* src/scan-gram.l (code_start): Always initialize it when entering

[bison.git] / src / symtab.c

/* Symbol table manager for Bison.

   Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.

   This file is part of Bison, the GNU Compiler Compiler.

   Bison is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   Bison is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with Bison; see the file COPYING.  If not, write to
   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */


#include "system.h"

#include <hash.h>
#include <quotearg.h>

#include "complain.h"
#include "gram.h"
#include "symtab.h"

/*------------------------.
| Distinguished symbols.  |
`------------------------*/

symbol *errtoken = NULL;
symbol *undeftoken = NULL;
symbol *endtoken = NULL;
symbol *accept = NULL;
symbol *startsymbol = NULL;
location startsymbol_location;

/*---------------------------------.
| Create a new symbol, named TAG.  |
`---------------------------------*/

static symbol *
symbol_new (uniqstr tag, location loc)
{
  symbol *res = MALLOC (res, 1);

  uniqstr_assert (tag);
  res->tag = tag;
  res->location = loc;

  res->type_name = NULL;
  res->destructor = NULL;
  res->printer = NULL;

  res->number = NUMBER_UNDEFINED;
  res->prec = 0;
  res->assoc = undef_assoc;
  res->user_token_number = USER_NUMBER_UNDEFINED;

  res->alias = NULL;
  res->class = unknown_sym;

  nsyms++;
  return res;
}


/*-----------------------------------------------------------------.
| Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
| as TYPE_NAME.                                                    |
`-----------------------------------------------------------------*/

void
symbol_type_set (symbol *sym, uniqstr type_name, location loc)
{
  if (type_name)
    {
      if (sym->type_name)
	complain_at (loc, _("type redeclaration for %s"), sym->tag);
      uniqstr_assert (type_name);
      sym->type_name = type_name;
    }
}


/*------------------------------------------------------------------.
| Set the DESTRUCTOR associated with SYM.  Do nothing if passed 0.  |
`------------------------------------------------------------------*/

void
symbol_destructor_set (symbol *sym, char *destructor, location loc)
{
  if (destructor)
    {
      if (sym->destructor)
	complain_at (loc, _("%s redeclaration for %s"),
		     "%destructor", sym->tag);
      sym->destructor = destructor;
      sym->destructor_location = loc;
    }
}


/*---------------------------------------------------------------.
| Set the PRINTER associated with SYM.  Do nothing if passed 0.  |
`---------------------------------------------------------------*/

void
symbol_printer_set (symbol *sym, char *printer, location loc)
{
  if (printer)
    {
      if (sym->printer)
	complain_at (loc, _("%s redeclaration for %s"),
		     "%printer", sym->tag);
      sym->printer = printer;
      sym->printer_location = loc;
    }
}


/*-----------------------------------------------------------------.
| Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
| with UNDEF_ASSOC as ASSOC.                                       |
`-----------------------------------------------------------------*/

void
symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
{
  if (a != undef_assoc)
    {
      if (sym->prec != 0)
	complain_at (loc, _("redefining precedence of %s"), sym->tag);
      sym->prec = prec;
      sym->assoc = a;
    }

  /* Only terminals have a precedence. */
  symbol_class_set (sym, token_sym, loc);
}


/*------------------------------------.
| Set the CLASS associated with SYM.  |
`------------------------------------*/

void
symbol_class_set (symbol *sym, symbol_class class, location loc)
{
  if (sym->class != unknown_sym && sym->class != class)
    complain_at (loc, _("symbol %s redefined"), sym->tag);

  if (class == nterm_sym && sym->class != nterm_sym)
    sym->number = nvars++;
  else if (class == token_sym && sym->number == NUMBER_UNDEFINED)
    sym->number = ntokens++;

  sym->class = class;
}


/*------------------------------------------------.
| Set the USER_TOKEN_NUMBER associated with SYM.  |
`------------------------------------------------*/

void
symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
{
  if (sym->class != token_sym)
    abort ();

  if (sym->user_token_number != USER_NUMBER_UNDEFINED
      && sym->user_token_number != user_token_number)
    complain_at (loc, _("redefining user token number of %s"), sym->tag);

  sym->user_token_number = user_token_number;
  /* User defined $end token? */
  if (user_token_number == 0)
    {
      endtoken = sym;
      endtoken->number = 0;
      /* It is always mapped to 0, so it was already counted in
	 NTOKENS.  */
      --ntokens;
    }
}


/*----------------------------------------------------------.
| If SYM is not defined, report an error, and consider it a |
| nonterminal.                                              |
`----------------------------------------------------------*/

static inline bool
symbol_check_defined (symbol *sym)
{
  if (sym->class == unknown_sym)
    {
      complain_at
	(sym->location,
	 _("symbol %s is used, but is not defined as a token and has no rules"),
	 sym->tag);
      sym->class = nterm_sym;
      sym->number = nvars++;
    }

  return true;
}

static bool
symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
{
  return symbol_check_defined (sym);
}


/*------------------------------------------------------------------.
| Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |
| SYMVAL with SYM's type.                                           |
`------------------------------------------------------------------*/

void
symbol_make_alias (symbol *sym, symbol *symval, location loc)
{
  if (symval->alias)
    warn_at (loc, _("symbol `%s' used more than once as a literal string"),
	  symval->tag);
  else if (sym->alias)
    warn_at (loc, _("symbol `%s' given more than one literal string"),
	  sym->tag);
  else
    {
      symval->class = token_sym;
      symval->user_token_number = sym->user_token_number;
      sym->user_token_number = USER_NUMBER_ALIAS;
      symval->alias = sym;
      sym->alias = symval;
      /* sym and symval combined are only one symbol.  */
      nsyms--;
      ntokens--;
      if (ntokens != sym->number && ntokens != symval->number)
	abort ();
      sym->number = symval->number =
	(symval->number < sym->number) ? symval->number : sym->number;
      symbol_type_set (symval, sym->type_name, loc);
    }
}


/*---------------------------------------------------------.
| Check that THIS, and its alias, have same precedence and |
| associativity.                                           |
`---------------------------------------------------------*/

static inline bool
symbol_check_alias_consistency (symbol *this)
{
  /* Check only those who _are_ the aliases. */
  if (this->alias && this->user_token_number == USER_NUMBER_ALIAS)
    {
      if (this->prec != this->alias->prec)
	{
	  if (this->prec != 0 && this->alias->prec != 0)
	    complain_at (this->alias->location,
			 _("conflicting precedences for %s and %s"),
			 this->tag, this->alias->tag);
	  if (this->prec != 0)
	    this->alias->prec = this->prec;
	  else
	    this->prec = this->alias->prec;
	}

      if (this->assoc != this->alias->assoc)
	{
	  if (this->assoc != undef_assoc && this->alias->assoc != undef_assoc)
	    complain_at (this->alias->location,
			 _("conflicting associativities for %s (%s) and %s (%s)"),
			 this->tag, assoc_to_string (this->assoc),
			 this->alias->tag, assoc_to_string (this->alias->assoc));
	  if (this->assoc != undef_assoc)
	    this->alias->assoc = this->assoc;
	  else
	    this->assoc = this->alias->assoc;
	}
    }
  return true;
}

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


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

static unsigned int
hash_symbol_hasher (void const *m, unsigned int 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;

  /* Keep the symbol in a printable form.  */
  key = uniqstr_new (quotearg_style (escape_quoting_style, 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;
    }

  CALLOC (token_translations, max_user_token_number + 1);

  /* 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)
{
  CALLOC (symbols, nsyms);

  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);
}