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 | SYMVAL with SYM's type.                                           |
 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       symbol_type_set (symval, sym->type_name, loc);
 251     }
 252 }
 253
 254
 255 /*---------------------------------------------------------.
 256 | Check that THIS, and its alias, have same precedence and |
 257 | associativity.                                           |
 258 `---------------------------------------------------------*/
 259
 260 static inline bool
 261 symbol_check_alias_consistency (symbol *this)
 262 {
 263   /* Check only those who _are_ the aliases. */
 264   if (this->alias && this->user_token_number == USER_NUMBER_ALIAS)
 265     {
 266       if (this->prec != this->alias->prec)
 267         {
 268           if (this->prec != 0 && this->alias->prec != 0)
 269             complain_at (this->alias->location,
 270                          _("conflicting precedences for %s and %s"),
 271                          this->tag, this->alias->tag);
 272           if (this->prec != 0)
 273             this->alias->prec = this->prec;
 274           else
 275             this->prec = this->alias->prec;
 276         }
 277
 278       if (this->assoc != this->alias->assoc)
 279         {
 280           if (this->assoc != undef_assoc && this->alias->assoc != undef_assoc)
 281             complain_at (this->alias->location,
 282                          _("conflicting associativities for %s (%s) and %s (%s)"),
 283                          this->tag, assoc_to_string (this->assoc),
 284                          this->alias->tag, assoc_to_string (this->alias->assoc));
 285           if (this->assoc != undef_assoc)
 286             this->alias->assoc = this->assoc;
 287           else
 288             this->assoc = this->alias->assoc;
 289         }
 290     }
 291   return true;
 292 }
 293
 294 static bool
 295 symbol_check_alias_consistency_processor (void *this,
 296                                           void *null ATTRIBUTE_UNUSED)
 297 {
 298   return symbol_check_alias_consistency (this);
 299 }
 300
 301
 302 /*-------------------------------------------------------------------.
 303 | Assign a symbol number, and write the definition of the token name |
 304 | into FDEFINES.  Put in SYMBOLS.                                    |
 305 `-------------------------------------------------------------------*/
 306
 307 static inline bool
 308 symbol_pack (symbol *this)
 309 {
 310   if (this->class == nterm_sym)
 311     {
 312       this->number += ntokens;
 313     }
 314   else if (this->alias)
 315     {
 316       /* This symbol and its alias are a single token defn.
 317          Allocate a tokno, and assign to both check agreement of
 318          prec and assoc fields and make both the same */
 319       if (this->number == NUMBER_UNDEFINED)
 320         {
 321           if (this == endtoken || this->alias == endtoken)
 322             this->number = this->alias->number = 0;
 323           else
 324             {
 325               if (this->alias->number == NUMBER_UNDEFINED)
 326                 abort ();
 327               this->number = this->alias->number;
 328             }
 329         }
 330       /* Do not do processing below for USER_NUMBER_ALIASes.  */
 331       if (this->user_token_number == USER_NUMBER_ALIAS)
 332         return true;
 333     }
 334   else /* this->class == token_sym */
 335     {
 336       if (this->number == NUMBER_UNDEFINED)
 337         abort ();
 338     }
 339
 340   symbols[this->number] = this;
 341   return true;
 342 }
 343
 344 static bool
 345 symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
 346 {
 347   return symbol_pack (this);
 348 }
 349
 350
 351
 352
 353 /*--------------------------------------------------.
 354 | Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
 355 `--------------------------------------------------*/
 356
 357 static inline bool
 358 symbol_translation (symbol *this)
 359 {
 360   /* Non-terminal? */
 361   if (this->class == token_sym
 362       && this->user_token_number != USER_NUMBER_ALIAS)
 363     {
 364       /* A token which translation has already been set? */
 365       if (token_translations[this->user_token_number] != undeftoken->number)
 366         complain_at (this->location,
 367                      _("tokens %s and %s both assigned number %d"),
 368                      symbols[token_translations[this->user_token_number]]->tag,
 369                      this->tag, this->user_token_number);
 370
 371       token_translations[this->user_token_number] = this->number;
 372     }
 373
 374   return true;
 375 }
 376
 377 static bool
 378 symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
 379 {
 380   return symbol_translation (this);
 381 }
 382
 383
 384 /*----------------------.
 385 | A symbol hash table.  |
 386 `----------------------*/
 387
 388 /* Initial capacity of symbols hash table.  */
 389 #define HT_INITIAL_CAPACITY 257
 390
 391 static struct hash_table *symbol_table = NULL;
 392
 393 static inline bool
 394 hash_compare_symbol (const symbol *m1, const symbol *m2)
 395 {
 396   /* Since tags are unique, we can compare the pointers themselves.  */
 397   return UNIQSTR_EQ (m1->tag, m2->tag);
 398 }
 399
 400 static bool
 401 hash_symbol_comparator (void const *m1, void const *m2)
 402 {
 403   return hash_compare_symbol (m1, m2);
 404 }
 405
 406 static inline unsigned int
 407 hash_symbol (const symbol *m, unsigned int tablesize)
 408 {
 409   /* Since tags are unique, we can hash the pointer itself.  */
 410   return ((uintptr_t) m->tag) % tablesize;
 411 }
 412
 413 static unsigned int
 414 hash_symbol_hasher (void const *m, unsigned int tablesize)
 415 {
 416   return hash_symbol (m, tablesize);
 417 }
 418
 419
 420 /*-------------------------------.
 421 | Create the symbol hash table.  |
 422 `-------------------------------*/
 423
 424 void
 425 symbols_new (void)
 426 {
 427   symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
 428                                   NULL,
 429                                   hash_symbol_hasher,
 430                                   hash_symbol_comparator,
 431                                   free);
 432 }
 433
 434
 435 /*----------------------------------------------------------------.
 436 | Find the symbol named KEY, and return it.  If it does not exist |
 437 | yet, create it.                                                 |
 438 `----------------------------------------------------------------*/
 439
 440 symbol *
 441 symbol_get (const char *key, location loc)
 442 {
 443   symbol probe;
 444   symbol *entry;
 445
 446   /* Keep the symbol in a printable form.  */
 447   key = uniqstr_new (quotearg_style (escape_quoting_style, key));
 448   probe.tag = key;
 449   entry = hash_lookup (symbol_table, &probe);
 450
 451   if (!entry)
 452     {
 453       /* First insertion in the hash. */
 454       entry = symbol_new (key, loc);
 455       hash_insert (symbol_table, entry);
 456     }
 457   return entry;
 458 }
 459
 460
 461 /*------------------------------------------------------------------.
 462 | Generate a dummy nonterminal, whose name cannot conflict with the |
 463 | user's names.                                                     |
 464 `------------------------------------------------------------------*/
 465
 466 symbol *
 467 dummy_symbol_get (location loc)
 468 {
 469   /* Incremented for each generated symbol.  */
 470   static int dummy_count = 0;
 471   static char buf[256];
 472
 473   symbol *sym;
 474
 475   sprintf (buf, "@%d", ++dummy_count);
 476   sym = symbol_get (buf, loc);
 477   sym->class = nterm_sym;
 478   sym->number = nvars++;
 479   return sym;
 480 }
 481
 482
 483 /*-------------------.
 484 | Free the symbols.  |
 485 `-------------------*/
 486
 487 void
 488 symbols_free (void)
 489 {
 490   hash_free (symbol_table);
 491   free (symbols);
 492 }
 493
 494
 495 /*---------------------------------------------------------------.
 496 | Look for undefined symbols, report an error, and consider them |
 497 | terminals.                                                     |
 498 `---------------------------------------------------------------*/
 499
 500 static void
 501 symbols_do (Hash_processor processor, void *processor_data)
 502 {
 503   hash_do_for_each (symbol_table, processor, processor_data);
 504 }
 505
 506
 507 /*--------------------------------------------------------------.
 508 | Check that all the symbols are defined.  Report any undefined |
 509 | symbols and consider them nonterminals.                       |
 510 `--------------------------------------------------------------*/
 511
 512 void
 513 symbols_check_defined (void)
 514 {
 515   symbols_do (symbol_check_defined_processor, NULL);
 516 }
 517
 518 /*------------------------------------------------------------------.
 519 | Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
 520 | number.                                                           |
 521 `------------------------------------------------------------------*/
 522
 523 static void
 524 symbols_token_translations_init (void)
 525 {
 526   bool num_256_available_p = true;
 527   int i;
 528
 529   /* Find the highest user token number, and whether 256, the POSIX
 530      preferred user token number for the error token, is used.  */
 531   max_user_token_number = 0;
 532   for (i = 0; i < ntokens; ++i)
 533     {
 534       symbol *this = symbols[i];
 535       if (this->user_token_number != USER_NUMBER_UNDEFINED)
 536         {
 537           if (this->user_token_number > max_user_token_number)
 538             max_user_token_number = this->user_token_number;
 539           if (this->user_token_number == 256)
 540             num_256_available_p = false;
 541         }
 542     }
 543
 544   /* If 256 is not used, assign it to error, to follow POSIX.  */
 545   if (num_256_available_p
 546       && errtoken->user_token_number == USER_NUMBER_UNDEFINED)
 547     errtoken->user_token_number = 256;
 548
 549   /* Set the missing user numbers. */
 550   if (max_user_token_number < 256)
 551     max_user_token_number = 256;
 552
 553   for (i = 0; i < ntokens; ++i)
 554     {
 555       symbol *this = symbols[i];
 556       if (this->user_token_number == USER_NUMBER_UNDEFINED)
 557         this->user_token_number = ++max_user_token_number;
 558       if (this->user_token_number > max_user_token_number)
 559         max_user_token_number = this->user_token_number;
 560     }
 561
 562   CALLOC (token_translations, max_user_token_number + 1);
 563
 564   /* Initialize all entries for literal tokens to 2, the internal
 565      token number for $undefined, which represents all invalid inputs.
 566      */
 567   for (i = 0; i < max_user_token_number + 1; i++)
 568     token_translations[i] = undeftoken->number;
 569   symbols_do (symbol_translation_processor, NULL);
 570 }
 571
 572
 573 /*----------------------------------------------------------------.
 574 | Assign symbol numbers, and write definition of token names into |
 575 | FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
 576 `----------------------------------------------------------------*/
 577
 578 void
 579 symbols_pack (void)
 580 {
 581   CALLOC (symbols, nsyms);
 582
 583   symbols_do (symbol_check_alias_consistency_processor, NULL);
 584   symbols_do (symbol_pack_processor, NULL);
 585
 586   symbols_token_translations_init ();
 587
 588   if (startsymbol->class == unknown_sym)
 589     fatal_at (startsymbol_location,
 590               _("the start symbol %s is undefined"),
 591               startsymbol->tag);
 592   else if (startsymbol->class == token_sym)
 593     fatal_at (startsymbol_location,
 594               _("the start symbol %s is a token"),
 595               startsymbol->tag);
 596 }