]> git.saurik.com Git - bison.git/blobdiff - data/lalr1.cc
style: variant: remove empty line
[bison.git] / data / lalr1.cc
index b0d14dc0e8c06ebf1c9fadca77510b0684fcc7fb..3294f591106d6cbe53c80c32241e1632990861b9 100644 (file)
@@ -1,7 +1,6 @@
 # C++ skeleton for Bison
 
-# Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2008
-# Free Software Foundation, Inc.
+# Copyright (C) 2002-2013 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
 
 m4_include(b4_pkgdatadir/[c++.m4])
 
+# api.value.type=variant is valid.
+m4_define([b4_value_type_setup_variant])
 
 # b4_integral_parser_table_declare(TABLE-NAME, CONTENT, COMMENT)
 # --------------------------------------------------------------
-# Declare "parser::yy<TABLE-NAME>_" which contents is CONTENT.
+# Declare "parser::yy<TABLE-NAME>_" whose contents is CONTENT.
 m4_define([b4_integral_parser_table_declare],
-[m4_ifval([$3], [b4_c_comment([$3], [  ])
+[m4_ifval([$3], [b4_comment([$3], [  ])
 ])dnl
   static const b4_int_type_for([$2]) yy$1_[[]];dnl
 ])
 
 # b4_integral_parser_table_define(TABLE-NAME, CONTENT, COMMENT)
-# ---------------------------------------------
-# Define "parser::yy<TABLE-NAME>_" which contents is CONTENT.
+# -------------------------------------------------------------
+# Define "parser::yy<TABLE-NAME>_" whose contents is CONTENT.
 m4_define([b4_integral_parser_table_define],
 [  const b4_int_type_for([$2])
   b4_parser_class_name::yy$1_[[]] =
@@ -39,13 +40,14 @@ m4_define([b4_integral_parser_table_define],
   };dnl
 ])
 
-
 # b4_symbol_value_template(VAL, [TYPE])
 # -------------------------------------
 # Same as b4_symbol_value, but used in a template method.  It makes
-# a difference when using variants.
+# a difference when using variants.  Note that b4_value_type_setup_union
+# overrides b4_symbol_value, so we must override it again.
 m4_copy([b4_symbol_value], [b4_symbol_value_template])
-
+m4_append([b4_value_type_setup_union],
+          [m4_copy_force([b4_symbol_value_union], [b4_symbol_value_template])])
 
 # b4_lhs_value([TYPE])
 # --------------------
@@ -99,195 +101,78 @@ m4_define([b4_rhs_location],
 # Same as in C, but using references instead of pointers.
 m4_define([b4_symbol_action],
 [b4_symbol_if([$1], [has_$2],
-[m4_pushdef([b4_dollar_dollar],
-    [b4_symbol_value_template([yysym.value],
-                              b4_symbol_if([$1], [has_type],
-                                           [b4_symbol([$1], [type])]))])dnl
-m4_pushdef([b4_at_dollar], [yysym.location])dnl
+[m4_pushdef([b4_symbol_value], m4_defn([b4_symbol_value_template]))[]dnl
+b4_dollar_pushdef([yysym.value],
+                   b4_symbol_if([$1], [has_type],
+                                [m4_dquote(b4_symbol([$1], [type]))]),
+                   [yysym.location])dnl
       b4_symbol_case_([$1])
 b4_syncline([b4_symbol([$1], [$2_line])], ["b4_symbol([$1], [$2_file])"])
         b4_symbol([$1], [$2])
 b4_syncline([@oline@], [@ofile@])
         break;
 
-m4_popdef([b4_at_dollar])dnl
-m4_popdef([b4_dollar_dollar])dnl
+m4_popdef([b4_symbol_value])[]dnl
+b4_dollar_popdef[]dnl
 ])])
 
-# b4_symbol_constructor_declare_(SYMBOL-NUMBER)
-# ---------------------------------------------
-# Declare the overloaded version of make_symbol for the (common) type of
-# these SYMBOL-NUMBERS.  Use at class-level.
-m4_define([b4_symbol_constructor_declare_],
-[b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
-[    static inline
-    symbol_type
-    make_[]b4_symbol_([$1], [id]) (dnl
-b4_args(b4_symbol_if([$1], [has_type],
-                     [const b4_symbol([$1], [type])& v]),
-        b4_locations_if([const location_type& l])));
-
-])])])
-
-
-# b4_symbol_constructor_declare
-# -----------------------------
-# Declare symbol constructors for all the value types.
-# Use at class-level.
-m4_define([b4_symbol_constructor_declare],
-[b4_variant_if([
-    // Symbol constructors declarations.
-b4_symbol_foreach([b4_symbol_constructor_declare_])])])
-
-
-
-# b4_symbol_constructor_define_(SYMBOL-NUMBER)
-# --------------------------------------------
-# Define symbol constructor for this SYMBOL-NUMBER.
-m4_define([b4_symbol_constructor_define_],
-[b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
-[  b4_parser_class_name::symbol_type
-  b4_parser_class_name::make_[]b4_symbol_([$1], [id]) (dnl
-b4_args(b4_symbol_if([$1], [has_type],
-                     [const b4_symbol([$1], [type])& v]),
-        b4_locations_if([const location_type& l])))
-  {
-    return symbol_type (b4_args([yytranslate_ (token::b4_symbol([$1], [id]))],
-                                b4_symbol_if([$1], [has_type], [v]),
-                                b4_locations_if([l])));
-  }
-
-])])])
-
 
-# b4_symbol_constructor_define
-# ----------------------------
-# Define the overloaded versions of make_symbol for all the value types.
-m4_define([b4_symbol_constructor_define],
-[b4_variant_if([
-  // Implementation of make_symbol for each symbol type.
-b4_symbol_foreach([b4_symbol_constructor_define_])])])
-
-
-# b4_yytranslate_define
-# ---------------------
-# Define yytranslate_.  Sometimes we want it in the header file,
-# sometimes the cc file suffices.
-m4_define([b4_yytranslate_define],
-[[  // Symbol number corresponding to token number t.
-  ]b4_parser_class_name[::token_number_type
-  ]b4_parser_class_name[::yytranslate_ (]b4_lex_symbol_if([token_type],
-                                                          [int])[ t)
-  {
-    static
-    const token_number_type
-    translate_table[] =
-    {
-]b4_translate[
-    };
-    const unsigned int user_token_number_max_ = ]b4_user_token_number_max[;
-    const token_number_type undef_token_ = ]b4_undef_token_number[;
-
-    if (static_cast<int>(t) <= yyeof_)
-      return yyeof_;
-    else if (static_cast<unsigned int> (t) <= user_token_number_max_)
-      return translate_table[t];
-    else
-      return undef_token_;
-  }
-]])
+# b4_lex
+# ------
+# Call yylex.
+m4_define([b4_lex],
+[b4_token_ctor_if(
+[b4_function_call([yylex],
+                  [symbol_type], m4_ifdef([b4_lex_param], b4_lex_param))],
+[b4_function_call([yylex], [int],
+                  [b4_api_PREFIX[STYPE*], [&yyla.value]][]dnl
+b4_locations_if([, [[location*], [&yyla.location]]])dnl
+m4_ifdef([b4_lex_param], [, ]b4_lex_param))])])
 
 
 m4_pushdef([b4_copyright_years],
-           [2002, 2003, 2004, 2005, 2006, 2007, 2008])
+           [2002-2013])
 
 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]])])
-
-b4_locations_if(
-[# Backward compatibility.
-m4_define([b4_location_constructors])
-m4_include(b4_pkgdatadir/[location.cc])])
+b4_bison_locations_if([# Backward compatibility.
+   m4_define([b4_location_constructors])
+   m4_include(b4_pkgdatadir/[location.cc])])
 m4_include(b4_pkgdatadir/[stack.hh])
 b4_variant_if([m4_include(b4_pkgdatadir/[variant.hh])])
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
-@output(b4_spec_defines_file@)@
-b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++])
-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]])[
-
-]b4_assert_if([#include <cassert>])[
-#include <string>
-#include <iostream>
-#include "stack.hh"
+# b4_shared_declarations
+# ----------------------
+# Declaration that might either go into the header (if --defines)
+# or open coded in the parser body.
+m4_define([b4_shared_declarations],
+[b4_percent_code_get([[requires]])[
+]b4_parse_assert_if([# include <cassert>])[
+# include <vector>
+# include <iostream>
+# include <stdexcept>
+# include <string>]b4_defines_if([[
+# include "stack.hh"
+]b4_bison_locations_if([[# include "location.hh"]])])[
+]b4_variant_if([b4_variant_includes])[
+
+]b4_YYDEBUG_define[
 
 ]b4_namespace_open[
-]b4_locations_if([  class position;
-  class location;])[
-]b4_variant_if([b4_variant_define])[
-]b4_namespace_close[
 
-]b4_locations_if([#include "location.hh"])[
+]b4_defines_if([],
+[b4_stack_define
+b4_bison_locations_if([b4_position_define
+b4_location_define])])[
 
-/* 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
-
-]b4_locations_if([dnl
-[/* 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].location.begin;                \
-      (Current).end   = (Rhs)[N].location.end;                 \
-    }                                                           \
-  else                                                          \
-    {                                                           \
-      (Current).begin = (Current).end = (Rhs)[0].location.end; \
-    }                                                           \
-} while (false)
-#endif]])[
-
-]b4_namespace_open[
+]b4_variant_if([b4_variant_define])[
 
   /// A Bison parser.
   class ]b4_parser_class_name[
   {
   public:
 ]b4_public_types_declare[
-]b4_symbol_constructor_declare[
     /// Build a parser object.
     ]b4_parser_class_name[ (]b4_parse_param_decl[);
     virtual ~]b4_parser_class_name[ ();
@@ -296,7 +181,7 @@ do {                                                            \
     /// \returns  0 iff parsing succeeded.
     virtual int parse ();
 
-#if YYDEBUG
+#if ]b4_api_PREFIX[DEBUG
     /// The current debugging stream.
     std::ostream& debug_stream () const;
     /// Set the current debugging stream.
@@ -310,89 +195,122 @@ do {                                                            \
     void set_debug_level (debug_level_type l);
 #endif
 
-    /// Report a syntax error.]b4_locations_if([
-    /// \param loc    where the syntax error is found.])[
+    /// Report a syntax error.]b4_locations_if([[
+    /// \param loc    where the syntax error is found.]])[
     /// \param msg    a description of the syntax error.
-    virtual void error (]b4_locations_if([const location_type& loc, ])[const std::string& msg);
+    virtual void error (]b4_locations_if([[const location_type& loc, ]])[const std::string& msg);
+
+    /// Report a syntax error.
+    void error (const syntax_error& err);
 
   private:
-    /// 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);
+    /// This class is not copyable.
+    ]b4_parser_class_name[ (const ]b4_parser_class_name[&);
+    ]b4_parser_class_name[& operator= (const ]b4_parser_class_name[&);
 
     /// State numbers.
     typedef int state_type;
 
-    /// Internal symbol numbers.
-    typedef ]b4_int_type_for([b4_translate])[ token_number_type;
+    /// Generate an error message.
+    /// \param yystate   the state where the error occurred.
+    /// \param yytoken   the lookahead token type, or yyempty_.
+    virtual std::string yysyntax_error_ (state_type yystate,
+                                         symbol_number_type yytoken) const;
+
+    /// Compute post-reduction state.
+    /// \param yystate   the current state
+    /// \param yylhs     the nonterminal to push on the stack
+    state_type yy_lr_goto_state_ (state_type yystate, int yylhs);
+
+    /// 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);
+
     static const ]b4_int_type(b4_pact_ninf, b4_pact_ninf)[ yypact_ninf_;
     static const ]b4_int_type(b4_table_ninf, b4_table_ninf)[ yytable_ninf_;
 
-    /* Tables.  */
-]b4_parser_tables_declare[
+    /// Convert a scanner token number \a t to a symbol number.
+    static token_number_type yytranslate_ (]b4_token_ctor_if([token_type], [int])[ t);
 
-#if YYDEBUG || YYERROR_VERBOSE || YYTOKEN_TABLE
-    /// For a symbol, its name in clear.
-    static const char* const yytname_[];
-#endif]b4_error_verbose_if([
+    // Tables.
+]b4_parser_tables_declare[]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
+]b4_token_table_if([], [[#if ]b4_api_PREFIX[DEBUG]])[
+    /// For a symbol, its name in clear.
+    static const char* const yytname_[];
+]b4_token_table_if([[#if ]b4_api_PREFIX[DEBUG]])[
 ]b4_integral_parser_table_declare([rline], [b4_rline],
-     [YYRLINE[YYN] -- Source line where rule number YYN was defined.])[
+     [[YYRLINE[YYN] -- Source line where rule number YYN was defined.]])[
     /// 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.  */
+    // Debugging.
     int yydebug_;
     std::ostream* yycdebug_;
-#endif
 
-    /// Convert a scanner token number \a t to a symbol number.
-    static inline token_number_type yytranslate_ (]b4_lex_symbol_if([token_type], [int])[ t);
-
-#if YYDEBUG
     /// \brief Display a symbol type, value and location.
     /// \param yyo    The output stream.
     /// \param yysym  The symbol.
-    template <typename Exact>
-    void yy_print_ (std::ostream& yyo,
-                    const symbol_base_type<Exact>& yysym) const;
+    template <typename Base>
+    void yy_print_ (std::ostream& yyo, const basic_symbol<Base>& yysym) const;
 #endif
 
     /// \brief Reclaim the memory associated to a symbol.
     /// \param yymsg     Why this token is reclaimed.
     ///                  If null, print nothing.
     /// \param s         The symbol.
-    template <typename Exact>
-    inline void yy_destroy_ (const char* yymsg,
-                             symbol_base_type<Exact>& yysym) const;
+    template <typename Base>
+    void yy_destroy_ (const char* yymsg, basic_symbol<Base>& yysym) const;
 
   private:
-    /// Element of the stack: a state and its attributes.
-    struct stack_symbol_type : symbol_base_type<stack_symbol_type>
+    /// Type access provider for state based symbols.
+    struct by_state
     {
-      /// The parent class.
-      typedef symbol_base_type<stack_symbol_type> super_type;
-
       /// Default constructor.
-      inline stack_symbol_type ();
+      by_state ();
+
+      /// The symbol type as needed by the constructor.
+      typedef state_type kind_type;
 
       /// Constructor.
-      inline stack_symbol_type (]b4_args([state_type s],
-                                         [const semantic_type& v],
-                                         b4_locations_if([const location_type& l]))[);
+      by_state (kind_type s);
+
+      /// Copy constructor.
+      by_state (const by_state& other);
+
+      /// Steal the symbol type from \a that.
+      void move (by_state& that);
+
+      /// The (internal) type number (corresponding to \a state).
+      /// "empty" when empty.
+      symbol_number_type type_get () const;
+
+      enum { empty = 0 };
 
       /// The state.
       state_type state;
+    };
 
-      /// Return the type corresponding to this state.
-      inline int type_get_ () const;
+    /// "Internal" symbol: element of the stack.
+    struct stack_symbol_type : basic_symbol<by_state>
+    {
+      /// Superclass.
+      typedef basic_symbol<by_state> super_type;
+      /// Construct an empty symbol.
+      stack_symbol_type ();
+      /// Steal the contents from \a sym to build this.
+      stack_symbol_type (state_type s, symbol_type& sym);
+      /// Assignment, needed by push_back.
+      stack_symbol_type& operator= (const stack_symbol_type& that);
     };
 
     /// Stack type.
@@ -406,7 +324,7 @@ do {                                                            \
     ///             if null, no trace is output.
     /// \param s    the symbol
     /// \warning the contents of \a s.value is stolen.
-    inline void yypush_ (const char* m, stack_symbol_type& s);
+    void yypush_ (const char* m, stack_symbol_type& s);
 
     /// Push a new look ahead token on the state on the stack.
     /// \param m    a debug message to display
@@ -414,12 +332,12 @@ do {                                                            \
     /// \param s    the state
     /// \param sym  the symbol (for its value and location).
     /// \warning the contents of \a s.value is stolen.
-    inline void yypush_ (const char* m, state_type s, symbol_type& sym);
+    void yypush_ (const char* m, state_type s, symbol_type& sym);
 
     /// Pop \a n symbols the three stacks.
-    inline void yypop_ (unsigned int n = 1);
+    void yypop_ (unsigned int n = 1);
 
-    /* Constants.  */
+    // Constants.
     enum
     {
       yyeof_ = 0,
@@ -429,29 +347,46 @@ do {                                                            \
       yyfinal_ = ]b4_final_state_number[, //< Termination state number.
       yyterror_ = 1,
       yyerrcode_ = 256,
-      yyntokens_ = ]b4_tokens_number[,   //< Number of tokens.
+      yyntokens_ = ]b4_tokens_number[    //< Number of tokens.
     };
 
 ]b4_parse_param_vars[
   };
 
-]b4_lex_symbol_if([b4_yytranslate_define
-b4_public_types_define
-b4_symbol_constructor_define])[
+]b4_token_ctor_if([b4_yytranslate_define
+b4_public_types_define])[
 ]b4_namespace_close[
 
 ]b4_percent_define_flag_if([[global_tokens_and_yystype]],
-[b4_token_defines(b4_tokens)
+[b4_token_defines
 
-#ifndef YYSTYPE
- /* Redirection for backward compatibility.  */
-# define YYSTYPE b4_namespace_ref::b4_parser_class_name::semantic_type
+#ifndef ]b4_api_PREFIX[STYPE
+ // Redirection for backward compatibility.
+# define ]b4_api_PREFIX[STYPE b4_namespace_ref::b4_parser_class_name::semantic_type
 #endif
+])[
+]b4_percent_code_get([[provides]])[
+]])
+
+b4_defines_if(
+[b4_output_begin([b4_spec_defines_file])
+b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++])
+[
+/**
+ ** \file ]b4_spec_defines_file[
+ ** Define the ]b4_namespace_ref[::parser class.
+ */
+
+// C++ LALR(1) parser skeleton written by Akim Demaille.
+
+]b4_cpp_guard_open([b4_spec_defines_file])[
+]b4_shared_declarations[
+]b4_cpp_guard_close([b4_spec_defines_file])
+b4_output_end()
 ])
-b4_percent_code_get([[provides]])[]dnl
 
-[#endif /* ! defined PARSER_HEADER_H */]
-@output(b4_parser_file_name@)@
+
+b4_output_begin([b4_parser_file_name])
 b4_copyright([Skeleton implementation for Bison LALR(1) parsers in C++])
 b4_percent_code_get([[top]])[]dnl
 m4_if(b4_prefix, [yy], [],
@@ -459,19 +394,22 @@ m4_if(b4_prefix, [yy], [],
 // Take the name prefix into account.
 #define yylex   b4_prefix[]lex])[
 
-/* First part of user declarations.  */
+// First part of user declarations.
 ]b4_user_pre_prologue[
 
-#include "@basename(]b4_spec_defines_file[@)"
+]b4_null_define[
+
+]b4_defines_if([[#include "@basename(]b4_spec_defines_file[@)"]],
+               [b4_shared_declarations])[
 
-/* User implementation prologue.  */
-]b4_user_post_prologue
-b4_percent_code_get[]dnl
+// User implementation prologue.
+]b4_user_post_prologue[
+]b4_percent_code_get[
 
-[#ifndef YY_
-# if YYENABLE_NLS
+#ifndef YY_
+# if defined YYENABLE_NLS && YYENABLE_NLS
 #  if ENABLE_NLS
-#   include <libintl.h> /* FIXME: INFRINGES ON USER NAME SPACE */
+#   include <libintl.h> // FIXME: INFRINGES ON USER NAME SPACE.
 #   define YY_(msgid) dgettext ("bison-runtime", msgid)
 #  endif
 # endif
@@ -480,13 +418,17 @@ b4_percent_code_get[]dnl
 # endif
 #endif
 
-/* Suppress unused-variable warnings by "using" E.  */
-#define YYUSE(e) ((void) (e))
+]b4_locations_if([dnl
+[#define YYRHSLOC(Rhs, K) ((Rhs)[K].location)
+]b4_yylloc_default_define])[
+
+// Suppress unused-variable warnings by "using" E.
+#define YYUSE(E) ((void) (E))
 
-/* Enable debugging if requested.  */
-#if YYDEBUG
+// Enable debugging if requested.
+#if ]b4_api_PREFIX[DEBUG
 
-/* A pseudo ostream that takes yydebug_ into account.  */
+// A pseudo ostream that takes yydebug_ into account.
 # define YYCDEBUG if (yydebug_) (*yycdebug_)
 
 # define YY_SYMBOL_PRINT(Title, Symbol)         \
@@ -499,26 +441,26 @@ b4_percent_code_get[]dnl
     }                                           \
   } while (false)
 
-# define YY_REDUCE_PRINT(Rule)         \
-  do {                                 \
+# define YY_REDUCE_PRINT(Rule)          \
+  do {                                  \
     if (yydebug_)                       \
-      yy_reduce_print_ (Rule);         \
+      yy_reduce_print_ (Rule);          \
   } while (false)
 
-# define YY_STACK_PRINT()              \
-  do {                                 \
+# define YY_STACK_PRINT()               \
+  do {                                  \
     if (yydebug_)                       \
       yystack_print_ ();                \
   } while (false)
 
-#else /* !YYDEBUG */
+#else // !]b4_api_PREFIX[DEBUG
 
 # define YYCDEBUG if (false) std::cerr
-# define YY_SYMBOL_PRINT(Title, Symbol)  static_cast<void>(0)
+# define YY_SYMBOL_PRINT(Title, Symbol)  YYUSE(Symbol)
 # define YY_REDUCE_PRINT(Rule)           static_cast<void>(0)
 # define YY_STACK_PRINT()                static_cast<void>(0)
 
-#endif /* !YYDEBUG */
+#endif // !]b4_api_PREFIX[DEBUG
 
 #define yyerrok         (yyerrstatus_ = 0)
 #define yyclearin       (yyempty = true)
@@ -553,7 +495,7 @@ b4_percent_code_get[]dnl
             case '\\':
               if (*++yyp != '\\')
                 goto do_not_strip_quotes;
-              /* Fall through.  */
+              // Fall through.
             default:
               yyr += *yyp;
               break;
@@ -571,131 +513,136 @@ b4_percent_code_get[]dnl
   /// Build a parser object.
   ]b4_parser_class_name::b4_parser_class_name[ (]b4_parse_param_decl[)]m4_ifset([b4_parse_param], [
     :])[
-#if YYDEBUG
+#if ]b4_api_PREFIX[DEBUG
     ]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[ ()
-  {
-  }
+  {}
 
 
   /*---------------.
   | Symbol types.  |
   `---------------*/
 
-]b4_lex_symbol_if([], [b4_public_types_define
-b4_symbol_constructor_define])[
+]b4_token_ctor_if([], [b4_public_types_define])[
 
-  // stack_symbol_type.
-  ]b4_parser_class_name[::stack_symbol_type::stack_symbol_type ()
-    : super_type ()
-    , state ()
+  // by_state.
+  inline
+  ]b4_parser_class_name[::by_state::by_state ()
+    : state (empty)
+  {}
+
+  inline
+  ]b4_parser_class_name[::by_state::by_state (const by_state& other)
+    : state (other.state)
+  {}
+
+  inline
+  void
+  ]b4_parser_class_name[::by_state::move (by_state& that)
   {
+    state = that.state;
+    that.state = empty;
   }
 
-  ]b4_parser_class_name[::stack_symbol_type::stack_symbol_type (]b4_args(
-                 [state_type s],
-                 [const semantic_type& v],
-                 b4_locations_if([const location_type& l]))[)
-    : super_type (v]b4_locations_if([, l])[)
-    , state (s)
+  inline
+  ]b4_parser_class_name[::by_state::by_state (state_type s)
+    : state (s)
+  {}
+
+  inline
+  ]b4_parser_class_name[::symbol_number_type
+  ]b4_parser_class_name[::by_state::type_get () const
   {
+    return state == empty ? 0 : yystos_[state];
   }
 
-  int
-  ]b4_parser_class_name[::stack_symbol_type::type_get_ () const
+  inline
+  ]b4_parser_class_name[::stack_symbol_type::stack_symbol_type ()
+  {}
+
+
+  inline
+  ]b4_parser_class_name[::stack_symbol_type::stack_symbol_type (state_type s, symbol_type& that)
+    : super_type (s]b4_locations_if([, that.location])[)
+  {
+    ]b4_variant_if([b4_symbol_variant([that.type_get ()],
+                                      [value], [move], [that.value])],
+                   [[value = that.value;]])[
+    // that is emptied.
+    that.type = empty;
+  }
+
+  inline
+  ]b4_parser_class_name[::stack_symbol_type&
+  ]b4_parser_class_name[::stack_symbol_type::operator= (const stack_symbol_type& that)
   {
-    return yystos_[state];
+    state = that.state;
+    ]b4_variant_if([b4_symbol_variant([that.type_get ()],
+                                      [value], [copy], [that.value])],
+                   [[value = that.value;]])[]b4_locations_if([
+    location = that.location;])[
+    return *this;
   }
 
 
-  template <typename Exact>
+  template <typename Base>
+  inline
   void
-  ]b4_parser_class_name[::yy_destroy_ (const char* yymsg,
-                                       symbol_base_type<Exact>& yysym) const
+  ]b4_parser_class_name[::yy_destroy_ (const char* yymsg, basic_symbol<Base>& yysym) const
   {
-    int yytype = yysym.type_get ();
-    YYUSE (yymsg);
     if (yymsg)
-      YY_SYMBOL_PRINT (yymsg, yysym);
+      YY_SYMBOL_PRINT (yymsg, yysym);]b4_variant_if([], [
 
     // User destructor.
-    switch (yytype)
-      {
-]b4_symbol_foreach([b4_symbol_destructor])dnl
-[       default:
-          break;
-      }]b4_variant_if([
-
-    // Type destructor.
-  b4_symbol_variant([[yytype]], [[yysym.value]], [[template destroy]])])[
+    b4_symbol_actions([destructor], [yysym.type_get ()])])[
   }
 
-#if YYDEBUG
-  template <typename Exact>
+#if ]b4_api_PREFIX[DEBUG
+  template <typename Base>
   void
   ]b4_parser_class_name[::yy_print_ (std::ostream& yyo,
-                                     const symbol_base_type<Exact>& yysym) const
+                                     const basic_symbol<Base>& yysym) const
   {
-    int yytype = yysym.type_get ();
+    std::ostream& yyoutput = yyo;
+    YYUSE (yyoutput);
+    symbol_number_type yytype = yysym.type_get ();
     yyo << (yytype < yyntokens_ ? "token" : "nterm")
         << ' ' << yytname_[yytype] << " ("]b4_locations_if([
         << yysym.location << ": "])[;
-    switch (yytype)
-      {
-]b4_symbol_foreach([b4_symbol_printer])dnl
-[       default:
-         break;
-      }
+    ]b4_symbol_actions([printer])[
     yyo << ')';
   }
 #endif
 
+  inline
   void
-  ]b4_parser_class_name[::yypush_ (const char* m, state_type s,
-                                   symbol_type& sym)
+  ]b4_parser_class_name[::yypush_ (const char* m, state_type s, symbol_type& sym)
   {
-    if (m)
-      YY_SYMBOL_PRINT (m, sym);
-]b4_variant_if(
-[[    yystack_.push (stack_symbol_type (]b4_args(
-                    [s],
-                    [semantic_type()],
-                    b4_locations_if([sym.location]))[));
-    ]b4_symbol_variant([[yystos_[s]]], [[yystack_[0].value]],
-                       [build], [sym.value])],
-[[    yystack_.push (stack_symbol_type (]b4_args(
-                      [s],
-                      [sym.value],
-                      b4_locations_if([sym.location]))[));]])[
+    stack_symbol_type t (s, sym);
+    yypush_ (m, t);
   }
 
+  inline
   void
   ]b4_parser_class_name[::yypush_ (const char* m, stack_symbol_type& s)
   {
     if (m)
       YY_SYMBOL_PRINT (m, s);
-]b4_variant_if(
-[[    yystack_.push (stack_symbol_type (]b4_args(
-                       [s.state],
-                       [semantic_type()],
-                       b4_locations_if([s.location]))[));
-    ]b4_symbol_variant([[yystos_[s.state]]], [[yystack_[0].value]],
-                       [build], [s.value])],
-[    yystack_.push (s);])[
+    yystack_.push (s);
   }
 
+  inline
   void
   ]b4_parser_class_name[::yypop_ (unsigned int n)
   {
     yystack_.pop (n);
   }
 
-#if YYDEBUG
+#if ]b4_api_PREFIX[DEBUG
   std::ostream&
   ]b4_parser_class_name[::debug_stream () const
   {
@@ -720,7 +667,29 @@ b4_symbol_constructor_define])[
   {
     yydebug_ = l;
   }
-#endif
+#endif // ]b4_api_PREFIX[DEBUG
+
+  inline ]b4_parser_class_name[::state_type
+  ]b4_parser_class_name[::yy_lr_goto_state_ (state_type yystate, int yylhs)
+  {
+    int yyr = yypgoto_[yylhs - yyntokens_] + yystate;
+    if (0 <= yyr && yyr <= yylast_ && yycheck_[yyr] == yystate)
+      return yytable_[yyr];
+    else
+      return yydefgoto_[yylhs - yyntokens_];
+  }
+
+  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 ()
@@ -728,12 +697,11 @@ b4_symbol_constructor_define])[
     /// Whether yyla contains a lookahead.
     bool yyempty = true;
 
-    /* State.  */
+    // State.
     int yyn;
     int yylen = 0;
-    int yystate = 0;
 
-    /* Error handling.  */
+    // Error handling.
     int yynerrs_ = 0;
     int yyerrstatus_ = 0;
 
@@ -741,100 +709,102 @@ b4_symbol_constructor_define])[
     symbol_type yyla;]b4_locations_if([[
 
     /// The locations where the error started and ended.
-    stack_symbol_type yyerror_range[2];]])[
+    stack_symbol_type yyerror_range[3];]])[
 
     /// $$ and @@$.
     stack_symbol_type yylhs;
 
-    /// The return value of parse().
+    /// The return value of parse ().
     int yyresult;
 
+    // FIXME: This shoud be completely indented.  It is not yet to
+    // avoid gratuitous conflicts when merging into the master branch.
+    try
+      {
     YYCDEBUG << "Starting parse" << std::endl;
 
 ]m4_ifdef([b4_initial_action], [
-m4_pushdef([b4_at_dollar],     [yyla.location])dnl
-m4_pushdef([b4_dollar_dollar], [yyla.value])dnl
-    /* User initialization code.  */
+b4_dollar_pushdef([yyla.value], [], [yyla.location])dnl
+    // User initialization code.
     b4_user_initial_action
-m4_popdef([b4_dollar_dollar])dnl
-m4_popdef([b4_at_dollar])])dnl
+b4_dollar_popdef])[]dnl
 
   [  /* Initialize the stack.  The initial state will be set in
        yynewstate, since the latter expects the semantical and the
        location values to have been already stored, initialize these
        stacks with a primary value.  */
-    yystack_ = stack_type (0);
-    yypush_ (0, 0, yyla);
+    yystack_.clear ();
+    yypush_ (YY_NULL, 0, yyla);
 
-    // A new state was pushed on the stack.
-    // Invariant: yystate == yystack_[0].state, i.e.,
-    // yystate was just pushed onto the state stack.
+    // A new symbol was pushed on the stack.
   yynewstate:
-    YYCDEBUG << "Entering state " << yystate << std::endl;
+    YYCDEBUG << "Entering state " << yystack_[0].state << std::endl;
 
-    /* Accept?  */
-    if (yystate == yyfinal_)
+    // Accept?
+    if (yystack_[0].state == yyfinal_)
       goto yyacceptlab;
 
     goto yybackup;
 
-    /* Backup.  */
+    // Backup.
   yybackup:
 
-    /* Try to take a decision without lookahead.  */
-    yyn = yypact_[yystate];
-    if (yyn == yypact_ninf_)
+    // Try to take a decision without lookahead.
+    yyn = yypact_[yystack_[0].state];
+    if (yy_pact_value_is_default_ (yyn))
       goto yydefault;
 
-    /* Read a lookahead token.  */
+    // Read a lookahead token.
     if (yyempty)
       {
         YYCDEBUG << "Reading a token: ";
-]b4_lex_symbol_if(
-[        yyla = b4_c_function_call([yylex], [symbol_type],
-                                   m4_ifdef([b4_lex_param], b4_lex_param));],
-[        yyla.type = yytranslate_ (b4_c_function_call([yylex], [int],
-                                    [[YYSTYPE*], [&yyla.value]][]dnl
-b4_locations_if([, [[location*], [&yyla.location]]])dnl
-m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
+        try
+          {]b4_token_ctor_if([[
+            symbol_type yylookahead (]b4_lex[);
+            yyla.move (yylookahead);]], [[
+            yyla.type = yytranslate_ (]b4_lex[);]])[
+          }
+        catch (const syntax_error& yyexc)
+          {
+            error (yyexc);
+            goto yyerrlab1;
+          }
         yyempty = false;
       }
     YY_SYMBOL_PRINT ("Next token is", yyla);
 
     /* If the proper action on seeing token YYLA.TYPE is to reduce or
        to detect an error, take that action.  */
-    yyn += yyla.type;
-    if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yyla.type)
+    yyn += yyla.type_get ();
+    if (yyn < 0 || yylast_ < yyn || yycheck_[yyn] != yyla.type_get ())
       goto yydefault;
 
-    /* Reduce or error.  */
+    // Reduce or error.
     yyn = yytable_[yyn];
     if (yyn <= 0)
       {
-       if (yyn == 0 || yyn == yytable_ninf_)
-         goto yyerrlab;
-       yyn = -yyn;
-       goto yyreduce;
+        if (yy_table_value_is_error_ (yyn))
+          goto yyerrlab;
+        yyn = -yyn;
+        goto yyreduce;
       }
 
-    /* Discard the token being shifted.  */
+    // Discard the token being shifted.
     yyempty = true;
 
-    /* Count tokens shifted since error; after three, turn off error
-       status.  */
+    // Count tokens shifted since error; after three, turn off error status.
     if (yyerrstatus_)
       --yyerrstatus_;
 
-    /* Shift the lookahead token.  */
-    yystate = yyn;
-    yypush_ ("Shifting", yystate, yyla);
+    // Shift the lookahead token.
+    yypush_ ("Shifting", yyn, yyla);
     goto yynewstate;
 
   /*-----------------------------------------------------------.
   | yydefault -- do the default action for the current state.  |
   `-----------------------------------------------------------*/
   yydefault:
-    yyn = yydefact_[yystate];
+    yyn = yydefact_[yystack_[0].state];
     if (yyn == 0)
       goto yyerrlab;
     goto yyreduce;
@@ -843,13 +813,14 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
   | yyreduce -- Do a reduction.  |
   `-----------------------------*/
   yyreduce:
-    yylen = yyr2_[yyn];]b4_variant_if([
+    yylen = yyr2_[yyn];
+    yylhs.state = yy_lr_goto_state_(yystack_[yylen].state, yyr1_[yyn]);]b4_variant_if([
     /* Variants are always initialized to an empty instance of the
        correct type. The default $$=$1 action is NOT applied when using
        variants.  */
-    ]b4_symbol_variant([[yyr1_@{yyn@}]], [yylhs.value], [build]),[
+    b4_symbol_variant([[yyr1_@{yyn@}]], [yylhs.value], [build])],[
     /* If YYLEN is nonzero, implement the default value of the action:
-       `$$ = $1'.  Otherwise, use the top of the stack.
+       '$$ = $1'.  Otherwise, use the top of the stack.
 
        Otherwise, the following line sets YYLHS.VALUE to garbage.
        This behavior is undocumented and Bison
@@ -868,76 +839,60 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
 
     // Perform the reduction.
     YY_REDUCE_PRINT (yyn);
-    switch (yyn)
+    try
       {
+        switch (yyn)
+          {
 ]b4_user_actions[
-       default:
-          break;
+          default:
+            break;
+          }
+      }
+    catch (const syntax_error& yyexc)
+      {
+        error (yyexc);
+        YYERROR;
       }
-    // Compute post-reduction state.
-    yyn = yyr1_[yyn];
-    yystate = yypgoto_[yyn - yyntokens_] + yystack_[yylen].state;
-    if (0 <= yystate && yystate <= yylast_
-       && yycheck_[yystate] == yystack_[yylen].state)
-      yystate = yytable_[yystate];
-    else
-      yystate = yydefgoto_[yyn - yyntokens_];
-    yylhs.state = yystate;
     YY_SYMBOL_PRINT ("-> $$ =", yylhs);
-]b4_variant_if([[
-    // Destroy the rhs symbols.
-    for (int i = 0; i < yylen; ++i)
-      // Destroy a variant which value may have been swapped with
-      // yylhs.value (for instance if the action was "std::swap($$,
-      // $1)").  The value of yylhs.value (hence possibly one of these
-      // rhs symbols) depends on the default contruction for this
-      // type.  In the case of pointers for instance, no
-      // initialization is done, so the value is junk.  Therefore do
-      // not try to report the value of symbols about to be destroyed
-      // in the debug trace, it's possibly junk.  Hence yymsg = 0.
-      // Besides, that keeps exactly the same traces as with the other
-      // Bison skeletons.
-      yy_destroy_ (0, yystack_[i]);]])[
-
     yypop_ (yylen);
     yylen = 0;
     YY_STACK_PRINT ();
 
-    /* Shift the result of the reduction.  */
-    yypush_ (0, yylhs);
+    // Shift the result of the reduction.
+    yypush_ (YY_NULL, yylhs);
     goto yynewstate;
 
   /*--------------------------------------.
   | yyerrlab -- here on detecting error.  |
   `--------------------------------------*/
   yyerrlab:
-    /* If not already recovering from an error, report this error.  */
+    // If not already recovering from an error, report this error.
     if (!yyerrstatus_)
       {
-       ++yynerrs_;
-       error (]b4_args(b4_locations_if([yyla.location]),
-                        [yysyntax_error_ (yystate, yyla.type)])[);
+        ++yynerrs_;
+        error (]b4_join(b4_locations_if([yyla.location]),
+                        [[yysyntax_error_ (yystack_[0].state,
+                                           yyempty ? yyempty_ : yyla.type_get ())]])[);
       }
 
 ]b4_locations_if([[
-    yyerror_range[0].location = yyla.location;]])[
+    yyerror_range[1].location = yyla.location;]])[
     if (yyerrstatus_ == 3)
       {
-       /* If just tried and failed to reuse lookahead token after an
+        /* If just tried and failed to reuse lookahead token after an
            error, discard it.  */
 
-        /* Return failure if at end of input.  */
-        if (yyla.type == yyeof_)
+        // Return failure if at end of input.
+        if (yyla.type_get () == yyeof_)
           YYABORT;
-        else
+        else if (!yyempty)
           {
             yy_destroy_ ("Error: discarding", yyla);
             yyempty = true;
-         }
+          }
       }
 
-    /* Else will try to reuse lookahead token after shifting the error
-       token.  */
+    // Else will try to reuse lookahead token after shifting the error token.
     goto yyerrlab1;
 
 
@@ -950,28 +905,28 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
        YYERROR and the label yyerrorlab therefore never appears in user
        code.  */
     if (false)
-      goto yyerrorlab;
-
-]b4_locations_if([[
-    yyerror_range[0].location = yystack_[yylen - 1].location;]])[
-    /* Do not reclaim the symbols of the rule which action triggered
+      goto yyerrorlab;]b4_locations_if([[
+    yyerror_range[1].location = yystack_[yylen - 1].location;]])b4_variant_if([[
+    /* $$ was initialized before running the user action.  */
+    YY_SYMBOL_PRINT ("Error: discarding", yylhs);
+    yylhs.~stack_symbol_type();]])[
+    /* Do not reclaim the symbols of the rule whose action triggered
        this YYERROR.  */
     yypop_ (yylen);
     yylen = 0;
-    yystate = yystack_[0].state;
     goto yyerrlab1;
 
   /*-------------------------------------------------------------.
   | yyerrlab1 -- common code for both syntax error and YYERROR.  |
   `-------------------------------------------------------------*/
   yyerrlab1:
-    yyerrstatus_ = 3;  /* Each real token shifted decrements this.  */
+    yyerrstatus_ = 3;   // Each real token shifted decrements this.
     {
       stack_symbol_type error_token;
       for (;;)
         {
-          yyn = yypact_[yystate];
-          if (yyn != yypact_ninf_)
+          yyn = yypact_[yystack_[0].state];
+          if (!yy_pact_value_is_default_ (yyn))
             {
               yyn += yyterror_;
               if (0 <= yyn && yyn <= yylast_ && yycheck_[yyn] == yyterror_)
@@ -986,28 +941,27 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
           if (yystack_.size () == 1)
             YYABORT;
 ]b4_locations_if([[
-          yyerror_range[0].location = yystack_[0].location;]])[
+          yyerror_range[1].location = yystack_[0].location;]])[
           yy_destroy_ ("Error: popping", yystack_[0]);
           yypop_ ();
-          yystate = yystack_[0].state;
           YY_STACK_PRINT ();
         }
 ]b4_locations_if([[
-      yyerror_range[1].location = yyla.location;
-      YYLLOC_DEFAULT (error_token.location, (yyerror_range - 1), 2);]])[
+      yyerror_range[2].location = yyla.location;
+      YYLLOC_DEFAULT (error_token.location, yyerror_range, 2);]])[
 
-      /* Shift the error token.  */
-      error_token.state = yystate = yyn;
+      // Shift the error token.
+      error_token.state = yyn;
       yypush_ ("Shifting", error_token);
     }
     goto yynewstate;
 
-    /* Accept.  */
+    // Accept.
   yyacceptlab:
     yyresult = 0;
     goto yyreturn;
 
-    /* Abort.  */
+    // Abort.
   yyabortlab:
     yyresult = 1;
     goto yyreturn;
@@ -1016,85 +970,138 @@ m4_ifdef([b4_lex_param], [, ]b4_lex_param)));])[
     if (!yyempty)
       yy_destroy_ ("Cleanup: discarding lookahead", yyla);
 
-    /* Do not reclaim the symbols of the rule which action triggered
+    /* Do not reclaim the symbols of the rule whose action triggered
        this YYABORT or YYACCEPT.  */
     yypop_ (yylen);
-    while (yystack_.size () != 1)
+    while (1 < yystack_.size ())
       {
-       yy_destroy_ ("Cleanup: popping", yystack_[0]);
-       yypop_ ();
+        yy_destroy_ ("Cleanup: popping", yystack_[0]);
+        yypop_ ();
       }
 
     return yyresult;
   }
+    catch (...)
+      {
+        YYCDEBUG << "Exception caught: cleaning lookahead and stack"
+                 << std::endl;
+        // Do not try to display the values of the reclaimed symbols,
+        // as their printer might throw an exception.
+        if (!yyempty)
+          yy_destroy_ (YY_NULL, yyla);
+
+        while (1 < yystack_.size ())
+          {
+            yy_destroy_ (YY_NULL, yystack_[0]);
+            yypop_ ();
+          }
+        throw;
+      }
+  }
+
+  void
+  ]b4_parser_class_name[::error (const syntax_error& yyexc)
+  {
+    error (]b4_join(b4_locations_if([yyexc.location]),
+                    [[yyexc.what()]])[);
+  }
 
   // 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_)
+b4_error_verbose_if([state_type yystate, symbol_number_type yytoken],
+                    [state_type, symbol_number_type])[) const
+  {]b4_error_verbose_if([[
+    std::string yyres;
+    // Number of reported tokens (one for the "unexpected", one per
+    // "expected").
+    size_t yycount = 0;
+    // Its maximum.
+    enum { YYERROR_VERBOSE_ARGS_MAXIMUM = 5 };
+    // Arguments of yyformat.
+    char const *yyarg[YYERROR_VERBOSE_ARGS_MAXIMUM];
+
+    /* There are many possibilities here to consider:
+       - If this state is a consistent state with a default action, then
+         the only way this function was invoked is if the default action
+         is an error action.  In that case, don't check for expected
+         tokens because there are none.
+       - The only way there can be no lookahead present (in yytoken) is
+         if this state is a consistent state with a default action.
+         Thus, detecting the absence of a lookahead is sufficient to
+         determine that there is no unexpected or expected token to
+         report.  In that case, just report a simple "syntax error".
+       - Don't assume there isn't a lookahead just because this state is
+         a consistent state with a default action.  There might have
+         been a previous inconsistent state, consistent state with a
+         non-default action, or user semantic action that manipulated
+         yyla.  (However, yyla is currently not documented for users.)
+       - Of course, the expected token list depends on states to have
+         correct lookahead information, and it depends on the parser not
+         to perform extra reductions after fetching a lookahead from the
+         scanner and before detecting a syntax error.  Thus, state
+         merging (from LALR or IELR) and default reductions corrupt the
+         expected token list.  However, the list is correct for
+         canonical LR with one exception: it will still contain any
+         token that will not be accepted due to an error action in a
+         later state.
+    */
+    if (yytoken != yyempty_)
       {
-       /* Start YYX at -YYN if negative to avoid negative indexes in
-          YYCHECK.  */
-       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 reported tokens (one for the "unexpected", one per
-        // "expected").
-       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_)
+        int yyn = yypact_[yystate];
+        if (!yy_pact_value_is_default_ (yyn))
           {
-            if (yycount == YYERROR_VERBOSE_ARGS_MAXIMUM)
-            {
-              yycount = 1;
-              break;
-            }
-            else
-              yyarg[yycount++] = yytname_[yyx];
+            /* 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_;
+            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"));
+    char const* yyformat = YY_NULL;
+    switch (yycount)
+      {
+#define YYCASE_(N, S)                         \
+        case N:                               \
+          yyformat = S;                       \
+        break
+        YYCASE_(0, YY_("syntax error"));
+        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;
+
+    // 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;
+    return yyres;]], [[
+    return YY_("syntax error");]])[
   }
 
 
@@ -1104,17 +1111,16 @@ b4_error_verbose_if([int yystate, int yytoken],
 
 ]b4_parser_tables_define[
 
-#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.  */
+]b4_token_table_if([], [[#if ]b4_api_PREFIX[DEBUG]])[
+  // 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
+]b4_token_table_if([[#if ]b4_api_PREFIX[DEBUG]])[
 ]b4_integral_parser_table_define([rline], [b4_rline])[
 
   // Print the state stack on the debug stream.
@@ -1125,7 +1131,7 @@ b4_error_verbose_if([int yystate, int yytoken],
     for (stack_type::const_iterator
            i = yystack_.begin (),
            i_end = yystack_.end ();
-        i != i_end; ++i)
+         i != i_end; ++i)
       *yycdebug_ << ' ' << i->state;
     *yycdebug_ << std::endl;
   }
@@ -1136,18 +1142,20 @@ b4_error_verbose_if([int yystate, int yytoken],
   {
     unsigned int yylno = yyrline_[yyrule];
     int yynrhs = yyr2_[yyrule];
-    /* Print the symbols being reduced, and their result.  */
+    // Print the symbols being reduced, and their result.
     *yycdebug_ << "Reducing stack by rule " << yyrule - 1
-              << " (line " << yylno << "):" << std::endl;
-    /* The symbols being reduced.  */
+               << " (line " << yylno << "):" << std::endl;
+    // The symbols being reduced.
     for (int yyi = 0; yyi < yynrhs; yyi++)
       YY_SYMBOL_PRINT ("   $" << yyi + 1 << " =",
                        ]b4_rhs_data(yynrhs, yyi + 1)[);
   }
-#endif // YYDEBUG
+#endif // ]b4_api_PREFIX[DEBUG
 
-]b4_lex_symbol_if([], [b4_yytranslate_define])[
+]b4_token_ctor_if([], [b4_yytranslate_define])[
 ]b4_namespace_close[
 ]b4_epilogue[]dnl
-m4_divert_pop(0)
+b4_output_end()
+
+
 m4_popdef([b4_copyright_years])dnl