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	rregexec.c - 9base - revived minimalist port of Plan 9 userland to Unix
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	rregexec.c (4729B)
	---
	1 #include "lib9.h"
	2 #include "regexp9.h"
	3 #include "regcomp.h"
	4
	5 /*
	6 * return 0 if no match
	7 * >0 if a match
	8 * <0 if we ran out of _relist space
	9 */
	10 static int
	11 rregexec1(Reprog progp, / program to run */
	12 Rune bol, / string to run machine on */
	13 Resub mp, / subexpression elements */
	14 int ms, /* number of elements at mp */
	15 Reljunk *j)
	16 {
	17 int flag=0;
	18 Reinst *inst;
	19 Relist *tlp;
	20 Rune *s;
	21 int i, checkstart;
	22 Rune r, rp, ep;
	23 Relist* tl; /* This list, next list */
	24 Relist* nl;
	25 Relist* tle; /* ends of this and next list */
	26 Relist* nle;
	27 int match;
	28 Rune *p;
	29
	30 match = 0;
	31 checkstart = j->startchar;
	32 if(mp)
	33 for(i=0; i<ms; i++) {
	34 mp[i].s.rsp = 0;
	35 mp[i].e.rep = 0;
	36 }
	37 j->relist[0][0].inst = 0;
	38 j->relist[1][0].inst = 0;
	39
	40 /* Execute machine once for each character, including terminal N…
	41 s = j->rstarts;
	42 do{
	43
	44 /* fast check for first char */
	45 if(checkstart) {
	46 switch(j->starttype) {
	47 case RUNE:
	48 p = runestrchr(s, j->startchar);
	49 if(p == 0 \|\| p == j->reol)
	50 return match;
	51 s = p;
	52 break;
	53 case BOL:
	54 if(s == bol)
	55 break;
	56 p = runestrchr(s, '\n');
	57 if(p == 0 \|\| s == j->reol)
	58 return match;
	59 s = p+1;
	60 break;
	61 }
	62 }
	63
	64 r = *s;
	65
	66 /* switch run lists */
	67 tl = j->relist[flag];
	68 tle = j->reliste[flag];
	69 nl = j->relist[flag^=1];
	70 nle = j->reliste[flag];
	71 nl->inst = 0;
	72
	73 /* Add first instruction to current list */
	74 _rrenewemptythread(tl, progp->startinst, ms, s);
	75
	76 /* Execute machine until current list is empty */
	77 for(tlp=tl; tlp->inst; tlp++){
	78 for(inst=tlp->inst; ; inst = inst->u2.next){
	79 switch(inst->type){
	80 case RUNE: /* regular character */
	81 if(inst->u1.r == r)
	82 if(_renewthread(nl, inst…
	83 return -1;
	84 break;
	85 case LBRA:
	86 tlp->se.m[inst->u1.subid].s.rsp …
	87 continue;
	88 case RBRA:
	89 tlp->se.m[inst->u1.subid].e.rep …
	90 continue;
	91 case ANY:
	92 if(r != '\n')
	93 if(_renewthread(nl, inst…
	94 return -1;
	95 break;
	96 case ANYNL:
	97 if(_renewthread(nl, inst->u2.nex…
	98 return -1;
	99 break;
	100 case BOL:
	101 if(s == bol \|\| *(s-1) == '\n')
	102 continue;
	103 break;
	104 case EOL:
	105 if(s == j->reol \|\| r == 0 \|\| r =…
	106 continue;
	107 break;
	108 case CCLASS:
	109 ep = inst->u1.cp->end;
	110 for(rp = inst->u1.cp->spans; rp …
	111 if(r >= rp[0] && r <= rp…
	112 if(_renewthread(…
	113 return -…
	114 break;
	115 }
	116 break;
	117 case NCCLASS:
	118 ep = inst->u1.cp->end;
	119 for(rp = inst->u1.cp->spans; rp …
	120 if(r >= rp[0] && r <= rp…
	121 break;
	122 if(rp == ep)
	123 if(_renewthread(nl, inst…
	124 return -1;
	125 break;
	126 case OR:
	127 /* evaluate right choice later */
	128 if(_renewthread(tlp, inst->u1.ri…
	129 return -1;
	130 /* efficiency: advance and re-ev…
	131 continue;
	132 case END: /* Match! */
	133 match = 1;
	134 tlp->se.m[0].e.rep = s;
	135 if(mp != 0)
	136 _renewmatch(mp, ms, &tlp…
	137 break;
	138 }
	139 break;
	140 }
	141 }
	142 if(s == j->reol)
	143 break;
	144 checkstart = j->startchar && nl->inst==0;
	145 s++;
	146 }while(r);
	147 return match;
	148 }
	149
	150 static int
	151 rregexec2(Reprog progp, / program to run */
	152 Rune bol, / string to run machine on */
	153 Resub mp, / subexpression elements */
	154 int ms, /* number of elements at mp */
	155 Reljunk *j
	156 )
	157 {
	158 Relist relist0[5LISTSIZE], relist1[5LISTSIZE];
	159
	160 /* mark space */
	161 j->relist[0] = relist0;
	162 j->relist[1] = relist1;
	163 j->reliste[0] = relist0 + nelem(relist0) - 2;
	164 j->reliste[1] = relist1 + nelem(relist1) - 2;
	165
	166 return rregexec1(progp, bol, mp, ms, j);
	167 }
	168
	169 extern int
	170 rregexec(Reprog progp, / program to run */
	171 Rune bol, / string to run machine on */
	172 Resub mp, / subexpression elements */
	173 int ms) /* number of elements at mp */
	174 {
	175 Reljunk j;
	176 Relist relist0[LISTSIZE], relist1[LISTSIZE];
	177 int rv;
	178
	179 /*
	180 * use user-specified starting/ending location if specified
	181 */
	182 j.rstarts = bol;
	183 j.reol = 0;
	184 if(mp && ms>0){
	185 if(mp->s.sp)
	186 j.rstarts = mp->s.rsp;
	187 if(mp->e.ep)
	188 j.reol = mp->e.rep;
	189 }
	190 j.starttype = 0;
	191 j.startchar = 0;
	192 if(progp->startinst->type == RUNE && progp->startinst->u1.r < Ru…
	193 j.starttype = RUNE;
	194 j.startchar = progp->startinst->u1.r;
	195 }
	196 if(progp->startinst->type == BOL)
	197 j.starttype = BOL;
	198
	199 /* mark space */
	200 j.relist[0] = relist0;
	201 j.relist[1] = relist1;
	202 j.reliste[0] = relist0 + nelem(relist0) - 2;
	203 j.reliste[1] = relist1 + nelem(relist1) - 2;
	204
	205 rv = rregexec1(progp, bol, mp, ms, &j);
	206 if(rv >= 0)
	207 return rv;
	208 rv = rregexec2(progp, bol, mp, ms, &j);
	209 if(rv >= 0)
	210 return rv;
	211 return -1;
	212 }