X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/a945ec3929db92bcebd8c93f2842ff6b2ea84dd4..0906b12cd56f9777fb684b8a257a0e56c090a93c:/src/symtab.c?ds=sidebyside

diff --git a/src/symtab.c b/src/symtab.c
index ef03b284..b8074a0a 100644
--- a/src/symtab.c
+++ b/src/symtab.c
@@ -1,57 +1,75 @@
-/* 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, 2000-2002, 2004-2012 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 "complain.h"
-#include "symtab.h"
 #include "gram.h"
+#include "symtab.h"
+
+/*-------------------------------------------------------------------.
+| Symbols sorted by tag.  Allocated by the first invocation of       |
+| symbols_do, after which no more symbols should be created.         |
+`-------------------------------------------------------------------*/
+
+static symbol **symbols_sorted = NULL;
+static symbol **semantic_types_sorted = NULL;
 
 /*------------------------.
 | 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;
+
 
 /*---------------------------------.
 | 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);
+
+  uniqstr_assert (tag);
 
-  res->tag = xstrdup (tag);
-  res->location = location;
+  /* If the tag is not a string (starts with a double quote), check
+     that it is valid for Yacc. */
+  if (tag[0] != '\"' && tag[0] != '\'' && strchr (tag, '-'))
+    complain (&loc, Wyacc,
+              _("POSIX Yacc forbids dashes in symbol names: %s"), tag);
+
+  res->tag = tag;
+  res->location = loc;
 
   res->type_name = NULL;
-  res->destructor = NULL;
-  res->printer = NULL;
+  for (int i = 0; i < CODE_PROPS_SIZE; ++i)
+    code_props_none_init (&res->props[i]);
 
   res->number = NUMBER_UNDEFINED;
   res->prec = 0;
@@ -60,205 +78,399 @@ symbol_new (const char *tag, location_t location)
 
   res->alias = NULL;
   res->class = unknown_sym;
+  res->status = undeclared;
 
+  if (nsyms == SYMBOL_NUMBER_MAXIMUM)
+    complain (NULL, fatal, _("too many symbols in input grammar (limit is %d)"),
+              SYMBOL_NUMBER_MAXIMUM);
   nsyms++;
   return res;
 }
 
+char const *
+code_props_type_string (code_props_type kind)
+{
+  switch (kind)
+    {
+    case destructor:
+      return "%destructor";
+    case printer:
+      return "%printer";
+    }
+  assert (0);
+}
 
-/*------------------------------------------------------------------.
-| Set the TYPE_NAME associated to SYMBOL.  Does nothing if passed 0 |
-| as TYPE_NAME.                                                     |
-`------------------------------------------------------------------*/
+/*----------------------------------------.
+| Create a new semantic type, named TAG.  |
+`----------------------------------------*/
+
+static semantic_type *
+semantic_type_new (uniqstr tag, const location *loc)
+{
+  semantic_type *res = xmalloc (sizeof *res);
+
+  uniqstr_assert (tag);
+  res->tag = tag;
+  if (loc)
+    res->location = *loc;
+  for (int i = 0; i < CODE_PROPS_SIZE; ++i)
+    code_props_none_init (&res->props[i]);
+
+  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->props[Attr].code)                                              \
+    fprintf (f, " %s { %s }", #Attr, s->props[Attr].code)
 
 void
-symbol_type_set (symbol_t *symbol, char *type_name, location_t location)
+symbol_print (symbol const *s, FILE *f)
 {
-  if (type_name)
+  if (s)
     {
-      if (symbol->type_name)
-	complain_at (location,
-		     _("type redeclaration for %s"), symbol->tag);
-      symbol->type_name = type_name;
+      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 DESTRUCTOR associated to SYMBOL.  Do nothing if passed 0.  |
-`-------------------------------------------------------------------*/
+
+/*----------------------------------.
+| Whether S is a valid identifier.  |
+`----------------------------------*/
+
+static bool
+is_identifier (uniqstr s)
+{
+  static char const alphanum[26 + 26 + 1 + 10] =
+    "abcdefghijklmnopqrstuvwxyz"
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+    "_"
+    "0123456789";
+  if (!s || ! memchr (alphanum, *s, sizeof alphanum - 10))
+    return false;
+  for (++s; *s; ++s)
+    if (! memchr (alphanum, *s, sizeof alphanum))
+      return false;
+  return true;
+}
+
+
+/*-----------------------------------------------.
+| Get the identifier associated to this symbol.  |
+`-----------------------------------------------*/
+uniqstr
+symbol_id_get (symbol const *sym)
+{
+  aver (sym->user_token_number != USER_NUMBER_HAS_STRING_ALIAS);
+  if (sym->alias)
+    sym = sym->alias;
+  return is_identifier (sym->tag) ? sym->tag : 0;
+}
+
+
+/*------------------------------------------------------------------.
+| 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)
+{
+  unsigned i = 0;
+  complain_indent (&second, complaint, &i,
+                   _("%s redeclaration for %s"), what, s->tag);
+  i += SUB_INDENT;
+  complain_indent (&first, complaint, &i,
+                   _("previous declaration"));
+}
+
+static void
+semantic_type_redeclaration (semantic_type *s, const char *what, location first,
+                             location second)
+{
+  unsigned i = 0;
+  complain_indent (&second, complaint, &i,
+                   _("%s redeclaration for <%s>"), what, s->tag);
+  i += SUB_INDENT;
+  complain_indent (&first, complaint, &i,
+                   _("previous declaration"));
+}
+
+
+
+/*-----------------------------------------------------------------.
+| Set the TYPE_NAME associated with SYM.  Does nothing if passed 0 |
+| as TYPE_NAME.                                                    |
+`-----------------------------------------------------------------*/
 
 void
-symbol_destructor_set (symbol_t *symbol, char *destructor, location_t location)
+symbol_type_set (symbol *sym, uniqstr type_name, location loc)
 {
-  if (destructor)
+  if (type_name)
     {
-      if (symbol->destructor)
-	complain_at (location,
-		     _("%s redeclaration for %s"),
-		     "%destructor", symbol->tag);
-      symbol->destructor = destructor;
-      symbol->destructor_location = location;
+      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;
     }
 }
 
+/*--------------------------------------------------------.
+| Set the DESTRUCTOR or PRINTER associated with the SYM.  |
+`--------------------------------------------------------*/
 
-/*----------------------------------------------------------------.
-| Set the PRITNER associated to SYMBOL.  Do nothing if passed 0.  |
-`----------------------------------------------------------------*/
+void
+symbol_code_props_set (symbol *sym, code_props_type kind,
+                       code_props const *code)
+{
+  if (sym->props[kind].code)
+    symbol_redeclaration (sym, code_props_type_string (kind),
+                          sym->props[kind].location,
+                          code->location);
+  sym->props[kind] = *code;
+}
+
+/*-----------------------------------------------------.
+| Set the DESTRUCTOR or PRINTER associated with TYPE.  |
+`-----------------------------------------------------*/
 
 void
-symbol_printer_set (symbol_t *symbol, char *printer, location_t location)
+semantic_type_code_props_set (semantic_type *type,
+                              code_props_type kind,
+                              code_props const *code)
+{
+  if (type->props[kind].code)
+    semantic_type_redeclaration (type, code_props_type_string (kind),
+                                 type->props[kind].location,
+                                 code->location);
+  type->props[kind] = *code;
+}
+
+/*---------------------------------------------------.
+| Get the computed %destructor or %printer for SYM.  |
+`---------------------------------------------------*/
+
+code_props *
+symbol_code_props_get (symbol *sym, code_props_type kind)
 {
-  if (printer)
+  /* Per-symbol code props.  */
+  if (sym->props[kind].code)
+    return &sym->props[kind];
+
+  /* Per-type code props.  */
+  if (sym->type_name)
     {
-      if (symbol->printer)
-	complain_at (location,
-		     _("%s redeclaration for %s"),
-		     "%printer", symbol->tag);
-      symbol->printer = printer;
-      symbol->printer_location = location;
+      code_props *code =
+        &semantic_type_get (sym->type_name, NULL)->props[kind];
+      if (code->code)
+        return code;
     }
-}
 
+  /* Apply default code props's only to user-defined symbols.  */
+  if (sym->tag[0] != '$' && sym != errtoken)
+    {
+      code_props *code =
+        &semantic_type_get (sym->type_name ? "*" : "", NULL)->props[kind];
+      if (code->code)
+        return code;
+    }
+  return &code_props_none;
+}
 
-/*------------------------------------------------------------------.
-| Set the PRECEDENCE associated to SYMBOL.  Does nothing if invoked |
-| with UNDEF_ASSOC as ASSOC.                                        |
-`------------------------------------------------------------------*/
+/*-----------------------------------------------------------------.
+| Set the PRECEDENCE associated with SYM.  Does nothing if invoked |
+| with UNDEF_ASSOC as ASSOC.                                       |
+`-----------------------------------------------------------------*/
 
 void
-symbol_precedence_set (symbol_t *symbol,
-		       int prec, assoc_t assoc, location_t location)
+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);
-      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, location);
+  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, location_t location)
+symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
 {
-  if (symbol->class != unknown_sym && symbol->class != class)
-    complain_at (location, _("symbol %s redefined"), symbol->tag);
+  bool warned = false;
+  if (sym->class != unknown_sym && sym->class != class)
+    {
+      complain (&loc, complaint, _("symbol %s redefined"), sym->tag);
+      // Don't report both "redefined" and "redeclared".
+      warned = true;
+    }
+
+  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->status == declared && !warned)
+        complain (&loc, Wother, _("symbol %s redeclared"), sym->tag);
+      sym->status = declared;
+    }
 }
 
 
-/*-------------------------------------------------.
-| 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, location_t location)
+symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
 {
-  assert (symbol->class == token_sym);
-
-  if (symbol->user_token_number != USER_NUMBER_UNDEFINED
-      && symbol->user_token_number != user_token_number)
-    complain_at (location, _("redefining user token number of %s"),
-		 symbol->tag);
+  int *user_token_numberp;
 
-  symbol->user_token_number = user_token_number;
-  /* User defined EOF token? */
+  if (sym->user_token_number != USER_NUMBER_HAS_STRING_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 (&loc, complaint, _("redefining user token number of %s"),
+              sym->tag);
+
+  *user_token_numberp = user_token_number;
+  /* User defined $end token? */
   if (user_token_number == 0)
     {
-      eoftoken = symbol;
-      eoftoken->number = 0;
+      endtoken = sym;
       /* It is always mapped to 0, so it was already counted in
-	 NTOKENS.  */
-      --ntokens;
+         NTOKENS.  */
+      if (endtoken->number != NUMBER_UNDEFINED)
+        --ntokens;
+      endtoken->number = 0;
     }
 }
 
 
-/*------------.
-| Free THIS.  |
-`------------*/
+/*----------------------------------------------------------.
+| If SYM is not defined, report an error, and consider it a |
+| nonterminal.                                              |
+`----------------------------------------------------------*/
 
-static void
-symbol_free (symbol_t *this)
+static inline bool
+symbol_check_defined (symbol *sym)
 {
-#if 0
-  /* This causes crashes because one string can appear more
-     than once.  */
-  XFREE (this->type_name);
-#endif
-  XFREE (this->tag);
-  XFREE (this);
-}
+  if (sym->class == unknown_sym)
+    {
+      assert (sym->status != declared);
+      complain (&sym->location,
+                sym->status == needed ? complaint : Wother,
+                _("symbol %s is used, but is not defined as a token"
+                  " and has no rules"),
+                  sym->tag);
+      sym->class = nterm_sym;
+      sym->number = nvars++;
+    }
 
+  for (int i = 0; i < 2; ++i)
+    symbol_code_props_get (sym, i)->is_used = true;
 
-/*-----------------------------------------------------------.
-| If THIS is not defined, report an error, and consider it a |
-| nonterminal.                                               |
-`-----------------------------------------------------------*/
+  /* Set the semantic type status associated to the current symbol to
+     'declared' so that we could check semantic types unnecessary uses. */
+  if (sym->type_name)
+    {
+      semantic_type *sem_type = semantic_type_get (sym->type_name, NULL);
+      if (sem_type)
+        sem_type->status = declared;
+    }
 
-static bool
-symbol_check_defined (symbol_t *this)
+  return true;
+}
+
+static inline bool
+semantic_type_check_defined (semantic_type *sem_type)
 {
-  if (this->class == unknown_sym)
+  // <*> and <> do not have to be "declared".
+  if (sem_type->status == declared
+      || !*sem_type->tag
+      || STREQ(sem_type->tag, "*"))
     {
-      complain_at
-	(this->location,
-	 _("symbol %s is used, but is not defined as a token and has no rules"),
-	 this->tag);
-      this->class = nterm_sym;
-      this->number = nvars++;
+      for (int i = 0; i < 2; ++i)
+        if (sem_type->props[i].kind != CODE_PROPS_NONE
+            && ! sem_type->props[i].is_used)
+          complain (&sem_type->location, Wother,
+                    _("useless %s for type <%s>"),
+                    code_props_type_string (i), sem_type->tag);
     }
+  else
+    complain (&sem_type->location, Wother,
+              _("type <%s> is used, but is not associated to any symbol"),
+              sem_type->tag);
 
-  return TRUE;
+  return true;
 }
 
+static bool
+symbol_check_defined_processor (void *sym, void *null ATTRIBUTE_UNUSED)
+{
+  return symbol_check_defined (sym);
+}
+
+static bool
+semantic_type_check_defined_processor (void *sem_type,
+                                       void *null ATTRIBUTE_UNUSED)
+{
+  return semantic_type_check_defined (sem_type);
+}
 
-/*-------------------------------------------------------------------.
-| Declare the new SYMBOL.  Make it an alias of SYMVAL, and type them |
-| with TYPENAME.                                                     |
-`-------------------------------------------------------------------*/
 
 void
-symbol_make_alias (symbol_t *symbol, symbol_t *symval, location_t loc)
-{
-  if (symval->alias)
-    warn_at (loc, _("symbol `%s' used more than once as a literal string"),
-	  symval->tag);
-  else if (symbol->alias)
-    warn_at (loc, _("symbol `%s' given more than one literal string"),
-	  symbol->tag);
+symbol_make_alias (symbol *sym, symbol *str, location loc)
+{
+  if (str->alias)
+    complain (&loc, Wother,
+              _("symbol %s used more than once as a literal string"), str->tag);
+  else if (sym->alias)
+    complain (&loc, Wother,
+              _("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;
+      str->class = token_sym;
+      str->user_token_number = sym->user_token_number;
+      sym->user_token_number = USER_NUMBER_HAS_STRING_ALIAS;
+      str->alias = sym;
+      sym->alias = str;
+      str->number = sym->number;
+      symbol_type_set (str, sym->type_name, loc);
     }
 }
 
@@ -268,38 +480,49 @@ symbol_make_alias (symbol_t *symbol, symbol_t *symval, location_t loc)
 | 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 *sym = this;
+  symbol *str = this->alias;
+
+  /* Check only the symbol in the symbol-string pair.  */
+  if (!(this->alias
+        && this->user_token_number == USER_NUMBER_HAS_STRING_ALIAS))
+    return;
+
+  if (str->type_name != sym->type_name)
+    {
+      if (str->type_name)
+        symbol_type_set (sym, str->type_name, str->type_location);
+      else
+        symbol_type_set (str, sym->type_name, sym->type_location);
+    }
+
+
+  for (int i = 0; i < CODE_PROPS_SIZE; ++i)
+    if (str->props[i].code)
+      symbol_code_props_set (sym, i, &str->props[i]);
+    else if (sym->props[i].code)
+      symbol_code_props_set (str, i, &sym->props[i]);
+
+  if (sym->prec || str->prec)
     {
-      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;
-	}
+      if (str->prec)
+        symbol_precedence_set (sym, str->prec, str->assoc,
+                               str->prec_location);
+      else
+        symbol_precedence_set (str, sym->prec, sym->assoc,
+                               sym->prec_location);
     }
-  return TRUE;
+}
+
+static bool
+symbol_check_alias_consistency_processor (void *this,
+                                          void *null ATTRIBUTE_UNUSED)
+{
+  symbol_check_alias_consistency (this);
+  return true;
 }
 
 
@@ -308,90 +531,142 @@ 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)
 {
+  aver (this->number != NUMBER_UNDEFINED);
   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 == eoftoken || this->alias == eoftoken)
-	    this->number = this->alias->number = 0;
-	  else
-	    {
-	      assert (this->alias->number != NUMBER_UNDEFINED);
-	      this->number = this->alias->number;
-	    }
-	}
-      /* Do not do processing below for USER_NUMBER_ALIASs.  */
-      if (this->user_token_number == USER_NUMBER_ALIAS)
-	return TRUE;
-    }
-  else /* this->class == token_sym */
-    {
-      assert (this->number != NUMBER_UNDEFINED);
-    }
+    this->number += ntokens;
+  else if (this->user_token_number == USER_NUMBER_HAS_STRING_ALIAS)
+    return true;
 
   symbols[this->number] = this;
-  return TRUE;
+  return true;
+}
+
+static bool
+symbol_pack_processor (void *this, void *null ATTRIBUTE_UNUSED)
+{
+  return symbol_pack (this);
 }
 
 
+static void
+user_token_number_redeclaration (int num, symbol *first, symbol *second)
+{
+  unsigned i = 0;
+  /* User token numbers are not assigned during the parsing, but in a
+     second step, via a traversal of the symbol table sorted on tag.
 
+     However, error messages make more sense if we keep the first
+     declaration first.  */
+  if (location_cmp (first->location, second->location) > 0)
+    {
+      symbol* tmp = first;
+      first = second;
+      second = tmp;
+    }
+  complain_indent (&second->location, complaint, &i,
+                   _("user token number %d redeclaration for %s"),
+                   num, second->tag);
+  i += SUB_INDENT;
+  complain_indent (&first->location, complaint, &i,
+                   _("previous declaration for %s"),
+                   first->tag);
+}
 
 /*--------------------------------------------------.
 | 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
-      && this->user_token_number != USER_NUMBER_ALIAS)
+      && this->user_token_number != USER_NUMBER_HAS_STRING_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);
+        user_token_number_redeclaration
+          (this->user_token_number,
+           symbols[token_translations[this->user_token_number]],
+           this);
 
       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 strcmp (m1->tag, m2->tag) ? FALSE : TRUE;
+  return hash_compare_symbol (m1, m2);
 }
 
-static unsigned int
-hash_symbol_t (const symbol_t *m, unsigned int tablesize)
+static bool
+hash_semantic_type_comparator (void const *m1, void const *m2)
 {
-  return hash_string (m->tag, tablesize);
+  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;
+}
+
+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);
+}
+
+static size_t
+hash_semantic_type_hasher (void const *m, size_t tablesize)
+{
+  return hash_semantic_type (m, tablesize);
+}
 
 /*-------------------------------.
 | Create the symbol hash table.  |
@@ -401,10 +676,15 @@ void
 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);
+                                  NULL,
+                                  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);
 }
 
 
@@ -413,48 +693,102 @@ symbols_new (void)
 | yet, create it.                                                 |
 `----------------------------------------------------------------*/
 
-symbol_t *
-symbol_get (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;
 
-  /* Keep the symbol in a printable form.  */
-  key = quotearg_style (escape_quoting_style, key);
-  (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);
-      hash_insert (symbol_table, entry);
+      aver (!symbols_sorted);
+      entry = symbol_new (key, loc);
+      if (!hash_insert (symbol_table, entry))
+        xalloc_die ();
+    }
+  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, const location *loc)
+{
+  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, loc);
+      if (!hash_insert (semantic_type_table, entry))
+        xalloc_die ();
     }
   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, const location *loc)
+{
+  return semantic_type_from_uniqstr (uniqstr_new (key), loc);
+}
+
+
 /*------------------------------------------------------------------.
 | Generate a dummy nonterminal, whose name cannot conflict with the |
 | user's names.                                                     |
 `------------------------------------------------------------------*/
 
-symbol_t *
-dummy_symbol_get (location_t location)
+symbol *
+dummy_symbol_get (location loc)
 {
   /* Incremented for each generated symbol.  */
   static int dummy_count = 0;
   static char buf[256];
 
-  symbol_t *sym;
+  symbol *sym;
 
-  sprintf (buf, "@%d", ++dummy_count);
-  sym = symbol_get (buf, location);
+  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.  |
@@ -464,7 +798,9 @@ void
 symbols_free (void)
 {
   hash_free (symbol_table);
+  hash_free (semantic_type_table);
   free (symbols);
+  free (symbols_sorted);
 }
 
 
@@ -473,14 +809,35 @@ symbols_free (void)
 | terminals.                                                     |
 `---------------------------------------------------------------*/
 
-void
-symbols_do (symbol_processor processor, void *processor_data)
+static int
+symbols_cmp (symbol const *a, symbol const *b)
 {
-  hash_do_for_each (symbol_table,
-		    (Hash_processor) processor,
-		    processor_data);
+  return strcmp (a->tag, b->tag);
 }
 
+static int
+symbols_cmp_qsort (void const *a, void const *b)
+{
+  return symbols_cmp (*(symbol * const *)a, *(symbol * const *)b);
+}
+
+static void
+symbols_do (Hash_processor processor, void *processor_data,
+            struct hash_table *table, symbol **sorted)
+{
+  size_t count = hash_get_n_entries (table);
+  if (!sorted)
+    {
+      sorted = xnmalloc (count, sizeof *sorted);
+      hash_get_entries (table, (void**)sorted, count);
+      qsort (sorted, count, sizeof *sorted, symbols_cmp_qsort);
+    }
+  {
+    size_t i;
+    for (i = 0; i < count; ++i)
+      processor (sorted[i], processor_data);
+  }
+}
 
 /*--------------------------------------------------------------.
 | Check that all the symbols are defined.  Report any undefined |
@@ -490,7 +847,10 @@ 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,
+              symbol_table, symbols_sorted);
+  symbols_do (semantic_type_check_defined_processor, NULL,
+              semantic_type_table, semantic_types_sorted);
 }
 
 /*------------------------------------------------------------------.
@@ -501,7 +861,7 @@ 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
@@ -509,14 +869,14 @@ 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;
-	}
+        {
+          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.  */
@@ -530,21 +890,22 @@ 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;
+        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;
+        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.  */
+  /* Initialize all entries for literal tokens to 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, NULL);
+  symbols_do (symbol_translation_processor, NULL,
+              symbol_table, symbols_sorted);
 }
 
 
@@ -556,19 +917,44 @@ 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,
+              symbol_table, symbols_sorted);
+
+  symbols = xcalloc (nsyms, sizeof *symbols);
+  symbols_do (symbol_pack_processor, NULL, symbol_table, symbols_sorted);
+
+  /* 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"),
-	      startsymbol->tag);
+    complain (&startsymbol_location, fatal,
+              _("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);
+    complain (&startsymbol_location, fatal,
+              _("the start symbol %s is a token"),
+              startsymbol->tag);
 }