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 | Create a new symbol, named TAG.  |
  46 `---------------------------------*/
  47
  48 static symbol *
  49 symbol_new (uniqstr tag, location loc)
  50 {
  51   symbol *res = xmalloc (sizeof *res);
  52
  53   uniqstr_assert (tag);
  54   res->tag = tag;
  55   res->location = loc;
  56
  57   res->type_name = NULL;
  58   res->destructor = NULL;
  59   res->printer = NULL;
  60
  61   res->number = NUMBER_UNDEFINED;
  62   res->prec = 0;
  63   res->assoc = undef_assoc;
  64   res->user_token_number = USER_NUMBER_UNDEFINED;
  65
  66   res->alias = NULL;
  67   res->class = unknown_sym;
  68   res->declared = false;
  69
  70   if (nsyms == SYMBOL_NUMBER_MAXIMUM)
  71     fatal (_("too many symbols in input grammar (limit is %d)"),
  72            SYMBOL_NUMBER_MAXIMUM);
  73   nsyms++;
  74   return res;
  75 }
  76
  77
  78 /*-----------------.
  79 | Print a symbol.  |
  80 `-----------------*/
  81
  82 #define SYMBOL_ATTR_PRINT(Attr)                         \
  83   if (s->Attr)                                          \
  84     fprintf (f, " %s { %s }", #Attr, s->Attr)
  85
  86 void
  87 symbol_print (symbol *s, FILE *f)
  88 {
  89   if (s)
  90     {
  91       fprintf (f, "\"%s\"", s->tag);
  92       SYMBOL_ATTR_PRINT (type_name);
  93       SYMBOL_ATTR_PRINT (destructor);
  94       SYMBOL_ATTR_PRINT (printer);
  95     }
  96   else
  97     fprintf (f, "<NULL>");
  98 }
  99
 100 #undef SYMBOL_ATTR_PRINT
 101
 102 /*------------------------------------------------------------------.
 103 | Complain that S's WHAT is redeclared at SECOND, and was first set |
 104 | at FIRST.                                                         |
 105 `------------------------------------------------------------------*/
 106
 107 static void
 108 redeclaration (symbol* s, const char *what, location first, location second)
 109 {
 110   complain_at (second, _("%s redeclaration for %s"), what, s->tag);
 111   complain_at (first, _("first declaration"));
 112 }
 113
 114
 115 /*-----------------------------------------------------------------.
 116 | Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
 117 | as TYPE_NAME.                                                    |
 118 `-----------------------------------------------------------------*/
 119
 120 void
 121 symbol_type_set (symbol *sym, uniqstr type_name, location loc)
 122 {
 123   if (type_name)
 124     {
 125       if (sym->type_name)
 126         redeclaration (sym, "%type", sym->type_location, loc);
 127       uniqstr_assert (type_name);
 128       sym->type_name = type_name;
 129       sym->type_location = loc;
 130     }
 131 }
 132
 133
 134 /*------------------------------------------------------------------.
 135 | Set the DESTRUCTOR associated with SYM.  Do nothing if passed 0.  |
 136 `------------------------------------------------------------------*/
 137
 138 void
 139 symbol_destructor_set (symbol *sym, const char *destructor, location loc)
 140 {
 141   if (destructor)
 142     {
 143       if (sym->destructor)
 144         redeclaration (sym, "%destructor", sym->destructor_location, loc);
 145       sym->destructor = destructor;
 146       sym->destructor_location = loc;
 147     }
 148 }
 149
 150
 151 /*---------------------------------------------------------------.
 152 | Set the PRINTER associated with SYM.  Do nothing if passed 0.  |
 153 `---------------------------------------------------------------*/
 154
 155 void
 156 symbol_printer_set (symbol *sym, const char *printer, location loc)
 157 {
 158   if (printer)
 159     {
 160       if (sym->printer)
 161         redeclaration (sym, "%printer", sym->destructor_location, loc);
 162       sym->printer = printer;
 163       sym->printer_location = loc;
 164     }
 165 }
 166
 167
 168 /*-----------------------------------------------------------------.
 169 | Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
 170 | with UNDEF_ASSOC as ASSOC.                                       |
 171 `-----------------------------------------------------------------*/
 172
 173 void
 174 symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
 175 {
 176   if (a != undef_assoc)
 177     {
 178       if (sym->prec != 0)
 179         redeclaration (sym, assoc_to_string (a), sym->prec_location, loc);
 180       sym->prec = prec;
 181       sym->assoc = a;
 182       sym->prec_location = loc;
 183     }
 184
 185   /* Only terminals have a precedence. */
 186   symbol_class_set (sym, token_sym, loc, false);
 187 }
 188
 189
 190 /*------------------------------------.
 191 | Set the CLASS associated with SYM.  |
 192 `------------------------------------*/
 193
 194 void
 195 symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
 196 {
 197   if (sym->class != unknown_sym && sym->class != class)
 198     {
 199       complain_at (loc, _("symbol %s redefined"), sym->tag);
 200       sym->declared = false;
 201     }
 202
 203   if (class == nterm_sym && sym->class != nterm_sym)
 204     sym->number = nvars++;
 205   else if (class == token_sym && sym->number == NUMBER_UNDEFINED)
 206     sym->number = ntokens++;
 207
 208   sym->class = class;
 209
 210   if (declaring)
 211     {
 212       if (sym->declared)
 213         warn_at (loc, _("symbol %s redeclared"), sym->tag);
 214       sym->declared = true;
 215     }
 216 }
 217
 218
 219 /*------------------------------------------------.
 220 | Set the USER_TOKEN_NUMBER associated with SYM.  |
 221 `------------------------------------------------*/
 222
 223 void
 224 symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 225 {
 226   assert (sym->class == token_sym);
 227
 228   if (sym->user_token_number != USER_NUMBER_UNDEFINED
 229       && sym->user_token_number != user_token_number)
 230     complain_at (loc, _("redefining user token number of %s"), sym->tag);
 231
 232   sym->user_token_number = user_token_number;
 233   /* User defined $end token? */
 234   if (user_token_number == 0)
 235     {
 236       endtoken = sym;
 237       endtoken->number = 0;
 238       /* It is always mapped to 0, so it was already counted in
 239          NTOKENS.  */
 240       --ntokens;
 241     }
 242 }
 243
 244
 245 /*----------------------------------------------------------.
 246 | If SYM is not defined, report an error, and consider it a |
 247 | nonterminal.                                              |
 248 `----------------------------------------------------------*/
 249
 250 static inline bool
 251 symbol_check_defined (symbol *sym)
 252 {
 253   if (sym->class == unknown_sym)
 254     {
 255       complain_at
 256         (sym->location,
 257          _("symbol %s is used, but is not defined as a token and has no rules"),
 258          sym->tag);
 259       sym->class = nterm_sym;
 260       sym->number = nvars++;
 261     }
 262
 263   return true;
 264 }
 265
 266 static bool
 267 symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
 268 {
 269   return symbol_check_defined (sym);
 270 }
 271
 272
 273 /*------------------------------------------------------------------.
 274 | Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |
 275 | SYMVAL with SYM's type.                                           |
 276 `------------------------------------------------------------------*/
 277
 278 void
 279 symbol_make_alias (symbol *sym, symbol *symval, location loc)
 280 {
 281   if (symval->alias)
 282     warn_at (loc, _("symbol `%s' used more than once as a literal string"),
 283              symval->tag);
 284   else if (sym->alias)
 285     warn_at (loc, _("symbol `%s' given more than one literal string"),
 286              sym->tag);
 287   else
 288     {
 289       symval->class = token_sym;
 290       symval->user_token_number = sym->user_token_number;
 291       sym->user_token_number = USER_NUMBER_ALIAS;
 292       symval->alias = sym;
 293       sym->alias = symval;
 294       /* sym and symval combined are only one symbol.  */
 295       nsyms--;
 296       ntokens--;
 297       assert (ntokens == sym->number || ntokens == symval->number);
 298       sym->number = symval->number =
 299         (symval->number < sym->number) ? symval->number : sym->number;
 300       symbol_type_set (symval, sym->type_name, loc);
 301     }
 302 }
 303
 304
 305 /*---------------------------------------------------------.
 306 | Check that THIS, and its alias, have same precedence and |
 307 | associativity.                                           |
 308 `---------------------------------------------------------*/
 309
 310 static inline void
 311 symbol_check_alias_consistency (symbol *this)
 312 {
 313   symbol *alias = this;
 314   symbol *orig  = this->alias;
 315
 316   /* Check only those that _are_ the aliases.  */
 317   if (!(this->alias && this->user_token_number == USER_NUMBER_ALIAS))
 318     return;
 319
 320   if (orig->type_name != alias->type_name)
 321     {
 322       if (orig->type_name)
 323         symbol_type_set (alias, orig->type_name, orig->type_location);
 324       else
 325         symbol_type_set (orig, alias->type_name, alias->type_location);
 326     }
 327
 328
 329   if (orig->destructor || alias->destructor)
 330     {
 331       if (orig->destructor)
 332         symbol_destructor_set (alias, orig->destructor,
 333                                orig->destructor_location);
 334       else
 335         symbol_destructor_set (orig, alias->destructor,
 336                                alias->destructor_location);
 337     }
 338
 339   if (orig->printer || alias->printer)
 340     {
 341       if (orig->printer)
 342         symbol_printer_set (alias, orig->printer, orig->printer_location);
 343       else
 344         symbol_printer_set (orig, alias->printer, alias->printer_location);
 345     }
 346
 347   if (alias->prec || orig->prec)
 348     {
 349       if (orig->prec)
 350         symbol_precedence_set (alias, orig->prec, orig->assoc,
 351                                orig->prec_location);
 352       else
 353         symbol_precedence_set (orig, alias->prec, alias->assoc,
 354                                alias->prec_location);
 355     }
 356 }
 357
 358 static bool
 359 symbol_check_alias_consistency_processor (void *this,
 360                                           void *null ATTRIBUTE_UNUSED)
 361 {
 362   symbol_check_alias_consistency (this);
 363   return true;
 364 }
 365
 366
 367 /*-------------------------------------------------------------------.
 368 | Assign a symbol number, and write the definition of the token name |
 369 | into FDEFINES.  Put in SYMBOLS.                                    |
 370 `-------------------------------------------------------------------*/
 371
 372 static inline bool
 373 symbol_pack (symbol *this)
 374 {
 375   if (this->class == nterm_sym)
 376     {
 377       this->number += ntokens;
 378     }
 379   else if (this->alias)
 380     {
 381       /* This symbol and its alias are a single token defn.
 382          Allocate a tokno, and assign to both check agreement of
 383          prec and assoc fields and make both the same */
 384       if (this->number == NUMBER_UNDEFINED)
 385         {
 386           if (this == endtoken || this->alias == endtoken)
 387             this->number = this->alias->number = 0;
 388           else
 389             {
 390               assert (this->alias->number != NUMBER_UNDEFINED);
 391               this->number = this->alias->number;
 392             }
 393         }
 394       /* Do not do processing below for USER_NUMBER_ALIASes.  */
 395       if (this->user_token_number == USER_NUMBER_ALIAS)
 396         return true;
 397     }
 398   else /* this->class == token_sym */
 399     assert (this->number != NUMBER_UNDEFINED);
 400
 401   symbols[this->number] = this;
 402   return true;
 403 }
 404
 405 static bool
 406 symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
 407 {
 408   return symbol_pack (this);
 409 }
 410
 411
 412
 413
 414 /*--------------------------------------------------.
 415 | Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
 416 `--------------------------------------------------*/
 417
 418 static inline bool
 419 symbol_translation (symbol *this)
 420 {
 421   /* Non-terminal? */
 422   if (this->class == token_sym
 423       && this->user_token_number != USER_NUMBER_ALIAS)
 424     {
 425       /* A token which translation has already been set? */
 426       if (token_translations[this->user_token_number] != undeftoken->number)
 427         complain_at (this->location,
 428                      _("tokens %s and %s both assigned number %d"),
 429                      symbols[token_translations[this->user_token_number]]->tag,
 430                      this->tag, this->user_token_number);
 431
 432       token_translations[this->user_token_number] = this->number;
 433     }
 434
 435   return true;
 436 }
 437
 438 static bool
 439 symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
 440 {
 441   return symbol_translation (this);
 442 }
 443
 444
 445 /*----------------------.
 446 | A symbol hash table.  |
 447 `----------------------*/
 448
 449 /* Initial capacity of symbols hash table.  */
 450 #define HT_INITIAL_CAPACITY 257
 451
 452 static struct hash_table *symbol_table = NULL;
 453
 454 static inline bool
 455 hash_compare_symbol (const symbol *m1, const symbol *m2)
 456 {
 457   /* Since tags are unique, we can compare the pointers themselves.  */
 458   return UNIQSTR_EQ (m1->tag, m2->tag);
 459 }
 460
 461 static bool
 462 hash_symbol_comparator (void const *m1, void const *m2)
 463 {
 464   return hash_compare_symbol (m1, m2);
 465 }
 466
 467 static inline size_t
 468 hash_symbol (const symbol *m, size_t tablesize)
 469 {
 470   /* Since tags are unique, we can hash the pointer itself.  */
 471   return ((uintptr_t) m->tag) % tablesize;
 472 }
 473
 474 static size_t
 475 hash_symbol_hasher (void const *m, size_t tablesize)
 476 {
 477   return hash_symbol (m, tablesize);
 478 }
 479
 480
 481 /*-------------------------------.
 482 | Create the symbol hash table.  |
 483 `-------------------------------*/
 484
 485 void
 486 symbols_new (void)
 487 {
 488   symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
 489                                   NULL,
 490                                   hash_symbol_hasher,
 491                                   hash_symbol_comparator,
 492                                   free);
 493 }
 494
 495
 496 /*----------------------------------------------------------------.
 497 | Find the symbol named KEY, and return it.  If it does not exist |
 498 | yet, create it.                                                 |
 499 `----------------------------------------------------------------*/
 500
 501 symbol *
 502 symbol_get (const char *key, location loc)
 503 {
 504   symbol probe;
 505   symbol *entry;
 506
 507   key = uniqstr_new (key);
 508   probe.tag = key;
 509   entry = hash_lookup (symbol_table, &probe);
 510
 511   if (!entry)
 512     {
 513       /* First insertion in the hash. */
 514       entry = symbol_new (key, loc);
 515       hash_insert (symbol_table, entry);
 516     }
 517   return entry;
 518 }
 519
 520
 521 /*------------------------------------------------------------------.
 522 | Generate a dummy nonterminal, whose name cannot conflict with the |
 523 | user's names.                                                     |
 524 `------------------------------------------------------------------*/
 525
 526 symbol *
 527 dummy_symbol_get (location loc)
 528 {
 529   /* Incremented for each generated symbol.  */
 530   static int dummy_count = 0;
 531   static char buf[256];
 532
 533   symbol *sym;
 534
 535   sprintf (buf, "@%d", ++dummy_count);
 536   sym = symbol_get (buf, loc);
 537   sym->class = nterm_sym;
 538   sym->number = nvars++;
 539   return sym;
 540 }
 541
 542
 543 /*-------------------.
 544 | Free the symbols.  |
 545 `-------------------*/
 546
 547 void
 548 symbols_free (void)
 549 {
 550   hash_free (symbol_table);
 551   free (symbols);
 552 }
 553
 554
 555 /*---------------------------------------------------------------.
 556 | Look for undefined symbols, report an error, and consider them |
 557 | terminals.                                                     |
 558 `---------------------------------------------------------------*/
 559
 560 static void
 561 symbols_do (Hash_processor processor, void *processor_data)
 562 {
 563   hash_do_for_each (symbol_table, processor, processor_data);
 564 }
 565
 566
 567 /*--------------------------------------------------------------.
 568 | Check that all the symbols are defined.  Report any undefined |
 569 | symbols and consider them nonterminals.                       |
 570 `--------------------------------------------------------------*/
 571
 572 void
 573 symbols_check_defined (void)
 574 {
 575   symbols_do (symbol_check_defined_processor, NULL);
 576 }
 577
 578 /*------------------------------------------------------------------.
 579 | Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
 580 | number.                                                           |
 581 `------------------------------------------------------------------*/
 582
 583 static void
 584 symbols_token_translations_init (void)
 585 {
 586   bool num_256_available_p = true;
 587   int i;
 588
 589   /* Find the highest user token number, and whether 256, the POSIX
 590      preferred user token number for the error token, is used.  */
 591   max_user_token_number = 0;
 592   for (i = 0; i < ntokens; ++i)
 593     {
 594       symbol *this = symbols[i];
 595       if (this->user_token_number != USER_NUMBER_UNDEFINED)
 596         {
 597           if (this->user_token_number > max_user_token_number)
 598             max_user_token_number = this->user_token_number;
 599           if (this->user_token_number == 256)
 600             num_256_available_p = false;
 601         }
 602     }
 603
 604   /* If 256 is not used, assign it to error, to follow POSIX.  */
 605   if (num_256_available_p
 606       && errtoken->user_token_number == USER_NUMBER_UNDEFINED)
 607     errtoken->user_token_number = 256;
 608
 609   /* Set the missing user numbers. */
 610   if (max_user_token_number < 256)
 611     max_user_token_number = 256;
 612
 613   for (i = 0; i < ntokens; ++i)
 614     {
 615       symbol *this = symbols[i];
 616       if (this->user_token_number == USER_NUMBER_UNDEFINED)
 617         this->user_token_number = ++max_user_token_number;
 618       if (this->user_token_number > max_user_token_number)
 619         max_user_token_number = this->user_token_number;
 620     }
 621
 622   token_translations = xnmalloc (max_user_token_number + 1,
 623                                  sizeof *token_translations);
 624
 625   /* Initialize all entries for literal tokens to 2, the internal
 626      token number for $undefined, which represents all invalid inputs.
 627      */
 628   for (i = 0; i < max_user_token_number + 1; i++)
 629     token_translations[i] = undeftoken->number;
 630   symbols_do (symbol_translation_processor, NULL);
 631 }
 632
 633
 634 /*----------------------------------------------------------------.
 635 | Assign symbol numbers, and write definition of token names into |
 636 | FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
 637 `----------------------------------------------------------------*/
 638
 639 void
 640 symbols_pack (void)
 641 {
 642   symbols = xcalloc (nsyms, sizeof *symbols);
 643
 644   symbols_do (symbol_check_alias_consistency_processor, NULL);
 645   symbols_do (symbol_pack_processor, NULL);
 646
 647   symbols_token_translations_init ();
 648
 649   if (startsymbol->class == unknown_sym)
 650     fatal_at (startsymbol_location,
 651               _("the start symbol %s is undefined"),
 652               startsymbol->tag);
 653   else if (startsymbol->class == token_sym)
 654     fatal_at (startsymbol_location,
 655               _("the start symbol %s is a token"),
 656               startsymbol->tag);
 657 }