Prefer M4 to CPP.

[bison.git] / data / lalr1.cc

# C++ skeleton for Bison

# Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
# Free Software Foundation, Inc.

# 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/>.

m4_include(b4_pkgdatadir/[c++.m4])

m4_define([b4_parser_class_name],
          [b4_percent_define_get([[parser_class_name]])])

# The header is mandatory.
b4_defines_if([],
              [b4_fatal([b4_skeleton[: using %%defines is mandatory]])])

# Backward compatibility.
m4_define([b4_location_constructors])
m4_include(b4_pkgdatadir/[location.cc])

# We do want M4 expansion after # for CPP macros.
m4_changecom()
m4_divert_push(0)dnl
b4_defines_if(
[@output(b4_spec_defines_file@)@
b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++],
             [2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009])
dnl FIXME: This is wrong, we want computed header guards.
[
/* C++ LALR(1) parser skeleton written by Akim Demaille.  */

#ifndef PARSER_HEADER_H
# define PARSER_HEADER_H

]b4_percent_code_get([[requires]])[

#include <string>
#include <iostream>
#include "stack.hh"

]b4_namespace_open[
  class position;
  class location;
]b4_namespace_close[

#include "location.hh"

/* Enabling traces.  */
#ifndef YYDEBUG
# define YYDEBUG ]b4_debug_flag[
#endif

/* Enabling verbose error messages.  */
#ifdef YYERROR_VERBOSE
# undef YYERROR_VERBOSE
# define YYERROR_VERBOSE 1
#else
# define YYERROR_VERBOSE ]b4_error_verbose_flag[
#endif

/* Enabling the token table.  */
#ifndef YYTOKEN_TABLE
# define YYTOKEN_TABLE ]b4_token_table[
#endif

/* YYLLOC_DEFAULT -- Set CURRENT to span from RHS[1] to RHS[N].
   If N is 0, then set CURRENT to the empty location which ends
   the previous symbol: RHS[0] (always defined).  */

#ifndef YYLLOC_DEFAULT
# define YYLLOC_DEFAULT(Current, Rhs, N)		\
do {							\
  if (N)						\
    {							\
      (Current).begin = (Rhs)[1].begin;			\
      (Current).end   = (Rhs)[N].end;			\
    }							\
  else							\
    {							\
      (Current).begin = (Current).end = (Rhs)[0].end;	\
    }							\
} while (false)
#endif

]b4_namespace_open[

  /// A Bison parser.
  class ]b4_parser_class_name[
  {
  public:
    /// Symbol semantic values.
#ifndef YYSTYPE
]m4_ifdef([b4_stype],
[    union semantic_type
    {
b4_user_stype
    };],
[m4_if(b4_tag_seen_flag, 0,
[[    typedef int semantic_type;]],
[[    typedef YYSTYPE semantic_type;]])])[
#else
    typedef YYSTYPE semantic_type;
#endif
    /// Symbol locations.
    typedef ]b4_percent_define_get([[location_type]])[ location_type;
    /// Tokens.
    struct token
    {
      ]b4_token_enums(b4_tokens)[
    };
    /// Token type.
    typedef token::yytokentype token_type;

    /// Build a parser object.
    ]b4_parser_class_name[ (]b4_parse_param_decl[);
    virtual ~]b4_parser_class_name[ ();

    /// Parse.
    /// \returns  0 iff parsing succeeded.
    virtual int parse ();

#if YYDEBUG
    /// The current debugging stream.
    std::ostream& debug_stream () const;
    /// Set the current debugging stream.
    void set_debug_stream (std::ostream &);

    /// Type for debugging levels.
    typedef int debug_level_type;
    /// The current debugging level.
    debug_level_type debug_level () const;
    /// Set the current debugging level.
    void set_debug_level (debug_level_type l);
#endif

  private:
    /// Report a syntax error.
    /// \param loc    where the syntax error is found.
    /// \param msg    a description of the syntax error.
    virtual void error (const location_type& loc, const std::string& msg);

    /// Generate an error message.
    /// \param state   the state where the error occurred.
    /// \param tok     the lookahead token.
    virtual std::string yysyntax_error_ (int yystate, int tok);

#if YYDEBUG
    /// \brief Report a symbol value on the debug stream.
    /// \param yytype       The token type.
    /// \param yyvaluep     Its semantic value.
    /// \param yylocationp  Its location.
    virtual void yy_symbol_value_print_ (int yytype,
					 const semantic_type* yyvaluep,
					 const location_type* yylocationp);
    /// \brief Report a symbol on the debug stream.
    /// \param yytype       The token type.
    /// \param yyvaluep     Its semantic value.
    /// \param yylocationp  Its location.
    virtual void yy_symbol_print_ (int yytype,
				   const semantic_type* yyvaluep,
				   const location_type* yylocationp);
#endif


    /// State numbers.
    typedef int state_type;
    /// State stack type.
    typedef stack<state_type>    state_stack_type;
    /// Semantic value stack type.
    typedef stack<semantic_type> semantic_stack_type;
    /// location stack type.
    typedef stack<location_type> location_stack_type;

    /// The state stack.
    state_stack_type yystate_stack_;
    /// The semantic value stack.
    semantic_stack_type yysemantic_stack_;
    /// The location stack.
    location_stack_type yylocation_stack_;

    /// Whether the given \c yypact_ value indicates a defaulted state.
    /// \param yyvalue   the value to check
    static bool yy_pact_value_is_default_ (int yyvalue);

    /// Whether the given \c yytable_ value indicates a syntax error.
    /// \param yyvalue   the value to check
    static bool yy_table_value_is_error_ (int yyvalue);

    /// Internal symbol numbers.
    typedef ]b4_int_type_for([b4_translate])[ token_number_type;
    /* Tables.  */
    /// For a state, the index in \a yytable_ of its portion.
    static const ]b4_int_type_for([b4_pact])[ yypact_[];
    static const ]b4_int_type(b4_pact_ninf, b4_pact_ninf)[ yypact_ninf_;

    /// For a state, default reduction number.
    /// Unless\a  yytable_ specifies something else to do.
    /// Zero means the default is an error.
    static const ]b4_int_type_for([b4_defact])[ yydefact_[];

    static const ]b4_int_type_for([b4_pgoto])[ yypgoto_[];
    static const ]b4_int_type_for([b4_defgoto])[ yydefgoto_[];

    /// What to do in a state.
    /// \a yytable_[yypact_[s]]: what to do in state \a s.
    /// - if positive, shift that token.
    /// - if negative, reduce the rule which number is the opposite.
    /// - if zero, do what YYDEFACT says.
    static const ]b4_int_type_for([b4_table])[ yytable_[];
    static const ]b4_int_type(b4_table_ninf, b4_table_ninf)[ yytable_ninf_;

    static const ]b4_int_type_for([b4_check])[ yycheck_[];

    /// For a state, its accessing symbol.
    static const ]b4_int_type_for([b4_stos])[ yystos_[];

    /// For a rule, its LHS.
    static const ]b4_int_type_for([b4_r1])[ yyr1_[];
    /// For a rule, its RHS length.
    static const ]b4_int_type_for([b4_r2])[ yyr2_[];

#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
    /// For a symbol, its name in clear.
    static const char* const yytname_[];
#endif]b4_error_verbose_if([

    /// Convert the symbol name \a n to a form suitable for a diagnostic.
    static std::string yytnamerr_ (const char *n);])[

#if YYDEBUG
    /// A type to store symbol numbers and -1.
    typedef ]b4_int_type_for([b4_rhs])[ rhs_number_type;
    /// A `-1'-separated list of the rules' RHS.
    static const rhs_number_type yyrhs_[];
    /// For each rule, the index of the first RHS symbol in \a yyrhs_.
    static const ]b4_int_type_for([b4_prhs])[ yyprhs_[];
    /// For each rule, its source line number.
    static const ]b4_int_type_for([b4_rline])[ yyrline_[];
    /// For each scanner token number, its symbol number.
    static const ]b4_int_type_for([b4_toknum])[ yytoken_number_[];
    /// Report on the debug stream that the rule \a r is going to be reduced.
    virtual void yy_reduce_print_ (int r);
    /// Print the state stack on the debug stream.
    virtual void yystack_print_ ();

    /* Debugging.  */
    int yydebug_;
    std::ostream* yycdebug_;
#endif

    /// Convert a scanner token number \a t to a symbol number.
    token_number_type yytranslate_ (int t);

    /// \brief Reclaim the memory associated to a symbol.
    /// \param yymsg        Why this token is reclaimed.
    /// \param yytype       The symbol type.
    /// \param yyvaluep     Its semantic value.
    /// \param yylocationp  Its location.
    inline void yydestruct_ (const char* yymsg,
			     int yytype,
			     semantic_type* yyvaluep,
			     location_type* yylocationp);

    /// Pop \a n symbols the three stacks.
    inline void yypop_ (unsigned int n = 1);

    /* Constants.  */
    static const int yyeof_;
    /* LAST_ -- Last index in TABLE_.  */
    static const int yylast_;
    static const int yynnts_;
    static const int yyempty_;
    static const int yyfinal_;
    static const int yyterror_;
    static const int yyerrcode_;
    static const int yyntokens_;
    static const unsigned int yyuser_token_number_max_;
    static const token_number_type yyundef_token_;
]b4_parse_param_vars[
  };
]b4_namespace_close[

]b4_percent_define_flag_if([[global_tokens_and_yystype]],
[b4_token_defines(b4_tokens)

#ifndef YYSTYPE
 /* Redirection for backward compatibility.  */
# define YYSTYPE b4_namespace_ref::b4_parser_class_name::semantic_type
#endif
])
b4_percent_code_get([[provides]])[]dnl

[#endif /* ! defined PARSER_HEADER_H */]
])dnl
@output(b4_parser_file_name@)@
b4_copyright([Skeleton implementation for Bison LALR(1) parsers in C++],
             [2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009])
b4_percent_code_get([[top]])[]dnl
m4_if(b4_prefix, [yy], [],
[
// Take the name prefix into account.
#define yylex   b4_prefix[]lex])[

/* First part of user declarations.  */
]b4_user_pre_prologue

b4_defines_if([[
#include "@basename(]b4_spec_defines_file[@)"]])[

/* User implementation prologue.  */
]b4_user_post_prologue
b4_percent_code_get[]dnl

[#ifndef YY_
# if defined YYENABLE_NLS && YYENABLE_NLS
#  if ENABLE_NLS
#   include <libintl.h> /* FIXME: INFRINGES ON USER NAME SPACE */
#   define YY_(msgid) dgettext ("bison-runtime", msgid)
#  endif
# endif
# ifndef YY_
#  define YY_(msgid) msgid
# endif
#endif

/* Suppress unused-variable warnings by "using" E.  */
#define YYUSE(e) ((void) (e))

/* Enable debugging if requested.  */
#if YYDEBUG

/* A pseudo ostream that takes yydebug_ into account.  */
# define YYCDEBUG if (yydebug_) (*yycdebug_)

# define YY_SYMBOL_PRINT(Title, Type, Value, Location)	\
do {							\
  if (yydebug_)						\
    {							\
      *yycdebug_ << Title << ' ';			\
      yy_symbol_print_ ((Type), (Value), (Location));	\
      *yycdebug_ << std::endl;				\
    }							\
} while (false)

# define YY_REDUCE_PRINT(Rule)		\
do {					\
  if (yydebug_)				\
    yy_reduce_print_ (Rule);		\
} while (false)

# define YY_STACK_PRINT()		\
do {					\
  if (yydebug_)				\
    yystack_print_ ();			\
} while (false)

#else /* !YYDEBUG */

# define YYCDEBUG if (false) std::cerr
# define YY_SYMBOL_PRINT(Title, Type, Value, Location)
# define YY_REDUCE_PRINT(Rule)
# define YY_STACK_PRINT()

#endif /* !YYDEBUG */

#define yyerrok		(yyerrstatus_ = 0)
#define yyclearin	(yychar = yyempty_)

#define YYACCEPT	goto yyacceptlab
#define YYABORT		goto yyabortlab
#define YYERROR		goto yyerrorlab
#define YYRECOVERING()  (!!yyerrstatus_)

]b4_namespace_open[]b4_error_verbose_if([[

  /* Return YYSTR after stripping away unnecessary quotes and
     backslashes, so that it's suitable for yyerror.  The heuristic is
     that double-quoting is unnecessary unless the string contains an
     apostrophe, a comma, or backslash (other than backslash-backslash).
     YYSTR is taken from yytname.  */
  std::string
  ]b4_parser_class_name[::yytnamerr_ (const char *yystr)
  {
    if (*yystr == '"')
      {
        std::string yyr = "";
        char const *yyp = yystr;

        for (;;)
          switch (*++yyp)
            {
            case '\'':
            case ',':
              goto do_not_strip_quotes;

            case '\\':
              if (*++yyp != '\\')
                goto do_not_strip_quotes;
              /* Fall through.  */
            default:
              yyr += *yyp;
              break;

            case '"':
              return yyr;
            }
      do_not_strip_quotes: ;
      }

    return yystr;
  }
]])[

  /// Build a parser object.
  ]b4_parser_class_name::b4_parser_class_name[ (]b4_parse_param_decl[)]m4_ifset([b4_parse_param], [
    :])[
#if YYDEBUG
    ]m4_ifset([b4_parse_param], [  ], [ :])[yydebug_ (false),
      yycdebug_ (&std::cerr)]m4_ifset([b4_parse_param], [,])[
#endif]b4_parse_param_cons[
  {
  }

  ]b4_parser_class_name::~b4_parser_class_name[ ()
  {
  }

#if YYDEBUG
  /*--------------------------------.
  | Print this symbol on YYOUTPUT.  |
  `--------------------------------*/

  inline void
  ]b4_parser_class_name[::yy_symbol_value_print_ (int yytype,
			   const semantic_type* yyvaluep, const location_type* yylocationp)
  {
    YYUSE (yylocationp);
    YYUSE (yyvaluep);
    switch (yytype)
      {
  ]m4_map([b4_symbol_actions], m4_defn([b4_symbol_printers]))dnl
[       default:
	  break;
      }
  }


  void
  ]b4_parser_class_name[::yy_symbol_print_ (int yytype,
			   const semantic_type* yyvaluep, const location_type* yylocationp)
  {
    *yycdebug_ << (yytype < yyntokens_ ? "token" : "nterm")
	       << ' ' << yytname_[yytype] << " ("
	       << *yylocationp << ": ";
    yy_symbol_value_print_ (yytype, yyvaluep, yylocationp);
    *yycdebug_ << ')';
  }
#endif

  void
  ]b4_parser_class_name[::yydestruct_ (const char* yymsg,
			   int yytype, semantic_type* yyvaluep, location_type* yylocationp)
  {
    YYUSE (yylocationp);
    YYUSE (yymsg);
    YYUSE (yyvaluep);

    YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);

    switch (yytype)
      {
  ]m4_map([b4_symbol_actions], m4_defn([b4_symbol_destructors]))[
	default:
	  break;
      }
  }

  void
  ]b4_parser_class_name[::yypop_ (unsigned int n)
  {
    yystate_stack_.pop (n);
    yysemantic_stack_.pop (n);
    yylocation_stack_.pop (n);
  }

#if YYDEBUG
  std::ostream&
  ]b4_parser_class_name[::debug_stream () const
  {
    return *yycdebug_;
  }

  void
  ]b4_parser_class_name[::set_debug_stream (std::ostream& o)
  {
    yycdebug_ = &o;
  }


  ]b4_parser_class_name[::debug_level_type
  ]b4_parser_class_name[::debug_level () const
  {
    return yydebug_;
  }

  void
  ]b4_parser_class_name[::set_debug_level (debug_level_type l)
  {
    yydebug_ = l;
  }
#endif

  inline bool
  ]b4_parser_class_name[::yy_pact_value_is_default_ (int yyvalue)
  {
    return yyvalue == yypact_ninf_;
  }

  inline bool
  ]b4_parser_class_name[::yy_table_value_is_error_ (int yyvalue)
  {
    return yyvalue == yytable_ninf_;
  }

  int
  ]b4_parser_class_name[::parse ()
  {
    /// Lookahead and lookahead in internal form.
    int yychar = yyempty_;
    int yytoken = 0;

    /* State.  */
    int yyn;
    int yylen = 0;
    int yystate = 0;

    /* Error handling.  */
    int yynerrs_ = 0;
    int yyerrstatus_ = 0;

    /// Semantic value of the lookahead.
    semantic_type yylval;
    /// Location of the lookahead.
    location_type yylloc;
    /// The locations where the error started and ended.
    location_type yyerror_range[2];

    /// $$.
    semantic_type yyval;
    /// @@$.
    location_type yyloc;

    int yyresult;

    YYCDEBUG << "Starting parse" << std::endl;

]m4_ifdef([b4_initial_action], [
m4_pushdef([b4_at_dollar],     [yylloc])dnl
m4_pushdef([b4_dollar_dollar], [yylval])dnl
    /* User initialization code.  */
    b4_user_initial_action
m4_popdef([b4_dollar_dollar])dnl
m4_popdef([b4_at_dollar])])dnl

  [  /* Initialize the stacks.  The initial state will be pushed in
       yynewstate, since the latter expects the semantical and the
       location values to have been already stored, initialize these
       stacks with a primary value.  */
    yystate_stack_ = state_stack_type (0);
    yysemantic_stack_ = semantic_stack_type (0);
    yylocation_stack_ = location_stack_type (0);
    yysemantic_stack_.push (yylval);
    yylocation_stack_.push (yylloc);

    /* New state.  */
  yynewstate:
    yystate_stack_.push (yystate);
    YYCDEBUG << "Entering state " << yystate << std::endl;

    /* Accept?  */
    if (yystate == yyfinal_)
      goto yyacceptlab;

    goto yybackup;

    /* Backup.  */
  yybackup:

    /* Try to take a decision without lookahead.  */
    yyn = yypact_[yystate];
    if (yy_pact_value_is_default_ (yyn))
      goto yydefault;

    /* Read a lookahead token.  */
    if (yychar == yyempty_)
      {
	YYCDEBUG << "Reading a token: ";
	yychar = ]b4_c_function_call([yylex], [int],
				     [[YYSTYPE*], [&yylval]][]dnl
b4_locations_if([, [[location*], [&yylloc]]])dnl
m4_ifdef([b4_lex_param], [, ]b4_lex_param))[;
      }


    /* Convert token to internal form.  */
    if (yychar <= yyeof_)
      {
	yychar = yytoken = yyeof_;
	YYCDEBUG << "Now at end of input." << std::endl;
      }
    else
      {
	yytoken = yytranslate_ (yychar);
	YY_SYMBOL_PRINT ("Next token is", yytoken, &yylval, &yylloc);
      }

    /* If the proper action on seeing token YYTOKEN is to reduce or to
       detect an error, take that action.  */
    yyn += yytoken;
    if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yytoken)
      goto yydefault;

    /* Reduce or error.  */
    yyn = yytable_[yyn];
    if (yyn <= 0)
      {
	if (yy_table_value_is_error_ (yyn))
	  goto yyerrlab;
	yyn = -yyn;
	goto yyreduce;
      }

    /* Shift the lookahead token.  */
    YY_SYMBOL_PRINT ("Shifting", yytoken, &yylval, &yylloc);

    /* Discard the token being shifted.  */
    yychar = yyempty_;

    yysemantic_stack_.push (yylval);
    yylocation_stack_.push (yylloc);

    /* Count tokens shifted since error; after three, turn off error
       status.  */
    if (yyerrstatus_)
      --yyerrstatus_;

    yystate = yyn;
    goto yynewstate;

  /*-----------------------------------------------------------.
  | yydefault -- do the default action for the current state.  |
  `-----------------------------------------------------------*/
  yydefault:
    yyn = yydefact_[yystate];
    if (yyn == 0)
      goto yyerrlab;
    goto yyreduce;

  /*-----------------------------.
  | yyreduce -- Do a reduction.  |
  `-----------------------------*/
  yyreduce:
    yylen = yyr2_[yyn];
    /* If YYLEN is nonzero, implement the default value of the action:
       `$$ = $1'.  Otherwise, use the top of the stack.

       Otherwise, the following line sets YYVAL to garbage.
       This behavior is undocumented and Bison
       users should not rely upon it.  */
    if (yylen)
      yyval = yysemantic_stack_[yylen - 1];
    else
      yyval = yysemantic_stack_[0];

    {
      slice<location_type, location_stack_type> slice (yylocation_stack_, yylen);
      YYLLOC_DEFAULT (yyloc, slice, yylen);
    }
    YY_REDUCE_PRINT (yyn);
    switch (yyn)
      {
	]b4_user_actions[
	default:
          break;
      }
    YY_SYMBOL_PRINT ("-> $$ =", yyr1_[yyn], &yyval, &yyloc);

    yypop_ (yylen);
    yylen = 0;
    YY_STACK_PRINT ();

    yysemantic_stack_.push (yyval);
    yylocation_stack_.push (yyloc);

    /* Shift the result of the reduction.  */
    yyn = yyr1_[yyn];
    yystate = yypgoto_[yyn - yyntokens_] + yystate_stack_[0];
    if (0 <= yystate && yystate <= yylast_
	&& yycheck_[yystate] == yystate_stack_[0])
      yystate = yytable_[yystate];
    else
      yystate = yydefgoto_[yyn - yyntokens_];
    goto yynewstate;

  /*------------------------------------.
  | yyerrlab -- here on detecting error |
  `------------------------------------*/
  yyerrlab:
    /* If not already recovering from an error, report this error.  */
    if (!yyerrstatus_)
      {
	++yynerrs_;
	error (yylloc, yysyntax_error_ (yystate, yytoken));
      }

    yyerror_range[0] = yylloc;
    if (yyerrstatus_ == 3)
      {
	/* If just tried and failed to reuse lookahead token after an
	 error, discard it.  */

	if (yychar <= yyeof_)
	  {
	  /* Return failure if at end of input.  */
	  if (yychar == yyeof_)
	    YYABORT;
	  }
	else
	  {
	    yydestruct_ ("Error: discarding", yytoken, &yylval, &yylloc);
	    yychar = yyempty_;
	  }
      }

    /* Else will try to reuse lookahead token after shifting the error
       token.  */
    goto yyerrlab1;


  /*---------------------------------------------------.
  | yyerrorlab -- error raised explicitly by YYERROR.  |
  `---------------------------------------------------*/
  yyerrorlab:

    /* Pacify compilers like GCC when the user code never invokes
       YYERROR and the label yyerrorlab therefore never appears in user
       code.  */
    if (false)
      goto yyerrorlab;

    yyerror_range[0] = yylocation_stack_[yylen - 1];
    /* Do not reclaim the symbols of the rule which action triggered
       this YYERROR.  */
    yypop_ (yylen);
    yylen = 0;
    yystate = yystate_stack_[0];
    goto yyerrlab1;

  /*-------------------------------------------------------------.
  | yyerrlab1 -- common code for both syntax error and YYERROR.  |
  `-------------------------------------------------------------*/
  yyerrlab1:
    yyerrstatus_ = 3;	/* Each real token shifted decrements this.  */

    for (;;)
      {
	yyn = yypact_[yystate];
	if (!yy_pact_value_is_default_ (yyn))
	{
	  yyn += yyterror_;
	  if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == yyterror_)
	    {
	      yyn = yytable_[yyn];
	      if (0 < yyn)
		break;
	    }
	}

	/* Pop the current state because it cannot handle the error token.  */
	if (yystate_stack_.height () == 1)
	YYABORT;

	yyerror_range[0] = yylocation_stack_[0];
	yydestruct_ ("Error: popping",
		     yystos_[yystate],
		     &yysemantic_stack_[0], &yylocation_stack_[0]);
	yypop_ ();
	yystate = yystate_stack_[0];
	YY_STACK_PRINT ();
      }

    yyerror_range[1] = yylloc;
    // Using YYLLOC is tempting, but would change the location of
    // the lookahead.  YYLOC is available though.
    YYLLOC_DEFAULT (yyloc, (yyerror_range - 1), 2);
    yysemantic_stack_.push (yylval);
    yylocation_stack_.push (yyloc);

    /* Shift the error token.  */
    YY_SYMBOL_PRINT ("Shifting", yystos_[yyn],
		     &yysemantic_stack_[0], &yylocation_stack_[0]);

    yystate = yyn;
    goto yynewstate;

    /* Accept.  */
  yyacceptlab:
    yyresult = 0;
    goto yyreturn;

    /* Abort.  */
  yyabortlab:
    yyresult = 1;
    goto yyreturn;

  yyreturn:
    if (yychar != yyempty_)
      yydestruct_ ("Cleanup: discarding lookahead", yytoken, &yylval, &yylloc);

    /* Do not reclaim the symbols of the rule which action triggered
       this YYABORT or YYACCEPT.  */
    yypop_ (yylen);
    while (yystate_stack_.height () != 1)
      {
	yydestruct_ ("Cleanup: popping",
		   yystos_[yystate_stack_[0]],
		   &yysemantic_stack_[0],
		   &yylocation_stack_[0]);
	yypop_ ();
      }

    return yyresult;
  }

  // Generate an error message.
  std::string
  ]b4_parser_class_name[::yysyntax_error_ (]dnl
b4_error_verbose_if([int yystate, int yytoken],
                    [int, int])[)
  {
    std::string yyres;]b4_error_verbose_if([[
    int yyn = yypact_[yystate];
    if (yypact_ninf_ < yyn && yyn <= yylast_)
      {
	/* Start YYX at -YYN if negative to avoid negative indexes in
	   YYCHECK.  In other words, skip the first -YYN actions for this
	   state because they are default actions.  */
	int yyxbegin = yyn < 0 ? -yyn : 0;

	/* Stay within bounds of both yycheck and yytname.  */
	int yychecklim = yylast_ - yyn + 1;
	int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;

        // Number of "expected" tokens.
	size_t yycount = 0;
        // Its maximum.
        enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };
        // Arguments of yyformat.
        char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
        yyarg[yycount++] = yytname_[yytoken];
	for (int yyx = yyxbegin; yyx < yyxend; ++yyx)
	  if (yycheck_[yyx + yyn] == yyx && yyx != yyterror_
	      && !yy_table_value_is_error_ (yytable_[yyx + yyn]))
          {
            if (yycount == YYERROR_VERBOSE_ARGS_MAXIMUM)
            {
              yycount = 1;
              break;
            }
            else
              yyarg[yycount++] = yytname_[yyx];
          }

        char const* yyformat = 0;
        switch (yycount)
        {
#define YYCASE_(N, S)                           \
          case N:                               \
            yyformat = S;                       \
          break
          YYCASE_(1, YY_("syntax error, unexpected %s"));
          YYCASE_(2, YY_("syntax error, unexpected %s, expecting %s"));
          YYCASE_(3, YY_("syntax error, unexpected %s, expecting %s or %s"));
          YYCASE_(4, YY_("syntax error, unexpected %s, expecting %s or %s or %s"));
          YYCASE_(5, YY_("syntax error, unexpected %s, expecting %s or %s or %s or %s"));
#undef YYCASE_
        }
        // Argument number.
        size_t yyi = 0;
        for (char const* yyp = yyformat; *yyp; ++yyp)
          if (yyp[0] == '%' && yyp[1] == 's' && yyi < yycount)
          {
            yyres += yytnamerr_ (yyarg[yyi++]);
            ++yyp;
          }
          else
            yyres += *yyp;
      }
    else
  ]])dnl
[    yyres = YY_("syntax error");
    return yyres;
  }


  /* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
     STATE-NUM.  */
  const ]b4_int_type(b4_pact_ninf, b4_pact_ninf) b4_parser_class_name::yypact_ninf_ = b4_pact_ninf[;
  const ]b4_int_type_for([b4_pact])[
  ]b4_parser_class_name[::yypact_[] =
  {
    ]b4_pact[
  };

  /* YYDEFACT[S] -- default reduction number in state S.  Performed when
     YYTABLE doesn't specify something else to do.  Zero means the
     default is an error.  */
  const ]b4_int_type_for([b4_defact])[
  ]b4_parser_class_name[::yydefact_[] =
  {
    ]b4_defact[
  };

  /* YYPGOTO[NTERM-NUM].  */
  const ]b4_int_type_for([b4_pgoto])[
  ]b4_parser_class_name[::yypgoto_[] =
  {
    ]b4_pgoto[
  };

  /* YYDEFGOTO[NTERM-NUM].  */
  const ]b4_int_type_for([b4_defgoto])[
  ]b4_parser_class_name[::yydefgoto_[] =
  {
    ]b4_defgoto[
  };

  /* YYTABLE[YYPACT[STATE-NUM]].  What to do in state STATE-NUM.  If
     positive, shift that token.  If negative, reduce the rule which
     number is the opposite.  If YYTABLE_NINF_, syntax error.  */
  const ]b4_int_type(b4_table_ninf, b4_table_ninf) b4_parser_class_name::yytable_ninf_ = b4_table_ninf[;
  const ]b4_int_type_for([b4_table])[
  ]b4_parser_class_name[::yytable_[] =
  {
    ]b4_table[
  };

  /* YYCHECK.  */
  const ]b4_int_type_for([b4_check])[
  ]b4_parser_class_name[::yycheck_[] =
  {
    ]b4_check[
  };

  /* STOS_[STATE-NUM] -- The (internal number of the) accessing
     symbol of state STATE-NUM.  */
  const ]b4_int_type_for([b4_stos])[
  ]b4_parser_class_name[::yystos_[] =
  {
    ]b4_stos[
  };

#if YYDEBUG
  /* TOKEN_NUMBER_[YYLEX-NUM] -- Internal symbol number corresponding
     to YYLEX-NUM.  */
  const ]b4_int_type_for([b4_toknum])[
  ]b4_parser_class_name[::yytoken_number_[] =
  {
    ]b4_toknum[
  };
#endif

  /* YYR1[YYN] -- Symbol number of symbol that rule YYN derives.  */
  const ]b4_int_type_for([b4_r1])[
  ]b4_parser_class_name[::yyr1_[] =
  {
    ]b4_r1[
  };

  /* YYR2[YYN] -- Number of symbols composing right hand side of rule YYN.  */
  const ]b4_int_type_for([b4_r2])[
  ]b4_parser_class_name[::yyr2_[] =
  {
    ]b4_r2[
  };

#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
  /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
     First, the terminals, then, starting at \a yyntokens_, nonterminals.  */
  const char*
  const ]b4_parser_class_name[::yytname_[] =
  {
    ]b4_tname[
  };
#endif

#if YYDEBUG
  /* YYRHS -- A `-1'-separated list of the rules' RHS.  */
  const ]b4_parser_class_name[::rhs_number_type
  ]b4_parser_class_name[::yyrhs_[] =
  {
    ]b4_rhs[
  };

  /* YYPRHS[YYN] -- Index of the first RHS symbol of rule number YYN in
     YYRHS.  */
  const ]b4_int_type_for([b4_prhs])[
  ]b4_parser_class_name[::yyprhs_[] =
  {
    ]b4_prhs[
  };

  /* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
  const ]b4_int_type_for([b4_rline])[
  ]b4_parser_class_name[::yyrline_[] =
  {
    ]b4_rline[
  };

  // Print the state stack on the debug stream.
  void
  ]b4_parser_class_name[::yystack_print_ ()
  {
    *yycdebug_ << "Stack now";
    for (state_stack_type::const_iterator i = yystate_stack_.begin ();
	 i != yystate_stack_.end (); ++i)
      *yycdebug_ << ' ' << *i;
    *yycdebug_ << std::endl;
  }

  // Report on the debug stream that the rule \a yyrule is going to be reduced.
  void
  ]b4_parser_class_name[::yy_reduce_print_ (int yyrule)
  {
    unsigned int yylno = yyrline_[yyrule];
    int yynrhs = yyr2_[yyrule];
    /* Print the symbols being reduced, and their result.  */
    *yycdebug_ << "Reducing stack by rule " << yyrule - 1
	       << " (line " << yylno << "):" << std::endl;
    /* The symbols being reduced.  */
    for (int yyi = 0; yyi < yynrhs; yyi++)
      YY_SYMBOL_PRINT ("   $" << yyi + 1 << " =",
		       yyrhs_[yyprhs_[yyrule] + yyi],
		       &]b4_rhs_value(yynrhs, yyi + 1)[,
		       &]b4_rhs_location(yynrhs, yyi + 1)[);
  }
#endif // YYDEBUG

  /* YYTRANSLATE(YYLEX) -- Bison symbol number corresponding to YYLEX.  */
  ]b4_parser_class_name[::token_number_type
  ]b4_parser_class_name[::yytranslate_ (int t)
  {
    static
    const token_number_type
    translate_table[] =
    {
      ]b4_translate[
    };
    if ((unsigned int) t <= yyuser_token_number_max_)
      return translate_table[t];
    else
      return yyundef_token_;
  }

  const int ]b4_parser_class_name[::yyeof_ = 0;
  const int ]b4_parser_class_name[::yylast_ = ]b4_last[;
  const int ]b4_parser_class_name[::yynnts_ = ]b4_nterms_number[;
  const int ]b4_parser_class_name[::yyempty_ = -2;
  const int ]b4_parser_class_name[::yyfinal_ = ]b4_final_state_number[;
  const int ]b4_parser_class_name[::yyterror_ = 1;
  const int ]b4_parser_class_name[::yyerrcode_ = 256;
  const int ]b4_parser_class_name[::yyntokens_ = ]b4_tokens_number[;

  const unsigned int ]b4_parser_class_name[::yyuser_token_number_max_ = ]b4_user_token_number_max[;
  const ]b4_parser_class_name[::token_number_type ]b4_parser_class_name[::yyundef_token_ = ]b4_undef_token_number[;

]b4_namespace_close[

]b4_epilogue
dnl
@output(b4_dir_prefix[]stack.hh@)@
b4_copyright([Stack handling for Bison parsers in C++],
             [2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009])[

#ifndef BISON_STACK_HH
# define BISON_STACK_HH

#include <deque>

]b4_namespace_open[
  template <class T, class S = std::deque<T> >
  class stack
  {
  public:

    // Hide our reversed order.
    typedef typename S::reverse_iterator iterator;
    typedef typename S::const_reverse_iterator const_iterator;

    stack () : seq_ ()
    {
    }

    stack (unsigned int n) : seq_ (n)
    {
    }

    inline
    T&
    operator [] (unsigned int i)
    {
      return seq_[i];
    }

    inline
    const T&
    operator [] (unsigned int i) const
    {
      return seq_[i];
    }

    inline
    void
    push (const T& t)
    {
      seq_.push_front (t);
    }

    inline
    void
    pop (unsigned int n = 1)
    {
      for (; n; --n)
	seq_.pop_front ();
    }

    inline
    unsigned int
    height () const
    {
      return seq_.size ();
    }

    inline const_iterator begin () const { return seq_.rbegin (); }
    inline const_iterator end () const { return seq_.rend (); }

  private:

    S seq_;
  };

  /// Present a slice of the top of a stack.
  template <class T, class S = stack<T> >
  class slice
  {
  public:

    slice (const S& stack,
	   unsigned int range) : stack_ (stack),
				 range_ (range)
    {
    }

    inline
    const T&
    operator [] (unsigned int i) const
    {
      return stack_[range_ - i];
    }

  private:

    const S& stack_;
    unsigned int range_;
  };
]b4_namespace_close[

#endif // not BISON_STACK_HH[]dnl
]
m4_divert_pop(0)