symtab.c

bison 2.0 主要可以用来做语法分析用的

/* Symbol table manager for Bison.

   Copyright (C) 1984, 1989, 2000, 2001, 2002, 2004 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 = xmalloc (sizeof *res);

  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;

  if (nsyms == SYMBOL_NUMBER_MAXIMUM)
    fatal (_("too many symbols in input grammar (limit is %d)"),
	   SYMBOL_NUMBER_MAXIMUM);
  nsyms++;
  return res;
}


/*------------------------------------------------------------------.
| Complain that S's WHAT is redeclared at SECOND, and was first set |
| at FIRST.                                                         |
`------------------------------------------------------------------*/

static void
redeclaration (symbol* s, const char *what, location first, location second)
{
  complain_at (second, _("%s redeclaration for %s"), what, s->tag);
  complain_at (first, _("first declaration"));
}


/*-----------------------------------------------------------------.
| 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)
	redeclaration (sym, "%type", sym->type_location, loc);
      uniqstr_assert (type_name);
      sym->type_name = type_name;
      sym->type_location = loc;
    }
}


/*------------------------------------------------------------------.
| 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)
	redeclaration (sym, "%destructor", sym->destructor_location, loc);
      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)
	redeclaration (sym, "%printer", sym->destructor_location, loc);
      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)
	redeclaration (sym, assoc_to_string (a), sym->prec_location, loc);
      sym->prec = prec;
      sym->assoc = a;
      sym->prec_location = loc;
    }

  /* 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;
    }
}


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

static inline void
symbol_check_alias_consistency (symbol *this)
{
  symbol *alias = this;
  symbol *orig  = this->alias;

  /* Check only those that _are_ the aliases.  */
  if (!(this->alias && this->user_token_number == USER_NUMBER_ALIAS))
    return;

  if (orig->type_name || alias->type_name)
    {
      if (orig->type_name)
	symbol_type_set (alias, orig->type_name, orig->type_location);
      else
	symbol_type_set (orig, alias->type_name, alias->type_location);
    }


  if (orig->destructor || alias->destructor)
    {
      if (orig->destructor)
	symbol_destructor_set (alias, orig->destructor,
			       orig->destructor_location);
      else
	symbol_destructor_set (orig, alias->destructor,
			       alias->destructor_location);
    }

  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)