X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/366eea36d3a9aaccf80a78c2fcd8c3cd6b563e25..25f6da67d3bcacc570804c76b9312f74699c22fe:/src/symtab.c

diff --git a/src/symtab.c b/src/symtab.c
index 57bb7965..e438e4fc 100644
--- a/src/symtab.c
+++ b/src/symtab.c
@@ -1,223 +1,379 @@
-/* Symbol table manager for Bison,
-   Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
+/* Symbol table manager for Bison.
+
+   Copyright (C) 1984, 1989, 2000, 2001, 2002, 2004, 2005, 2006, 2007 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
+   This program 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.
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   Bison is distributed in the hope that it will be useful,
+   This program 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.  */
-
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
+#include <config.h>
 #include "system.h"
-#include "quotearg.h"
-#include "hash.h"
+
+#include <hash.h>
+#include <quotearg.h>
+
 #include "complain.h"
-#include "symtab.h"
 #include "gram.h"
+#include "symtab.h"
 
 /*------------------------.
 | Distinguished symbols.  |
 `------------------------*/
 
-symbol_t *errtoken = NULL;
-symbol_t *undeftoken = NULL;
-symbol_t *eoftoken = NULL;
-symbol_t *axiom = NULL;
-symbol_t *startsymbol = NULL;
-location_t startsymbol_location;
+symbol *errtoken = NULL;
+symbol *undeftoken = NULL;
+symbol *endtoken = NULL;
+symbol *accept = NULL;
+symbol *startsymbol = NULL;
+location startsymbol_location;
+
+/*---------------------------------------.
+| Default %destructor's and %printer's.  |
+`---------------------------------------*/
+
+static code_props default_tagged_destructor = CODE_PROPS_NONE_INIT;
+static code_props default_tagless_destructor = CODE_PROPS_NONE_INIT;
+static code_props default_tagged_printer = CODE_PROPS_NONE_INIT;
+static code_props default_tagless_printer = CODE_PROPS_NONE_INIT;
 
 /*---------------------------------.
 | Create a new symbol, named TAG.  |
 `---------------------------------*/
 
-static symbol_t *
-symbol_new (const char *tag, location_t location)
+static symbol *
+symbol_new (uniqstr tag, location loc)
 {
-  symbol_t *res = XMALLOC (symbol_t, 1);
+  symbol *res = xmalloc (sizeof *res);
 
-  res->tag = xstrdup (tag);
-  res->location = location;
+  uniqstr_assert (tag);
+  res->tag = tag;
+  res->location = loc;
 
   res->type_name = NULL;
-  res->destructor = NULL;
+  code_props_none_init (&res->destructor);
+  code_props_none_init (&res->printer);
 
   res->number = NUMBER_UNDEFINED;
   res->prec = 0;
-  res->assoc = right_assoc;
+  res->assoc = undef_assoc;
   res->user_token_number = USER_NUMBER_UNDEFINED;
+
   res->alias = NULL;
   res->class = unknown_sym;
+  res->declared = false;
 
+  if (nsyms == SYMBOL_NUMBER_MAXIMUM)
+    fatal (_("too many symbols in input grammar (limit is %d)"),
+	   SYMBOL_NUMBER_MAXIMUM);
   nsyms++;
   return res;
 }
 
+/*----------------------------------------.
+| Create a new semantic type, named TAG.  |
+`----------------------------------------*/
 
-/*-----------------------------------------------------------------.
-| Return the tag of this SYMBOL in a printable form.  Warning: use |
-| the first QUOTEARG slot: 0.                                      |
-`-----------------------------------------------------------------*/
-
-const char *
-symbol_tag_get (symbol_t *symbol)
+static semantic_type *
+semantic_type_new (uniqstr tag)
 {
-  return quotearg_style (escape_quoting_style, symbol->tag);
-}
+  semantic_type *res = xmalloc (sizeof *res);
 
+  uniqstr_assert (tag);
+  res->tag = tag;
+  code_props_none_init (&res->destructor);
+  code_props_none_init (&res->printer);
 
-/*------------------------------------------------------------.
-| Return the tag of this SYMBOL in a printable form.  Use the |
-| QUOTEARG slot number N.                                     |
-`------------------------------------------------------------*/
-
-const char *
-symbol_tag_get_n (symbol_t *symbol, int n)
-{
-  return quotearg_n_style (n, escape_quoting_style, symbol->tag);
+  return res;
 }
 
 
-/*-------------------------------.
-| Print the tag of this SYMBOL.  |
-`-------------------------------*/
+/*-----------------.
+| Print a symbol.  |
+`-----------------*/
+
+#define SYMBOL_ATTR_PRINT(Attr)				\
+  if (s->Attr)						\
+    fprintf (f, " %s { %s }", #Attr, s->Attr)
+
+#define SYMBOL_CODE_PRINT(Attr)                         \
+  if (s->Attr.code)                                     \
+    fprintf (f, " %s { %s }", #Attr, s->Attr.code)
 
 void
-symbol_tag_print (symbol_t *symbol, FILE *out)
+symbol_print (symbol *s, FILE *f)
 {
-  fputs (symbol_tag_get (symbol), out);
+  if (s)
+    {
+      fprintf (f, "\"%s\"", s->tag);
+      SYMBOL_ATTR_PRINT (type_name);
+      SYMBOL_CODE_PRINT (destructor);
+      SYMBOL_CODE_PRINT (printer);
+    }
+  else
+    fprintf (f, "<NULL>");
 }
 
+#undef SYMBOL_ATTR_PRINT
+#undef SYMBOL_CODE_PRINT
 
 /*------------------------------------------------------------------.
-| Set the TYPE_NAME associated to SYMBOL.  Does nothing if passed 0 |
-| as TYPE_NAME.                                                     |
+| Complain that S's WHAT is redeclared at SECOND, and was first set |
+| at FIRST.                                                         |
 `------------------------------------------------------------------*/
 
+static void
+symbol_redeclaration (symbol *s, const char *what, location first,
+                      location second)
+{
+  complain_at (second, _("%s redeclaration for %s"), what, s->tag);
+  complain_at (first, _("previous declaration"));
+}
+
+static void
+semantic_type_redeclaration (semantic_type *s, const char *what, location first,
+                             location second)
+{
+  complain_at (second, _("%s redeclaration for <%s>"), what, s->tag);
+  complain_at (first, _("previous declaration"));
+}
+
+
+/*-----------------------------------------------------------------.
+| Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
+| as TYPE_NAME.                                                    |
+`-----------------------------------------------------------------*/
+
 void
-symbol_type_set (symbol_t *symbol, location_t location, char *type_name)
+symbol_type_set (symbol *sym, uniqstr type_name, location loc)
 {
   if (type_name)
     {
-      if (symbol->type_name)
-	complain_at (location,
-		     _("type redeclaration for %s"), symbol_tag_get (symbol));
-      symbol->type_name = type_name;
+      if (sym->type_name)
+	symbol_redeclaration (sym, "%type", sym->type_location, loc);
+      uniqstr_assert (type_name);
+      sym->type_name = type_name;
+      sym->type_location = loc;
     }
 }
 
+/*-----------------------------------.
+| Get the CLASS associated with SYM. |
+`-----------------------------------*/
 
-/*-------------------------------------------------------------------.
-| Set the DESTRUCTOR associated to SYMBOL.  Do nothing if passed 0.  |
-`-------------------------------------------------------------------*/
+const char *
+symbol_class_get_string (symbol *sym)
+{
+  if (sym->class)
+    {
+      if (sym->class == token_sym)
+	return "terminal";
+      else if (sym->class == nterm_sym)
+	return "nonterminal";
+    }
+  return "unknown";
+}
+
+
+/*-----------------------------------------.
+| Set the DESTRUCTOR associated with SYM.  |
+`-----------------------------------------*/
 
 void
-symbol_destructor_set (symbol_t *symbol, location_t location, char *destructor)
+symbol_destructor_set (symbol *sym, code_props const *destructor)
+{
+  if (sym->destructor.code)
+    symbol_redeclaration (sym, "%destructor", sym->destructor.location,
+                          destructor->location);
+  sym->destructor = *destructor;
+}
+
+/*------------------------------------------.
+| Set the DESTRUCTOR associated with TYPE.  |
+`------------------------------------------*/
+
+void
+semantic_type_destructor_set (semantic_type *type,
+                              code_props const *destructor)
+{
+  if (type->destructor.code)
+    semantic_type_redeclaration (type, "%destructor",
+                                 type->destructor.location,
+                                 destructor->location);
+  type->destructor = *destructor;
+}
+
+/*---------------------------------------.
+| Get the computed %destructor for SYM.  |
+`---------------------------------------*/
+
+code_props const *
+symbol_destructor_get (symbol const *sym)
 {
-  if (destructor)
+  /* Per-symbol %destructor.  */
+  if (sym->destructor.code)
+    return &sym->destructor;
+
+  /* Per-type %destructor.  */
+  if (sym->type_name)
     {
-      if (symbol->destructor)
-	complain_at (location,
-		     _("%s redeclaration for %s"),
-		     "%destructor", symbol_tag_get (symbol));
-      symbol->destructor = destructor;
-      symbol->destructor_location = location;
+      code_props const *destructor =
+        &semantic_type_get (sym->type_name)->destructor;
+      if (destructor->code)
+        return destructor;
     }
+
+  /* Apply default %destructor's only to user-defined symbols.  */
+  if (sym->tag[0] == '$' || sym == errtoken)
+    return &code_props_none;
+
+  if (sym->type_name)
+    return &default_tagged_destructor;
+  return &default_tagless_destructor;
 }
 
+/*--------------------------------------.
+| Set the PRINTER associated with SYM.  |
+`--------------------------------------*/
 
-/*----------------------------------------------------------------.
-| Set the PRITNER associated to SYMBOL.  Do nothing if passed 0.  |
-`----------------------------------------------------------------*/
+void
+symbol_printer_set (symbol *sym, code_props const *printer)
+{
+  if (sym->printer.code)
+    symbol_redeclaration (sym, "%printer",
+                          sym->printer.location, printer->location);
+  sym->printer = *printer;
+}
+
+/*---------------------------------------.
+| Set the PRINTER associated with TYPE.  |
+`---------------------------------------*/
 
 void
-symbol_printer_set (symbol_t *symbol, char *printer, location_t location)
+semantic_type_printer_set (semantic_type *type, code_props const *printer)
 {
-  if (printer)
+  if (type->printer.code)
+    semantic_type_redeclaration (type, "%printer",
+                                 type->printer.location, printer->location);
+  type->printer = *printer;
+}
+
+/*------------------------------------.
+| Get the computed %printer for SYM.  |
+`------------------------------------*/
+
+code_props const *
+symbol_printer_get (symbol const *sym)
+{
+  /* Per-symbol %printer.  */
+  if (sym->printer.code)
+    return &sym->printer;
+
+  /* Per-type %printer.  */
+  if (sym->type_name)
     {
-      if (symbol->printer)
-	complain_at (location,
-		     _("%s redeclaration for %s"),
-		     "%printer", symbol_tag_get (symbol));
-      symbol->printer = printer;
-      symbol->printer_location = location;
+      code_props const *printer = &semantic_type_get (sym->type_name)->printer;
+      if (printer->code)
+        return printer;
     }
-}
 
+  /* Apply the default %printer only to user-defined symbols.  */
+  if (sym->tag[0] == '$' || sym == errtoken)
+    return &code_props_none;
 
-/*------------------------------------------------------------------.
-| Set the PRECEDENCE associated to SYMBOL.  Does nothing if invoked |
-| with UNDEF_ASSOC as ASSOC.                                        |
-`------------------------------------------------------------------*/
+  if (sym->type_name)
+    return &default_tagged_printer;
+  return &default_tagless_printer;
+}
+
+/*-----------------------------------------------------------------.
+| Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
+| with UNDEF_ASSOC as ASSOC.                                       |
+`-----------------------------------------------------------------*/
 
 void
-symbol_precedence_set (symbol_t *symbol, location_t location,
-		       int prec, associativity assoc)
+symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
 {
-  if (assoc != undef_assoc)
+  if (a != undef_assoc)
     {
-      if (symbol->prec != 0)
-	complain_at (location,
-		     _("redefining precedence of %s"),
-		     symbol_tag_get (symbol));
-      symbol->prec = prec;
-      symbol->assoc = assoc;
+      if (sym->prec != 0)
+	symbol_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 (symbol, token_sym);
+  symbol_class_set (sym, token_sym, loc, false);
 }
 
 
-/*-------------------------------------.
-| Set the CLASS associated to SYMBOL.  |
-`-------------------------------------*/
+/*------------------------------------.
+| Set the CLASS associated with SYM.  |
+`------------------------------------*/
 
 void
-symbol_class_set (symbol_t *symbol, symbol_class class)
+symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
 {
-  if (symbol->class != unknown_sym && symbol->class != class)
-    complain (_("symbol %s redefined"), symbol_tag_get (symbol));
+  if (sym->class != unknown_sym && sym->class != class)
+    {
+      complain_at (loc, _("symbol %s redefined"), sym->tag);
+      sym->declared = false;
+    }
+
+  if (class == nterm_sym && sym->class != nterm_sym)
+    sym->number = nvars++;
+  else if (class == token_sym && sym->number == NUMBER_UNDEFINED)
+    sym->number = ntokens++;
 
-  if (class == nterm_sym && symbol->class != nterm_sym)
-    symbol->number = nvars++;
-  else if (class == token_sym && symbol->number == NUMBER_UNDEFINED)
-    symbol->number = ntokens++;
+  sym->class = class;
 
-  symbol->class = class;
+  if (declaring)
+    {
+      if (sym->declared)
+	warn_at (loc, _("symbol %s redeclared"), sym->tag);
+      sym->declared = true;
+    }
 }
 
 
-/*-------------------------------------------------.
-| Set the USER_TOKEN_NUMBER associated to SYMBOL.  |
-`-------------------------------------------------*/
+/*------------------------------------------------.
+| Set the USER_TOKEN_NUMBER associated with SYM.  |
+`------------------------------------------------*/
 
 void
-symbol_user_token_number_set (symbol_t *symbol, int user_token_number)
+symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 {
-  assert (symbol->class == token_sym);
+  int *user_token_numberp;
+
+  aver (sym->class == token_sym);
 
-  if (symbol->user_token_number != USER_NUMBER_UNDEFINED
-      && symbol->user_token_number != user_token_number)
-    complain (_("redefining user token number of %s"),
-	      symbol_tag_get (symbol));
+  if (sym->user_token_number != USER_NUMBER_ALIAS)
+    user_token_numberp = &sym->user_token_number;
+  else
+    user_token_numberp = &sym->alias->user_token_number;
+  if (*user_token_numberp != USER_NUMBER_UNDEFINED
+      && *user_token_numberp != user_token_number)
+    complain_at (loc, _("redefining user token number of %s"), sym->tag);
 
-  symbol->user_token_number = user_token_number;
-  /* User defined EOF token? */
+  *user_token_numberp = user_token_number;
+  /* User defined $end token? */
   if (user_token_number == 0)
     {
-      eoftoken = symbol;
-      eoftoken->number = 0;
+      endtoken = sym;
+      endtoken->number = 0;
       /* It is always mapped to 0, so it was already counted in
 	 NTOKENS.  */
       --ntokens;
@@ -225,72 +381,57 @@ symbol_user_token_number_set (symbol_t *symbol, int user_token_number)
 }
 
 
-/*------------.
-| Free THIS.  |
-`------------*/
-
-static void
-symbol_free (symbol_t *this)
-{
-#if 0
-  /* This causes crashes because one string can appear more
-     than once.  */
-  XFREE (this->type_name);
-#endif
-  XFREE (this->tag);
-  XFREE (this);
-}
-
-
-/*-----------------------------------------------------------.
-| If THIS is not defined, report an error, and consider it a |
-| nonterminal.                                               |
-`-----------------------------------------------------------*/
+/*----------------------------------------------------------.
+| If SYM is not defined, report an error, and consider it a |
+| nonterminal.                                              |
+`----------------------------------------------------------*/
 
-static bool
-symbol_check_defined (symbol_t *this)
+static inline bool
+symbol_check_defined (symbol *sym)
 {
-  if (this->class == unknown_sym)
+  if (sym->class == unknown_sym)
     {
       complain_at
-	(this->location,
+	(sym->location,
 	 _("symbol %s is used, but is not defined as a token and has no rules"),
-	 symbol_tag_get (this));
-      this->class = nterm_sym;
-      this->number = nvars++;
+	 sym->tag);
+      sym->class = nterm_sym;
+      sym->number = nvars++;
     }
 
-  return TRUE;
+  return true;
 }
 
+static bool
+symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
+{
+  return symbol_check_defined (sym);
+}
 
-/*-------------------------------------------------------------------.
-| Declare the new SYMBOL.  Make it an alias of SYMVAL, and type them |
-| with TYPENAME.                                                     |
-`-------------------------------------------------------------------*/
+
+/*------------------------------------------------------------------.
+| Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |
+| SYMVAL with SYM's type.                                           |
+`------------------------------------------------------------------*/
 
 void
-symbol_make_alias (symbol_t *symbol, symbol_t *symval)
+symbol_make_alias (symbol *sym, symbol *symval, location loc)
 {
   if (symval->alias)
-    warn (_("symbol `%s' used more than once as a literal string"),
-	  symbol_tag_get (symval));
-  else if (symbol->alias)
-    warn (_("symbol `%s' given more than one literal string"),
-	  symbol_tag_get (symbol));
+    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 = symbol->user_token_number;
-      symbol->user_token_number = USER_NUMBER_ALIAS;
-      symval->alias = symbol;
-      symbol->alias = symval;
-      /* symbol and symval combined are only one symbol */
-      nsyms--;
-      ntokens--;
-      assert (ntokens == symbol->number || ntokens == symval->number);
-      symbol->number = symval->number =
-	(symval->number < symbol->number) ? symval->number : symbol->number;
+      symval->user_token_number = sym->user_token_number;
+      sym->user_token_number = USER_NUMBER_ALIAS;
+      symval->alias = sym;
+      sym->alias = symval;
+      symval->number = sym->number;
+      symbol_type_set (symval, sym->type_name, loc);
     }
 }
 
@@ -300,39 +441,58 @@ symbol_make_alias (symbol_t *symbol, symbol_t *symval)
 | associativity.                                           |
 `---------------------------------------------------------*/
 
-static bool
-symbol_check_alias_consistence (symbol_t *this)
+static inline void
+symbol_check_alias_consistency (symbol *this)
 {
-  /* Check only those who _are_ the aliases. */
-  if (this->alias && this->user_token_number == USER_NUMBER_ALIAS)
+  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 (this->prec != this->alias->prec)
-	{
-	  if (this->prec != 0 && this->alias->prec != 0)
-	    complain (_("conflicting precedences for %s and %s"),
-		      symbol_tag_get (this), symbol_tag_get (this->alias));
-	  if (this->prec != 0)
-	    this->alias->prec = this->prec;
-	  else
-	    this->prec = this->alias->prec;
-	}
+      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 (this->assoc != this->alias->assoc)
-	{
-	  /* FIXME: For some reason (probably the S/R => keep the S),
-	     the right assoc is chosen has the ``not set''.  This is
-	     not nice, fix this!  */
-	  if (this->assoc != right_assoc
-	      && this->alias->assoc != right_assoc)
-	    complain (_("conflicting associativities for %s and %s"),
-		      symbol_tag_get (this), symbol_tag_get (this->alias));
-	  if (this->assoc != 0)
-	    this->alias->assoc = this->assoc;
-	  else
-	    this->assoc = this->alias->assoc;
-	}
+
+  if (orig->destructor.code || alias->destructor.code)
+    {
+      if (orig->destructor.code)
+	symbol_destructor_set (alias, &orig->destructor);
+      else
+	symbol_destructor_set (orig, &alias->destructor);
+    }
+
+  if (orig->printer.code || alias->printer.code)
+    {
+      if (orig->printer.code)
+	symbol_printer_set (alias, &orig->printer);
+      else
+	symbol_printer_set (orig, &alias->printer);
+    }
+
+  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);
     }
-  return TRUE;
+}
+
+static bool
+symbol_check_alias_consistency_processor (void *this,
+					  void *null ATTRIBUTE_UNUSED)
+{
+  symbol_check_alias_consistency (this);
+  return true;
 }
 
 
@@ -341,8 +501,8 @@ symbol_check_alias_consistence (symbol_t *this)
 | into FDEFINES.  Put in SYMBOLS.                                    |
 `-------------------------------------------------------------------*/
 
-static bool
-symbol_pack (symbol_t *this)
+static inline bool
+symbol_pack (symbol *this)
 {
   if (this->class == nterm_sym)
     {
@@ -355,25 +515,29 @@ symbol_pack (symbol_t *this)
 	 prec and assoc fields and make both the same */
       if (this->number == NUMBER_UNDEFINED)
 	{
-	  if (this == eoftoken || this->alias == eoftoken)
+	  if (this == endtoken || this->alias == endtoken)
 	    this->number = this->alias->number = 0;
 	  else
 	    {
-	      assert (this->alias->number != NUMBER_UNDEFINED);
+	      aver (this->alias->number != NUMBER_UNDEFINED);
 	      this->number = this->alias->number;
 	    }
 	}
-      /* Do not do processing below for USER_NUMBER_ALIASs.  */
+      /* Do not do processing below for USER_NUMBER_ALIASes.  */
       if (this->user_token_number == USER_NUMBER_ALIAS)
-	return TRUE;
+	return true;
     }
   else /* this->class == token_sym */
-    {
-      assert (this->number != NUMBER_UNDEFINED);
-    }
+    aver (this->number != NUMBER_UNDEFINED);
 
   symbols[this->number] = this;
-  return TRUE;
+  return true;
+}
+
+static bool
+symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
+{
+  return symbol_pack (this);
 }
 
 
@@ -383,8 +547,8 @@ symbol_pack (symbol_t *this)
 | Put THIS in TOKEN_TRANSLATIONS if it is a token.  |
 `--------------------------------------------------*/
 
-static bool
-symbol_translation (symbol_t *this)
+static inline bool
+symbol_translation (symbol *this)
 {
   /* Non-terminal? */
   if (this->class == token_sym
@@ -392,38 +556,85 @@ symbol_translation (symbol_t *this)
     {
       /* A token which translation has already been set? */
       if (token_translations[this->user_token_number] != undeftoken->number)
-	complain (_("tokens %s and %s both assigned number %d"),
-		  symbol_tag_get (symbols[token_translations[this->user_token_number]]),
-		  symbol_tag_get (this), this->user_token_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;
+  return true;
+}
+
+static bool
+symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
+{
+  return symbol_translation (this);
 }
 
 
-/*----------------------.
-| A symbol hash table.  |
-`----------------------*/
+/*---------------------------------------.
+| Symbol and semantic type hash tables.  |
+`---------------------------------------*/
 
-/* Initial capacity of symbols hash table.  */
+/* Initial capacity of symbol and semantic type hash table.  */
 #define HT_INITIAL_CAPACITY 257
 
 static struct hash_table *symbol_table = NULL;
+static struct hash_table *semantic_type_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 inline bool
+hash_compare_semantic_type (const semantic_type *m1, const semantic_type *m2)
+{
+  /* Since names are unique, we can compare the pointers themselves.  */
+  return UNIQSTR_EQ (m1->tag, m2->tag);
+}
 
 static bool
-hash_compare_symbol_t (const symbol_t *m1, const symbol_t *m2)
+hash_symbol_comparator (void const *m1, void const *m2)
+{
+  return hash_compare_symbol (m1, m2);
+}
+
+static bool
+hash_semantic_type_comparator (void const *m1, void const *m2)
+{
+  return hash_compare_semantic_type (m1, m2);
+}
+
+static inline size_t
+hash_symbol (const symbol *m, size_t tablesize)
 {
-  return strcmp (m1->tag, m2->tag) ? FALSE : TRUE;
+  /* Since tags are unique, we can hash the pointer itself.  */
+  return ((uintptr_t) m->tag) % tablesize;
 }
 
-static unsigned int
-hash_symbol_t (const symbol_t *m, unsigned int tablesize)
+static inline size_t
+hash_semantic_type (const semantic_type *m, size_t tablesize)
 {
-  return hash_string (m->tag, tablesize);
+  /* Since names 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);
+}
+
+static size_t
+hash_semantic_type_hasher (void const *m, size_t tablesize)
+{
+  return hash_semantic_type (m, tablesize);
+}
 
 /*-------------------------------.
 | Create the symbol hash table.  |
@@ -434,9 +645,14 @@ symbols_new (void)
 {
   symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
 				  NULL,
-				  (Hash_hasher) hash_symbol_t,
-				  (Hash_comparator) hash_compare_symbol_t,
-				  (Hash_data_freer) symbol_free);
+				  hash_symbol_hasher,
+				  hash_symbol_comparator,
+				  free);
+  semantic_type_table = hash_initialize (HT_INITIAL_CAPACITY,
+				         NULL,
+				         hash_semantic_type_hasher,
+				         hash_semantic_type_comparator,
+				         free);
 }
 
 
@@ -445,25 +661,100 @@ symbols_new (void)
 | yet, create it.                                                 |
 `----------------------------------------------------------------*/
 
-symbol_t *
-getsym (const char *key, location_t location)
+symbol *
+symbol_from_uniqstr (const uniqstr key, location loc)
 {
-  symbol_t probe;
-  symbol_t *entry;
+  symbol probe;
+  symbol *entry;
 
-  (const char *) probe.tag = key;
+  probe.tag = key;
   entry = hash_lookup (symbol_table, &probe);
 
   if (!entry)
     {
       /* First insertion in the hash. */
-      entry = symbol_new (key, location);
+      entry = symbol_new (key, loc);
       hash_insert (symbol_table, entry);
     }
   return entry;
 }
 
 
+/*-----------------------------------------------------------------------.
+| Find the semantic type named KEY, and return it.  If it does not exist |
+| yet, create it.                                                        |
+`-----------------------------------------------------------------------*/
+
+semantic_type *
+semantic_type_from_uniqstr (const uniqstr key)
+{
+  semantic_type probe;
+  semantic_type *entry;
+
+  probe.tag = key;
+  entry = hash_lookup (semantic_type_table, &probe);
+
+  if (!entry)
+    {
+      /* First insertion in the hash. */
+      entry = semantic_type_new (key);
+      hash_insert (semantic_type_table, entry);
+    }
+  return entry;
+}
+
+
+/*----------------------------------------------------------------.
+| Find the symbol named KEY, and return it.  If it does not exist |
+| yet, create it.                                                 |
+`----------------------------------------------------------------*/
+
+symbol *
+symbol_get (const char *key, location loc)
+{
+  return symbol_from_uniqstr (uniqstr_new (key), loc);
+}
+
+
+/*-----------------------------------------------------------------------.
+| Find the semantic type named KEY, and return it.  If it does not exist |
+| yet, create it.                                                        |
+`-----------------------------------------------------------------------*/
+
+semantic_type *
+semantic_type_get (const char *key)
+{
+  return semantic_type_from_uniqstr (uniqstr_new (key));
+}
+
+
+/*------------------------------------------------------------------.
+| 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, "$@%d", ++dummy_count);
+  sym = symbol_get (buf, loc);
+  sym->class = nterm_sym;
+  sym->number = nvars++;
+  return sym;
+}
+
+bool
+symbol_is_dummy (const symbol *sym)
+{
+  return sym->tag[0] == '@' || (sym->tag[0] == '$' && sym->tag[1] == '@');
+}
+
 /*-------------------.
 | Free the symbols.  |
 `-------------------*/
@@ -472,6 +763,8 @@ void
 symbols_free (void)
 {
   hash_free (symbol_table);
+  hash_free (semantic_type_table);
+  free (symbols);
 }
 
 
@@ -480,12 +773,10 @@ symbols_free (void)
 | terminals.                                                     |
 `---------------------------------------------------------------*/
 
-void
-symbols_do (symbol_processor processor, void *processor_data)
+static void
+symbols_do (Hash_processor processor, void *processor_data)
 {
-  hash_do_for_each (symbol_table,
-		    (Hash_processor) processor,
-		    processor_data);
+  hash_do_for_each (symbol_table, processor, processor_data);
 }
 
 
@@ -497,7 +788,7 @@ symbols_do (symbol_processor processor, void *processor_data)
 void
 symbols_check_defined (void)
 {
-  symbols_do (symbol_check_defined, NULL);
+  symbols_do (symbol_check_defined_processor, NULL);
 }
 
 /*------------------------------------------------------------------.
@@ -508,7 +799,7 @@ symbols_check_defined (void)
 static void
 symbols_token_translations_init (void)
 {
-  int num_256_available_p = TRUE;
+  bool num_256_available_p = true;
   int i;
 
   /* Find the highest user token number, and whether 256, the POSIX
@@ -516,13 +807,13 @@ symbols_token_translations_init (void)
   max_user_token_number = 0;
   for (i = 0; i < ntokens; ++i)
     {
-      symbol_t *this = symbols[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;
+	    num_256_available_p = false;
 	}
     }
 
@@ -537,21 +828,22 @@ symbols_token_translations_init (void)
 
   for (i = 0; i < ntokens; ++i)
     {
-      symbol_t *this = symbols[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 = XCALLOC (symbol_number_t, max_user_token_number + 1);
+  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.  */
+     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, NULL);
+  symbols_do (symbol_translation_processor, NULL);
 }
 
 
@@ -563,19 +855,100 @@ symbols_token_translations_init (void)
 void
 symbols_pack (void)
 {
-  symbols = XCALLOC (symbol_t *, nsyms);
-
-  symbols_do (symbol_check_alias_consistence, NULL);
-  symbols_do (symbol_pack, NULL);
+  symbols_do (symbol_check_alias_consistency_processor, NULL);
+
+  symbols = xcalloc (nsyms, sizeof *symbols);
+  symbols_do (symbol_pack_processor, NULL);
+
+  /* Aliases leave empty slots in symbols, so remove them.  */
+  {
+    int writei;
+    int readi;
+    int nsyms_old = nsyms;
+    for (writei = 0, readi = 0; readi < nsyms_old; readi += 1)
+      {
+        if (symbols[readi] == NULL)
+          {
+            nsyms -= 1;
+            ntokens -= 1;
+          }
+        else
+          {
+            symbols[writei] = symbols[readi];
+            symbols[writei]->number = writei;
+            if (symbols[writei]->alias)
+              symbols[writei]->alias->number = writei;
+            writei += 1;
+          }
+      }
+  }
+  symbols = xnrealloc (symbols, nsyms, sizeof *symbols);
 
   symbols_token_translations_init ();
 
   if (startsymbol->class == unknown_sym)
     fatal_at (startsymbol_location,
 	      _("the start symbol %s is undefined"),
-	      symbol_tag_get (startsymbol));
+	      startsymbol->tag);
   else if (startsymbol->class == token_sym)
     fatal_at (startsymbol_location,
 	      _("the start symbol %s is a token"),
-	      symbol_tag_get (startsymbol));
+	      startsymbol->tag);
+}
+
+
+/*--------------------------------------------------.
+| Set default tagged/tagless %destructor/%printer.  |
+`--------------------------------------------------*/
+
+void
+default_tagged_destructor_set (code_props const *destructor)
+{
+  if (default_tagged_destructor.code)
+    {
+      complain_at (destructor->location,
+                   _("redeclaration for default tagged %%destructor"));
+      complain_at (default_tagged_destructor.location,
+		   _("previous declaration"));
+    }
+  default_tagged_destructor = *destructor;
+}
+
+void
+default_tagless_destructor_set (code_props const *destructor)
+{
+  if (default_tagless_destructor.code)
+    {
+      complain_at (destructor->location,
+                   _("redeclaration for default tagless %%destructor"));
+      complain_at (default_tagless_destructor.location,
+		   _("previous declaration"));
+    }
+  default_tagless_destructor = *destructor;
+}
+
+void
+default_tagged_printer_set (code_props const *printer)
+{
+  if (default_tagged_printer.code)
+    {
+      complain_at (printer->location,
+                   _("redeclaration for default tagged %%printer"));
+      complain_at (default_tagged_printer.location,
+		   _("previous declaration"));
+    }
+  default_tagged_printer = *printer;
+}
+
+void
+default_tagless_printer_set (code_props const *printer)
+{
+  if (default_tagless_printer.code)
+    {
+      complain_at (printer->location,
+                   _("redeclaration for default tagless %%printer"));
+      complain_at (default_tagless_printer.location,
+		   _("previous declaration"));
+    }
+  default_tagless_printer = *printer;
 }