/* Symbol table manager for Bison.

   Copyright (C) 1984, 1989, 2000-2002, 2004-2013 Free Software
   Foundation, Inc.

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

   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 3 of the License, or
   (at your option) any later version.

   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 this program.  If not, see <http://www.gnu.org/licenses/>.  */

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

#include <hash.h>

#include "complain.h"
#include "gram.h"
#include "symtab.h"
#include "symlist.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 *errtoken = NULL;
symbol *undeftoken = NULL;
symbol *endtoken = NULL;
symbol *accept = NULL;
symbol *startsymbol = NULL;
location startsymbol_location;

/*---------------------------.
| Precedence relation graph. |
`---------------------------*/

static symgraph **prec_nodes;

/*-----------------------------------.
| Store which associativity is used. |
`-----------------------------------*/

bool *used_assoc = NULL;

/*-------------------------------------------------------------.
| The current precedence group of symbols. Used by the parser. |
`-------------------------------------------------------------*/

static symgroup *current_group = NULL;

/*-------------------------------------------------------.
| The list of symbols declared in the current statement. |
`-------------------------------------------------------*/

static symbol_list *current_prec_declaration = NULL;

/*-------------------------------------------------.
| A counter to distinguish precedence declarations |
`-------------------------------------------------*/

static int current_prec_level = 0;

/*-----------------------------.
| Constructor for a prec_link. |
`-----------------------------*/

static prec_link *
prec_link_new (prec_node *to, bool transitive)
{
  prec_link *res = malloc (sizeof *res);
  res->target = to;
  res->transitive = transitive;
  res->next = NULL;
  return res;
}

/*-------------------------------------.
| Destructor for a simple symbol list. |
`-------------------------------------*/

static void
symbol_list_prec_free (symbol_list *l)
{
  if (l)
    {
      symbol_list_prec_free (l->next);
      free (l);
    }
}

/*------------------------------------------------.
| Check if PARENT has a higher priority than SON. |
`------------------------------------------------*/

bool
is_prec_superior (prec_node *parent, prec_node *son)
{
  prec_link *l;
  for (l = parent->sons; l; l = l->next)
    if (l->target == son)
      return true;
  return false;
}

/*-----------------------------------------.
| Check if S1 has the same priority as S2. |
`-----------------------------------------*/

bool
is_prec_equal (prec_node *s1, prec_node *s2)
{
  prec_link *l;
  if (s1 == s2)
    return true;
  for (l = s1->equals; l; l = l->next)
    if (l->target == s2)
      return true;
  return false;
}

static inline void
complain_contradicting_prec (location *loc, uniqstr s1, uniqstr s2, char c1,
                             char c2)
{
  complain (loc, Wprecedence, _("contradicting declaration: %s %c %s is in "
            "conflict with the previous declaration: %s %c %s"), s1, c1, s2,
            s1, c2, s2);
}

/*-----------------------------------------------------------------------.
| Compare LINK with TARGET, and return whether they are equal.           |
| In case of equality, complain of the duplicate precedence declaration. |
`-----------------------------------------------------------------------*/

static inline bool
is_prec_target (prec_node *l, prec_node *target, uniqstr from, char c,
                location loc)
{
  if (l == target)
    {
      complain (&loc, Wprecedence, _("duplicate declaration of the precedence "
                                     "relationship %s %c %s"), from, c,
                target->symbol->tag);
      return true;
    }
  return false;
}

/*-----------------------------------------.
| Add a precedence relationship FROM > TO. |
`-----------------------------------------*/

static void
add_prec_link (prec_node *from, prec_node *to, bool transitive, location loc)
{
  if (is_prec_superior (to, from))
    complain_contradicting_prec(&loc, from->symbol->tag, to->symbol->tag,
                                '>', '<');
  else if (is_prec_equal (from, to))
    complain_contradicting_prec(&loc, from->symbol->tag, to->symbol->tag,
                                '>', '=');
  else
    {
      if (from->sons)
        {
          if (is_prec_target (from->sons->target, to, from->symbol->tag, '>',
                              loc))
            return;

          prec_link *son = from->sons;
          for (; son->next; son = son->next)
            if (is_prec_target (son->next->target, to, from->symbol->tag, '>',
                                loc))
              return;
          son->next = prec_link_new (to, transitive);
        }
      else
        from->sons = prec_link_new (to, transitive);
    }
}

/*-------------------------------------------------.
| Add a precedence relationship S1 == S2, one way. |
`-------------------------------------------------*/

static void
create_prec_equal_link (prec_node *s1, prec_node *s2, bool transitive,
                        location loc)
{
  if (s1->equals)
    {
            if (is_prec_target (s1->equals->target, s2, s1->symbol->tag, '=',
                                loc))
              return;
      prec_link *eq = s1->equals;
      for (; eq->next; eq = eq->next)
            if (is_prec_target (eq->next->target, s2, s1->symbol->tag, '=',
                                loc))
              return;
      eq->next = prec_link_new (s2, transitive);
    }
  else
    s1->equals = prec_link_new (s2, transitive);
}


/*---------------------------------------------------.
| Add a precedence relationship S1 == S2, both ways. |
`---------------------------------------------------*/

static void
add_prec_equal_link (prec_node *s1, prec_node *s2, bool transitive,
                     location loc)
{
  if (is_prec_superior (s2, s1))
    complain_contradicting_prec(&loc, s1->symbol->tag, s2->symbol->tag,
                                '=', '>');
  else if (is_prec_superior (s1, s2))
    complain_contradicting_prec(&loc, s1->symbol->tag, s2->symbol->tag,
                                '=', '<');
  create_prec_equal_link (s1, s2, transitive, loc);
  create_prec_equal_link (s2, s1, transitive, loc);
}


/* The function to use to register \a c type relations.  */
typedef void (*add_link_t) (prec_node *, prec_node *, bool, location);
static add_link_t
add_link_function (prec_rel_comparator c)
{
  switch (c)
    {
    case prec_superior_strict:
    case prec_superior:
      return &add_prec_link;
    case prec_equal:
      return &add_prec_equal_link;
    }
  abort ();
}


/*---------------------------------------------------------------------.
| Handle the precedence declaration between the elements of S1 and S2. |
`---------------------------------------------------------------------*/

void
declare_precedence_relation (symbol_list *s1, symbol_list *s2,
                             prec_rel_comparator c, location loc)
{
  void (*functionPtr) (prec_node *, prec_node *, bool, location)
    = add_link_function (c);
  bool transitive = c != prec_superior_strict;
  for (symbol_list *l1 = s1; l1; l1 = l1->next)
    for (symbol_list *l2 = s2; l2; l2 = l2->next)
      (*functionPtr)(l1->content.sym->content->prec_node,
                     l2->content.sym->content->prec_node, transitive, loc);
  symbol_list_free (s1);
  symbol_list_free (s2);
}

/*----------------------------------------------.
| Get the list of symbols contained in a group. |
`----------------------------------------------*/

symbol_list *
expand_symbol_group (symgroup *group, location loc)
{
  symbol_list *l = NULL;
  for (sym_content *s = group->symbol_list; s; s = s->group_next)
    l = symbol_list_append (l, symbol_list_sym_new (s->symbol, loc));
  return l;
}

/*------------------------------------------------------------------------.
| Add a symbol to the current declaration group, and declare the implicit |
| precedence links. SAME_LINE is true if the symbol was declared in the   |
| same statement as the previous one (same precedence level).             |
`------------------------------------------------------------------------*/

void
add_to_current_group (sym_content *s, bool same_line)
{
  if (!same_line)
    for (symbol_list *l = current_prec_declaration; l; l = l->next)
      {
        sym_content *symb = l->content.sym->content;
        if (!current_group->symbol_list)
          current_group->symbol_list = symb;
        else
          {
            sym_content *sym = current_group->symbol_list;
            while (sym->group_next)
              sym = sym->group_next;
            sym->group_next = symb;
          }
      }

  if (current_group->symbol_list)
    for (sym_content *sym = current_group->symbol_list; sym;
         sym = sym->group_next)
      add_prec_link (s->prec_node, sym->prec_node, true,
                     s->prec_node->prec_location);

  if (!same_line)
    {
      symbol_list_prec_free (current_prec_declaration);
      current_prec_declaration = malloc (sizeof *current_prec_declaration);
      current_prec_declaration->content.sym = s->symbol;
      current_prec_declaration->next = NULL;
    }
  else
    {
      symbol_list *l = current_prec_declaration;
      for (; true; l = l->next)
        {
          add_prec_equal_link (s->prec_node, l->content.sym->content->prec_node,
                               true, s->prec_node->prec_location);
          if (!l->next)
            break;
        }
      l->next = malloc (sizeof *l->next);
      l->next->content.sym = s->symbol;
      l->next->next = NULL;
    }
}

/*-----------------------------------------.
| Create a new prec_node for the symbol s. |
`-----------------------------------------*/

static prec_node *
prec_node_new (symbol * s)
{
  prec_node * res = malloc (sizeof *res);
  res->symbol = s;
  res->assoc = undef_assoc;
  res->sons = NULL;
  res-> equals = NULL;
  return res;
}


/*--------------------------.
| Create a new sym_content. |
`--------------------------*/

static sym_content *
sym_content_new (symbol *s)
{
  sym_content *res = xmalloc (sizeof *res);

  res->symbol = s;

  res->type_name = NULL;
  {
    int i;
    for (i = 0; i < CODE_PROPS_SIZE; ++i)
      code_props_none_init (&res->props[i]);
  }

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

  res->class = unknown_sym;
  res->status = undeclared;

  res->group_next = NULL;
  res->prec_node = prec_node_new (s);

  return res;
}

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

static symbol *
symbol_new (uniqstr tag, location loc)
{
  symbol *res = xmalloc (sizeof *res);
  uniqstr_assert (tag);

  /* 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->alias = NULL;
  res->content = sym_content_new (res);
  res->is_alias = false;

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

void
prec_link_free (prec_link * l)
{
  if (l)
    {
      prec_link_free (l->next);
      free (l);
    }
}

/*--------------------.
| Free one prec_node. |
`--------------------*/

static void
prec_node_free (prec_node * n)
{
  prec_link_free (n->sons);
  prec_link_free (n->equals);
  free (n);
}

/*--------------------.
| Free a sym_content. |
`--------------------*/

static void
sym_content_free (sym_content *sym)
{
  prec_node_free (sym->prec_node);
  free (sym);
}


/*---------------------------------------------------------.
| Free a symbol and its associated content if appropriate. |
`---------------------------------------------------------*/

static void
symbol_free (void *ptr)
{
  symbol *sym = (symbol *)ptr;
  if (!sym->is_alias)
    sym_content_free (sym->content);
  free (sym);
}

char const *
code_props_type_string (code_props_type kind)
{
  switch (kind)
    {
    case destructor:
      return "%destructor";
    case printer:
      return "%printer";
    }
  assert (0);
}

/*----------------------------------------.
| 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;
  res->location = loc ? *loc : empty_location;
  res->status = undeclared;
  {
    int i;
    for (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->content->Attr)                                 \
    fprintf (f, " %s { %s }", #Attr, s->content->Attr)

#define SYMBOL_CODE_PRINT(Attr)                                         \
  if (s->content->props[Attr].code)                                     \
    fprintf (f, " %s { %s }", #Attr, s->content->props[Attr].code)

void
symbol_print (symbol const *s, FILE *f)
{
  if (s)
    {
      fputs (s->tag, f);
      SYMBOL_ATTR_PRINT (type_name);
      SYMBOL_CODE_PRINT (destructor);
      SYMBOL_CODE_PRINT (printer);
    }
  else
    fputs ("<NULL>", f);
}

#undef SYMBOL_ATTR_PRINT
#undef SYMBOL_CODE_PRINT


/*----------------------------------.
| 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->content->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_type_set (symbol *sym, uniqstr type_name, location loc)
{
  if (type_name)
    {
      if (sym->content->type_name)
        symbol_redeclaration (sym, "%type", sym->content->type_location, loc);
      else
        {
          uniqstr_assert (type_name);
          sym->content->type_name = type_name;
          sym->content->type_location = loc;
        }
    }
}

/*--------------------------------------------------------.
| Set the DESTRUCTOR or PRINTER associated with the SYM.  |
`--------------------------------------------------------*/

void
symbol_code_props_set (symbol *sym, code_props_type kind,
                       code_props const *code)
{
  if (sym->content->props[kind].code)
    symbol_redeclaration (sym, code_props_type_string (kind),
                          sym->content->props[kind].location,
                          code->location);
  else
    sym->content->props[kind] = *code;
}

/*-----------------------------------------------------.
| Set the DESTRUCTOR or PRINTER associated with TYPE.  |
`-----------------------------------------------------*/

void
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);
  else
    type->props[kind] = *code;
}

/*---------------------------------------------------.
| Get the computed %destructor or %printer for SYM.  |
`---------------------------------------------------*/

code_props *
symbol_code_props_get (symbol *sym, code_props_type kind)
{
  /* Per-symbol code props.  */
  if (sym->content->props[kind].code)
    return &sym->content->props[kind];

  /* Per-type code props.  */
  if (sym->content->type_name)
    {
      code_props *code =
        &semantic_type_get (sym->content->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->content->type_name ? "*" : "",
                                             NULL)->props[kind];
      if (code->code)
        return code;
    }
  return &code_props_none;
}

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

void
symbol_precedence_set (symbol *sym, int prec, assoc a, location loc)
{
  sym_content *s = sym->content;
  if (a != undef_assoc)
    {
      if (s->prec_node->assoc != undef_assoc)
        symbol_redeclaration (sym, assoc_to_string (a),
                              s->prec_node->prec_location, loc);
      else
        {
          s->prec = prec;
          s->prec_node->assoc = a;
          s->prec_node->prec_location = loc;
          add_to_current_group (s, prec == current_prec_level);
          current_prec_level = prec;
        }
    }

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


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

void
symbol_class_set (symbol *sym, symbol_class class, location loc, bool declaring)
{
  bool warned = false;
  if (sym->content->class != unknown_sym && sym->content->class != class)
    {
      complain (&loc, complaint, _("symbol %s redefined"), sym->tag);
      /* Don't report both "redefined" and "redeclared".  */
      warned = true;
    }

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

  sym->content->class = class;

  if (declaring)
    {
      if (sym->content->status == declared && !warned)
        complain (&loc, Wother, _("symbol %s redeclared"), sym->tag);
      else
        sym->content->status = declared;
    }
}


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

void
symbol_user_token_number_set (symbol *sym, int user_token_number, location loc)
{
  int *user_token_numberp;

  user_token_numberp = &sym->content->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)
    {
      endtoken = sym->content->symbol;
      /* It is always mapped to 0, so it was already counted in
         NTOKENS.  */
      if (endtoken->content->number != NUMBER_UNDEFINED)
        --ntokens;
      endtoken->content->number = 0;
    }
}


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

static inline bool
symbol_check_defined (symbol *sym)
{
  sym_content *s = sym->content;
  if (s->class == unknown_sym)
    {
      assert (s->status != declared);
      complain (&sym->location,
                s->status == needed ? complaint : Wother,
                _("symbol %s is used, but is not defined as a token"
                  " and has no rules"),
                  sym->tag);
      s->class = nterm_sym;
      s->number = nvars++;
    }

  {
    int i;
    for (i = 0; i < 2; ++i)
      symbol_code_props_get (sym, i)->is_used = true;
  }

  /* Set the semantic type status associated to the current symbol to
     'declared' so that we could check semantic types unnecessary uses. */
  if (s->type_name)
    {
      semantic_type *sem_type = semantic_type_get (s->type_name, NULL);
      if (sem_type)
        sem_type->status = declared;
    }

  return true;
}

static inline bool
semantic_type_check_defined (semantic_type *sem_type)
{
  /* <*> and <> do not have to be "declared".  */
  if (sem_type->status == declared
      || !*sem_type->tag
      || STREQ (sem_type->tag, "*"))
    {
      int i;
      for (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;
}

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);
}


void
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
    {
      sym_content_free (str->content);
      str->content = sym->content;
      str->content->symbol = str;
      str->is_alias = true;
      str->alias = sym;
      sym->alias = str;
    }
}


/*-------------------------------------------------------------------.
| Assign a symbol number, and write the definition of the token name |
| into FDEFINES.  Put in SYMBOLS.                                    |
`-------------------------------------------------------------------*/

static inline bool
symbol_pack (symbol *this)
{
  aver (this->content->number != NUMBER_UNDEFINED);
  if (this->content->class == nterm_sym)
    this->content->number += ntokens;
  else if (this->content->user_token_number == USER_NUMBER_HAS_STRING_ALIAS)
    return true;

  symbols[this->content->number] = this->content->symbol;
  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 inline bool
symbol_translation (symbol *this)
{
  /* Non-terminal? */
  if (this->content->class == token_sym
      && !this->is_alias)
    {
      /* A token which translation has already been set?*/
      if (token_translations[this->content->user_token_number]
          != undeftoken->content->number)
        user_token_number_redeclaration
          (this->content->user_token_number,
           symbols[token_translations[this->content->user_token_number]], this);
      else
        token_translations[this->content->user_token_number]
          = this->content->number;
    }

  return true;
}

static bool
symbol_translation_processor (void *this, void *null ATTRIBUTE_UNUSED)
{
  return symbol_translation (this);
}


/*---------------------------------------.
| Symbol and semantic type hash tables.  |
`---------------------------------------*/

/* 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_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)
{
  /* 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);
}

/*-------------------------------------.
| Symbol precedence group hash table.  |
`-------------------------------------*/

static struct hash_table *group_table = NULL;

static inline bool
hash_compare_group (const symgroup *m1, const symgroup *m2)
{
  /* Since tags are unique, we can compare the pointers themselves.  */
  return UNIQSTR_EQ (m1->tag, m2->tag);
}

static bool
hash_group_comparator (void const *m1, void const *m2)
{
  return hash_compare_group (m1, m2);
}

static inline size_t
hash_group (const symgroup *m, size_t tablesize)
{
  /* Since tags are unique, we can hash the pointer itself.  */
  return ((uintptr_t) m->tag) % tablesize;
}

static size_t
hash_group_hasher (void const *m, size_t tablesize)
{
  return hash_group (m, tablesize);
}

/*-------------------------------.
| Create the symbol hash table.  |
`-------------------------------*/

void
symbols_new (void)
{
  symbol_table = hash_initialize (HT_INITIAL_CAPACITY,
                                  NULL,
                                  hash_symbol_hasher,
                                  hash_symbol_comparator,
                                  symbol_free);
  semantic_type_table = hash_initialize (HT_INITIAL_CAPACITY,
                                         NULL,
                                         hash_semantic_type_hasher,
                                         hash_semantic_type_comparator,
                                         free);
  group_table = hash_initialize (HT_INITIAL_CAPACITY,
                                  NULL,
                                  hash_group_hasher,
                                  hash_group_comparator,
                                  free);
  set_current_group (DEFAULT_GROUP_NAME, NULL);
}


/*----------------------------------------------------------------.
| Find the symbol named KEY, and return it.  If it does not exist |
| yet, create it.                                                 |
`----------------------------------------------------------------*/

symbol *
symbol_from_uniqstr (const uniqstr key, location loc)
{
  symbol probe;
  symbol *entry;

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

  if (!entry)
    {
      /* First insertion in the hash. */
      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 *
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->content->class = nterm_sym;
  sym->content->number = nvars++;
  return sym;
}

bool
symbol_is_dummy (const symbol *sym)
{
  return sym->tag[0] == '@' || (sym->tag[0] == '$' && sym->tag[1] == '@');
}

/*-------------------.
| Free the symbols.  |
`-------------------*/

void
symbols_free (void)
{
  hash_free (symbol_table);
  hash_free (semantic_type_table);
  hash_free (group_table);
  free (symbols);
  free (symbols_sorted);
  free (semantic_types_sorted);
  symbol_list_prec_free (current_prec_declaration);
}


/*---------------------------------------------------------------.
| Look for undefined symbols, report an error, and consider them |
| terminals.                                                     |
`---------------------------------------------------------------*/

static int
symbols_cmp (symbol const *a, symbol const *b)
{
  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 |
| symbols and consider them nonterminals.                       |
`--------------------------------------------------------------*/

void
symbols_check_defined (void)
{
  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);
}

/*------------------------------------------------------------------.
| Set TOKEN_TRANSLATIONS.  Check that no two symbols share the same |
| number.                                                           |
`------------------------------------------------------------------*/

static void
symbols_token_translations_init (void)
{
  bool num_256_available_p = true;
  int i;

  /* Find the highest user token number, and whether 256, the POSIX
     preferred user token number for the error token, is used.  */
  max_user_token_number = 0;
  for (i = 0; i < ntokens; ++i)
    {
      sym_content *this = symbols[i]->content;
      if (this->user_token_number != USER_NUMBER_UNDEFINED)
        {
          if (this->user_token_number > max_user_token_number)
            max_user_token_number = this->user_token_number;
          if (this->user_token_number == 256)
            num_256_available_p = false;
        }
    }

  /* If 256 is not used, assign it to error, to follow POSIX.  */
  if (num_256_available_p
      && errtoken->content->user_token_number == USER_NUMBER_UNDEFINED)
    errtoken->content->user_token_number = 256;

  /* Set the missing user numbers. */
  if (max_user_token_number < 256)
    max_user_token_number = 256;

  for (i = 0; i < ntokens; ++i)
    {
      sym_content *this = symbols[i]->content;
      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 = xnmalloc (max_user_token_number + 1,
                                 sizeof *token_translations);

  /* 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->content->number;
  symbols_do (symbol_translation_processor, NULL,
              symbol_table, &symbols_sorted);
}


/*----------------------------------------------------------------.
| Assign symbol numbers, and write definition of token names into |
| FDEFINES.  Set up vectors SYMBOL_TABLE, TAGS of symbols.        |
`----------------------------------------------------------------*/

void
symbols_pack (void)
{
  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]->content->number = writei;
            writei += 1;
          }
      }
  }
  symbols = xnrealloc (symbols, nsyms, sizeof *symbols);

  symbols_token_translations_init ();

  if (startsymbol->content->class == unknown_sym)
    complain (&startsymbol_location, fatal,
              _("the start symbol %s is undefined"),
              startsymbol->tag);
  else if (startsymbol->content->class == token_sym)
    complain (&startsymbol_location, fatal,
              _("the start symbol %s is a token"),
              startsymbol->tag);
}

/*---------------------------------.
| Initialize relation graph nodes. |
`---------------------------------*/

static void
init_prec_nodes (void)
{
  int i;
  prec_nodes = xcalloc (nsyms, sizeof *prec_nodes);
  for (i = 0; i < nsyms; ++i)
    {
      prec_nodes[i] = xmalloc (sizeof *prec_nodes[i]);
      symgraph *s = prec_nodes[i];
      s->id = i;
      s->succ = 0;
      s->pred = 0;
    }
}

/*----------------.
| Create a link.  |
`----------------*/

static symgraphlink *
symgraphlink_new (graphid id, symgraphlink *next)
{
  symgraphlink *l = xmalloc (sizeof *l);
  l->id = id;
  l->next = next;
  return l;
}


/*------------------------------------------------------------------.
| Register the second symbol of the precedence relation, and return |
| whether this relation is new.  Use only in register_precedence.   |
`------------------------------------------------------------------*/

static bool
register_precedence_second_symbol (symgraphlink **first, graphid sym)
{
  if (!*first || sym < (*first)->id)
    *first = symgraphlink_new (sym, *first);
  else
    {
      symgraphlink *slist = *first;

      while (slist->next && slist->next->id <= sym)
        slist = slist->next;

      if (slist->id == sym)
        /* Relation already present. */
        return false;

      slist->next = symgraphlink_new (sym, slist->next);
    }
  return true;
}

/*------------------------------------------------------------------.
| Register a new relation between symbols as used. The first symbol |
| has a greater precedence than the second one.                     |
`------------------------------------------------------------------*/

void
register_precedence (graphid first, graphid snd)
{
  if (!prec_nodes)
    init_prec_nodes ();
  register_precedence_second_symbol (&(prec_nodes[first]->succ), snd);
  register_precedence_second_symbol (&(prec_nodes[snd]->pred), first);
}


/*---------------------------------------.
| Deep clear a linked / adjacency list). |
`---------------------------------------*/

static void
linkedlist_free (symgraphlink *node)
{
  if (node)
    {
      while (node->next)
        {
          symgraphlink *tmp = node->next;
          free (node);
          node = tmp;
        }
      free (node);
    }
}

/*----------------------------------------------.
| Clear and destroy association tracking table. |
`----------------------------------------------*/

static void
assoc_free (void)
{
  int i;
  for (i = 0; i < nsyms; ++i)
    {
      linkedlist_free (prec_nodes[i]->pred);
      linkedlist_free (prec_nodes[i]->succ);
      free (prec_nodes[i]);
    }
  free (prec_nodes);
}

/*---------------------------------------.
| Initialize association tracking table. |
`---------------------------------------*/

static void
init_assoc (void)
{
  graphid i;
  used_assoc = xcalloc (nsyms, sizeof *used_assoc);
  for (i = 0; i < nsyms; ++i)
    used_assoc[i] = false;
}

/*------------------------------------------------------------------.
| Test if the associativity for the symbols is defined and useless. |
`------------------------------------------------------------------*/

static inline bool
is_assoc_useless (symbol *s)
{
  return s
      && s->content->prec_node->assoc != undef_assoc
      && s->content->prec_node->assoc != precedence_assoc
      && !used_assoc[s->content->number];
}

/*-------------------------------.
| Register a used associativity. |
`-------------------------------*/

void
register_assoc (graphid i, graphid j)
{
  if (!used_assoc)
    init_assoc ();
  used_assoc[i] = true;
  used_assoc[j] = true;
}

/*--------------------------------------------------.
| Print a warning for unused precedence relations.  |
`--------------------------------------------------*/

void
print_precedence_warnings (void)
{
  int i;
  if (!prec_nodes)
    init_prec_nodes ();
  if (!used_assoc)
    init_assoc ();
  for (i = 0; i < nsyms; ++i)
    {
      symbol *s = symbols[i];
      if (s
          && !prec_nodes[i]->pred
          && !prec_nodes[i]->succ)
        {
          if (is_assoc_useless (s))
            complain (&s->content->prec_node->prec_location, Wprecedence,
                      _("useless precedence and associativity for %s"), s->tag);
          else if (s->content->prec_node->assoc == precedence_assoc)
            complain (&s->content->prec_node->prec_location, Wprecedence,
                      _("useless precedence for %s"), s->tag);
        }
      else if (is_assoc_useless (s))
        complain (&s->content->prec_node->prec_location, Wprecedence,
                  _("useless associativity for %s, use %%precedence"), s->tag);
    }
  free (used_assoc);
  assoc_free ();
}

/*------------------------------------------------.
| Counter to create unique anonymous group names. |
`------------------------------------------------*/

static unsigned int anon_group_counter = 0;

/*-------------------------------------------------.
| Return a new unique name for an anonymous group. |
`-------------------------------------------------*/

uniqstr new_anonymous_group_name (void)
{
  char buff[20];
  snprintf (buff, 20, "__anon%u__", anon_group_counter++);
  return uniqstr_new (buff);
}

/*-------------------------------------------.
| Constructor for a symbol precedence group. |
`-------------------------------------------*/

symgroup *
symgroup_new (const uniqstr tag, location loc)
{
  symgroup *group = xmalloc (sizeof (*group));
  group->tag = tag;
  group->symbol_list = NULL;
  group->location = loc;
  return group;
}

/*----------------------------------------.
| Check if there is a group by that name. |
`----------------------------------------*/

bool
is_prec_group (const uniqstr key)
{
  symgroup probe;
  symgroup *entry;
  probe.tag = key;
  entry = hash_lookup (group_table, &probe);
  return entry != NULL;
}

/*--------------------------------------------------------------------------.
| Get the symbol precedence group by that name. If not present, a new group |
| is created and inserted in the table, with the location information       |
| provided, if any.                                                         |
`--------------------------------------------------------------------------*/

symgroup *
symgroup_from_uniqstr (const uniqstr key, location *loc)
{
  bool null_loc = loc == NULL;
  if (null_loc)
    {
      loc = malloc (sizeof *loc);
      boundary_set (&loc->start, uniqstr_new (""), 1, 1);
      boundary_set (&loc->end, uniqstr_new (""), 1, 1);
    }
  symgroup probe;
  symgroup *entry;

  probe.tag = key;
  entry = hash_lookup (group_table, &probe);

  if (!entry)
    {
      /* First insertion in the hash. */
      entry = symgroup_new (key, *loc);
      if (!hash_insert (group_table, entry))
        xalloc_die ();
    }
  if (null_loc)
    free (loc);
  return entry;
}

/*--------------------------------------------------------------------------.
| Change the current group to the one designated by the name, and create it |
| if necessary. The location information is used for creation if available. |
`--------------------------------------------------------------------------*/

void set_current_group (const uniqstr tag, location *loc)
{
  for (symbol_list *l = current_prec_declaration; l; l = l->next)
    {
      sym_content *symb = l->content.sym->content;
      if (!current_group->symbol_list)
        current_group->symbol_list = symb;
      else
        {
          sym_content *sym = current_group->symbol_list;
          for (; sym->group_next; sym = sym->group_next)
            {}
          sym->group_next = symb;
        }
    }
  symbol_list_prec_free (current_prec_declaration);
  current_prec_declaration = NULL;
  current_group = symgroup_from_uniqstr (tag, loc);
}