src/symtab.c

   1 /* Symbol table manager for Bison.
   2
   3    Copyright (C) 1984, 1989, 2000, 2001, 2002, 2004, 2005, 2006 Free
   4    Software Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    Bison is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 2, or (at your option)
  11    any later version.
  12
  13    Bison is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bison; see the file COPYING.  If not, write to
  20    the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  21    Boston, MA 02110-1301, USA.  */
  22
  23 #include <config.h>
  24 #include "system.h"
  25
  26 #include <hash.h>
  27 #include <quotearg.h>
  28
  29 #include "complain.h"
  30 #include "gram.h"
  31 #include "symtab.h"
  32
  33 /*------------------------.
  34 | Distinguished symbols.  |
  35 `------------------------*/
  36
  37 symbol *errtoken = NULL;
  38 symbol *undeftoken = NULL;
  39 symbol *endtoken = NULL;
  40 symbol *accept = NULL;
  41 symbol *startsymbol = NULL;
  42 location startsymbol_location;
  43
  44 /*---------------------------------------.
  45 | Default %destructor's and %printer's.  |
  46 `---------------------------------------*/
  47
  48 static const char *default_tagged_destructor = NULL;
  49 static location default_tagged_destructor_location;
  50 static const char *default_tagless_destructor = NULL;
  51 static location default_tagless_destructor_location;
  52
  53 static const char *default_tagged_printer = NULL;
  54 static location default_tagged_printer_location;
  55 static const char *default_tagless_printer = NULL;
  56 static location default_tagless_printer_location;
  57
  58 /*---------------------------------.
  59 | Create a new symbol, named TAG.  |
  60 `---------------------------------*/
  61
  62 static symbol *
  63 symbol_new (uniqstr tag, location loc)
  64 {
  65   symbol *res = xmalloc (sizeof *res);
  66
  67   uniqstr_assert (tag);
  68   res->tag = tag;
  69   res->location = loc;
  70
  71   res->type_name = NULL;
  72   res->destructor = NULL;
  73   res->printer = NULL;
  74
  75   res->number = NUMBER_UNDEFINED;
  76   res->prec = 0;
  77   res->assoc = undef_assoc;
  78   res->user_token_number = USER_NUMBER_UNDEFINED;
  79
  80   res->alias = NULL;
  81   res->class = unknown_sym;
  82   res->declared = false;
  83
  84   if (nsyms == SYMBOL_NUMBER_MAXIMUM)
  85     fatal (_("too many symbols in input grammar (limit is %d)"),
  86            SYMBOL_NUMBER_MAXIMUM);
  87   nsyms++;
  88   return res;
  89 }
  90
  91 /*----------------------------------------.
  92 | Create a new semantic type, named TAG.  |
  93 `----------------------------------------*/
  94
  95 static semantic_type *
  96 semantic_type_new (uniqstr tag)
  97 {
  98   semantic_type *res = xmalloc (sizeof *res);
  99
 100   uniqstr_assert (tag);
 101   res->tag = tag;
 102   res->destructor = NULL;
 103   res->printer = NULL;
 104
 105   return res;
 106 }
 107
 108
 109 /*-----------------.
 110 | Print a symbol.  |
 111 `-----------------*/
 112
 113 #define SYMBOL_ATTR_PRINT(Attr)                         \
 114   if (s->Attr)                                          \
 115     fprintf (f, " %s { %s }", #Attr, s->Attr)
 116
 117 void
 118 symbol_print (symbol *s, FILE *f)
 119 {
 120   if (s)
 121     {
 122       fprintf (f, "\"%s\"", s->tag);
 123       SYMBOL_ATTR_PRINT (type_name);
 124       SYMBOL_ATTR_PRINT (destructor);
 125       SYMBOL_ATTR_PRINT (printer);
 126     }
 127   else
 128     fprintf (f, "<NULL>");
 129 }
 130
 131 #undef SYMBOL_ATTR_PRINT
 132
 133 /*------------------------------------------------------------------.
 134 | Complain that S's WHAT is redeclared at SECOND, and was first set |
 135 | at FIRST.                                                         |
 136 `------------------------------------------------------------------*/
 137
 138 static void
 139 symbol_redeclaration (symbol *s, const char *what, location first,
 140                       location second)
 141 {
 142   complain_at (second, _("%s redeclaration for %s"), what, s->tag);
 143   complain_at (first, _("previous declaration"));
 144 }
 145
 146 static void
 147 semantic_type_redeclaration (semantic_type *s, const char *what, location first,
 148                              location second)
 149 {
 150   complain_at (second, _("%s redeclaration for <%s>"), what, s->tag);
 151   complain_at (first, _("previous declaration"));
 152 }
 153
 154
 155 /*-----------------------------------------------------------------.
 156 | Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
 157 | as TYPE_NAME.                                                    |
 158 `-----------------------------------------------------------------*/
 159
 160 void
 161 symbol_type_set (symbol *sym, uniqstr type_name, location loc)
 162 {
 163   if (type_name)
 164     {
 165       if (sym->type_name)
 166         symbol_redeclaration (sym, "%type", sym->type_location, loc);
 167       uniqstr_assert (type_name);
 168       sym->type_name = type_name;
 169       sym->type_location = loc;
 170     }
 171 }
 172
 173
 174 /*------------------------------------------------------------------.
 175 | Set the DESTRUCTOR associated with SYM.  Do nothing if passed 0.  |
 176 `------------------------------------------------------------------*/
 177
 178 void
 179 symbol_destructor_set (symbol *sym, const char *destructor, location loc)
 180 {
 181   if (destructor)
 182     {
 183       if (sym->destructor)
 184         symbol_redeclaration (sym, "%destructor", sym->destructor_location,
 185                               loc);
 186       sym->destructor = destructor;
 187       sym->destructor_location = loc;
 188     }
 189 }
 190
 191 /*-------------------------------------------------------------------.
 192 | Set the DESTRUCTOR associated with TYPE.  Do nothing if passed 0.  |
 193 `-------------------------------------------------------------------*/
 194
 195 void
 196 semantic_type_destructor_set (semantic_type *type, const char *destructor,
 197                               location loc)
 198 {
 199   if (destructor)
 200     {
 201       if (type->destructor)
 202         semantic_type_redeclaration (type, "%destructor",
 203                                      type->destructor_location, loc);
 204       type->destructor = destructor;
 205       type->destructor_location = loc;
 206     }
 207 }
 208
 209 /*---------------------------------------.
 210 | Get the computed %destructor for SYM.  |
 211 `---------------------------------------*/
 212
 213 const char *
 214 symbol_destructor_get (symbol *sym)
 215 {
 216   /* Per-symbol %destructor.  */
 217   if (sym->destructor != NULL)
 218     return sym->destructor;
 219
 220   /* Per-type %destructor.  */
 221   if (sym->type_name)
 222     {
 223       semantic_type *type = semantic_type_get (sym->type_name);
 224       if (type->destructor)
 225         return type->destructor;
 226     }
 227
 228   /* Apply default %destructor's only to user-defined symbols.  */
 229   if (sym->tag[0] == '$' || sym == errtoken)
 230     return NULL;
 231
 232   if (sym->type_name)
 233     return default_tagged_destructor;
 234   return default_tagless_destructor;
 235 }
 236
 237 /*---------------------------------------------------------------.
 238 | Get the grammar location of the %destructor computed for SYM.  |
 239 `---------------------------------------------------------------*/
 240
 241 location
 242 symbol_destructor_location_get (symbol *sym)
 243 {
 244   if (sym->destructor != NULL)
 245     return sym->destructor_location;
 246   if (sym->type_name)
 247     {
 248       semantic_type *type = semantic_type_get (sym->type_name);
 249       if (type->destructor)
 250         return type->destructor_location;
 251       return default_tagged_destructor_location;
 252     }
 253   return default_tagless_destructor_location;
 254 }
 255
 256 /*---------------------------------------------------------------.
 257 | Set the PRINTER associated with SYM.  Do nothing if passed 0.  |
 258 `---------------------------------------------------------------*/
 259
 260 void
 261 symbol_printer_set (symbol *sym, const char *printer, location loc)
 262 {
 263   if (printer)
 264     {
 265       if (sym->printer)
 266         symbol_redeclaration (sym, "%printer", sym->printer_location, loc);
 267       sym->printer = printer;
 268       sym->printer_location = loc;
 269     }
 270 }
 271
 272 /*----------------------------------------------------------------.
 273 | Set the PRINTER associated with TYPE.  Do nothing if passed 0.  |
 274 `----------------------------------------------------------------*/
 275
 276 void
 277 semantic_type_printer_set (semantic_type *type, const char *printer,
 278                            location loc)
 279 {
 280   if (printer)
 281     {
 282       if (type->printer)
 283         semantic_type_redeclaration (type, "%printer", type->printer_location,
 284                                      loc);
 285       type->printer = printer;
 286       type->printer_location = loc;
 287     }
 288 }
 289
 290 /*------------------------------------.
 291 | Get the computed %printer for SYM.  |
 292 `------------------------------------*/
 293
 294 const char *
 295 symbol_printer_get (symbol *sym)
 296 {
 297   /* Per-symbol %printer.  */
 298   if (sym->printer != NULL)
 299     return sym->printer;
 300
 301   /* Per-type %printer.  */
 302   if (sym->type_name)
 303     {
 304       semantic_type *type = semantic_type_get (sym->type_name);
 305       if (type->printer)
 306         return type->printer;
 307     }
 308
 309   /* Apply the default %printer only to user-defined symbols.  */
 310   if (sym->tag[0] == '$' || sym == errtoken)
 311     return NULL;
 312
 313   if (sym->type_name)
 314     return default_tagged_printer;
 315   return default_tagless_printer;
 316 }
 317
 318 /*------------------------------------------------------------.
 319 | Get the grammar location of the %printer computed for SYM.  |
 320 `------------------------------------------------------------*/
 321
 322 location
 323 symbol_printer_location_get (symbol *sym)
 324 {
 325   if (sym->printer != NULL)
 326     return sym->printer_location;
 327   if (sym->type_name)
 328     {
 329       semantic_type *type = semantic_type_get (sym->type_name);
 330       if (type->printer)
 331         return type->printer_location;
 332       return default_tagged_printer_location;
 333     }
 334   return default_tagless_printer_location;
 335 }
 336
 337
 338 /*-----------------------------------------------------------------.
 339 | Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
 340 | with UNDEF_ASSOC as ASSOC.                                       |
 341 `-----------------------------------------------------------------*/
 342
 343 void
 344 symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
 345 {
 346   if (a != undef_assoc)
 347     {
 348       if (sym->prec != 0)
 349         symbol_redeclaration (sym, assoc_to_string (a), sym->prec_location,
 350                               loc);
 351       sym->prec = prec;
 352       sym->assoc = a;
 353       sym->prec_location = loc;
 354     }
 355
 356   /* Only terminals have a precedence. */
 357   symbol_class_set (sym, token_sym, loc, false);
 358 }
 359
 360
 361 /*------------------------------------.
 362 | Set the CLASS associated with SYM.  |
 363 `------------------------------------*/
 364
 365 void
 366 symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
 367 {
 368   if (sym->class != unknown_sym && sym->class != class)
 369     {
 370       complain_at (loc, _("symbol %s redefined"), sym->tag);
 371       sym->declared = false;
 372     }
 373
 374   if (class == nterm_sym && sym->class != nterm_sym)
 375     sym->number = nvars++;
 376   else if (class == token_sym && sym->number == NUMBER_UNDEFINED)
 377     sym->number = ntokens++;
 378
 379   sym->class = class;
 380
 381   if (declaring)
 382     {
 383       if (sym->declared)
 384         warn_at (loc, _("symbol %s redeclared"), sym->tag);
 385       sym->declared = true;
 386     }
 387 }
 388
 389
 390 /*------------------------------------------------.
 391 | Set the USER_TOKEN_NUMBER associated with SYM.  |
 392 `------------------------------------------------*/
 393
 394 void
 395 symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 396 {
 397   int *user_token_numberp;
 398
 399   aver (sym->class == token_sym);
 400
 401   if (sym->user_token_number != USER_NUMBER_ALIAS)
 402     user_token_numberp = &sym->user_token_number;
 403   else
 404     user_token_numberp = &sym->alias->user_token_number;
 405   if (*user_token_numberp != USER_NUMBER_UNDEFINED
 406       && *user_token_numberp != user_token_number)
 407     complain_at (loc, _("redefining user token number of %s"), sym->tag);
 408
 409   *user_token_numberp = user_token_number;
 410   /* User defined $end token? */
 411   if (user_token_number == 0)
 412     {
 413       endtoken = sym;
 414       endtoken->number = 0;
 415       /* It is always mapped to 0, so it was already counted in
 416          NTOKENS.  */
 417       --ntokens;
 418     }
 419 }
 420
 421
 422 /*----------------------------------------------------------.
 423 | If SYM is not defined, report an error, and consider it a |
 424 | nonterminal.                                              |
 425 `----------------------------------------------------------*/
 426
 427 static inline bool
 428 symbol_check_defined (symbol *sym)
 429 {
 430   if (sym->class == unknown_sym)
 431     {
 432       complain_at
 433         (sym->location,
 434          _("symbol %s is used, but is not defined as a token and has no rules"),
 435          sym->tag);
 436       sym->class = nterm_sym;
 437       sym->number = nvars++;
 438     }
 439
 440   return true;
 441 }
 442
 443 static bool
 444 symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
 445 {
 446   return symbol_check_defined (sym);
 447 }
 448
 449
 450 /*------------------------------------------------------------------.
 451 | Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |
 452 | SYMVAL with SYM's type.                                           |
 453 `------------------------------------------------------------------*/
 454
 455 void
 456 symbol_make_alias (symbol *sym, symbol *symval, location loc)
 457 {
 458   if (symval->alias)
 459     warn_at (loc, _("symbol `%s' used more than once as a literal string"),
 460              symval->tag);
 461   else if (sym->alias)
 462     warn_at (loc, _("symbol `%s' given more than one literal string"),
 463              sym->tag);
 464   else
 465     {
 466       symval->class = token_sym;
 467       symval->user_token_number = sym->user_token_number;
 468       sym->user_token_number = USER_NUMBER_ALIAS;
 469       symval->alias = sym;
 470       sym->alias = symval;
 471       symval->number = sym->number;
 472       symbol_type_set (symval, sym->type_name, loc);
 473     }
 474 }
 475
 476
 477 /*---------------------------------------------------------.
 478 | Check that THIS, and its alias, have same precedence and |
 479 | associativity.                                           |
 480 `---------------------------------------------------------*/
 481
 482 static inline void
 483 symbol_check_alias_consistency (symbol *this)
 484 {
 485   symbol *alias = this;
 486   symbol *orig  = this->alias;
 487
 488   /* Check only those that _are_ the aliases.  */
 489   if (!(this->alias && this->user_token_number == USER_NUMBER_ALIAS))
 490     return;
 491
 492   if (orig->type_name != alias->type_name)
 493     {
 494       if (orig->type_name)
 495         symbol_type_set (alias, orig->type_name, orig->type_location);
 496       else
 497         symbol_type_set (orig, alias->type_name, alias->type_location);
 498     }
 499
 500
 501   if (orig->destructor || alias->destructor)
 502     {
 503       if (orig->destructor)
 504         symbol_destructor_set (alias, orig->destructor,
 505                                orig->destructor_location);
 506       else
 507         symbol_destructor_set (orig, alias->destructor,
 508                                alias->destructor_location);
 509     }
 510
 511   if (orig->printer || alias->printer)
 512     {
 513       if (orig->printer)
 514         symbol_printer_set (alias, orig->printer, orig->printer_location);
 515       else
 516         symbol_printer_set (orig, alias->printer, alias->printer_location);
 517     }
 518
 519   if (alias->prec || orig->prec)
 520     {
 521       if (orig->prec)
 522         symbol_precedence_set (alias, orig->prec, orig->assoc,
 523                                orig->prec_location);
 524       else
 525         symbol_precedence_set (orig, alias->prec, alias->assoc,
 526                                alias->prec_location);
 527     }
 528 }
 529
 530 static bool
 531 symbol_check_alias_consistency_processor (void *this,
 532                                           void *null ATTRIBUTE_UNUSED)
 533 {
 534   symbol_check_alias_consistency (this);
 535   return true;
 536 }
 537
 538
 539 /*-------------------------------------------------------------------.
 540 | Assign a symbol number, and write the definition of the token name |
 541 | into FDEFINES.  Put in SYMBOLS.                                    |
 542 `-------------------------------------------------------------------*/
 543
 544 static inline bool
 545 symbol_pack (symbol *this)
 546 {
 547   if (this->class == nterm_sym)
 548     {
 549       this->number += ntokens;
 550     }
 551   else if (this->alias)
 552     {
 553       /* This symbol and its alias are a single token defn.
 554          Allocate a tokno, and assign to both check agreement of
 555          prec and assoc fields and make both the same */
 556       if (this->number == NUMBER_UNDEFINED)
 557         {
 558           if (this == endtoken || this->alias == endtoken)
 559             this->number = this->alias->number = 0;
 560           else
 561             {
 562               aver (this->alias->number != NUMBER_UNDEFINED);
 563               this->number = this->alias->number;
 564             }
 565         }
 566       /* Do not do processing below for USER_NUMBER_ALIASes.  */
 567       if (this->user_token_number == USER_NUMBER_ALIAS)
 568         return true;
 569     }
 570   else /* this->class == token_sym */
 571     aver (this->number != NUMBER_UNDEFINED);
 572
 573   symbols[this->number] = this;
 574   return true;
 575 }
 576
 577 static bool
 578 symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
 579 {
 580   return symbol_pack (this);
 581 }
 582
 583
 584
 585
 586 /*--------------------------------------------------.
 587 | Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
 588 `--------------------------------------------------*/
 589
 590 static inline bool
 591 symbol_translation (symbol *this)
 592 {
 593   /* Non-terminal? */
 594   if (this->class == token_sym
 595       && this->user_token_number != USER_NUMBER_ALIAS)
 596     {
 597       /* A token which translation has already been set? */
 598       if (token_translations[this->user_token_number] != undeftoken->number)
 599         complain_at (this->location,
 600                      _("tokens %s and %s both assigned number %d"),
 601                      symbols[token_translations[this->user_token_number]]->tag,
 602                      this->tag, this->user_token_number);
 603
 604       token_translations[this->user_token_number] = this->number;
 605     }
 606
 607   return true;
 608 }
 609
 610 static bool
 611 symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
 612 {
 613   return symbol_translation (this);
 614 }
 615
 616
 617 /*---------------------------------------.
 618 | Symbol and semantic type hash tables.  |
 619 `---------------------------------------*/
 620
 621 /* Initial capacity of symbol and semantic type hash table.  */
 622 #define HT_INITIAL_CAPACITY 257
 623
 624 static struct hash_table *symbol_table = NULL;
 625 static struct hash_table *semantic_type_table = NULL;
 626
 627 static inline bool
 628 hash_compare_symbol (const symbol *m1, const symbol *m2)
 629 {
 630   /* Since tags are unique, we can compare the pointers themselves.  */
 631   return UNIQSTR_EQ (m1->tag, m2->tag);
 632 }
 633
 634 static inline bool
 635 hash_compare_semantic_type (const semantic_type *m1, const semantic_type *m2)
 636 {
 637   /* Since names are unique, we can compare the pointers themselves.  */
 638   return UNIQSTR_EQ (m1->tag, m2->tag);
 639 }
 640
 641 static bool
 642 hash_symbol_comparator (void const *m1, void const *m2)
 643 {
 644   return hash_compare_symbol (m1, m2);
 645 }
 646
 647 static bool
 648 hash_semantic_type_comparator (void const *m1, void const *m2)
 649 {
 650   return hash_compare_semantic_type (m1, m2);
 651 }
 652
 653 static inline size_t
 654 hash_symbol (const symbol *m, size_t tablesize)
 655 {
 656   /* Since tags are unique, we can hash the pointer itself.  */
 657   return ((uintptr_t) m->tag) % tablesize;
 658 }
 659
 660 static inline size_t
 661 hash_semantic_type (const semantic_type *m, size_t tablesize)
 662 {
 663   /* Since names are unique, we can hash the pointer itself.  */
 664   return ((uintptr_t) m->tag) % tablesize;
 665 }
 666
 667 static size_t
 668 hash_symbol_hasher (void const *m, size_t tablesize)
 669 {
 670   return hash_symbol (m, tablesize);
 671 }
 672
 673 static size_t
 674 hash_semantic_type_hasher (void const *m, size_t tablesize)
 675 {
 676   return hash_semantic_type (m, tablesize);
 677 }
 678
 679 /*-------------------------------.
 680 | Create the symbol hash table.  |
 681 `-------------------------------*/
 682
 683 void
 684 symbols_new (void)
 685 {
 686   symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
 687                                   NULL,
 688                                   hash_symbol_hasher,
 689                                   hash_symbol_comparator,
 690                                   free);
 691   semantic_type_table = hash_initialize (HT_INITIAL_CAPACITY,
 692                                          NULL,
 693                                          hash_semantic_type_hasher,
 694                                          hash_semantic_type_comparator,
 695                                          free);
 696 }
 697
 698
 699 /*----------------------------------------------------------------.
 700 | Find the symbol named KEY, and return it.  If it does not exist |
 701 | yet, create it.                                                 |
 702 `----------------------------------------------------------------*/
 703
 704 symbol *
 705 symbol_from_uniqstr (const uniqstr key, location loc)
 706 {
 707   symbol probe;
 708   symbol *entry;
 709
 710   probe.tag = key;
 711   entry = hash_lookup (symbol_table, &probe);
 712
 713   if (!entry)
 714     {
 715       /* First insertion in the hash. */
 716       entry = symbol_new (key, loc);
 717       hash_insert (symbol_table, entry);
 718     }
 719   return entry;
 720 }
 721
 722
 723 /*-----------------------------------------------------------------------.
 724 | Find the semantic type named KEY, and return it.  If it does not exist |
 725 | yet, create it.                                                        |
 726 `-----------------------------------------------------------------------*/
 727
 728 semantic_type *
 729 semantic_type_from_uniqstr (const uniqstr key)
 730 {
 731   semantic_type probe;
 732   semantic_type *entry;
 733
 734   probe.tag = key;
 735   entry = hash_lookup (semantic_type_table, &probe);
 736
 737   if (!entry)
 738     {
 739       /* First insertion in the hash. */
 740       entry = semantic_type_new (key);
 741       hash_insert (semantic_type_table, entry);
 742     }
 743   return entry;
 744 }
 745
 746
 747 /*----------------------------------------------------------------.
 748 | Find the symbol named KEY, and return it.  If it does not exist |
 749 | yet, create it.                                                 |
 750 `----------------------------------------------------------------*/
 751
 752 symbol *
 753 symbol_get (const char *key, location loc)
 754 {
 755   return symbol_from_uniqstr (uniqstr_new (key), loc);
 756 }
 757
 758
 759 /*-----------------------------------------------------------------------.
 760 | Find the semantic type named KEY, and return it.  If it does not exist |
 761 | yet, create it.                                                        |
 762 `-----------------------------------------------------------------------*/
 763
 764 semantic_type *
 765 semantic_type_get (const char *key)
 766 {
 767   return semantic_type_from_uniqstr (uniqstr_new (key));
 768 }
 769
 770
 771 /*------------------------------------------------------------------.
 772 | Generate a dummy nonterminal, whose name cannot conflict with the |
 773 | user's names.                                                     |
 774 `------------------------------------------------------------------*/
 775
 776 symbol *
 777 dummy_symbol_get (location loc)
 778 {
 779   /* Incremented for each generated symbol.  */
 780   static int dummy_count = 0;
 781   static char buf[256];
 782
 783   symbol *sym;
 784
 785   sprintf (buf, "$@%d", ++dummy_count);
 786   sym = symbol_get (buf, loc);
 787   sym->class = nterm_sym;
 788   sym->number = nvars++;
 789   return sym;
 790 }
 791
 792 bool
 793 symbol_is_dummy (const symbol *sym)
 794 {
 795   return sym->tag[0] == '@' || (sym->tag[0] == '$' && sym->tag[1] == '@');
 796 }
 797
 798 /*-------------------.
 799 | Free the symbols.  |
 800 `-------------------*/
 801
 802 void
 803 symbols_free (void)
 804 {
 805   hash_free (symbol_table);
 806   hash_free (semantic_type_table);
 807   free (symbols);
 808 }
 809
 810
 811 /*---------------------------------------------------------------.
 812 | Look for undefined symbols, report an error, and consider them |
 813 | terminals.                                                     |
 814 `---------------------------------------------------------------*/
 815
 816 static void
 817 symbols_do (Hash_processor processor, void *processor_data)
 818 {
 819   hash_do_for_each (symbol_table, processor, processor_data);
 820 }
 821
 822
 823 /*--------------------------------------------------------------.
 824 | Check that all the symbols are defined.  Report any undefined |
 825 | symbols and consider them nonterminals.                       |
 826 `--------------------------------------------------------------*/
 827
 828 void
 829 symbols_check_defined (void)
 830 {
 831   symbols_do (symbol_check_defined_processor, NULL);
 832 }
 833
 834 /*------------------------------------------------------------------.
 835 | Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
 836 | number.                                                           |
 837 `------------------------------------------------------------------*/
 838
 839 static void
 840 symbols_token_translations_init (void)
 841 {
 842   bool num_256_available_p = true;
 843   int i;
 844
 845   /* Find the highest user token number, and whether 256, the POSIX
 846      preferred user token number for the error token, is used.  */
 847   max_user_token_number = 0;
 848   for (i = 0; i < ntokens; ++i)
 849     {
 850       symbol *this = symbols[i];
 851       if (this->user_token_number != USER_NUMBER_UNDEFINED)
 852         {
 853           if (this->user_token_number > max_user_token_number)
 854             max_user_token_number = this->user_token_number;
 855           if (this->user_token_number == 256)
 856             num_256_available_p = false;
 857         }
 858     }
 859
 860   /* If 256 is not used, assign it to error, to follow POSIX.  */
 861   if (num_256_available_p
 862       && errtoken->user_token_number == USER_NUMBER_UNDEFINED)
 863     errtoken->user_token_number = 256;
 864
 865   /* Set the missing user numbers. */
 866   if (max_user_token_number < 256)
 867     max_user_token_number = 256;
 868
 869   for (i = 0; i < ntokens; ++i)
 870     {
 871       symbol *this = symbols[i];
 872       if (this->user_token_number == USER_NUMBER_UNDEFINED)
 873         this->user_token_number = ++max_user_token_number;
 874       if (this->user_token_number > max_user_token_number)
 875         max_user_token_number = this->user_token_number;
 876     }
 877
 878   token_translations = xnmalloc (max_user_token_number + 1,
 879                                  sizeof *token_translations);
 880
 881   /* Initialize all entries for literal tokens to 2, the internal
 882      token number for $undefined, which represents all invalid inputs.
 883      */
 884   for (i = 0; i < max_user_token_number + 1; i++)
 885     token_translations[i] = undeftoken->number;
 886   symbols_do (symbol_translation_processor, NULL);
 887 }
 888
 889
 890 /*----------------------------------------------------------------.
 891 | Assign symbol numbers, and write definition of token names into |
 892 | FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
 893 `----------------------------------------------------------------*/
 894
 895 void
 896 symbols_pack (void)
 897 {
 898   symbols_do (symbol_check_alias_consistency_processor, NULL);
 899
 900   symbols = xcalloc (nsyms, sizeof *symbols);
 901   symbols_do (symbol_pack_processor, NULL);
 902
 903   /* Aliases leave empty slots in symbols, so remove them.  */
 904   {
 905     int writei;
 906     int readi;
 907     int nsyms_old = nsyms;
 908     for (writei = 0, readi = 0; readi < nsyms_old; readi += 1)
 909       {
 910         if (symbols[readi] == NULL)
 911           {
 912             nsyms -= 1;
 913             ntokens -= 1;
 914           }
 915         else
 916           {
 917             symbols[writei] = symbols[readi];
 918             symbols[writei]->number = writei;
 919             if (symbols[writei]->alias)
 920               symbols[writei]->alias->number = writei;
 921             writei += 1;
 922           }
 923       }
 924   }
 925   symbols = xnrealloc (symbols, nsyms, sizeof *symbols);
 926
 927   symbols_token_translations_init ();
 928
 929   if (startsymbol->class == unknown_sym)
 930     fatal_at (startsymbol_location,
 931               _("the start symbol %s is undefined"),
 932               startsymbol->tag);
 933   else if (startsymbol->class == token_sym)
 934     fatal_at (startsymbol_location,
 935               _("the start symbol %s is a token"),
 936               startsymbol->tag);
 937 }
 938
 939
 940 /*--------------------------------------------------.
 941 | Set default tagged/tagless %destructor/%printer.  |
 942 `--------------------------------------------------*/
 943
 944 void
 945 default_tagged_destructor_set (const char *destructor, location loc)
 946 {
 947   if (default_tagged_destructor != NULL)
 948     {
 949       complain_at (loc, _("redeclaration for default tagged %%destructor"));
 950       complain_at (default_tagged_destructor_location,
 951                    _("previous declaration"));
 952     }
 953   default_tagged_destructor = destructor;
 954   default_tagged_destructor_location = loc;
 955 }
 956
 957 void
 958 default_tagless_destructor_set (const char *destructor, location loc)
 959 {
 960   if (default_tagless_destructor != NULL)
 961     {
 962       complain_at (loc, _("redeclaration for default tagless %%destructor"));
 963       complain_at (default_tagless_destructor_location,
 964                    _("previous declaration"));
 965     }
 966   default_tagless_destructor = destructor;
 967   default_tagless_destructor_location = loc;
 968 }
 969
 970 void
 971 default_tagged_printer_set (const char *printer, location loc)
 972 {
 973   if (default_tagged_printer != NULL)
 974     {
 975       complain_at (loc, _("redeclaration for default tagged %%printer"));
 976       complain_at (default_tagged_printer_location,
 977                    _("previous declaration"));
 978     }
 979   default_tagged_printer = printer;
 980   default_tagged_printer_location = loc;
 981 }
 982
 983 void
 984 default_tagless_printer_set (const char *printer, location loc)
 985 {
 986   if (default_tagless_printer != NULL)
 987     {
 988       complain_at (loc, _("redeclaration for default tagless %%printer"));
 989       complain_at (default_tagless_printer_location,
 990                    _("previous declaration"));
 991     }
 992   default_tagless_printer = printer;
 993   default_tagless_printer_location = loc;
 994 }