2007-02-07 Paolo Bonzini <bonzini@gnu.org>

[bison.git] / src / symtab.c

diff --git a/src/symtab.c b/src/symtab.c
index fb6a02e6e36762c14726f0926556e07144bd9c61..8910f09c4ee0e4744f848b1aad4ec655c24e5dfe 100644 (file)
--- a/src/symtab.c
+++ b/src/symtab.c
@@ -1,6 +1,7 @@
 /* Symbol table manager for Bison.
 
 /* Symbol table manager for Bison.
 

-   Copyright (C) 1984, 1989, 2000, 2001, 2002 Free Software Foundation, Inc.
+   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.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 


@@ -16,10 +17,10 @@
 
    You should have received a copy of the GNU General Public License
    along with Bison; see the file COPYING.  If not, write to
 
    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.  */
-
+   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */

 
 

+#include <config.h>

 #include "system.h"
 
 #include <hash.h>
 #include "system.h"
 
 #include <hash.h>


@@ -40,6 +41,15 @@ symbol *accept = NULL;
 symbol *startsymbol = NULL;
 location startsymbol_location;
 
 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.  |
 `---------------------------------*/
 /*---------------------------------.
 | Create a new symbol, named TAG.  |
 `---------------------------------*/


@@ -47,15 +57,15 @@ location startsymbol_location;
 static symbol *
 symbol_new (uniqstr tag, location loc)
 {
 static symbol *
 symbol_new (uniqstr tag, location loc)
 {

-  symbol *res = MALLOC (res, 1);
+  symbol *res = xmalloc (sizeof *res);

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

-  res->destructor = NULL;
-  res->printer = NULL;
+  code_props_none_init (&res->destructor);
+  code_props_none_init (&res->printer);

 
   res->number = NUMBER_UNDEFINED;
   res->prec = 0;
 
   res->number = NUMBER_UNDEFINED;
   res->prec = 0;


@@ -64,11 +74,83 @@ symbol_new (uniqstr tag, location loc)
 
   res->alias = NULL;
   res->class = unknown_sym;
 
   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;
 }
 
   nsyms++;
   return res;
 }
 

+/*----------------------------------------.
+| Create a new semantic type, named TAG.  |
+`----------------------------------------*/
+
+static semantic_type *
+semantic_type_new (uniqstr 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 res;
+}
+
+
+/*-----------------.
+| 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_print (symbol *s, FILE *f)
+{
+  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
+
+/*------------------------------------------------------------------.
+| 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 |
 
 /*-----------------------------------------------------------------.
 | Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |


@@ -81,48 +163,124 @@ symbol_type_set (symbol *sym, uniqstr type_name, location loc)
   if (type_name)
     {
       if (sym->type_name)
   if (type_name)
     {
       if (sym->type_name)

-       complain_at (loc, _("type redeclaration for %s"), sym->tag);
+       symbol_redeclaration (sym, "%type", sym->type_location, loc);

       uniqstr_assert (type_name);
       sym->type_name = type_name;
       uniqstr_assert (type_name);
       sym->type_name = type_name;

+      sym->type_location = loc;

     }
 }
 
 
     }
 }
 
 

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

 
 void
 
 void

-symbol_destructor_set (symbol *sym, char *destructor, location loc)
+symbol_destructor_set (symbol *sym, code_props const *destructor)

 {
 {

-  if (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)
+{
+  /* Per-symbol %destructor.  */
+  if (sym->destructor.code)
+    return &sym->destructor;
+
+  /* Per-type %destructor.  */
+  if (sym->type_name)

     {
     {

-      if (sym->destructor)
-       complain_at (loc, _("%s redeclaration for %s"),
-                    "%destructor", sym->tag);
-      sym->destructor = destructor;
-      sym->destructor_location = loc;
+      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 PRINTER associated with SYM.  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
 
 void

-symbol_printer_set (symbol *sym, char *printer, location loc)
+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 (sym->printer)
-       complain_at (loc, _("%s redeclaration for %s"),
-                    "%printer", sym->tag);
-      sym->printer = printer;
-      sym->printer_location = loc;
+      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;
+
+  if (sym->type_name)
+    return &default_tagged_printer;
+  return &default_tagless_printer;
+}

 
 /*-----------------------------------------------------------------.
 | Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
 
 /*-----------------------------------------------------------------.
 | Set the PRECEDENCE associated with SYM.  Does nothing if invoked |


@@ -135,13 +293,15 @@ symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
   if (a != undef_assoc)
     {
       if (sym->prec != 0)
   if (a != undef_assoc)
     {
       if (sym->prec != 0)

-       complain_at (loc, _("redefining precedence of %s"), sym->tag);
+       symbol_redeclaration (sym, assoc_to_string (a), sym->prec_location,
+                              loc);

       sym->prec = prec;
       sym->assoc = a;
       sym->prec = prec;
       sym->assoc = a;

+      sym->prec_location = loc;

     }
 
   /* Only terminals have a precedence. */
     }
 
   /* Only terminals have a precedence. */

-  symbol_class_set (sym, token_sym, loc);
+  symbol_class_set (sym, token_sym, loc, false);

 }
 
 
 }
 
 


@@ -150,10 +310,13 @@ symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
 `------------------------------------*/
 
 void
 `------------------------------------*/
 
 void

-symbol_class_set (symbol *sym, symbol_class class, location loc)
+symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)

 {
   if (sym->class != unknown_sym && sym->class != class)
 {
   if (sym->class != unknown_sym && sym->class != class)

-    complain_at (loc, _("symbol %s redefined"), sym->tag);
+    {
+      complain_at (loc, _("symbol %s redefined"), sym->tag);
+      sym->declared = false;
+    }

 
   if (class == nterm_sym && sym->class != nterm_sym)
     sym->number = nvars++;
 
   if (class == nterm_sym && sym->class != nterm_sym)
     sym->number = nvars++;


@@ -161,6 +324,13 @@ symbol_class_set (symbol *sym, symbol_class class, location loc)
     sym->number = ntokens++;
 
   sym->class = class;
     sym->number = ntokens++;
 
   sym->class = class;

+
+  if (declaring)
+    {
+      if (sym->declared)
+       warn_at (loc, _("symbol %s redeclared"), sym->tag);
+      sym->declared = true;
+    }

 }
 
 
 }
 
 


@@ -171,14 +341,19 @@ symbol_class_set (symbol *sym, symbol_class class, location loc)
 void
 symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 {
 void
 symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 {

-  if (sym->class != token_sym)
-    abort ();
+  int *user_token_numberp;
+
+  aver (sym->class == token_sym);

 
 

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

-  sym->user_token_number = user_token_number;
+  *user_token_numberp = user_token_number;

   /* User defined $end token? */
   if (user_token_number == 0)
     {
   /* User defined $end token? */
   if (user_token_number == 0)
     {


@@ -221,7 +396,7 @@ symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
 
 /*------------------------------------------------------------------.
 | Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |
 
 /*------------------------------------------------------------------.
 | Declare the new symbol SYM.  Make it an alias of SYMVAL, and type |

-| them with TYPENAME.                                               |
+| SYMVAL with SYM's type.                                           |

 `------------------------------------------------------------------*/
 
 void
 `------------------------------------------------------------------*/
 
 void


@@ -229,10 +404,10 @@ 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"),
 {
   if (symval->alias)
     warn_at (loc, _("symbol `%s' used more than once as a literal string"),

-         symval->tag);
+            symval->tag);

   else if (sym->alias)
     warn_at (loc, _("symbol `%s' given more than one literal string"),
   else if (sym->alias)
     warn_at (loc, _("symbol `%s' given more than one literal string"),

-         sym->tag);
+            sym->tag);

   else
     {
       symval->class = token_sym;
   else
     {
       symval->class = token_sym;


@@ -240,13 +415,8 @@ symbol_make_alias (symbol *sym, symbol *symval, location loc)
       sym->user_token_number = USER_NUMBER_ALIAS;
       symval->alias = sym;
       sym->alias = symval;
       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;
+      symval->number = sym->number;
+      symbol_type_set (symval, sym->type_name, loc);

     }
 }
 
     }
 }
 


@@ -256,45 +426,58 @@ symbol_make_alias (symbol *sym, symbol *symval, location loc)
 | associativity.                                           |
 `---------------------------------------------------------*/
 
 | associativity.                                           |
 `---------------------------------------------------------*/
 

-static inline bool
+static inline void

 symbol_check_alias_consistency (symbol *this)
 {
 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_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 (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)
-       {
-         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;
-       }
+
+  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)
 {
 }
 
 static bool
 symbol_check_alias_consistency_processor (void *this,
                                          void *null ATTRIBUTE_UNUSED)
 {

-  return symbol_check_alias_consistency (this);
+  symbol_check_alias_consistency (this);
+  return true;

 }
 
 
 }
 
 


@@ -321,8 +504,7 @@ symbol_pack (symbol *this)
            this->number = this->alias->number = 0;
          else
            {
            this->number = this->alias->number = 0;
          else
            {

-             if (this->alias->number == NUMBER_UNDEFINED)
-               abort ();
+             aver (this->alias->number != NUMBER_UNDEFINED);

              this->number = this->alias->number;
            }
        }
              this->number = this->alias->number;
            }
        }


@@ -331,10 +513,7 @@ symbol_pack (symbol *this)
        return true;
     }
   else /* this->class == token_sym */
        return true;
     }
   else /* this->class == token_sym */

-    {
-      if (this->number == NUMBER_UNDEFINED)
-       abort ();
-    }
+    aver (this->number != NUMBER_UNDEFINED);

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


@@ -380,14 +559,15 @@ symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
 }
 
 
 }
 
 

-/*----------------------.
-| 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;
 #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)
 
 static inline bool
 hash_compare_symbol (const symbol *m1, const symbol *m2)


@@ -396,25 +576,50 @@ hash_compare_symbol (const symbol *m1, const symbol *m2)
   return UNIQSTR_EQ (m1->tag, m2->tag);
 }
 
   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_symbol_comparator (void const *m1, void const *m2)
 {
   return hash_compare_symbol (m1, m2);
 }
 
 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)
+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)

 {
   /* Since tags are unique, we can hash the pointer itself.  */
   return ((uintptr_t) m->tag) % 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)
+static inline size_t
+hash_semantic_type (const semantic_type *m, size_t 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);
 }
 
 {
   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.  |
 
 /*-------------------------------.
 | Create the symbol hash table.  |


@@ -428,6 +633,11 @@ symbols_new (void)
                                  hash_symbol_hasher,
                                  hash_symbol_comparator,
                                  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);

 }
 
 
 }
 
 


@@ -437,13 +647,11 @@ symbols_new (void)
 `----------------------------------------------------------------*/
 
 symbol *
 `----------------------------------------------------------------*/
 
 symbol *

-symbol_get (const char *key, location loc)
+symbol_from_uniqstr (const uniqstr key, location loc)

 {
   symbol probe;
   symbol *entry;
 
 {
   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);
 
   probe.tag = key;
   entry = hash_lookup (symbol_table, &probe);
 


@@ -457,6 +665,54 @@ symbol_get (const char *key, location loc)
 }
 
 
 }
 
 

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


@@ -471,13 +727,18 @@ dummy_symbol_get (location loc)
 
   symbol *sym;
 
 
   symbol *sym;
 

-  sprintf (buf, "@%d", ++dummy_count);
+  sprintf (buf, "$@%d", ++dummy_count);

   sym = symbol_get (buf, loc);
   sym->class = nterm_sym;
   sym->number = nvars++;
   return sym;
 }
 
   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.  |
 
 /*-------------------.
 | Free the symbols.  |


@@ -487,6 +748,7 @@ void
 symbols_free (void)
 {
   hash_free (symbol_table);
 symbols_free (void)
 {
   hash_free (symbol_table);

+  hash_free (semantic_type_table);

   free (symbols);
 }
 
   free (symbols);
 }
 


@@ -558,7 +820,8 @@ symbols_token_translations_init (void)
        max_user_token_number = this->user_token_number;
     }
 
        max_user_token_number = this->user_token_number;
     }
 

-  CALLOC (token_translations, 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.
 
   /* Initialize all entries for literal tokens to 2, the internal
      token number for $undefined, which represents all invalid inputs.


@@ -577,11 +840,35 @@ symbols_token_translations_init (void)
 void
 symbols_pack (void)
 {
 void
 symbols_pack (void)
 {

-  CALLOC (symbols, nsyms);
-

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

+
+  symbols = xcalloc (nsyms, sizeof *symbols);

   symbols_do (symbol_pack_processor, NULL);
 
   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)
   symbols_token_translations_init ();
 
   if (startsymbol->class == unknown_sym)


@@ -593,3 +880,61 @@ symbols_pack (void)
              _("the start symbol %s is a token"),
              startsymbol->tag);
 }
              _("the start symbol %s is a token"),
              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;
+}
+