symtab.c

GNU的词法/语法分析器bison源码

  if (orig->printer || alias->printer)
    {
      if (orig->printer)
	symbol_printer_set (alias, orig->printer, orig->printer_location);
      else
	symbol_printer_set (orig, alias->printer, alias->printer_location);
    }

  if (alias->prec || orig->prec)
    {
      if (orig->prec)
	symbol_precedence_set (alias, orig->prec, orig->assoc,
			       orig->prec_location);
      else
	symbol_precedence_set (orig, alias->prec, alias->assoc,
			       alias->prec_location);
    }
}

static bool
symbol_check_alias_consistency_processor (void *this,
					  void *null ATTRIBUTE_UNUSED)
{
  symbol_check_alias_consistency (this);
  return true;
}


/*-------------------------------------------------------------------.
| Assign a symbol number, and write the definition of the token name |
| into FDEFINES.  Put in SYMBOLS.                                    |
`-------------------------------------------------------------------*/

static inline bool
symbol_pack (symbol *this)
{
  if (this->class == nterm_sym)
    {
      this->number += ntokens;
    }
  else if (this->alias)
    {
      /* This symbol and its alias are a single token defn.
	 Allocate a tokno, and assign to both check agreement of
	 prec and assoc fields and make both the same */
      if (this->number == NUMBER_UNDEFINED)
	{
	  if (this == endtoken || this->alias == endtoken)
	    this->number = this->alias->number = 0;
	  else
	    {
	      if (this->alias->number == NUMBER_UNDEFINED)
		abort ();
	      this->number = this->alias->number;
	    }
	}
      /* Do not do processing below for USER_NUMBER_ALIASes.  */
      if (this->user_token_number == USER_NUMBER_ALIAS)
	return true;
    }
  else /* this->class == token_sym */
    {
      if (this->number == NUMBER_UNDEFINED)
	abort ();
    }

  symbols[this->number] = this;
  return true;
}

static bool
symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
{
  return symbol_pack (this);
}




/*--------------------------------------------------.
| Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
`--------------------------------------------------*/

static inline bool
symbol_translation (symbol *this)
{
  /* Non-terminal? */
  if (this->class == token_sym
      && this->user_token_number != USER_NUMBER_ALIAS)
    {
      /* A token which translation has already been set? */
      if (token_translations[this->user_token_number] != undeftoken->number)
	complain_at (this->location,
		     _("tokens %s and %s both assigned number %d"),
		     symbols[token_translations[this->user_token_number]]->tag,
		     this->tag, this->user_token_number);

      token_translations[this->user_token_number] = this->number;
    }

  return true;
}

static bool
symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
{
  return symbol_translation (this);
}


/*----------------------.
| A symbol hash table.  |
`----------------------*/

/* Initial capacity of symbols hash table.  */
#define HT_INITIAL_CAPACITY 257

static struct hash_table *symbol_table = NULL;

static inline bool
hash_compare_symbol (const symbol *m1, const symbol *m2)
{
  /* Since tags are unique, we can compare the pointers themselves.  */
  return UNIQSTR_EQ (m1->tag, m2->tag);
}

static bool
hash_symbol_comparator (void const *m1, void const *m2)
{
  return hash_compare_symbol (m1, m2);
}

static inline size_t
hash_symbol (const symbol *m, size_t tablesize)
{
  /* Since tags are unique, we can hash the pointer itself.  */
  return ((uintptr_t) m->tag) % tablesize;
}

static size_t
hash_symbol_hasher (void const *m, size_t tablesize)
{
  return hash_symbol (m, tablesize);
}


/*-------------------------------.
| Create the symbol hash table.  |
`-------------------------------*/

void
symbols_new (void)
{
  symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
				  NULL,
				  hash_symbol_hasher,
				  hash_symbol_comparator,
				  free);
}


/*----------------------------------------------------------------.
| Find the symbol named KEY, and return it.  If it does not exist |
| yet, create it.                                                 |
`----------------------------------------------------------------*/

symbol *
symbol_get (const char *key, location loc)
{
  symbol probe;
  symbol *entry;

  key = uniqstr_new (key);
  probe.tag = key;
  entry = hash_lookup (symbol_table, &probe);

  if (!entry)
    {
      /* First insertion in the hash. */
      entry = symbol_new (key, loc);
      hash_insert (symbol_table, entry);
    }
  return entry;
}


/*------------------------------------------------------------------.
| Generate a dummy nonterminal, whose name cannot conflict with the |
| user's names.                                                     |
`------------------------------------------------------------------*/

symbol *
dummy_symbol_get (location loc)
{
  /* Incremented for each generated symbol.  */
  static int dummy_count = 0;
  static char buf[256];

  symbol *sym;

  sprintf (buf, "@%d", ++dummy_count);
  sym = symbol_get (buf, loc);
  sym->class = nterm_sym;
  sym->number = nvars++;
  return sym;
}


/*-------------------.
| Free the symbols.  |
`-------------------*/

void
symbols_free (void)
{
  hash_free (symbol_table);
  free (symbols);
}


/*---------------------------------------------------------------.
| Look for undefined symbols, report an error, and consider them |
| terminals.                                                     |
`---------------------------------------------------------------*/

static void
symbols_do (Hash_processor processor, void *processor_data)
{
  hash_do_for_each (symbol_table, processor, processor_data);
}


/*--------------------------------------------------------------.
| Check that all the symbols are defined.  Report any undefined |
| symbols and consider them nonterminals.                       |
`--------------------------------------------------------------*/

void
symbols_check_defined (void)
{
  symbols_do (symbol_check_defined_processor, NULL);
}

/*------------------------------------------------------------------.
| Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
| number.                                                           |
`------------------------------------------------------------------*/

static void
symbols_token_translations_init (void)
{
  bool num_256_available_p = true;
  int i;

  /* Find the highest user token number, and whether 256, the POSIX
     preferred user token number for the error token, is used.  */
  max_user_token_number = 0;
  for (i = 0; i < ntokens; ++i)
    {
      symbol *this = symbols[i];
      if (this->user_token_number != USER_NUMBER_UNDEFINED)
	{
	  if (this->user_token_number > max_user_token_number)
	    max_user_token_number = this->user_token_number;
	  if (this->user_token_number == 256)
	    num_256_available_p = false;
	}
    }

  /* If 256 is not used, assign it to error, to follow POSIX.  */
  if (num_256_available_p
      && errtoken->user_token_number == USER_NUMBER_UNDEFINED)
    errtoken->user_token_number = 256;

  /* Set the missing user numbers. */
  if (max_user_token_number < 256)
    max_user_token_number = 256;

  for (i = 0; i < ntokens; ++i)
    {
      symbol *this = symbols[i];
      if (this->user_token_number == USER_NUMBER_UNDEFINED)
	this->user_token_number = ++max_user_token_number;
      if (this->user_token_number > max_user_token_number)
	max_user_token_number = this->user_token_number;
    }

  token_translations = xnmalloc (max_user_token_number + 1,
				 sizeof *token_translations);

  /* Initialize all entries for literal tokens to 2, the internal
     token number for $undefined, which represents all invalid inputs.
     */
  for (i = 0; i < max_user_token_number + 1; i++)
    token_translations[i] = undeftoken->number;
  symbols_do (symbol_translation_processor, NULL);
}


/*----------------------------------------------------------------.
| Assign symbol numbers, and write definition of token names into |
| FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
`----------------------------------------------------------------*/

void
symbols_pack (void)
{
  symbols = xcalloc (nsyms, sizeof *symbols);

  symbols_do (symbol_check_alias_consistency_processor, NULL);
  symbols_do (symbol_pack_processor, NULL);

  symbols_token_translations_init ();

  if (startsymbol->class == unknown_sym)
    fatal_at (startsymbol_location,
	      _("the start symbol %s is undefined"),
	      startsymbol->tag);
  else if (startsymbol->class == token_sym)
    fatal_at (startsymbol_location,
	      _("the start symbol %s is a token"),
	      startsymbol->tag);
}