2.9BSD - /usr/src/ucb/eyacc/ey3.c

   1: /* (c) 1979 Regents of the University of California */
   2: # include "ey.h"
   3: 
   4: cpres(){ /* conpute an array with the beginnings of  productions yielding given nonterminals
   5: 	The array pres points to these lists */
   6:     int i,j,c;
   7:     pres = yalloc(nnonter+1);
   8:     for(i=0;i<=nnonter;i++){
   9:         c = i+NTBASE;
  10:         pres[i] = mem;
  11:         fatfl = 0;  /* make undefined  symbols  nonfatal */
  12:         for(j=0;j<nprod;j++)
  13:         if (*prdptr[j] == c) *mem++ =  prdptr[j]+1;
  14:         if(pres[i] == mem){
  15:             error("nonterminal %s not defined!", nontrst[i].name);
  16:             }
  17:         }
  18:     pres[i] = mem;
  19:     fatfl = 1;
  20:     if( nerrors ){
  21:         summary();
  22:         cexit(1);
  23:         }
  24:     }
  25: 
  26: int indebug = 0;
  27: cpfir() {
  28:   /* compute an array with the first of nonterminals */
  29:   int i, ch, **s, **t, changes, *p;
  30: 
  31:   pfirst = yalloc(nnonter+1);
  32:   for (i=0;i<=nnonter;i++) {
  33:     aryfil( wsets[i].ws, tbitset, 0 );
  34:     t = pres[i+1];
  35:     for( s=pres[i]; s<t; ++s ){ /* initially fill the sets */
  36:       for( p = *s; (ch = *p) > 0 ; ++p ) {
  37:         if( ch < NTBASE ) {
  38:           wsets[i].ws[ch>>4] |= (1 << (ch&017) );
  39:           break;
  40:           }
  41:         else if( !pempty[ch-NTBASE] ) break;
  42:         }
  43:       }
  44:     }
  45: 
  46:   /* now, reflect transitivity */
  47: 
  48:   changes = 1;
  49:   while( changes ){
  50:     changes = 0;
  51:     for( i=0; i<=nnonter; ++i ){
  52:       t = pres[i+1];
  53:       for( s=pres[i]; s<t; ++s ){
  54:         for( p = *s; ( ch = (*p-NTBASE) ) >= 0; ++p ) {
  55:           changes |= UNION( wsets[i].ws, wsets[i].ws, wsets[ch].ws );
  56:           if( !pempty[ch] ) break;
  57:           }
  58:         }
  59:       }
  60:     }
  61: 
  62:   for( i=0; i<=nnonter; i++ ) pfirst[i] = flset( wsets[i].ws );
  63:   if( !indebug ) return;
  64:   settty();
  65:   for( i=0; i<=nnonter; i++ ){
  66:     fprintf( cout ,  "\n%s: ", nontrst[i].name );
  67:     prlook( pfirst[i] );
  68:     fprintf( cout ,  " %d\n", pempty[i] );
  69:     }
  70:   }
  71: 
  72: state(c){ /* sorts last state,and sees if it equals earlier ones. returns state number */
  73:     int s,size1,size2;
  74:     _REGISTER i;
  75:     struct item *p1, *p2, *k, *l, *q1, *q2;
  76:     p1 = pstate[nstate];
  77:     p2 = pstate[nstate+1];
  78:     if(p1==p2) return(0); /* null state */
  79:     /* sort the items */
  80:     for(k=p2-1;k>p1;k--) {  /* make k the biggest */
  81:         for(l=k-1;l>=p1;--l)if( l->pitem > k->pitem ){
  82:             s = k->pitem;
  83:             k->pitem = l->pitem;
  84:             l->pitem = s;
  85:             s = k->look;
  86:             k->look = l->look;
  87:             l->look = s;
  88:             }
  89:         }
  90:     size1 = p2 - p1; /* size of state */
  91: 
  92:     for( i= (c>=NTBASE)?ntstates[c-NTBASE]:tstates[c]; i != 0; i = mstates[i] ) {
  93:         /* get ith state */
  94:         q1 = pstate[i];
  95:         q2 = pstate[i+1];
  96:         size2 = q2 - q1;
  97:         if (size1 != size2) continue;
  98:         k=p1;
  99:         for(l=q1;l<q2;l++) {
 100:             if( l->pitem != k->pitem ) break;
 101:             ++k;
 102:             }
 103:         if (l != q2) continue;
 104:         /* found it */
 105:         pstate[nstate+1] = pstate[nstate]; /* delete last state */
 106:         /* fix up lookaheads */
 107:         k=p1;
 108:         for( l=q1; l<q2; ++l ){
 109:             if( UNION( clset.lset, l->look->lset, k->look->lset ) ) {
 110:                 tystate[i] = 1;
 111:                 /* register the new set */
 112:                 l->look = flset( &clset );
 113:                 }
 114:             ++k;
 115:             }
 116:         return (i);
 117:         }
 118: /* state is new */
 119:     pstate[nstate+2] = p2;
 120:     if(nstate+1 >= stsize) error("too many states");
 121:     if( c >= NTBASE ){
 122:         mstates[ nstate ] = ntstates[ c-NTBASE ];
 123:         ntstates[ c-NTBASE ] = nstate;
 124:         }
 125:     else {
 126:         mstates[ nstate ] = tstates[ c ];
 127:         tstates[ c ] = nstate;
 128:         }
 129:     tystate[nstate]=1;
 130:     return(nstate++);
 131:     }
 132: 
 133: int pidebug = 0; /* debugging flag for putitem */
 134: putitem ( ptr, lptr )       int *ptr; struct looksets *lptr;{
 135:     int *jip, k;
 136:     struct item *i, *j;
 137: 
 138:         if( pidebug ) {
 139:           settty();
 140:       fprintf( cout , "putitem(%s), state %d\n", writem(&ptr), nstate );
 141:           }
 142:     /* see if it's there */
 143:     j = pstate[nstate+1];
 144:         for( i=pstate[nstate]; i<j; ++i )
 145:         if(i->pitem == ptr) {
 146:             error("yacc error--duplicate item");
 147:             }
 148:     /* not there */
 149:     j->pitem = ptr;
 150:     j->look = flset( lptr );
 151:     pstate[nstate+1] = ++j;
 152:     jip = j;
 153:     if(jip-mem0 >= memsiz) error("out of state space");
 154:     }
 155: 
 156: cempty(){ /* mark nonterminals which derive the empty string */
 157: 
 158:   int i, *p;
 159: 
 160:   /* set pempty to 0 */
 161:   pempty = yalloc( nnonter );
 162:   aryfil( pempty, nnonter+1, 0 );
 163:   for( i=1; i<nprod; ++i ) /* loop over productions */
 164:     if( prdptr[i][1] <= 0 ) /* i is empty production */
 165:       pempty[ *prdptr[i]-NTBASE ] = 1;
 166: 
 167:   /* now, all explicitly empty nonterminals marked with pempty = 1 */
 168: 
 169:   /* loop as long as we keep finding nontrivial empty nonterminals */
 170: 
 171: again:
 172:   for( i=1; i<nprod; ++i ){
 173:     if( pempty[ *prdptr[i]-NTBASE ]==0 ){ /* not known to be empty */
 174:       for( p=prdptr[i]+1; *p>=NTBASE && pempty[*p-NTBASE]!=0 ; ++p ) ;
 175:       if( *p < 0 ){ /* we have a nontrivially empty nonterminal */
 176:         pempty[*prdptr[i]-NTBASE] = 1;
 177:         goto again; /* got one ... try for another */
 178:         }
 179:       }
 180:     }
 181:   }
 182: 
 183: int gsdebug = 0;
 184: stagen(){ /* generate the states */
 185: 
 186:   int i, j, k, c;
 187: 
 188:   /* initialize */
 189: 
 190:   nstate = 0;
 191:   pstate[0] = pstate[1] = mem;
 192:   aryfil( clset.lset, tbitset, 0 );
 193:   putitem( prdptr[0]+1, &clset );
 194:   tystate[0] = 1;
 195:   nstate = 1;
 196:   pstate[2] = pstate[1];
 197: 
 198:   memact = 0;
 199:   aryfil( amem, actsiz, 0 );
 200: 
 201:   /* now, the main state generation loop */
 202: 
 203:   more:
 204:   for( i=0; i<nstate; ++i ){
 205:     if( tystate[i] != 1 ) continue;
 206:     tystate[i] = 0;
 207:     aryfil( temp1, nterms+nnonter+1, 0 );
 208:     /* take state i, close it, and do gotos */
 209:     closure(i);
 210:     for( j=0; j<cwset; ++j ){ /* generate gotos */
 211:       if( wsets[j].flag ) continue;
 212:       wsets[j].flag = 1;
 213:       c = *(wsets[j].pitem);
 214:       if( c <= 1 ) {
 215:         if( pstate[i+1]-pstate[i] <= j ) tystate[i] = (tystate[i]==1)?1:2;
 216:         continue;
 217:         }
 218:       /* do a goto on c */
 219:       for( k=j; k<cwset; ++k ){
 220:         if( c == *(wsets[k].pitem) ){ /* this item contributes to the goto */
 221:           putitem( wsets[k].pitem + 1, wsets[k].ws );
 222:           wsets[k].flag = 1;
 223:           }
 224:         }
 225:       if( c < NTBASE ) temp1[c] = state(c);
 226:       else temp1[c-NTBASE+nterms] = state(c);
 227:       }
 228:     if( gsdebug ){
 229:       settty();
 230:       fprintf( cout ,  "%d: ", i );
 231:       for( j=1; j<=nterms; ++j ){
 232:         if( temp1[j] != 0 ) fprintf( cout ,  "%s %d, ", symnam(j), temp1[j]);
 233:         }
 234:       for( j=1; j<=nnonter; ++j ){
 235:         if( temp1[j+nterms] ) fprintf( cout ,  "%s %d, ", nontrst[j].name, temp1[j+nterms] );
 236:         }
 237:       fprintf( cout , "\n");
 238:       }
 239:     apstate[i] = apack( &temp1[0], nterms );
 240:     indgo[i] = apack( &temp1[nterms+1], nnonter-1 ) - 1;
 241:     goto more; /* we have done one goto; do some more */
 242:     }
 243:   /* no more to do... stop */
 244:   }
 245: 
 246: int cldebug = 0; /* debugging flag for closure */
 247: closure(i){ /* generate the closure of state i */
 248: 
 249:   int c, ch, work;
 250:   _REGISTER j, k;
 251:   int *pi;
 252:   int **s, **t;
 253:   struct item *q;
 254:   _REGISTER struct item *p;
 255: 
 256:   ++zzclose;
 257: 
 258:   /* first, copy kernel of state i to wsets */
 259: 
 260:   cwset = 0;
 261:   q = pstate[i+1];
 262:   for( p=pstate[i]; p<q; ++p ){
 263:     wsets[cwset].pitem = p->pitem;
 264:     wsets[cwset].flag = 1;    /* this item must get closed */
 265:     for( k=0; k<tbitset; ++k ) wsets[cwset].ws[k] = p->look->lset[k];
 266:     ++cwset;
 267:     }
 268: 
 269:   /* now, go through the loop, closing each item */
 270: 
 271:   work = 1;
 272:   while( work ){
 273:     work = 0;
 274:     for( j=0; j<cwset; ++j ){
 275: 
 276:       if( wsets[j].flag == 0 ) continue;
 277:       c = *(wsets[j].pitem);  /* dot is before c */
 278: 
 279:       if( c < NTBASE ){
 280:         wsets[j].flag = 0;
 281:         continue;  /* only interesting case is where . is before nonterminal */
 282:         }
 283: 
 284:       /* compute the lookahead */
 285:       aryfil( clset.lset, tbitset, 0 );
 286: 
 287:       /* find items involving c */
 288: 
 289:       for( k=j; k<cwset; ++k ){
 290:         if( wsets[k].flag == 1 && *(pi=wsets[k].pitem) == c ){
 291:           wsets[k].flag = 0;
 292:           if( nolook ) continue;
 293:           while( (ch= *++pi)>0 ){
 294:             if( ch < NTBASE ){ /* terminal symbol */
 295:               clset.lset[ch>>4] |= (1<<(ch&017));
 296:               break;
 297:               }
 298:             /* nonterminal symbol */
 299:             UNION( clset.lset, clset.lset, pfirst[ch-NTBASE] );
 300:             if( !pempty[ch-NTBASE] ) break;
 301:             }
 302:           if( ch<=0 ) UNION( clset.lset, clset.lset, wsets[k].ws );
 303:           }
 304:         }
 305: 
 306:       /*  now loop over productions derived from c */
 307: 
 308:       c -= NTBASE; /* c is now nonterminal number */
 309: 
 310:       t = pres[c+1];
 311:       for( s=pres[c]; s<t; ++s ){
 312:         /* put these items into the closure */
 313:         for( k=0; k<cwset; ++k ){ /* is the item there */
 314:           if( wsets[k].pitem == *s ){ /* yes, it is there */
 315:             if( nolook ) goto nexts;
 316:             if( UNION( wsets[k].ws, wsets[k].ws, clset.lset ) ) wsets[k].flag = work = 1;
 317:             goto nexts;
 318:             }
 319:           }
 320: 
 321:         /*  not there; make a new entry */
 322:         if( cwset+1 >= wssize ) error( "working set overflow" );
 323:         wsets[cwset].pitem = *s;
 324:         wsets[cwset].flag = 1;
 325:         if( nolook ){
 326:           cwset++;
 327:           goto nexts;
 328:           }
 329:         work = 1;
 330:         for( k=0; k<tbitset; ++k ) wsets[cwset].ws[k] = clset.lset[k];
 331:         cwset++;
 332: 
 333:       nexts: ;
 334:         }
 335: 
 336:       }
 337:     }
 338: 
 339:   /* have computed closure; flags are reset; return */
 340: 
 341:   if( cwset > zzcwset ) zzcwset = cwset;
 342:   if( !cldebug ) return;
 343:   settty();
 344:   fprintf( cout , "\nState %d, nolook = %d\n", i, nolook );
 345:   for( j=0; j<cwset; ++j ){
 346:     if( wsets[j].flag ) fprintf( cout , "flag set!\n");
 347:     wsets[j].flag = 0;
 348:     fprintf( cout , "\t%s", writem(&wsets[j].pitem));
 349:     prlook( wsets[j].ws );
 350:     fprintf( cout ,  "\n" );
 351:     }
 352: 
 353:   }
 354: 
 355: struct looksets *flset( p )
 356:     struct looksets *p;
 357:     {
 358:     /* decide if the lookahead set pointed to by p is known */
 359:     /* return pointer to a perminent location for the set */
 360: 
 361:     int j, *w;
 362:     _REGISTER *u, *v, i;
 363: 
 364:     for( i=0; i<nlset; ++i ){
 365:         u = p->lset;
 366:         v = lkst[i].lset;
 367:         w = & v[tbitset];
 368:         while( v<w) if( *u++ != *v++ ) goto more;
 369:         /* we have matched */
 370:         return( & lkst[i] );
 371:         more: ;
 372:         }
 373:     /* add a new one */
 374:     if( nlset+1 >= lsetsz )error("too many lookahead sets");
 375:     for( j=0; j<tbitset; ++j ){
 376:         lkst[nlset].lset[j] = p->lset[j];
 377:         }
 378:     return( & lkst[nlset++]);
 379:     }

Defined functions

Defined variables