src/symtab.c

   1 /* Symbol table manager for Bison.
   2
   3    Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
   4
   5    This file is part of Bison, the GNU Compiler Compiler.
   6
   7    Bison is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2, or (at your option)
  10    any later version.
  11
  12    Bison is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with Bison; see the file COPYING.  If not, write to
  19    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22
  23 #include "system.h"
  24
  25 #include <hash.h>
  26 #include <quotearg.h>
  27
  28 #include "complain.h"
  29 #include "gram.h"
  30 #include "symtab.h"
  31
  32 /*------------------------.
  33 | Distinguished symbols.  |
  34 `------------------------*/
  35
  36 symbol *errtoken = NULL;
  37 symbol *undeftoken = NULL;
  38 symbol *endtoken = NULL;
  39 symbol *accept = NULL;
  40 symbol *startsymbol = NULL;
  41 location startsymbol_location;
  42
  43 /*---------------------------------.
  44 | Create a new symbol, named TAG.  |
  45 `---------------------------------*/
  46
  47 static symbol *
  48 symbol_new (uniqstr tag, location loc)
  49 {
  50   symbol *res = MALLOC (res, 1);
  51
  52   uniqstr_assert (tag);
  53   res->tag = tag;
  54   res->location = loc;
  55
  56   res->type_name = NULL;
  57   res->destructor = NULL;
  58   res->printer = NULL;
  59
  60   res->number = NUMBER_UNDEFINED;
  61   res->prec = 0;
  62   res->assoc = undef_assoc;
  63   res->user_token_number = USER_NUMBER_UNDEFINED;
  64
  65   res->alias = NULL;
  66   res->class = unknown_sym;
  67
  68   nsyms++;
  69   return res;
  70 }
  71
  72
  73 /*-----------------------------------------------------------------.
  74 | Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
  75 | as TYPE_NAME.                                                    |
  76 `-----------------------------------------------------------------*/
  77
  78 void
  79 symbol_type_set (symbol *sym, uniqstr type_name, location loc)
  80 {
  81   if (type_name)
  82     {
  83       if (sym->type_name)
  84         complain_at (loc, _("type redeclaration for %s"), sym->tag);
  85       uniqstr_assert (type_name);
  86       sym->type_name = type_name;
  87     }
  88 }
  89
  90
  91 /*------------------------------------------------------------------.
  92 | Set the DESTRUCTOR associated with SYM.  Do nothing if passed 0.  |
  93 `------------------------------------------------------------------*/
  94
  95 void
  96 symbol_destructor_set (symbol *sym, char *destructor, location loc)
  97 {
  98   if (destructor)
  99     {
 100       if (sym->destructor)
 101         complain_at (loc, _("%s redeclaration for %s"),
 102                      "%destructor", sym->tag);
 103       sym->destructor = destructor;
 104       sym->destructor_location = loc;
 105     }
 106 }
 107
 108
 109 /*---------------------------------------------------------------.
 110 | Set the PRINTER associated with SYM.  Do nothing if passed 0.  |
 111 `---------------------------------------------------------------*/
 112
 113 void
 114 symbol_printer_set (symbol *sym, char *printer, location loc)
 115 {
 116   if (printer)
 117     {
 118       if (sym->printer)
 119         complain_at (loc, _("%s redeclaration for %s"),
 120                      "%printer", sym->tag);
 121       sym->printer = printer;
 122       sym->printer_location = loc;
 123     }
 124 }
 125
 126
 127 /*-----------------------------------------------------------------.
 128 | Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
 129 | with UNDEF_ASSOC as ASSOC.                                       |
 130 `-----------------------------------------------------------------*/
 131
 132 void
 133 symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
 134 {
 135   if (a != undef_assoc)
 136     {
 137       if (sym->prec != 0)
 138         complain_at (loc, _("redefining precedence of %s"), sym->tag);
 139       sym->prec = prec;
 140       sym->assoc = a;
 141     }
 142
 143   /* Only terminals have a precedence. */
 144   symbol_class_set (sym, token_sym, loc);
 145 }
 146
 147
 148 /*------------------------------------.
 149 | Set the CLASS associated with SYM.  |
 150 `------------------------------------*/
 151
 152 void
 153 symbol_class_set (symbol *sym, symbol_class class, location loc)
 154 {
 155   if (sym->class != unknown_sym && sym->class != class)
 156     complain_at (loc, _("symbol %s redefined"), sym->tag);
 157
 158   if (class == nterm_sym && sym->class != nterm_sym)
 159     sym->number = nvars++;
 160   else if (class == token_sym && sym->number == NUMBER_UNDEFINED)
 161     sym->number = ntokens++;
 162
 163   sym->class = class;
 164 }
 165
 166
 167 /*------------------------------------------------.
 168 | Set the USER_TOKEN_NUMBER associated with SYM.  |
 169 `------------------------------------------------*/
 170
 171 void
 172 symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 173 {
 174   if (sym->class != token_sym)
 175     abort ();
 176
 177   if (sym->user_token_number != USER_NUMBER_UNDEFINED
 178       && sym->user_token_number != user_token_number)
 179     complain_at (loc, _("redefining user token number of %s"), sym->tag);
 180
 181   sym->user_token_number = user_token_number;
 182   /* User defined $end token? */
 183   if (user_token_number == 0)
 184     {
 185       endtoken = sym;
 186       endtoken->number = 0;
 187       /* It is always mapped to 0, so it was already counted in
 188          NTOKENS.  */
 189       --ntokens;
 190     }
 191 }
 192
 193
 194 /*----------------------------------------------------------.
 195 | If SYM is not defined, report an error, and consider it a |
 196 | nonterminal.                                              |
 197 `----------------------------------------------------------*/
 198
 199 static inline bool
 200 symbol_check_defined (symbol *sym)
 201 {
 202   if (sym->class == unknown_sym)
 203     {
 204       complain_at
 205         (sym->location,
 206          _("symbol %s is used, but is not defined as a token and has no rules"),
 207          sym->tag);
 208       sym->class = nterm_sym;
 209       sym->number = nvars++;
 210     }
 211
 212   return true;
 213 }
 214
 215 static bool
 216 symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
 217 {
 218   return symbol_check_defined (sym);
 219 }
 220
 221
 222 /*------------------------------------------------------------------.
 223 | Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |
 224 | them with TYPENAME.                                               |
 225 `------------------------------------------------------------------*/
 226
 227 void
 228 symbol_make_alias (symbol *sym, symbol *symval, location loc)
 229 {
 230   if (symval->alias)
 231     warn_at (loc, _("symbol `%s' used more than once as a literal string"),
 232           symval->tag);
 233   else if (sym->alias)
 234     warn_at (loc, _("symbol `%s' given more than one literal string"),
 235           sym->tag);
 236   else
 237     {
 238       symval->class = token_sym;
 239       symval->user_token_number = sym->user_token_number;
 240       sym->user_token_number = USER_NUMBER_ALIAS;
 241       symval->alias = sym;
 242       sym->alias = symval;
 243       /* sym and symval combined are only one symbol.  */
 244       nsyms--;
 245       ntokens--;
 246       if (ntokens != sym->number && ntokens != symval->number)
 247         abort ();
 248       sym->number = symval->number =
 249         (symval->number < sym->number) ? symval->number : sym->number;
 250     }
 251 }
 252
 253
 254 /*---------------------------------------------------------.
 255 | Check that THIS, and its alias, have same precedence and |
 256 | associativity.                                           |
 257 `---------------------------------------------------------*/
 258
 259 static inline bool
 260 symbol_check_alias_consistency (symbol *this)
 261 {
 262   /* Check only those who _are_ the aliases. */
 263   if (this->alias && this->user_token_number == USER_NUMBER_ALIAS)
 264     {
 265       if (this->prec != this->alias->prec)
 266         {
 267           if (this->prec != 0 && this->alias->prec != 0)
 268             complain_at (this->alias->location,
 269                          _("conflicting precedences for %s and %s"),
 270                          this->tag, this->alias->tag);
 271           if (this->prec != 0)
 272             this->alias->prec = this->prec;
 273           else
 274             this->prec = this->alias->prec;
 275         }
 276
 277       if (this->assoc != this->alias->assoc)
 278         {
 279           if (this->assoc != undef_assoc && this->alias->assoc != undef_assoc)
 280             complain_at (this->alias->location,
 281                          _("conflicting associativities for %s (%s) and %s (%s)"),
 282                          this->tag, assoc_to_string (this->assoc),
 283                          this->alias->tag, assoc_to_string (this->alias->assoc));
 284           if (this->assoc != undef_assoc)
 285             this->alias->assoc = this->assoc;
 286           else
 287             this->assoc = this->alias->assoc;
 288         }
 289     }
 290   return true;
 291 }
 292
 293 static bool
 294 symbol_check_alias_consistency_processor (void *this,
 295                                           void *null ATTRIBUTE_UNUSED)
 296 {
 297   return symbol_check_alias_consistency (this);
 298 }
 299
 300
 301 /*-------------------------------------------------------------------.
 302 | Assign a symbol number, and write the definition of the token name |
 303 | into FDEFINES.  Put in SYMBOLS.                                    |
 304 `-------------------------------------------------------------------*/
 305
 306 static inline bool
 307 symbol_pack (symbol *this)
 308 {
 309   if (this->class == nterm_sym)
 310     {
 311       this->number += ntokens;
 312     }
 313   else if (this->alias)
 314     {
 315       /* This symbol and its alias are a single token defn.
 316          Allocate a tokno, and assign to both check agreement of
 317          prec and assoc fields and make both the same */
 318       if (this->number == NUMBER_UNDEFINED)
 319         {
 320           if (this == endtoken || this->alias == endtoken)
 321             this->number = this->alias->number = 0;
 322           else
 323             {
 324               if (this->alias->number == NUMBER_UNDEFINED)
 325                 abort ();
 326               this->number = this->alias->number;
 327             }
 328         }
 329       /* Do not do processing below for USER_NUMBER_ALIASes.  */
 330       if (this->user_token_number == USER_NUMBER_ALIAS)
 331         return true;
 332     }
 333   else /* this->class == token_sym */
 334     {
 335       if (this->number == NUMBER_UNDEFINED)
 336         abort ();
 337     }
 338
 339   symbols[this->number] = this;
 340   return true;
 341 }
 342
 343 static bool
 344 symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
 345 {
 346   return symbol_pack (this);
 347 }
 348
 349
 350
 351
 352 /*--------------------------------------------------.
 353 | Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
 354 `--------------------------------------------------*/
 355
 356 static inline bool
 357 symbol_translation (symbol *this)
 358 {
 359   /* Non-terminal? */
 360   if (this->class == token_sym
 361       && this->user_token_number != USER_NUMBER_ALIAS)
 362     {
 363       /* A token which translation has already been set? */
 364       if (token_translations[this->user_token_number] != undeftoken->number)
 365         complain_at (this->location,
 366                      _("tokens %s and %s both assigned number %d"),
 367                      symbols[token_translations[this->user_token_number]]->tag,
 368                      this->tag, this->user_token_number);
 369
 370       token_translations[this->user_token_number] = this->number;
 371     }
 372
 373   return true;
 374 }
 375
 376 static bool
 377 symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
 378 {
 379   return symbol_translation (this);
 380 }
 381
 382
 383 /*----------------------.
 384 | A symbol hash table.  |
 385 `----------------------*/
 386
 387 /* Initial capacity of symbols hash table.  */
 388 #define HT_INITIAL_CAPACITY 257
 389
 390 static struct hash_table *symbol_table = NULL;
 391
 392 static inline bool
 393 hash_compare_symbol (const symbol *m1, const symbol *m2)
 394 {
 395   /* Since tags are unique, we can compare the pointers themselves.  */
 396   return UNIQSTR_EQ (m1->tag, m2->tag);
 397 }
 398
 399 static bool
 400 hash_symbol_comparator (void const *m1, void const *m2)
 401 {
 402   return hash_compare_symbol (m1, m2);
 403 }
 404
 405 static inline unsigned int
 406 hash_symbol (const symbol *m, unsigned int tablesize)
 407 {
 408   /* Since tags are unique, we can hash the pointer itself.  */
 409   return ((uintptr_t) m->tag) % tablesize;
 410 }
 411
 412 static unsigned int
 413 hash_symbol_hasher (void const *m, unsigned int tablesize)
 414 {
 415   return hash_symbol (m, tablesize);
 416 }
 417
 418
 419 /*-------------------------------.
 420 | Create the symbol hash table.  |
 421 `-------------------------------*/
 422
 423 void
 424 symbols_new (void)
 425 {
 426   symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
 427                                   NULL,
 428                                   hash_symbol_hasher,
 429                                   hash_symbol_comparator,
 430                                   free);
 431 }
 432
 433
 434 /*----------------------------------------------------------------.
 435 | Find the symbol named KEY, and return it.  If it does not exist |
 436 | yet, create it.                                                 |
 437 `----------------------------------------------------------------*/
 438
 439 symbol *
 440 symbol_get (const char *key, location loc)
 441 {
 442   symbol probe;
 443   symbol *entry;
 444
 445   /* Keep the symbol in a printable form.  */
 446   key = uniqstr_new (quotearg_style (escape_quoting_style, key));
 447   probe.tag = key;
 448   entry = hash_lookup (symbol_table, &probe);
 449
 450   if (!entry)
 451     {
 452       /* First insertion in the hash. */
 453       entry = symbol_new (key, loc);
 454       hash_insert (symbol_table, entry);
 455     }
 456   return entry;
 457 }
 458
 459
 460 /*------------------------------------------------------------------.
 461 | Generate a dummy nonterminal, whose name cannot conflict with the |
 462 | user's names.                                                     |
 463 `------------------------------------------------------------------*/
 464
 465 symbol *
 466 dummy_symbol_get (location loc)
 467 {
 468   /* Incremented for each generated symbol.  */
 469   static int dummy_count = 0;
 470   static char buf[256];
 471
 472   symbol *sym;
 473
 474   sprintf (buf, "@%d", ++dummy_count);
 475   sym = symbol_get (buf, loc);
 476   sym->class = nterm_sym;
 477   sym->number = nvars++;
 478   return sym;
 479 }
 480
 481
 482 /*-------------------.
 483 | Free the symbols.  |
 484 `-------------------*/
 485
 486 void
 487 symbols_free (void)
 488 {
 489   hash_free (symbol_table);
 490   free (symbols);
 491 }
 492
 493
 494 /*---------------------------------------------------------------.
 495 | Look for undefined symbols, report an error, and consider them |
 496 | terminals.                                                     |
 497 `---------------------------------------------------------------*/
 498
 499 static void
 500 symbols_do (Hash_processor processor, void *processor_data)
 501 {
 502   hash_do_for_each (symbol_table, processor, processor_data);
 503 }
 504
 505
 506 /*--------------------------------------------------------------.
 507 | Check that all the symbols are defined.  Report any undefined |
 508 | symbols and consider them nonterminals.                       |
 509 `--------------------------------------------------------------*/
 510
 511 void
 512 symbols_check_defined (void)
 513 {
 514   symbols_do (symbol_check_defined_processor, NULL);
 515 }
 516
 517 /*------------------------------------------------------------------.
 518 | Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
 519 | number.                                                           |
 520 `------------------------------------------------------------------*/
 521
 522 static void
 523 symbols_token_translations_init (void)
 524 {
 525   bool num_256_available_p = true;
 526   int i;
 527
 528   /* Find the highest user token number, and whether 256, the POSIX
 529      preferred user token number for the error token, is used.  */
 530   max_user_token_number = 0;
 531   for (i = 0; i < ntokens; ++i)
 532     {
 533       symbol *this = symbols[i];
 534       if (this->user_token_number != USER_NUMBER_UNDEFINED)
 535         {
 536           if (this->user_token_number > max_user_token_number)
 537             max_user_token_number = this->user_token_number;
 538           if (this->user_token_number == 256)
 539             num_256_available_p = false;
 540         }
 541     }
 542
 543   /* If 256 is not used, assign it to error, to follow POSIX.  */
 544   if (num_256_available_p
 545       && errtoken->user_token_number == USER_NUMBER_UNDEFINED)
 546     errtoken->user_token_number = 256;
 547
 548   /* Set the missing user numbers. */
 549   if (max_user_token_number < 256)
 550     max_user_token_number = 256;
 551
 552   for (i = 0; i < ntokens; ++i)
 553     {
 554       symbol *this = symbols[i];
 555       if (this->user_token_number == USER_NUMBER_UNDEFINED)
 556         this->user_token_number = ++max_user_token_number;
 557       if (this->user_token_number > max_user_token_number)
 558         max_user_token_number = this->user_token_number;
 559     }
 560
 561   CALLOC (token_translations, max_user_token_number + 1);
 562
 563   /* Initialize all entries for literal tokens to 2, the internal
 564      token number for $undefined, which represents all invalid inputs.
 565      */
 566   for (i = 0; i < max_user_token_number + 1; i++)
 567     token_translations[i] = undeftoken->number;
 568   symbols_do (symbol_translation_processor, NULL);
 569 }
 570
 571
 572 /*----------------------------------------------------------------.
 573 | Assign symbol numbers, and write definition of token names into |
 574 | FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
 575 `----------------------------------------------------------------*/
 576
 577 void
 578 symbols_pack (void)
 579 {
 580   CALLOC (symbols, nsyms);
 581
 582   symbols_do (symbol_check_alias_consistency_processor, NULL);
 583   symbols_do (symbol_pack_processor, NULL);
 584
 585   symbols_token_translations_init ();
 586
 587   if (startsymbol->class == unknown_sym)
 588     fatal_at (startsymbol_location,
 589               _("the start symbol %s is undefined"),
 590               startsymbol->tag);
 591   else if (startsymbol->class == token_sym)
 592     fatal_at (startsymbol_location,
 593               _("the start symbol %s is a token"),
 594               startsymbol->tag);
 595 }