src/symtab.c

   1 /* Symbol table manager for Bison.
   2
   3    Copyright (C) 1984, 1989, 2000-2002, 2004-2013 Free Software
   4    Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program 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 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22 #include "system.h"
  23
  24 #include <hash.h>
  25
  26 #include "complain.h"
  27 #include "gram.h"
  28 #include "symtab.h"
  29
  30 /*-------------------------------------------------------------------.
  31 | Symbols sorted by tag.  Allocated by the first invocation of       |
  32 | symbols_do, after which no more symbols should be created.         |
  33 `-------------------------------------------------------------------*/
  34
  35 static symbol **symbols_sorted = NULL;
  36 static symbol **semantic_types_sorted = NULL;
  37
  38 /*------------------------.
  39 | Distinguished symbols.  |
  40 `------------------------*/
  41
  42 symbol *errtoken = NULL;
  43 symbol *undeftoken = NULL;
  44 symbol *endtoken = NULL;
  45 symbol *accept = NULL;
  46 symbol *startsymbol = NULL;
  47 location startsymbol_location;
  48
  49 /*---------------------------.
  50 | Precedence relation graph. |
  51 `---------------------------*/
  52
  53 static symgraph **prec_nodes;
  54
  55 /*-----------------------------------.
  56 | Store which associativity is used. |
  57 `-----------------------------------*/
  58
  59 bool *used_assoc = NULL;
  60
  61 /*---------------------------------.
  62 | Create a new symbol, named TAG.  |
  63 `---------------------------------*/
  64
  65 static symbol *
  66 symbol_new (uniqstr tag, location loc)
  67 {
  68   symbol *res = xmalloc (sizeof *res);
  69   uniqstr_assert (tag);
  70
  71   /* If the tag is not a string (starts with a double quote), check
  72      that it is valid for Yacc. */
  73   if (tag[0] != '\"' && tag[0] != '\'' && strchr (tag, '-'))
  74     complain (&loc, Wyacc,
  75               _("POSIX Yacc forbids dashes in symbol names: %s"), tag);
  76
  77   res->tag = tag;
  78   res->location = loc;
  79
  80   res->type_name = NULL;
  81   {
  82     int i;
  83     for (i = 0; i < CODE_PROPS_SIZE; ++i)
  84       code_props_none_init (&res->props[i]);
  85   }
  86
  87   res->number = NUMBER_UNDEFINED;
  88   res->prec = 0;
  89   res->assoc = undef_assoc;
  90   res->user_token_number = USER_NUMBER_UNDEFINED;
  91
  92   res->alias = NULL;
  93   res->class = unknown_sym;
  94   res->status = undeclared;
  95
  96   if (nsyms == SYMBOL_NUMBER_MAXIMUM)
  97     complain (NULL, fatal, _("too many symbols in input grammar (limit is %d)"),
  98               SYMBOL_NUMBER_MAXIMUM);
  99   nsyms++;
 100   return res;
 101 }
 102
 103 char const *
 104 code_props_type_string (code_props_type kind)
 105 {
 106   switch (kind)
 107     {
 108     case destructor:
 109       return "%destructor";
 110     case printer:
 111       return "%printer";
 112     }
 113   assert (0);
 114 }
 115
 116 /*----------------------------------------.
 117 | Create a new semantic type, named TAG.  |
 118 `----------------------------------------*/
 119
 120 static semantic_type *
 121 semantic_type_new (uniqstr tag, const location *loc)
 122 {
 123   semantic_type *res = xmalloc (sizeof *res);
 124
 125   uniqstr_assert (tag);
 126   res->tag = tag;
 127   res->location = loc ? *loc : empty_location;
 128   res->status = undeclared;
 129   {
 130     int i;
 131     for (i = 0; i < CODE_PROPS_SIZE; ++i)
 132       code_props_none_init (&res->props[i]);
 133   }
 134
 135   return res;
 136 }
 137
 138
 139 /*-----------------.
 140 | Print a symbol.  |
 141 `-----------------*/
 142
 143 #define SYMBOL_ATTR_PRINT(Attr)                         \
 144   if (s->Attr)                                          \
 145     fprintf (f, " %s { %s }", #Attr, s->Attr)
 146
 147 #define SYMBOL_CODE_PRINT(Attr)                                         \
 148   if (s->props[Attr].code)                                              \
 149     fprintf (f, " %s { %s }", #Attr, s->props[Attr].code)
 150
 151 void
 152 symbol_print (symbol const *s, FILE *f)
 153 {
 154   if (s)
 155     {
 156       fputs (s->tag, f);
 157       SYMBOL_ATTR_PRINT (type_name);
 158       SYMBOL_CODE_PRINT (destructor);
 159       SYMBOL_CODE_PRINT (printer);
 160     }
 161   else
 162     fputs ("<NULL>", f);
 163 }
 164
 165 #undef SYMBOL_ATTR_PRINT
 166 #undef SYMBOL_CODE_PRINT
 167
 168
 169 /*----------------------------------.
 170 | Whether S is a valid identifier.  |
 171 `----------------------------------*/
 172
 173 static bool
 174 is_identifier (uniqstr s)
 175 {
 176   static char const alphanum[26 + 26 + 1 + 10] =
 177     "abcdefghijklmnopqrstuvwxyz"
 178     "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 179     "_"
 180     "0123456789";
 181   if (!s || ! memchr (alphanum, *s, sizeof alphanum - 10))
 182     return false;
 183   for (++s; *s; ++s)
 184     if (! memchr (alphanum, *s, sizeof alphanum))
 185       return false;
 186   return true;
 187 }
 188
 189
 190 /*-----------------------------------------------.
 191 | Get the identifier associated to this symbol.  |
 192 `-----------------------------------------------*/
 193 uniqstr
 194 symbol_id_get (symbol const *sym)
 195 {
 196   aver (sym->user_token_number != USER_NUMBER_HAS_STRING_ALIAS);
 197   if (sym->alias)
 198     sym = sym->alias;
 199   return is_identifier (sym->tag) ? sym->tag : 0;
 200 }
 201
 202
 203 /*------------------------------------------------------------------.
 204 | Complain that S's WHAT is redeclared at SECOND, and was first set |
 205 | at FIRST.                                                         |
 206 `------------------------------------------------------------------*/
 207
 208 static void
 209 symbol_redeclaration (symbol *s, const char *what, location first,
 210                       location second)
 211 {
 212   unsigned i = 0;
 213   complain_indent (&second, complaint, &i,
 214                    _("%s redeclaration for %s"), what, s->tag);
 215   i += SUB_INDENT;
 216   complain_indent (&first, complaint, &i,
 217                    _("previous declaration"));
 218 }
 219
 220 static void
 221 semantic_type_redeclaration (semantic_type *s, const char *what, location first,
 222                              location second)
 223 {
 224   unsigned i = 0;
 225   complain_indent (&second, complaint, &i,
 226                    _("%s redeclaration for <%s>"), what, s->tag);
 227   i += SUB_INDENT;
 228   complain_indent (&first, complaint, &i,
 229                    _("previous declaration"));
 230 }
 231
 232
 233
 234 /*-----------------------------------------------------------------.
 235 | Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
 236 | as TYPE_NAME.                                                    |
 237 `-----------------------------------------------------------------*/
 238
 239 void
 240 symbol_type_set (symbol *sym, uniqstr type_name, location loc)
 241 {
 242   if (type_name)
 243     {
 244       if (sym->type_name)
 245         symbol_redeclaration (sym, "%type", sym->type_location, loc);
 246       else
 247         {
 248           uniqstr_assert (type_name);
 249           sym->type_name = type_name;
 250           sym->type_location = loc;
 251         }
 252     }
 253 }
 254
 255 /*--------------------------------------------------------.
 256 | Set the DESTRUCTOR or PRINTER associated with the SYM.  |
 257 `--------------------------------------------------------*/
 258
 259 void
 260 symbol_code_props_set (symbol *sym, code_props_type kind,
 261                        code_props const *code)
 262 {
 263   if (sym->props[kind].code)
 264     symbol_redeclaration (sym, code_props_type_string (kind),
 265                           sym->props[kind].location,
 266                           code->location);
 267   else
 268     sym->props[kind] = *code;
 269 }
 270
 271 /*-----------------------------------------------------.
 272 | Set the DESTRUCTOR or PRINTER associated with TYPE.  |
 273 `-----------------------------------------------------*/
 274
 275 void
 276 semantic_type_code_props_set (semantic_type *type,
 277                               code_props_type kind,
 278                               code_props const *code)
 279 {
 280   if (type->props[kind].code)
 281     semantic_type_redeclaration (type, code_props_type_string (kind),
 282                                  type->props[kind].location,
 283                                  code->location);
 284   else
 285     type->props[kind] = *code;
 286 }
 287
 288 /*---------------------------------------------------.
 289 | Get the computed %destructor or %printer for SYM.  |
 290 `---------------------------------------------------*/
 291
 292 code_props *
 293 symbol_code_props_get (symbol *sym, code_props_type kind)
 294 {
 295   /* Per-symbol code props.  */
 296   if (sym->props[kind].code)
 297     return &sym->props[kind];
 298
 299   /* Per-type code props.  */
 300   if (sym->type_name)
 301     {
 302       code_props *code =
 303         &semantic_type_get (sym->type_name, NULL)->props[kind];
 304       if (code->code)
 305         return code;
 306     }
 307
 308   /* Apply default code props's only to user-defined symbols.  */
 309   if (sym->tag[0] != '$' && sym != errtoken)
 310     {
 311       code_props *code =
 312         &semantic_type_get (sym->type_name ? "*" : "", NULL)->props[kind];
 313       if (code->code)
 314         return code;
 315     }
 316   return &code_props_none;
 317 }
 318
 319 /*-----------------------------------------------------------------.
 320 | Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
 321 | with UNDEF_ASSOC as ASSOC.                                       |
 322 `-----------------------------------------------------------------*/
 323
 324 void
 325 symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
 326 {
 327   if (a != undef_assoc)
 328     {
 329       if (sym->prec)
 330         symbol_redeclaration (sym, assoc_to_string (a), sym->prec_location,
 331                               loc);
 332       else
 333         {
 334           sym->prec = prec;
 335           sym->assoc = a;
 336           sym->prec_location = loc;
 337         }
 338     }
 339
 340   /* Only terminals have a precedence. */
 341   symbol_class_set (sym, token_sym, loc, false);
 342 }
 343
 344
 345 /*------------------------------------.
 346 | Set the CLASS associated with SYM.  |
 347 `------------------------------------*/
 348
 349 void
 350 symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
 351 {
 352   bool warned = false;
 353   if (sym->class != unknown_sym && sym->class != class)
 354     {
 355       complain (&loc, complaint, _("symbol %s redefined"), sym->tag);
 356       /* Don't report both "redefined" and "redeclared".  */
 357       warned = true;
 358     }
 359
 360   if (class == nterm_sym && sym->class != nterm_sym)
 361     sym->number = nvars++;
 362   else if (class == token_sym && sym->number == NUMBER_UNDEFINED)
 363     sym->number = ntokens++;
 364
 365   sym->class = class;
 366
 367   if (declaring)
 368     {
 369       if (sym->status == declared && !warned)
 370         complain (&loc, Wother, _("symbol %s redeclared"), sym->tag);
 371       else
 372         sym->status = declared;
 373     }
 374 }
 375
 376
 377 /*------------------------------------------------.
 378 | Set the USER_TOKEN_NUMBER associated with SYM.  |
 379 `------------------------------------------------*/
 380
 381 void
 382 symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 383 {
 384   int *user_token_numberp;
 385
 386   if (sym->user_token_number != USER_NUMBER_HAS_STRING_ALIAS)
 387     user_token_numberp = &sym->user_token_number;
 388   else
 389     user_token_numberp = &sym->alias->user_token_number;
 390   if (*user_token_numberp != USER_NUMBER_UNDEFINED
 391       && *user_token_numberp != user_token_number)
 392     complain (&loc, complaint, _("redefining user token number of %s"),
 393               sym->tag);
 394
 395   *user_token_numberp = user_token_number;
 396   /* User defined $end token? */
 397   if (user_token_number == 0)
 398     {
 399       endtoken = sym;
 400       /* It is always mapped to 0, so it was already counted in
 401          NTOKENS.  */
 402       if (endtoken->number != NUMBER_UNDEFINED)
 403         --ntokens;
 404       endtoken->number = 0;
 405     }
 406 }
 407
 408
 409 /*----------------------------------------------------------.
 410 | If SYM is not defined, report an error, and consider it a |
 411 | nonterminal.                                              |
 412 `----------------------------------------------------------*/
 413
 414 static inline bool
 415 symbol_check_defined (symbol *sym)
 416 {
 417   if (sym->class == unknown_sym)
 418     {
 419       assert (sym->status != declared);
 420       complain (&sym->location,
 421                 sym->status == needed ? complaint : Wother,
 422                 _("symbol %s is used, but is not defined as a token"
 423                   " and has no rules"),
 424                   sym->tag);
 425       sym->class = nterm_sym;
 426       sym->number = nvars++;
 427     }
 428
 429   {
 430     int i;
 431     for (i = 0; i < 2; ++i)
 432       symbol_code_props_get (sym, i)->is_used = true;
 433   }
 434
 435   /* Set the semantic type status associated to the current symbol to
 436      'declared' so that we could check semantic types unnecessary uses. */
 437   if (sym->type_name)
 438     {
 439       semantic_type *sem_type = semantic_type_get (sym->type_name, NULL);
 440       if (sem_type)
 441         sem_type->status = declared;
 442     }
 443
 444   return true;
 445 }
 446
 447 static inline bool
 448 semantic_type_check_defined (semantic_type *sem_type)
 449 {
 450   /* <*> and <> do not have to be "declared".  */
 451   if (sem_type->status == declared
 452       || !*sem_type->tag
 453       || STREQ (sem_type->tag, "*"))
 454     {
 455       int i;
 456       for (i = 0; i < 2; ++i)
 457         if (sem_type->props[i].kind != CODE_PROPS_NONE
 458             && ! sem_type->props[i].is_used)
 459           complain (&sem_type->location, Wother,
 460                     _("useless %s for type <%s>"),
 461                     code_props_type_string (i), sem_type->tag);
 462     }
 463   else
 464     complain (&sem_type->location, Wother,
 465               _("type <%s> is used, but is not associated to any symbol"),
 466               sem_type->tag);
 467
 468   return true;
 469 }
 470
 471 static bool
 472 symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
 473 {
 474   return symbol_check_defined (sym);
 475 }
 476
 477 static bool
 478 semantic_type_check_defined_processor (void *sem_type,
 479                                        void *null ATTRIBUTE_UNUSED)
 480 {
 481   return semantic_type_check_defined (sem_type);
 482 }
 483
 484
 485 void
 486 symbol_make_alias (symbol *sym, symbol *str, location loc)
 487 {
 488   if (str->alias)
 489     complain (&loc, Wother,
 490               _("symbol %s used more than once as a literal string"), str->tag);
 491   else if (sym->alias)
 492     complain (&loc, Wother,
 493               _("symbol %s given more than one literal string"), sym->tag);
 494   else
 495     {
 496       str->class = token_sym;
 497       str->user_token_number = sym->user_token_number;
 498       sym->user_token_number = USER_NUMBER_HAS_STRING_ALIAS;
 499       str->alias = sym;
 500       sym->alias = str;
 501       str->number = sym->number;
 502       symbol_type_set (str, sym->type_name, loc);
 503     }
 504 }
 505
 506
 507 /*---------------------------------------------------------.
 508 | Check that THIS, and its alias, have same precedence and |
 509 | associativity.                                           |
 510 `---------------------------------------------------------*/
 511
 512 static inline void
 513 symbol_check_alias_consistency (symbol *this)
 514 {
 515   symbol *sym = this;
 516   symbol *str = this->alias;
 517
 518   /* Check only the symbol in the symbol-string pair.  */
 519   if (!(this->alias
 520         && this->user_token_number == USER_NUMBER_HAS_STRING_ALIAS))
 521     return;
 522
 523   if (str->type_name != sym->type_name)
 524     {
 525       if (str->type_name)
 526         symbol_type_set (sym, str->type_name, str->type_location);
 527       else
 528         symbol_type_set (str, sym->type_name, sym->type_location);
 529     }
 530
 531
 532   {
 533     int i;
 534     for (i = 0; i < CODE_PROPS_SIZE; ++i)
 535       if (str->props[i].code)
 536         symbol_code_props_set (sym, i, &str->props[i]);
 537       else if (sym->props[i].code)
 538         symbol_code_props_set (str, i, &sym->props[i]);
 539   }
 540
 541   if (sym->prec || str->prec)
 542     {
 543       if (str->prec)
 544         symbol_precedence_set (sym, str->prec, str->assoc,
 545                                str->prec_location);
 546       else
 547         symbol_precedence_set (str, sym->prec, sym->assoc,
 548                                sym->prec_location);
 549     }
 550 }
 551
 552 static bool
 553 symbol_check_alias_consistency_processor (void *this,
 554                                           void *null ATTRIBUTE_UNUSED)
 555 {
 556   symbol_check_alias_consistency (this);
 557   return true;
 558 }
 559
 560
 561 /*-------------------------------------------------------------------.
 562 | Assign a symbol number, and write the definition of the token name |
 563 | into FDEFINES.  Put in SYMBOLS.                                    |
 564 `-------------------------------------------------------------------*/
 565
 566 static inline bool
 567 symbol_pack (symbol *this)
 568 {
 569   aver (this->number != NUMBER_UNDEFINED);
 570   if (this->class == nterm_sym)
 571     this->number += ntokens;
 572   else if (this->user_token_number == USER_NUMBER_HAS_STRING_ALIAS)
 573     return true;
 574
 575   symbols[this->number] = this;
 576   return true;
 577 }
 578
 579 static bool
 580 symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
 581 {
 582   return symbol_pack (this);
 583 }
 584
 585
 586 static void
 587 user_token_number_redeclaration (int num, symbol *first, symbol *second)
 588 {
 589   unsigned i = 0;
 590   /* User token numbers are not assigned during the parsing, but in a
 591      second step, via a traversal of the symbol table sorted on tag.
 592
 593      However, error messages make more sense if we keep the first
 594      declaration first.  */
 595   if (location_cmp (first->location, second->location) > 0)
 596     {
 597       symbol* tmp = first;
 598       first = second;
 599       second = tmp;
 600     }
 601   complain_indent (&second->location, complaint, &i,
 602                    _("user token number %d redeclaration for %s"),
 603                    num, second->tag);
 604   i += SUB_INDENT;
 605   complain_indent (&first->location, complaint, &i,
 606                    _("previous declaration for %s"),
 607                    first->tag);
 608 }
 609
 610 /*--------------------------------------------------.
 611 | Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
 612 `--------------------------------------------------*/
 613
 614 static inline bool
 615 symbol_translation (symbol *this)
 616 {
 617   /* Non-terminal? */
 618   if (this->class == token_sym
 619       && this->user_token_number != USER_NUMBER_HAS_STRING_ALIAS)
 620     {
 621       /* A token which translation has already been set? */
 622       if (token_translations[this->user_token_number] != undeftoken->number)
 623         user_token_number_redeclaration
 624           (this->user_token_number,
 625            symbols[token_translations[this->user_token_number]],
 626            this);
 627       else
 628         token_translations[this->user_token_number] = this->number;
 629     }
 630
 631   return true;
 632 }
 633
 634 static bool
 635 symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
 636 {
 637   return symbol_translation (this);
 638 }
 639
 640
 641 /*---------------------------------------.
 642 | Symbol and semantic type hash tables.  |
 643 `---------------------------------------*/
 644
 645 /* Initial capacity of symbol and semantic type hash table.  */
 646 #define HT_INITIAL_CAPACITY 257
 647
 648 static struct hash_table *symbol_table = NULL;
 649 static struct hash_table *semantic_type_table = NULL;
 650
 651 static inline bool
 652 hash_compare_symbol (const symbol *m1, const symbol *m2)
 653 {
 654   /* Since tags are unique, we can compare the pointers themselves.  */
 655   return UNIQSTR_EQ (m1->tag, m2->tag);
 656 }
 657
 658 static inline bool
 659 hash_compare_semantic_type (const semantic_type *m1, const semantic_type *m2)
 660 {
 661   /* Since names are unique, we can compare the pointers themselves.  */
 662   return UNIQSTR_EQ (m1->tag, m2->tag);
 663 }
 664
 665 static bool
 666 hash_symbol_comparator (void const *m1, void const *m2)
 667 {
 668   return hash_compare_symbol (m1, m2);
 669 }
 670
 671 static bool
 672 hash_semantic_type_comparator (void const *m1, void const *m2)
 673 {
 674   return hash_compare_semantic_type (m1, m2);
 675 }
 676
 677 static inline size_t
 678 hash_symbol (const symbol *m, size_t tablesize)
 679 {
 680   /* Since tags are unique, we can hash the pointer itself.  */
 681   return ((uintptr_t) m->tag) % tablesize;
 682 }
 683
 684 static inline size_t
 685 hash_semantic_type (const semantic_type *m, size_t tablesize)
 686 {
 687   /* Since names are unique, we can hash the pointer itself.  */
 688   return ((uintptr_t) m->tag) % tablesize;
 689 }
 690
 691 static size_t
 692 hash_symbol_hasher (void const *m, size_t tablesize)
 693 {
 694   return hash_symbol (m, tablesize);
 695 }
 696
 697 static size_t
 698 hash_semantic_type_hasher (void const *m, size_t tablesize)
 699 {
 700   return hash_semantic_type (m, tablesize);
 701 }
 702
 703 /*-------------------------------.
 704 | Create the symbol hash table.  |
 705 `-------------------------------*/
 706
 707 void
 708 symbols_new (void)
 709 {
 710   symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
 711                                   NULL,
 712                                   hash_symbol_hasher,
 713                                   hash_symbol_comparator,
 714                                   free);
 715   semantic_type_table = hash_initialize (HT_INITIAL_CAPACITY,
 716                                          NULL,
 717                                          hash_semantic_type_hasher,
 718                                          hash_semantic_type_comparator,
 719                                          free);
 720 }
 721
 722
 723 /*----------------------------------------------------------------.
 724 | Find the symbol named KEY, and return it.  If it does not exist |
 725 | yet, create it.                                                 |
 726 `----------------------------------------------------------------*/
 727
 728 symbol *
 729 symbol_from_uniqstr (const uniqstr key, location loc)
 730 {
 731   symbol probe;
 732   symbol *entry;
 733
 734   probe.tag = key;
 735   entry = hash_lookup (symbol_table, &probe);
 736
 737   if (!entry)
 738     {
 739       /* First insertion in the hash. */
 740       aver (!symbols_sorted);
 741       entry = symbol_new (key, loc);
 742       if (!hash_insert (symbol_table, entry))
 743         xalloc_die ();
 744     }
 745   return entry;
 746 }
 747
 748
 749 /*-----------------------------------------------------------------------.
 750 | Find the semantic type named KEY, and return it.  If it does not exist |
 751 | yet, create it.                                                        |
 752 `-----------------------------------------------------------------------*/
 753
 754 semantic_type *
 755 semantic_type_from_uniqstr (const uniqstr key, const location *loc)
 756 {
 757   semantic_type probe;
 758   semantic_type *entry;
 759
 760   probe.tag = key;
 761   entry = hash_lookup (semantic_type_table, &probe);
 762
 763   if (!entry)
 764     {
 765       /* First insertion in the hash. */
 766       entry = semantic_type_new (key, loc);
 767       if (!hash_insert (semantic_type_table, entry))
 768         xalloc_die ();
 769     }
 770   return entry;
 771 }
 772
 773
 774 /*----------------------------------------------------------------.
 775 | Find the symbol named KEY, and return it.  If it does not exist |
 776 | yet, create it.                                                 |
 777 `----------------------------------------------------------------*/
 778
 779 symbol *
 780 symbol_get (const char *key, location loc)
 781 {
 782   return symbol_from_uniqstr (uniqstr_new (key), loc);
 783 }
 784
 785
 786 /*-----------------------------------------------------------------------.
 787 | Find the semantic type named KEY, and return it.  If it does not exist |
 788 | yet, create it.                                                        |
 789 `-----------------------------------------------------------------------*/
 790
 791 semantic_type *
 792 semantic_type_get (const char *key, const location *loc)
 793 {
 794   return semantic_type_from_uniqstr (uniqstr_new (key), loc);
 795 }
 796
 797
 798 /*------------------------------------------------------------------.
 799 | Generate a dummy nonterminal, whose name cannot conflict with the |
 800 | user's names.                                                     |
 801 `------------------------------------------------------------------*/
 802
 803 symbol *
 804 dummy_symbol_get (location loc)
 805 {
 806   /* Incremented for each generated symbol.  */
 807   static int dummy_count = 0;
 808   static char buf[256];
 809
 810   symbol *sym;
 811
 812   sprintf (buf, "$@%d", ++dummy_count);
 813   sym = symbol_get (buf, loc);
 814   sym->class = nterm_sym;
 815   sym->number = nvars++;
 816   return sym;
 817 }
 818
 819 bool
 820 symbol_is_dummy (const symbol *sym)
 821 {
 822   return sym->tag[0] == '@' || (sym->tag[0] == '$' && sym->tag[1] == '@');
 823 }
 824
 825 /*-------------------.
 826 | Free the symbols.  |
 827 `-------------------*/
 828
 829 void
 830 symbols_free (void)
 831 {
 832   hash_free (symbol_table);
 833   hash_free (semantic_type_table);
 834   free (symbols);
 835   free (symbols_sorted);
 836   free (semantic_types_sorted);
 837 }
 838
 839
 840 /*---------------------------------------------------------------.
 841 | Look for undefined symbols, report an error, and consider them |
 842 | terminals.                                                     |
 843 `---------------------------------------------------------------*/
 844
 845 static int
 846 symbols_cmp (symbol const *a, symbol const *b)
 847 {
 848   return strcmp (a->tag, b->tag);
 849 }
 850
 851 static int
 852 symbols_cmp_qsort (void const *a, void const *b)
 853 {
 854   return symbols_cmp (*(symbol * const *)a, *(symbol * const *)b);
 855 }
 856
 857 static void
 858 symbols_do (Hash_processor processor, void *processor_data,
 859             struct hash_table *table, symbol ***sorted)
 860 {
 861   size_t count = hash_get_n_entries (table);
 862   if (!*sorted)
 863     {
 864       *sorted = xnmalloc (count, sizeof **sorted);
 865       hash_get_entries (table, (void**)*sorted, count);
 866       qsort (*sorted, count, sizeof **sorted, symbols_cmp_qsort);
 867     }
 868   {
 869     size_t i;
 870     for (i = 0; i < count; ++i)
 871       processor ((*sorted)[i], processor_data);
 872   }
 873 }
 874
 875 /*--------------------------------------------------------------.
 876 | Check that all the symbols are defined.  Report any undefined |
 877 | symbols and consider them nonterminals.                       |
 878 `--------------------------------------------------------------*/
 879
 880 void
 881 symbols_check_defined (void)
 882 {
 883   symbols_do (symbol_check_defined_processor, NULL,
 884               symbol_table, &symbols_sorted);
 885   symbols_do (semantic_type_check_defined_processor, NULL,
 886               semantic_type_table, &semantic_types_sorted);
 887 }
 888
 889 /*------------------------------------------------------------------.
 890 | Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
 891 | number.                                                           |
 892 `------------------------------------------------------------------*/
 893
 894 static void
 895 symbols_token_translations_init (void)
 896 {
 897   bool num_256_available_p = true;
 898   int i;
 899
 900   /* Find the highest user token number, and whether 256, the POSIX
 901      preferred user token number for the error token, is used.  */
 902   max_user_token_number = 0;
 903   for (i = 0; i < ntokens; ++i)
 904     {
 905       symbol *this = symbols[i];
 906       if (this->user_token_number != USER_NUMBER_UNDEFINED)
 907         {
 908           if (this->user_token_number > max_user_token_number)
 909             max_user_token_number = this->user_token_number;
 910           if (this->user_token_number == 256)
 911             num_256_available_p = false;
 912         }
 913     }
 914
 915   /* If 256 is not used, assign it to error, to follow POSIX.  */
 916   if (num_256_available_p
 917       && errtoken->user_token_number == USER_NUMBER_UNDEFINED)
 918     errtoken->user_token_number = 256;
 919
 920   /* Set the missing user numbers. */
 921   if (max_user_token_number < 256)
 922     max_user_token_number = 256;
 923
 924   for (i = 0; i < ntokens; ++i)
 925     {
 926       symbol *this = symbols[i];
 927       if (this->user_token_number == USER_NUMBER_UNDEFINED)
 928         this->user_token_number = ++max_user_token_number;
 929       if (this->user_token_number > max_user_token_number)
 930         max_user_token_number = this->user_token_number;
 931     }
 932
 933   token_translations = xnmalloc (max_user_token_number + 1,
 934                                  sizeof *token_translations);
 935
 936   /* Initialize all entries for literal tokens to the internal token
 937      number for $undefined, which represents all invalid inputs.  */
 938   for (i = 0; i < max_user_token_number + 1; i++)
 939     token_translations[i] = undeftoken->number;
 940   symbols_do (symbol_translation_processor, NULL,
 941               symbol_table, &symbols_sorted);
 942 }
 943
 944
 945 /*----------------------------------------------------------------.
 946 | Assign symbol numbers, and write definition of token names into |
 947 | FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
 948 `----------------------------------------------------------------*/
 949
 950 void
 951 symbols_pack (void)
 952 {
 953   symbols_do (symbol_check_alias_consistency_processor, NULL,
 954               symbol_table, &symbols_sorted);
 955
 956   symbols = xcalloc (nsyms, sizeof *symbols);
 957   symbols_do (symbol_pack_processor, NULL, symbol_table, &symbols_sorted);
 958
 959   /* Aliases leave empty slots in symbols, so remove them.  */
 960   {
 961     int writei;
 962     int readi;
 963     int nsyms_old = nsyms;
 964     for (writei = 0, readi = 0; readi < nsyms_old; readi += 1)
 965       {
 966         if (symbols[readi] == NULL)
 967           {
 968             nsyms -= 1;
 969             ntokens -= 1;
 970           }
 971         else
 972           {
 973             symbols[writei] = symbols[readi];
 974             symbols[writei]->number = writei;
 975             if (symbols[writei]->alias)
 976               symbols[writei]->alias->number = writei;
 977             writei += 1;
 978           }
 979       }
 980   }
 981   symbols = xnrealloc (symbols, nsyms, sizeof *symbols);
 982
 983   symbols_token_translations_init ();
 984
 985   if (startsymbol->class == unknown_sym)
 986     complain (&startsymbol_location, fatal,
 987               _("the start symbol %s is undefined"),
 988               startsymbol->tag);
 989   else if (startsymbol->class == token_sym)
 990     complain (&startsymbol_location, fatal,
 991               _("the start symbol %s is a token"),
 992               startsymbol->tag);
 993 }
 994
 995 /*---------------------------------.
 996 | Initialize relation graph nodes. |
 997 `---------------------------------*/
 998
 999 static void
1000 init_prec_nodes (void)
1001 {
1002   int i;
1003   prec_nodes = xcalloc (nsyms, sizeof *prec_nodes);
1004   for (i = 0; i < nsyms; ++i)
1005     {
1006       prec_nodes[i] = xmalloc (sizeof *prec_nodes[i]);
1007       symgraph *s = prec_nodes[i];
1008       s->id = i;
1009       s->succ = 0;
1010       s->pred = 0;
1011     }
1012 }
1013
1014 /*----------------.
1015 | Create a link.  |
1016 `----------------*/
1017
1018 static symgraphlink *
1019 symgraphlink_new (graphid id, symgraphlink *next)
1020 {
1021   symgraphlink *l = xmalloc (sizeof *l);
1022   l->id = id;
1023   l->next = next;
1024   return l;
1025 }
1026
1027
1028 /*------------------------------------------------------------------.
1029 | Register the second symbol of the precedence relation, and return |
1030 | whether this relation is new.  Use only in register_precedence.   |
1031 `------------------------------------------------------------------*/
1032
1033 static bool
1034 register_precedence_second_symbol (symgraphlink **first, graphid sym)
1035 {
1036   if (!*first || sym < (*first)->id)
1037     *first = symgraphlink_new (sym, *first);
1038   else
1039     {
1040       symgraphlink *slist = *first;
1041
1042       while (slist->next && slist->next->id <= sym)
1043         slist = slist->next;
1044
1045       if (slist->id == sym)
1046         /* Relation already present. */
1047         return false;
1048
1049       slist->next = symgraphlink_new (sym, slist->next);
1050     }
1051   return true;
1052 }
1053
1054 /*------------------------------------------------------------------.
1055 | Register a new relation between symbols as used. The first symbol |
1056 | has a greater precedence than the second one.                     |
1057 `------------------------------------------------------------------*/
1058
1059 void
1060 register_precedence (graphid first, graphid snd)
1061 {
1062   if (!prec_nodes)
1063     init_prec_nodes ();
1064   register_precedence_second_symbol (&(prec_nodes[first]->succ), snd);
1065   register_precedence_second_symbol (&(prec_nodes[snd]->pred), first);
1066 }
1067
1068
1069 /*---------------------------------------.
1070 | Deep clear a linked / adjacency list). |
1071 `---------------------------------------*/
1072
1073 static void
1074 linkedlist_free (symgraphlink *node)
1075 {
1076   if (node)
1077     {
1078       while (node->next)
1079         {
1080           symgraphlink *tmp = node->next;
1081           free (node);
1082           node = tmp;
1083         }
1084       free (node);
1085     }
1086 }
1087
1088 /*----------------------------------------------.
1089 | Clear and destroy association tracking table. |
1090 `----------------------------------------------*/
1091
1092 static void
1093 assoc_free (void)
1094 {
1095   int i;
1096   for (i = 0; i < nsyms; ++i)
1097     {
1098       linkedlist_free (prec_nodes[i]->pred);
1099       linkedlist_free (prec_nodes[i]->succ);
1100       free (prec_nodes[i]);
1101     }
1102   free (prec_nodes);
1103 }
1104
1105 /*---------------------------------------.
1106 | Initialize association tracking table. |
1107 `---------------------------------------*/
1108
1109 static void
1110 init_assoc (void)
1111 {
1112   graphid i;
1113   used_assoc = xcalloc (nsyms, sizeof *used_assoc);
1114   for (i = 0; i < nsyms; ++i)
1115     used_assoc[i] = false;
1116 }
1117
1118 /*------------------------------------------------------------------.
1119 | Test if the associativity for the symbols is defined and useless. |
1120 `------------------------------------------------------------------*/
1121
1122 static inline bool
1123 is_assoc_useless (symbol *s)
1124 {
1125   return s
1126       && s->assoc != undef_assoc
1127       && s->assoc != precedence_assoc
1128       && !used_assoc[s->number];
1129 }
1130
1131 /*-------------------------------.
1132 | Register a used associativity. |
1133 `-------------------------------*/
1134
1135 void
1136 register_assoc (graphid i, graphid j)
1137 {
1138   if (!used_assoc)
1139     init_assoc ();
1140   used_assoc[i] = true;
1141   used_assoc[j] = true;
1142 }
1143
1144 /*--------------------------------------------------.
1145 | Print a warning for unused precedence relations.  |
1146 `--------------------------------------------------*/
1147
1148 void
1149 print_precedence_warnings (void)
1150 {
1151   int i;
1152   if (!prec_nodes)
1153     init_prec_nodes ();
1154   if (!used_assoc)
1155     init_assoc ();
1156   for (i = 0; i < nsyms; ++i)
1157     {
1158       symbol *s = symbols[i];
1159       if (s
1160           && s->prec != 0
1161           && !prec_nodes[i]->pred
1162           && !prec_nodes[i]->succ)
1163         {
1164           if (is_assoc_useless (s))
1165             complain (&s->prec_location, Wprecedence,
1166                       _("useless precedence and associativity for %s"), s->tag);
1167           else if (s->assoc == precedence_assoc)
1168             complain (&s->prec_location, Wprecedence,
1169                       _("useless precedence for %s"), s->tag);
1170         }
1171       else if (is_assoc_useless (s))
1172         complain (&s->prec_location, Wprecedence,
1173                   _("useless associativity for %s, use %%precedence"), s->tag);
1174     }
1175   free (used_assoc);
1176   assoc_free ();
1177 }