			if((unsigned char)*lp >= 0200) {
				if(p1 >= curlp && (unsigned char)*p1 == SS2)
					lp = p1;
				else if(p2 >= curlp && (unsigned char)*p2 == SS3)
					lp = p2;
				else
					lp = lp - eucw1 + 1;
			}
			if(lp == locs)
				break;
			if(_advance(lp, ep))
				return(1);
		} while(lp > curlp);
		return(0);
	}
star:
	do {
		if(--lp == locs)
			break;
		if(_advance(lp, ep))
			return(1);
	} while(lp > curlp);
	return(0);
}

static
void getrnge(str)
register char *str;
{
	low = *str++ & 0377;
	size = (*str == 255)? 20000: (*str &0377) - low;
}

static cclass(ep, rp, neg)
register char *ep, **rp; 
int neg;
{
	register char *lp;
	register wchar_t c, d, f;
	register int n;
	wchar_t cl;
	char *endep; 
	lp = *rp;
	if((n = Popwchar(lp, cl)) == -1)
		return(-1);
	*rp = lp + (n ? n : 1);
	c = cl;
	/* look for eight bit characters in bitmap */
	if(c <= 0177 || c <= 0377 && iscntrl(c))
		return(ISTHERE(c) && !neg || !ISTHERE(c) && neg);
	else {
		/* look past bitmap for multibyte characters */
		endep = *(ep + 32) + ep + 32;
		ep += 33;
		while(1) {
			if(ep >= endep)
				return(neg);
			ep += Popwchar(ep, cl);
			d = cl;
			if(d == '-') {
				ep += Popwchar(ep, cl);
				d = cl;
				if(f <= c && c <= d)
					return(!neg);
			}
			if(d == c)
				return(!neg);
			f = d;
		}
	}
}
