4.3BSD - /usr/src/ucb/pascal/eyacc/ey3.c

   1: /*
   2:  * Copyright (c) 1979 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifndef lint
   8: static char sccsid[] = "@(#)ey3.c	5.1 (Berkeley) 4/29/85";
   9: #endif not lint
  10: 
  11: # include "ey.h"
  12: 
  13: cpres(){ /* conpute an array with the beginnings of  productions yielding given nonterminals
  14: 	The array pres points to these lists */
  15:     int i,j,c;
  16:     pres = (int ***)yalloc(nnonter+1);
  17:     for(i=0;i<=nnonter;i++){
  18:         c = i+NTBASE;
  19:         pres[i] = (int **)mem;
  20:         fatfl = 0;  /* make undefined  symbols  nonfatal */
  21:         for(j=0;j<nprod;j++)
  22:         if (*prdptr[j] == c) *mem++ =  (int)(prdptr[j]+1);
  23:         if(pres[i] == (int **)mem){
  24:             error("nonterminal %s not defined!", nontrst[i].name);
  25:             }
  26:         }
  27:     pres[i] = (int **)mem;
  28:     fatfl = 1;
  29:     if( nerrors ){
  30:         summary();
  31:         cexit(1);
  32:         }
  33:     }
  34: 
  35: int indebug = 0;
  36: cpfir() {
  37:   /* compute an array with the first of nonterminals */
  38:   int i, ch, **s, **t, changes, *p;
  39: 
  40:   pfirst = (struct looksets **)yalloc(nnonter+1);
  41:   for (i=0;i<=nnonter;i++) {
  42:     aryfil( wsets[i].ws, tbitset, 0 );
  43:     t = pres[i+1];
  44:     for( s=pres[i]; s<t; ++s ){ /* initially fill the sets */
  45:       for( p = *s; (ch = *p) > 0 ; ++p ) {
  46:         if( ch < NTBASE ) {
  47:           wsets[i].ws[ch>>4] |= (1 << (ch&017) );
  48:           break;
  49:           }
  50:         else if( !pempty[ch-NTBASE] ) break;
  51:         }
  52:       }
  53:     }
  54: 
  55:   /* now, reflect transitivity */
  56: 
  57:   changes = 1;
  58:   while( changes ){
  59:     changes = 0;
  60:     for( i=0; i<=nnonter; ++i ){
  61:       t = pres[i+1];
  62:       for( s=pres[i]; s<t; ++s ){
  63:         for( p = *s; ( ch = (*p-NTBASE) ) >= 0; ++p ) {
  64:           changes |= UNION( wsets[i].ws, wsets[i].ws, wsets[ch].ws );
  65:           if( !pempty[ch] ) break;
  66:           }
  67:         }
  68:       }
  69:     }
  70: 
  71:   for( i=0; i<=nnonter; i++ ) pfirst[i] = flset( wsets[i].ws );
  72:   if( !indebug ) return;
  73:   settty();
  74:   for( i=0; i<=nnonter; i++ ){
  75:     fprintf( cout ,  "\n%s: ", nontrst[i].name );
  76:     prlook( pfirst[i] );
  77:     fprintf( cout ,  " %d\n", pempty[i] );
  78:     }
  79:   }
  80: 
  81: state(c){ /* sorts last state,and sees if it equals earlier ones. returns state number */
  82:     int *s,size1,size2;
  83:     struct looksets *lp;
  84:     _REGISTER i;
  85:     struct item *p1, *p2, *k, *l, *q1, *q2;
  86:     p1 = pstate[nstate];
  87:     p2 = pstate[nstate+1];
  88:     if(p1==p2) return(0); /* null state */
  89:     /* sort the items */
  90:     for(k=p2-1;k>p1;k--) {  /* make k the biggest */
  91:         for(l=k-1;l>=p1;--l)if( l->pitem > k->pitem ){
  92:             s = k->pitem;
  93:             k->pitem = l->pitem;
  94:             l->pitem = s;
  95:             lp = k->look;
  96:             k->look = l->look;
  97:             l->look = lp;
  98:             }
  99:         }
 100:     size1 = p2 - p1; /* size of state */
 101: 
 102:     for( i= (c>=NTBASE)?ntstates[c-NTBASE]:tstates[c]; i != 0; i = mstates[i] ) {
 103:         /* get ith state */
 104:         q1 = pstate[i];
 105:         q2 = pstate[i+1];
 106:         size2 = q2 - q1;
 107:         if (size1 != size2) continue;
 108:         k=p1;
 109:         for(l=q1;l<q2;l++) {
 110:             if( l->pitem != k->pitem ) break;
 111:             ++k;
 112:             }
 113:         if (l != q2) continue;
 114:         /* found it */
 115:         pstate[nstate+1] = pstate[nstate]; /* delete last state */
 116:         /* fix up lookaheads */
 117:         k=p1;
 118:         for( l=q1; l<q2; ++l ){
 119:             if( UNION( clset.lset, l->look->lset, k->look->lset ) ) {
 120:                 tystate[i] = 1;
 121:                 /* register the new set */
 122:                 l->look = flset( &clset );
 123:                 }
 124:             ++k;
 125:             }
 126:         return (i);
 127:         }
 128: /* state is new */
 129:     pstate[nstate+2] = p2;
 130:     if(nstate+1 >= stsize) error("too many states");
 131:     if( c >= NTBASE ){
 132:         mstates[ nstate ] = ntstates[ c-NTBASE ];
 133:         ntstates[ c-NTBASE ] = nstate;
 134:         }
 135:     else {
 136:         mstates[ nstate ] = tstates[ c ];
 137:         tstates[ c ] = nstate;
 138:         }
 139:     tystate[nstate]=1;
 140:     return(nstate++);
 141:     }
 142: 
 143: int pidebug = 0; /* debugging flag for putitem */
 144: putitem ( ptr, lptr )       int *ptr; struct looksets *lptr;{
 145:     int *jip, k;
 146:     struct item *i, *j;
 147: 
 148:         if( pidebug ) {
 149:           settty();
 150:       fprintf( cout , "putitem(%s), state %d\n", writem(&ptr), nstate );
 151:           }
 152:     /* see if it's there */
 153:     j = pstate[nstate+1];
 154:         for( i=pstate[nstate]; i<j; ++i )
 155:         if(i->pitem == ptr) {
 156:             error("yacc error--duplicate item");
 157:             }
 158:     /* not there */
 159:     j->pitem = ptr;
 160:     j->look = flset( lptr );
 161:     pstate[nstate+1] = ++j;
 162:     jip = (int *)j;
 163:     if(jip-mem0 >= memsiz) error("out of state space");
 164:     }
 165: 
 166: cempty(){ /* mark nonterminals which derive the empty string */
 167: 
 168:   int i, *p;
 169: 
 170:   /* set pempty to 0 */
 171:   pempty = (char *)yalloc( nnonter / sizeof(int) + 1 );
 172:   aryfil( pempty, nnonter+1, 0 );
 173:   for( i=1; i<nprod; ++i ) /* loop over productions */
 174:     if( prdptr[i][1] <= 0 ) /* i is empty production */
 175:       pempty[ *prdptr[i]-NTBASE ] = 1;
 176: 
 177:   /* now, all explicitly empty nonterminals marked with pempty = 1 */
 178: 
 179:   /* loop as long as we keep finding nontrivial empty nonterminals */
 180: 
 181: again:
 182:   for( i=1; i<nprod; ++i ){
 183:     if( pempty[ *prdptr[i]-NTBASE ]==0 ){ /* not known to be empty */
 184:       for( p=prdptr[i]+1; *p>=NTBASE && pempty[*p-NTBASE]!=0 ; ++p ) ;
 185:       if( *p < 0 ){ /* we have a nontrivially empty nonterminal */
 186:         pempty[*prdptr[i]-NTBASE] = 1;
 187:         goto again; /* got one ... try for another */
 188:         }
 189:       }
 190:     }
 191:   }
 192: 
 193: int gsdebug = 0;
 194: stagen(){ /* generate the states */
 195: 
 196:   int i, j, k, c;
 197: 
 198:   /* initialize */
 199: 
 200:   nstate = 0;
 201:   pstate[0] = pstate[1] = (struct item *)mem;
 202:   aryfil( clset.lset, tbitset, 0 );
 203:   putitem( prdptr[0]+1, &clset );
 204:   tystate[0] = 1;
 205:   nstate = 1;
 206:   pstate[2] = pstate[1];
 207: 
 208:   memact = 0;
 209:   aryfil( amem, actsiz, 0 );
 210: 
 211:   /* now, the main state generation loop */
 212: 
 213:   more:
 214:   for( i=0; i<nstate; ++i ){
 215:     /* if tystate == 2, set to zero */
 216:     if( tystate[i] != 1 ) continue;
 217:     tystate[i] = 0;
 218:     aryfil( temp1, nterms+nnonter+1, 0 );
 219:     /* take state i, close it, and do gotos */
 220:     closure(i);
 221:     for( j=0; j<cwset; ++j ){ /* generate gotos */
 222:       if( wsets[j].flag ) continue;
 223:       wsets[j].flag = 1;
 224:       c = *(wsets[j].pitem);
 225:       /* if no symbols after the dot (ie empty rule) */
 226:       if( c <= 1 ) {
 227:     /* if not in kernel then tystate = 2 unless not done with it */
 228:     if( pstate[i+1]-pstate[i] <= j ) tystate[i] = (tystate[i]==1)?1:2;
 229:     continue;
 230:     }
 231:       /* do a goto on c */
 232:       for( k=j; k<cwset; ++k ){
 233:         if( c == *(wsets[k].pitem) ){ /* this item contributes to the goto */
 234:           putitem( wsets[k].pitem + 1, wsets[k].ws );
 235:           wsets[k].flag = 1;
 236:           }
 237:         }
 238:       if( c < NTBASE ) temp1[c] = state(c);
 239:       else temp1[c-NTBASE+nterms] = state(c);
 240:       }
 241:     if( gsdebug ){
 242:       settty();
 243:       fprintf( cout ,  "%d: ", i );
 244:       for( j=1; j<=nterms; ++j ){
 245:         if( temp1[j] != 0 ) fprintf( cout ,  "%s %d, ", symnam(j), temp1[j]);
 246:         }
 247:       for( j=1; j<=nnonter; ++j ){
 248:         if( temp1[j+nterms] ) fprintf( cout ,  "%s %d, ", nontrst[j].name, temp1[j+nterms] );
 249:         }
 250:       fprintf( cout , "\n");
 251:       }
 252:     apstate[i] = apack( &temp1[0], nterms );
 253:     indgo[i] = apack( &temp1[nterms+1], nnonter-1 ) - 1;
 254:     goto more; /* we have done one goto; do some more */
 255:     }
 256:   /* no more to do... stop */
 257:   }
 258: 
 259: int cldebug = 0; /* debugging flag for closure */
 260: closure(i){ /* generate the closure of state i */
 261: 
 262:   int c, ch, work;
 263:   _REGISTER j, k;
 264:   int *pi;
 265:   int **s, **t;
 266:   struct item *q;
 267:   _REGISTER struct item *p;
 268: 
 269:   ++zzclose;
 270: 
 271:   /* first, copy kernel of state i to wsets */
 272: 
 273:   lambdarule = -1;
 274:   cwset = 0;
 275:   q = pstate[i+1];
 276:   /* for every item in the kernel */
 277:   for( p=pstate[i]; p<q; ++p ){
 278:     wsets[cwset].pitem = p->pitem;
 279:     wsets[cwset].flag = 1;    /* this item must get closed */
 280:     for( k=0; k<tbitset; ++k ) wsets[cwset].ws[k] = p->look->lset[k];
 281:     ++cwset;
 282:     }
 283: 
 284:   /* now, go through the loop, closing each item */
 285: 
 286:   work = 1;
 287:   while( work ){
 288:     work = 0;
 289:     for( j=0; j<cwset; ++j ){
 290: 
 291:       /* for every item in state, if terminal after dot, flag = 0 */
 292:       if( wsets[j].flag == 0 ) continue;
 293:       /* dot is before c, since pitem of X -> A.B is B */
 294:       c = *(wsets[j].pitem);
 295: 
 296:       if( c < NTBASE ){
 297:         wsets[j].flag = 0;
 298:         continue;  /* only interesting case is where . is before nonterminal */
 299:         }
 300: 
 301:       /* compute the lookahead */
 302:       aryfil( clset.lset, tbitset, 0 );
 303: 
 304:       /* find items involving c */
 305: 
 306:       /* for all the rest of the items in the state */
 307:       for( k=j; k<cwset; ++k ){
 308:         if( wsets[k].flag == 1 && *(pi=wsets[k].pitem) == c ){
 309:           wsets[k].flag = 0;
 310:           if( nolook ) continue;
 311:           while( (ch= *++pi)>0 ){
 312:             if( ch < NTBASE ){ /* terminal symbol */
 313:           /* put ch in clset */
 314:               clset.lset[ch>>4] |= (1<<(ch&017));
 315:               break;
 316:               }
 317:             /* nonterminal symbol */
 318:         /* clset <- clset U first(ch) */
 319:             UNION( clset.lset, clset.lset, pfirst[ch-NTBASE] );
 320:         /* if ch cannot derive lambda we are done */
 321:             if( !pempty[ch-NTBASE] ) break;
 322:             }
 323:       /* if end of rule the clset <- clset U (lookahead for LHS) */
 324:           if( ch<=0 ) UNION( clset.lset, clset.lset, wsets[k].ws );
 325:           }
 326:         }
 327: 
 328:       /*  now loop over productions derived from c */
 329: 
 330:       c -= NTBASE; /* c is now nonterminal number */
 331: 
 332:       t = pres[c+1];
 333:       /* for each rule that c derives */
 334:       for( s=pres[c]; s<t; ++s ){
 335:         /* put these items into the closure */
 336:         for( k=0; k<cwset; ++k ){ /* is the item there */
 337:           if( wsets[k].pitem == *s ){ /* yes, it is there */
 338:             if( nolook ) goto nexts;
 339:         /* if something new in ws, set flag = 1 */
 340:             if( UNION( wsets[k].ws, wsets[k].ws, clset.lset ) )
 341:           wsets[k].flag = work = 1;
 342:             goto nexts;
 343:             }
 344:           }
 345: 
 346:         /*  not there; make a new entry */
 347:         if( cwset+1 >= wssize ) error( "working set overflow" );
 348:         wsets[cwset].pitem = *s;
 349:         wsets[cwset].flag = 1;
 350:     if (**s < 0)
 351:       lambdarule = cwset;
 352:         if( nolook ){
 353:           cwset++;
 354:           goto nexts;
 355:           }
 356:         work = 1;
 357:         for( k=0; k<tbitset; ++k ) wsets[cwset].ws[k] = clset.lset[k];
 358:         cwset++;
 359: 
 360:       nexts: ;
 361:         }
 362: 
 363:       }
 364:     }
 365: 
 366:   /* have computed closure; flags are reset; return */
 367: 
 368:   if( cwset > zzcwset ) zzcwset = cwset;
 369:   if( !cldebug ) return;
 370:   settty();
 371:   fprintf( cout , "\nState %d, nolook = %d\n", i, nolook );
 372:   for( j=0; j<cwset; ++j ){
 373:     if( wsets[j].flag ) fprintf( cout , "flag set!\n");
 374:     wsets[j].flag = 0;
 375:     fprintf( cout , "\t%s", writem(&wsets[j].pitem));
 376:     prlook( wsets[j].ws );
 377:     fprintf( cout ,  "\n" );
 378:     }
 379: 
 380:   }
 381: 
 382: struct looksets *flset( p )
 383:     struct looksets *p;
 384:     {
 385:     /* decide if the lookahead set pointed to by p is known */
 386:     /* return pointer to a perminent location for the set */
 387: 
 388:     int j, *w;
 389:     _REGISTER *u, *v, i;
 390: 
 391:     for( i=0; i<nlset; ++i ){
 392:         u = p->lset;
 393:         v = lkst[i].lset;
 394:         w = & v[tbitset];
 395:         while( v<w) if( *u++ != *v++ ) goto more;
 396:         /* we have matched */
 397:         return( & lkst[i] );
 398:         more: ;
 399:         }
 400:     /* add a new one */
 401:     if( nlset+1 >= lsetsz )error("too many lookahead sets");
 402:     for( j=0; j<tbitset; ++j ){
 403:         lkst[nlset].lset[j] = p->lset[j];
 404:         }
 405:     return( & lkst[nlset++]);
 406:     }

Defined functions

Defined variables