external/bsd/byacc/dist/lalr.c

   1 /*      $NetBSD: lalr.c,v 1.6 2015/01/03 23:22:52 christos Exp $        */
   2
   3 #include "defs.h"
   4 /* Id: lalr.c,v 1.11 2014/09/18 00:26:39 tom Exp  */
   5
   6 #include <sys/cdefs.h>
   7 __RCSID("$NetBSD: lalr.c,v 1.6 2015/01/03 23:22:52 christos Exp $");
   8
   9 typedef struct shorts
  10 {
  11     struct shorts *next;
  12     Value_t value;
  13 }
  14 shorts;
  15
  16 static Value_t map_goto(int state, int symbol);
  17 static Value_t **transpose(Value_t ** R, int n);
  18 static void add_lookback_edge(int stateno, int ruleno, int gotono);
  19 static void build_relations(void);
  20 static void compute_FOLLOWS(void);
  21 static void compute_lookaheads(void);
  22 static void digraph(Value_t ** relation);
  23 static void initialize_F(void);
  24 static void initialize_LA(void);
  25 static void set_accessing_symbol(void);
  26 static void set_goto_map(void);
  27 static void set_maxrhs(void);
  28 static void set_reduction_table(void);
  29 static void set_shift_table(void);
  30 static void set_state_table(void);
  31 static void traverse(int i);
  32
  33 static int tokensetsize;
  34 Value_t *lookaheads;
  35 Value_t *LAruleno;
  36 unsigned *LA;
  37 Value_t *accessing_symbol;
  38 core **state_table;
  39 shifts **shift_table;
  40 reductions **reduction_table;
  41 Value_t *goto_base;
  42 Value_t *goto_map;
  43 Value_t *from_state;
  44 Value_t *to_state;
  45
  46 static Value_t infinity;
  47 static int maxrhs;
  48 static int ngotos;
  49 static unsigned *F;
  50 static Value_t **includes;
  51 static shorts **lookback;
  52 static Value_t **R;
  53 static Value_t *INDEX;
  54 static Value_t *VERTICES;
  55 static Value_t top;
  56
  57 void
  58 lalr(void)
  59 {
  60     tokensetsize = WORDSIZE(ntokens);
  61
  62     set_state_table();
  63     set_accessing_symbol();
  64     set_shift_table();
  65     set_reduction_table();
  66     set_maxrhs();
  67     initialize_LA();
  68     set_goto_map();
  69     initialize_F();
  70     build_relations();
  71     compute_FOLLOWS();
  72     compute_lookaheads();
  73 }
  74
  75 static void
  76 set_state_table(void)
  77 {
  78     core *sp;
  79
  80     state_table = NEW2(nstates, core *);
  81     for (sp = first_state; sp; sp = sp->next)
  82         state_table[sp->number] = sp;
  83 }
  84
  85 static void
  86 set_accessing_symbol(void)
  87 {
  88     core *sp;
  89
  90     accessing_symbol = NEW2(nstates, Value_t);
  91     for (sp = first_state; sp; sp = sp->next)
  92         accessing_symbol[sp->number] = sp->accessing_symbol;
  93 }
  94
  95 static void
  96 set_shift_table(void)
  97 {
  98     shifts *sp;
  99
 100     shift_table = NEW2(nstates, shifts *);
 101     for (sp = first_shift; sp; sp = sp->next)
 102         shift_table[sp->number] = sp;
 103 }
 104
 105 static void
 106 set_reduction_table(void)
 107 {
 108     reductions *rp;
 109
 110     reduction_table = NEW2(nstates, reductions *);
 111     for (rp = first_reduction; rp; rp = rp->next)
 112         reduction_table[rp->number] = rp;
 113 }
 114
 115 static void
 116 set_maxrhs(void)
 117 {
 118     Value_t *itemp;
 119     Value_t *item_end;
 120     int length;
 121     int max;
 122
 123     length = 0;
 124     max = 0;
 125     item_end = ritem + nitems;
 126     for (itemp = ritem; itemp < item_end; itemp++)
 127     {
 128         if (*itemp >= 0)
 129         {
 130             length++;
 131         }
 132         else
 133         {
 134             if (length > max)
 135                 max = length;
 136             length = 0;
 137         }
 138     }
 139
 140     maxrhs = max;
 141 }
 142
 143 static void
 144 initialize_LA(void)
 145 {
 146     int i, j, k;
 147     reductions *rp;
 148
 149     lookaheads = NEW2(nstates + 1, Value_t);
 150
 151     k = 0;
 152     for (i = 0; i < nstates; i++)
 153     {
 154         lookaheads[i] = (Value_t) k;
 155         rp = reduction_table[i];
 156         if (rp)
 157             k += rp->nreds;
 158     }
 159     lookaheads[nstates] = (Value_t) k;
 160
 161     LA = NEW2(k * tokensetsize, unsigned);
 162     LAruleno = NEW2(k, Value_t);
 163     lookback = NEW2(k, shorts *);
 164
 165     k = 0;
 166     for (i = 0; i < nstates; i++)
 167     {
 168         rp = reduction_table[i];
 169         if (rp)
 170         {
 171             for (j = 0; j < rp->nreds; j++)
 172             {
 173                 LAruleno[k] = rp->rules[j];
 174                 k++;
 175             }
 176         }
 177     }
 178 }
 179
 180 static void
 181 set_goto_map(void)
 182 {
 183     shifts *sp;
 184     int i;
 185     int symbol;
 186     int k;
 187     Value_t *temp_base;
 188     Value_t *temp_map;
 189     Value_t state2;
 190     Value_t state1;
 191
 192     goto_base = NEW2(nvars + 1, Value_t);
 193     temp_base = NEW2(nvars + 1, Value_t);
 194
 195     goto_map = goto_base - ntokens;
 196     temp_map = temp_base - ntokens;
 197
 198     ngotos = 0;
 199     for (sp = first_shift; sp; sp = sp->next)
 200     {
 201         for (i = sp->nshifts - 1; i >= 0; i--)
 202         {
 203             symbol = accessing_symbol[sp->shift[i]];
 204
 205             if (ISTOKEN(symbol))
 206                 break;
 207
 208             if (ngotos == MAXYYINT)
 209                 fatal("too many gotos");
 210
 211             ngotos++;
 212             goto_map[symbol]++;
 213         }
 214     }
 215
 216     k = 0;
 217     for (i = ntokens; i < nsyms; i++)
 218     {
 219         temp_map[i] = (Value_t) k;
 220         k += goto_map[i];
 221     }
 222
 223     for (i = ntokens; i < nsyms; i++)
 224         goto_map[i] = temp_map[i];
 225
 226     goto_map[nsyms] = (Value_t) ngotos;
 227     temp_map[nsyms] = (Value_t) ngotos;
 228
 229     from_state = NEW2(ngotos, Value_t);
 230     to_state = NEW2(ngotos, Value_t);
 231
 232     for (sp = first_shift; sp; sp = sp->next)
 233     {
 234         state1 = sp->number;
 235         for (i = sp->nshifts - 1; i >= 0; i--)
 236         {
 237             state2 = sp->shift[i];
 238             symbol = accessing_symbol[state2];
 239
 240             if (ISTOKEN(symbol))
 241                 break;
 242
 243             k = temp_map[symbol]++;
 244             from_state[k] = state1;
 245             to_state[k] = state2;
 246         }
 247     }
 248
 249     FREE(temp_base);
 250 }
 251
 252 /*  Map_goto maps a state/symbol pair into its numeric representation.  */
 253
 254 static Value_t
 255 map_goto(int state, int symbol)
 256 {
 257     int high;
 258     int low;
 259     int middle;
 260     int s;
 261
 262     low = goto_map[symbol];
 263     high = goto_map[symbol + 1];
 264
 265     for (;;)
 266     {
 267         assert(low <= high);
 268         middle = (low + high) >> 1;
 269         s = from_state[middle];
 270         if (s == state)
 271             return (Value_t) (middle);
 272         else if (s < state)
 273             low = middle + 1;
 274         else
 275             high = middle - 1;
 276     }
 277 }
 278
 279 static void
 280 initialize_F(void)
 281 {
 282     int i;
 283     int j;
 284     int k;
 285     shifts *sp;
 286     Value_t *edge;
 287     unsigned *rowp;
 288     Value_t *rp;
 289     Value_t **reads;
 290     int nedges;
 291     int stateno;
 292     int symbol;
 293     int nwords;
 294
 295     nwords = ngotos * tokensetsize;
 296     F = NEW2(nwords, unsigned);
 297
 298     reads = NEW2(ngotos, Value_t *);
 299     edge = NEW2(ngotos + 1, Value_t);
 300     nedges = 0;
 301
 302     rowp = F;
 303     for (i = 0; i < ngotos; i++)
 304     {
 305         stateno = to_state[i];
 306         sp = shift_table[stateno];
 307
 308         if (sp)
 309         {
 310             k = sp->nshifts;
 311
 312             for (j = 0; j < k; j++)
 313             {
 314                 symbol = accessing_symbol[sp->shift[j]];
 315                 if (ISVAR(symbol))
 316                     break;
 317                 SETBIT(rowp, symbol);
 318             }
 319
 320             for (; j < k; j++)
 321             {
 322                 symbol = accessing_symbol[sp->shift[j]];
 323                 if (nullable[symbol])
 324                     edge[nedges++] = map_goto(stateno, symbol);
 325             }
 326
 327             if (nedges)
 328             {
 329                 reads[i] = rp = NEW2(nedges + 1, Value_t);
 330
 331                 for (j = 0; j < nedges; j++)
 332                     rp[j] = edge[j];
 333
 334                 rp[nedges] = -1;
 335                 nedges = 0;
 336             }
 337         }
 338
 339         rowp += tokensetsize;
 340     }
 341
 342     SETBIT(F, 0);
 343     digraph(reads);
 344
 345     for (i = 0; i < ngotos; i++)
 346     {
 347         if (reads[i])
 348             FREE(reads[i]);
 349     }
 350
 351     FREE(reads);
 352     FREE(edge);
 353 }
 354
 355 static void
 356 build_relations(void)
 357 {
 358     int i;
 359     int j;
 360     int k;
 361     Value_t *rulep;
 362     Value_t *rp;
 363     shifts *sp;
 364     int length;
 365     int nedges;
 366     int done_flag;
 367     Value_t state1;
 368     Value_t stateno;
 369     int symbol1;
 370     int symbol2;
 371     Value_t *shortp;
 372     Value_t *edge;
 373     Value_t *states;
 374     Value_t **new_includes;
 375
 376     includes = NEW2(ngotos, Value_t *);
 377     edge = NEW2(ngotos + 1, Value_t);
 378     states = NEW2(maxrhs + 1, Value_t);
 379
 380     for (i = 0; i < ngotos; i++)
 381     {
 382         nedges = 0;
 383         state1 = from_state[i];
 384         symbol1 = accessing_symbol[to_state[i]];
 385
 386         for (rulep = derives[symbol1]; *rulep >= 0; rulep++)
 387         {
 388             length = 1;
 389             states[0] = state1;
 390             stateno = state1;
 391
 392             for (rp = ritem + rrhs[*rulep]; *rp >= 0; rp++)
 393             {
 394                 symbol2 = *rp;
 395                 sp = shift_table[stateno];
 396                 k = sp->nshifts;
 397
 398                 for (j = 0; j < k; j++)
 399                 {
 400                     stateno = sp->shift[j];
 401                     if (accessing_symbol[stateno] == symbol2)
 402                         break;
 403                 }
 404
 405                 states[length++] = stateno;
 406             }
 407
 408             add_lookback_edge(stateno, *rulep, i);
 409
 410             length--;
 411             done_flag = 0;
 412             while (!done_flag)
 413             {
 414                 done_flag = 1;
 415                 rp--;
 416                 if (ISVAR(*rp))
 417                 {
 418                     stateno = states[--length];
 419                     edge[nedges++] = map_goto(stateno, *rp);
 420                     if (nullable[*rp] && length > 0)
 421                         done_flag = 0;
 422                 }
 423             }
 424         }
 425
 426         if (nedges)
 427         {
 428             includes[i] = shortp = NEW2(nedges + 1, Value_t);
 429             for (j = 0; j < nedges; j++)
 430                 shortp[j] = edge[j];
 431             shortp[nedges] = -1;
 432         }
 433     }
 434
 435     new_includes = transpose(includes, ngotos);
 436
 437     for (i = 0; i < ngotos; i++)
 438         if (includes[i])
 439             FREE(includes[i]);
 440
 441     FREE(includes);
 442
 443     includes = new_includes;
 444
 445     FREE(edge);
 446     FREE(states);
 447 }
 448
 449 static void
 450 add_lookback_edge(int stateno, int ruleno, int gotono)
 451 {
 452     int i, k;
 453     int found;
 454     shorts *sp;
 455
 456     i = lookaheads[stateno];
 457     k = lookaheads[stateno + 1];
 458     found = 0;
 459     while (!found && i < k)
 460     {
 461         if (LAruleno[i] == ruleno)
 462             found = 1;
 463         else
 464             ++i;
 465     }
 466     assert(found);
 467
 468     sp = NEW(shorts);
 469     sp->next = lookback[i];
 470     sp->value = (Value_t) gotono;
 471     lookback[i] = sp;
 472 }
 473
 474 static Value_t **
 475 transpose(Value_t ** R2, int n)
 476 {
 477     Value_t **new_R;
 478     Value_t **temp_R;
 479     Value_t *nedges;
 480     Value_t *sp;
 481     int i;
 482     int k;
 483
 484     nedges = NEW2(n, Value_t);
 485
 486     for (i = 0; i < n; i++)
 487     {
 488         sp = R2[i];
 489         if (sp)
 490         {
 491             while (*sp >= 0)
 492                 nedges[*sp++]++;
 493         }
 494     }
 495
 496     new_R = NEW2(n, Value_t *);
 497     temp_R = NEW2(n, Value_t *);
 498
 499     for (i = 0; i < n; i++)
 500     {
 501         k = nedges[i];
 502         if (k > 0)
 503         {
 504             sp = NEW2(k + 1, Value_t);
 505             new_R[i] = sp;
 506             temp_R[i] = sp;
 507             sp[k] = -1;
 508         }
 509     }
 510
 511     FREE(nedges);
 512
 513     for (i = 0; i < n; i++)
 514     {
 515         sp = R2[i];
 516         if (sp)
 517         {
 518             while (*sp >= 0)
 519                 *temp_R[*sp++]++ = (Value_t) i;
 520         }
 521     }
 522
 523     FREE(temp_R);
 524
 525     return (new_R);
 526 }
 527
 528 static void
 529 compute_FOLLOWS(void)
 530 {
 531     digraph(includes);
 532 }
 533
 534 static void
 535 compute_lookaheads(void)
 536 {
 537     int i, n;
 538     unsigned *fp1, *fp2, *fp3;
 539     shorts *sp, *next;
 540     unsigned *rowp;
 541
 542     rowp = LA;
 543     n = lookaheads[nstates];
 544     for (i = 0; i < n; i++)
 545     {
 546         fp3 = rowp + tokensetsize;
 547         for (sp = lookback[i]; sp; sp = sp->next)
 548         {
 549             fp1 = rowp;
 550             fp2 = F + tokensetsize * sp->value;
 551             while (fp1 < fp3)
 552                 *fp1++ |= *fp2++;
 553         }
 554         rowp = fp3;
 555     }
 556
 557     for (i = 0; i < n; i++)
 558         for (sp = lookback[i]; sp; sp = next)
 559         {
 560             next = sp->next;
 561             FREE(sp);
 562         }
 563
 564     FREE(lookback);
 565     FREE(F);
 566 }
 567
 568 static void
 569 digraph(Value_t ** relation)
 570 {
 571     int i;
 572
 573     infinity = (Value_t) (ngotos + 2);
 574     INDEX = NEW2(ngotos + 1, Value_t);
 575     VERTICES = NEW2(ngotos + 1, Value_t);
 576     top = 0;
 577
 578     R = relation;
 579
 580     for (i = 0; i < ngotos; i++)
 581         INDEX[i] = 0;
 582
 583     for (i = 0; i < ngotos; i++)
 584     {
 585         if (INDEX[i] == 0 && R[i])
 586             traverse(i);
 587     }
 588
 589     FREE(INDEX);
 590     FREE(VERTICES);
 591 }
 592
 593 static void
 594 traverse(int i)
 595 {
 596     unsigned *fp1;
 597     unsigned *fp2;
 598     unsigned *fp3;
 599     int j;
 600     Value_t *rp;
 601
 602     Value_t height;
 603     unsigned *base;
 604
 605     VERTICES[++top] = (Value_t) i;
 606     INDEX[i] = height = top;
 607
 608     base = F + i * tokensetsize;
 609     fp3 = base + tokensetsize;
 610
 611     rp = R[i];
 612     if (rp)
 613     {
 614         while ((j = *rp++) >= 0)
 615         {
 616             if (INDEX[j] == 0)
 617                 traverse(j);
 618
 619             if (INDEX[i] > INDEX[j])
 620                 INDEX[i] = INDEX[j];
 621
 622             fp1 = base;
 623             fp2 = F + j * tokensetsize;
 624
 625             while (fp1 < fp3)
 626                 *fp1++ |= *fp2++;
 627         }
 628     }
 629
 630     if (INDEX[i] == height)
 631     {
 632         for (;;)
 633         {
 634             j = VERTICES[top--];
 635             INDEX[j] = infinity;
 636
 637             if (i == j)
 638                 break;
 639
 640             fp1 = base;
 641             fp2 = F + j * tokensetsize;
 642
 643             while (fp1 < fp3)
 644                 *fp2++ = *fp1++;
 645         }
 646     }
 647 }
 648
 649 #ifdef NO_LEAKS
 650 void
 651 lalr_leaks(void)
 652 {
 653     int i;
 654
 655     if (includes != 0)
 656     {
 657         for (i = 0; i < ngotos; i++)
 658         {
 659             free(includes[i]);
 660         }
 661         DO_FREE(includes);
 662     }
 663 }
 664 #endif