]> git.saurik.com Git - bison.git/blobdiff - data/lalr1.cc
* data/lalr1.cc (yyreport_syntax_error_): Catch up with glr.c and
[bison.git] / data / lalr1.cc
index eb4376c04965df0d1fa9b23b2f57f01258b6d1f1..8e82cb51f3efc266ec5f6a08eedcbf3cfe80af30 100644 (file)
@@ -1,6 +1,6 @@
 m4_divert(-1)
 # C++ skeleton for Bison
-# Copyright (C) 2002, 2003 Free Software Foundation, Inc.
+# Copyright (C) 2002, 2003, 2004 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
@@ -21,9 +21,6 @@ m4_divert(-1)
 ## Default values.  ##
 ## ---------------- ##
 
-# Stack parameters.
-m4_define_default([b4_stack_depth_init],  [200])
-
 # Default Parser class name.
 m4_define_default([b4_parser_class_name], [Parser])
 
@@ -46,7 +43,7 @@ m4_define([b4_lhs_value],
 # Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
 # symbols on RHS.
 m4_define([b4_rhs_value],
-[semantic_stack_@{m4_eval([$1 - $2])@}m4_ifval([$3], [.$3])])
+[yysemantic_stack_@{m4_eval([$1 - $2])@}m4_ifval([$3], [.$3])])
 
 m4_define_default([b4_location_type], [Location])
 
@@ -62,26 +59,51 @@ m4_define([b4_lhs_location],
 # Expansion of @NUM, where the current rule has RULE-LENGTH symbols
 # on RHS.
 m4_define([b4_rhs_location],
-[location_stack_@{m4_eval([$1 - $2])@}])
-
-
-m4_define([b4_inherit],
-          [m4_ifdef([b4_root],
-                   [: public b4_root
-],
-                   [])])
-
-m4_define([b4_param],
-         [m4_ifdef([b4_root],
-                   [,
-            const Param& param],
-                   [])])
+[yylocation_stack_@{m4_eval([$1 - $2])@}])
+
+
+# b4_parse_param_decl
+# -------------------
+# Extra formal arguments of the constructor.
+# Change the parameter names from "foo" into "foo_yyarg", so that
+# there is no collision bw the user chosen attribute name, and the
+# argument name in the constructor.
+m4_define([b4_parse_param_decl],
+[m4_ifset([b4_parse_param],
+          [m4_map_sep([b4_parse_param_decl_1], [, ], [b4_parse_param])])])
+
+m4_define([b4_parse_param_decl_1],
+[$1_yyarg])
+
+
+
+# b4_parse_param_cons
+# -------------------
+# Extra initialisations of the constructor.
+m4_define([b4_parse_param_cons],
+          [m4_ifset([b4_parse_param],
+                   [,
+      b4_cc_constructor_calls(b4_parse_param)])])
+m4_define([b4_cc_constructor_calls],
+         [m4_map_sep([b4_cc_constructor_call], [,
+      ], [$@])])
+m4_define([b4_cc_constructor_call],
+         [$2 ($2_yyarg)])
+
+# b4_parse_param_vars
+# -------------------
+# Extra instance variables.
+m4_define([b4_parse_param_vars],
+          [m4_ifset([b4_parse_param],
+                   [
+    /* User arguments.  */
+b4_cc_var_decls(b4_parse_param)])])
+m4_define([b4_cc_var_decls],
+         [m4_map_sep([b4_cc_var_decl], [
+], [$@])])
+m4_define([b4_cc_var_decl],
+         [    $1;])
 
-m4_define([b4_constructor],
-         [m4_ifdef([b4_root],
-                   [b4_root (param),
-      ],
-                   [])])
 
 
 # We do want M4 expansion after # for CPP macros.
@@ -90,7 +112,7 @@ m4_divert(0)dnl
 m4_if(b4_defines_flag, 0, [],
 [@output @output_header_name@
 b4_copyright([C++ Skeleton parser for LALR(1) parsing with Bison],
-             [2002, 2003])[
+             [2002, 2003, 2004])[
 /* FIXME: This is wrong, we want computed header guards.
    I don't know why the macros are missing now. :( */
 #ifndef PARSER_HEADER_H
@@ -123,14 +145,16 @@ b4_syncline([@oline@], [@ofile@])[
 # define YYERROR_VERBOSE ]b4_error_verbose[
 #endif
 
-#ifndef YYSTYPE
+#if ! defined (YYSTYPE) && ! defined (YYSTYPE_IS_DECLARED)
 ]m4_ifdef([b4_stype],
 [b4_syncline([b4_stype_line], [b4_filename])
-typedef union b4_stype yystype;
+union YYSTYPE b4_stype;
 /* Line __line__ of lalr1.cc.  */
 b4_syncline([@oline@], [@ofile@])],
-[typedef int yystype;])[
-# define YYSTYPE yystype
+[typedef int YYSTYPE;])[
+# define yystype YYSTYPE /* obsolescent; will be withdrawn */
+# define YYSTYPE_IS_DECLARED 1
+# define YYSTYPE_IS_TRIVIAL 1
 #endif
 
 /* Copy the second part of user declarations.  */
@@ -138,58 +162,68 @@ b4_syncline([@oline@], [@ofile@])],
 
 ]/* Line __line__ of lalr1.cc.  */
 b4_syncline([@oline@], [@ofile@])[
+/* 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) \
-   Current.last = Rhs[N].last;
+# 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 (0)
 #endif
 
 namespace yy
 {
   class ]b4_parser_class_name[;
 
-  template < typename P >
+  template <typename P>
   struct Traits
   {
   };
 
-  template < >
-  struct Traits< ]b4_parser_class_name[ >
+  template <>
+  struct Traits<]b4_parser_class_name[>
   {
     typedef ]b4_int_type_for([b4_translate])[ TokenNumberType;
     typedef ]b4_int_type_for([b4_rhs])[       RhsNumberType;
-    typedef int      StateType;
-    typedef yystype  SemanticType;
+    typedef int StateType;
+    typedef YYSTYPE SemanticType;
     typedef ]b4_location_type[ LocationType;
   };
 }
 
 namespace yy
 {
-  class ]b4_parser_class_name b4_inherit[
+  class ]b4_parser_class_name[
   {
   public:
-
-    typedef Traits< ]b4_parser_class_name[ >::TokenNumberType TokenNumberType;
-    typedef Traits< ]b4_parser_class_name[ >::RhsNumberType   RhsNumberType;
-    typedef Traits< ]b4_parser_class_name[ >::StateType       StateType;
-    typedef Traits< ]b4_parser_class_name[ >::SemanticType    SemanticType;
-    typedef Traits< ]b4_parser_class_name[ >::LocationType    LocationType;
-
-    typedef Stack< StateType >    StateStack;
-    typedef Stack< SemanticType > SemanticStack;
-    typedef Stack< LocationType > LocationStack;
-
-#if YYLSP_NEEDED
-    ]b4_parser_class_name[ (bool debug,
-           LocationType initlocation][]b4_param[) :
-      ]b4_constructor[][debug_ (debug),
-      cdebug_ (std::cerr),
-      initlocation_ (initlocation)
-#else
-    ]b4_parser_class_name[ (bool debug][]b4_param[) :
-      ]b4_constructor[][debug_ (debug),
-      cdebug_ (std::cerr)
-#endif
+    /// Internal symbol numbers.
+    typedef Traits<]b4_parser_class_name[>::TokenNumberType TokenNumberType;
+    /// A type to store symbol numbers and -1.
+    typedef Traits<]b4_parser_class_name[>::RhsNumberType   RhsNumberType;
+    /// State numbers.
+    typedef Traits<]b4_parser_class_name[>::StateType       StateType;
+    /// Symbol semantic values.
+    typedef Traits<]b4_parser_class_name[>::SemanticType    SemanticType;
+    /// Symbol locations.
+    typedef Traits<]b4_parser_class_name[>::LocationType    LocationType;
+
+    typedef Stack<StateType>    StateStack;
+    typedef Stack<SemanticType> SemanticStack;
+    typedef Stack<LocationType> LocationStack;
+
+    ]b4_parser_class_name[ (]b4_parse_param_decl[) :
+      yydebug_ (false),
+      yycdebug_ (&std::cerr)]b4_parse_param_cons[
     {
     }
 
@@ -197,87 +231,140 @@ namespace yy
     {
     }
 
+    /// Parse.
+    /// \returns  0 iff parsing succeeded.
     virtual int parse ();
 
+    /// 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);
+
   private:
 
-    virtual void lex_ ();
+    /// Call the scanner.
+    virtual void yylex_ ();
     virtual void error_ ();
-    virtual void print_ ();
-
-    /* Stacks.  */
-    StateStack    state_stack_;
-    SemanticStack semantic_stack_;
-    LocationStack location_stack_;
+    /// Generate an error message, and invoke error. */
+    virtual void yyreport_syntax_error_ ();
+#if YYDEBUG
+    /// \brief Report a symbol on the debug stream.
+    /// \param yytype       The token type.
+    /// \param yyvaluep     Its semantic value.
+    /// \param yylocationp  Its location.
+    virtual void yysymprint_ (int yytype,
+                             const SemanticType* yyvaluep,
+                             const LocationType* yylocationp);
+#endif /* ! YYDEBUG */
+
+
+    /// The state stack.
+    StateStack    yystate_stack_;
+    /// The semantic value stack.
+    SemanticStack yysemantic_stack_;
+    /// The location stack.
+    LocationStack yylocation_stack_;
 
     /* Tables.  */
-    static const ]b4_int_type_for([b4_pact])[ pact_[];
-    static const ]b4_int_type_for([b4_pact])[ pact_ninf_;
-    static const ]b4_int_type_for([b4_defact])[ defact_[];
-    static const ]b4_int_type_for([b4_pgoto])[ pgoto_[];
-    static const ]b4_int_type_for([b4_defgoto])[ defgoto_[];
-    static const ]b4_int_type_for([b4_table])[ table_[];
-    static const ]b4_int_type_for([b4_table])[ table_ninf_;
-    static const ]b4_int_type_for([b4_check])[ check_[];
-    static const ]b4_int_type_for([b4_r1])[ r1_[];
-    static const ]b4_int_type_for([b4_r2])[ r2_[];
+    static const ]b4_int_type_for([b4_pact])[ yypact_[];
+    static const ]b4_int_type(b4_pact_ninf, b4_pact_ninf)[ yypact_ninf_;
+    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_[];
+    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_[];
+    static const ]b4_int_type_for([b4_stos])[ yystos_[];
+    static const ]b4_int_type_for([b4_r1])[ yyr1_[];
+    static const ]b4_int_type_for([b4_r2])[ yyr2_[];
 
 #if YYDEBUG || YYERROR_VERBOSE
-    static const char* const name_[];
+    static const char* const yyname_[];
 #endif
 
-    /* More tables, for debugging.  */
 #if YYDEBUG
-    static const RhsNumberType rhs_[];
-    static const ]b4_int_type_for([b4_prhs])[ prhs_[];
-    static const ]b4_int_type_for([b4_rline])[ rline_[];
-    static const ]b4_int_type_for([b4_stos])[ stos_[];
-    static const ]b4_int_type_for([b4_toknum])[ token_number_[];
+    /// A `-1'-separated list of the rules' RHS.
+    static const RhsNumberType 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 yyrule is going to be reduced.
+    virtual void yyreduce_print_ (int yyrule);
+/// Print the state stack on the debug stream.
+    virtual void yystack_print_ ();
 #endif
 
-    /* Even more tables.  */
-    static inline TokenNumberType translate_ (int token);
+    /// Convert a scanner token number to a symbol number.
+    inline TokenNumberType yytranslate_ (int token);
+
+    /// \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,
+                             SemanticType* yyvaluep,
+                             LocationType* yylocationp);
+
+    /// Pop \a n symbols the three stacks.
+    inline void yypop_ (unsigned int n = 1);
 
     /* Constants.  */
-    static const int eof_;
+    static const int yyeof_;
     /* LAST_ -- Last index in TABLE_.  */
-    static const int last_;
-    static const int nnts_;
-    static const int empty_;
-    static const int final_;
-    static const int terror_;
-    static const int errcode_;
-    static const int ntokens_;
-    static const int initdepth_;
-    static const unsigned user_token_number_max_;
-    static const TokenNumberType undef_token_;
+    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 TokenNumberType yyundef_token_;
 
     /* State.  */
-    int n_;
-    int len_;
-    int state_;
+    int yyn_;
+    int yylen_;
+    int yystate_;
+
+    /* Error handling. */
+    int yynerrs_;
+    int yyerrstatus_;
 
     /* Debugging.  */
-    int debug_;
-    std::ostream &cdebug_;
+    int yydebug_;
+    std::ostream* yycdebug_;
 
-    /* Lookahead and lookahead in internal form.  */
-    int looka_;
-    int ilooka_;
+    /* Look-ahead and look-ahead in internal form.  */
+    int yylooka_;
+    int yyilooka_;
 
     /* Message.  */
     std::string message;
 
-    /* Semantic value and location of lookahead token.  */
+    /// Semantic value of the look-ahead.
     SemanticType value;
+    /// Location of the look-ahead.
     LocationType location;
+    /// The locations where the error started and ended.
+    Location yyerror_range_[2];
 
-    /* @@$ and $$.  */
+    /// $$.
     SemanticType yyval;
+    /// @@$.
     LocationType yyloc;
-
-    /* Initial location.  */
-    LocationType initlocation_;
+]b4_parse_param_vars[
   };
 }
 
@@ -285,165 +372,274 @@ namespace yy
 ])dnl
 @output @output_parser_name@
 b4_copyright([C++ Skeleton parser for LALR(1) parsing with Bison],
-             [2002, 2003])
+             [2002, 2003, 2004])
+m4_if(b4_prefix[], [yy], [],
+[
+// Take the name prefix into account.
+#define yylex   b4_prefix[]lex])
+m4_if(b4_defines_flag, 0, [],
+[
+#include @output_header_name@])[
 
-m4_if(b4_defines_flag, 0, [], [#include @output_header_name@])[
+/* A pseudo ostream that takes yydebug_ into account. */
+# define YYCDEBUG                                                      \
+  for (bool yydebugcond_ = yydebug_; yydebugcond_; yydebugcond_ = false)       \
+    (*yycdebug_)
 
 /* Enable debugging if requested.  */
 #if YYDEBUG
-# define YYCDEBUG    if (debug_) cdebug_
+
+# define YY_SYMBOL_PRINT(Title, Type, Value, Location) \
+do {                                                   \
+  if (yydebug_)                                                \
+    {                                                  \
+      *yycdebug_ << (Title) << ' ';                    \
+      yysymprint_ ((Type), (Value), (Location));       \
+      *yycdebug_ << std::endl;                         \
+    }                                                  \
+} while (0)
+
+# define YY_REDUCE_PRINT(Rule)         \
+do {                                   \
+  if (yydebug_)                                \
+    yyreduce_print_ (Rule);            \
+} while (0)
+
+# define YY_STACK_PRINT()              \
+do {                                   \
+  if (yydebug_)                                \
+    yystack_print_ ();                 \
+} while (0)
+
 #else /* !YYDEBUG */
-# define YYCDEBUG    if (0) cdebug_
+
+# define YY_SYMBOL_PRINT(Title, Type, Value, Location)
+# define YY_REDUCE_PRINT(Rule)
+# define YY_STACK_PRINT()
+
 #endif /* !YYDEBUG */
 
+#define YYACCEPT       goto yyacceptlab
+#define YYABORT                goto yyabortlab
+#define YYERROR                goto yyerrorlab
+
+#if YYDEBUG
+/*--------------------------------.
+| Print this symbol on YYOUTPUT.  |
+`--------------------------------*/
+
+void
+yy::]b4_parser_class_name[::yysymprint_ (int yytype,
+                         const SemanticType* yyvaluep, const LocationType* yylocationp)
+{
+  /* Pacify ``unused variable'' warnings.  */
+  (void) yyvaluep;
+  (void) yylocationp;
+  /* Backward compatibility, but should be removed eventually. */
+  std::ostream& cdebug_ = *yycdebug_;
+  (void) cdebug_;
+
+  *yycdebug_ << (yytype < yyntokens_ ? "token" : "nterm")
+            << ' ' << yyname_[yytype] << " ("
+             << *yylocationp << ": ";
+  switch (yytype)
+    {
+]m4_map([b4_symbol_actions], m4_defn([b4_symbol_printers]))dnl
+[      default:
+        break;
+    }
+  *yycdebug_ << ')';
+}
+#endif /* ! YYDEBUG */
+
+void
+yy::]b4_parser_class_name[::yydestruct_ (const char* yymsg,
+                         int yytype, SemanticType* yyvaluep, LocationType* yylocationp)
+{
+  /* Pacify ``unused variable'' warnings.  */
+  (void) yyvaluep;
+  (void) yylocationp;
+
+  YY_SYMBOL_PRINT (yymsg, yytype, yyvaluep, yylocationp);
+
+  switch (yytype)
+    {
+]m4_map([b4_symbol_actions], m4_defn([b4_symbol_destructors]))[
+      default:
+        break;
+    }
+}
+
+void
+yy::]b4_parser_class_name[::yypop_ (unsigned int n)
+{
+  yystate_stack_.pop (n);
+  yysemantic_stack_.pop (n);
+  yylocation_stack_.pop (n);
+}
+
+std::ostream&
+yy::]b4_parser_class_name[::debug_stream () const
+{
+  return *yycdebug_;
+}
+
+void
+yy::]b4_parser_class_name[::set_debug_stream (std::ostream& o)
+{
+  yycdebug_ = &o;
+}
+
+
+yy::]b4_parser_class_name[::debug_level_type
+yy::]b4_parser_class_name[::debug_level () const
+{
+  return yydebug_;
+}
+
+void
+yy::]b4_parser_class_name[::set_debug_level (debug_level_type l)
+{
+  yydebug_ = l;
+}
+
+
 int
 yy::]b4_parser_class_name[::parse ()
 {
-  int nerrs = 0;
-  int errstatus = 0;
+  YYCDEBUG << "Starting parse" << std::endl;
 
-  /* Initialize the stacks.  The initial state will be pushed in
+  yynerrs_ = 0;
+  yyerrstatus_ = 0;
+
+  /* Start.  */
+  yystate_ = 0;
+  yylooka_ = yyempty_;
+
+]m4_ifdef([b4_initial_action], [
+m4_pushdef([b4_at_dollar],     [location])dnl
+m4_pushdef([b4_dollar_dollar], [value])dnl
+  /* User initialization code. */
+  b4_initial_action
+m4_popdef([b4_dollar_dollar])dnl
+m4_popdef([b4_at_dollar])dnl
+/* Line __line__ of yacc.c.  */
+b4_syncline([@oline@], [@ofile@])])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.  */
-  state_stack_ = StateStack (0);
-  semantic_stack_ = SemanticStack (1);
-  location_stack_ = LocationStack (1);
-
-  /* Start.  */
-  state_ = 0;
-  looka_ = empty_;
-#if YYLSP_NEEDED
-  location = initlocation_;
-#endif
-  YYCDEBUG << "Starting parse" << std::endl;
+  yystate_stack_ = StateStack (0);
+  yysemantic_stack_ = SemanticStack (0);
+  yylocation_stack_ = LocationStack (0);
+  yysemantic_stack_.push (value);
+  yylocation_stack_.push (location);
 
   /* New state.  */
- yynewstate:
-  state_stack_.push (state_);
-  YYCDEBUG << "Entering state " << state_ << std::endl;
+yynewstate:
+  yystate_stack_.push (yystate_);
+  YYCDEBUG << "Entering state " << yystate_ << std::endl;
   goto yybackup;
 
   /* Backup.  */
- yybackup:
+yybackup:
 
-  /* Try to take a decision without lookahead.  */
-  n_ = pact_[state_];
-  if (n_ == pact_ninf_)
+  /* Try to take a decision without look-ahead.  */
+  yyn_ = yypact_[yystate_];
+  if (yyn_ == yypact_ninf_)
     goto yydefault;
 
-  /* Read a lookahead token.  */
-  if (looka_ == empty_)
-    {
-      YYCDEBUG << "Reading a token: ";
-      lex_ ();
-    }
+  /* Read a look-ahead token.  */
+  if (yylooka_ == yyempty_)
+    yylex_ ();
 
   /* Convert token to internal form.  */
-  if (looka_ <= 0)
+  if (yylooka_ <= yyeof_)
     {
-      looka_ = eof_;
-      ilooka_ = 0;
+      yylooka_ = yyilooka_ = yyeof_;
       YYCDEBUG << "Now at end of input." << std::endl;
     }
   else
     {
-      ilooka_ = translate_ (looka_);
-#if YYDEBUG
-      if (debug_)
-       {
-         YYCDEBUG << "Next token is " << looka_
-                << " (" << name_[ilooka_];
-         print_ ();
-         YYCDEBUG << ')' << std::endl;
-       }
-#endif
+      yyilooka_ = yytranslate_ (yylooka_);
+      YY_SYMBOL_PRINT ("Next token is", yyilooka_, &value, &location);
     }
 
-  n_ += ilooka_;
-  if (n_ < 0 || last_ < n_ || check_[n_] != ilooka_)
+  /* If the proper action on seeing token ILOOKA_ is to reduce or to
+     detect an error, take that action.  */
+  yyn_ += yyilooka_;
+  if (yyn_ < 0 || yylast_ < yyn_ || yycheck_[yyn_] != yyilooka_)
     goto yydefault;
 
   /* Reduce or error.  */
-  n_ = table_[n_];
-  if (n_ < 0)
+  yyn_ = yytable_[yyn_];
+  if (yyn_ < 0)
     {
-      if (n_ == table_ninf_)
+      if (yyn_ == yytable_ninf_)
        goto yyerrlab;
       else
        {
-         n_ = -n_;
+         yyn_ = -yyn_;
          goto yyreduce;
        }
     }
-  else if (n_ == 0)
+  else if (yyn_ == 0)
     goto yyerrlab;
 
   /* Accept?  */
-  if (n_ == final_)
+  if (yyn_ == yyfinal_)
     goto yyacceptlab;
 
-  /* Shift the lookahead token.  */
-#if YYDEBUG
-  YYCDEBUG << "Shifting token " << looka_
-           << " (" << name_[ilooka_] << "), ";
-#endif
+  /* Shift the look-ahead token.  */
+  YY_SYMBOL_PRINT ("Shifting", yyilooka_, &value, &location);
 
   /* Discard the token being shifted unless it is eof.  */
-  if (looka_ != eof_)
-    looka_ = empty_;
+  if (yylooka_ != yyeof_)
+    yylooka_ = yyempty_;
 
-  semantic_stack_.push (value);
-  location_stack_.push (location);
+  yysemantic_stack_.push (value);
+  yylocation_stack_.push (location);
 
   /* Count tokens shifted since error; after three, turn off error
      status.  */
-  if (errstatus)
-    --errstatus;
+  if (yyerrstatus_)
+    --yyerrstatus_;
 
-  state_ = n_;
+  yystate_ = yyn_;
   goto yynewstate;
 
-  /* Default action.  */
- yydefault:
-  n_ = defact_[state_];
-  if (n_ == 0)
+/*-----------------------------------------------------------.
+| yydefault -- do the default action for the current state.  |
+`-----------------------------------------------------------*/
+yydefault:
+  yyn_ = yydefact_[yystate_];
+  if (yyn_ == 0)
     goto yyerrlab;
   goto yyreduce;
 
-  /* Reduce.  */
- yyreduce:
-  len_ = r2_[n_];
-  if (len_)
-    {
-      yyval = semantic_stack_[len_ - 1];
-      yyloc = location_stack_[len_ - 1];
-    }
+/*-----------------------------.
+| yyreduce -- Do a reduction.  |
+`-----------------------------*/
+yyreduce:
+  yylen_ = yyr2_[yyn_];
+  /* If LEN_ 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 = semantic_stack_[0];
-      yyloc = location_stack_[0];
-    }
+    yyval = yysemantic_stack_[0];
 
-#if YYDEBUG
-  if (debug_)
-    {
-      YYCDEBUG << "Reducing via rule " << n_ - 1
-            << " (line " << rline_[n_] << "), ";
-      for (]b4_int_type_for([b4_prhs])[ i = prhs_[n_];
-          0 <= rhs_[i]; ++i)
-       YYCDEBUG << name_[rhs_[i]] << ' ';
-      YYCDEBUG << "-> " << name_[r1_[n_]] << std::endl;
-    }
-#endif
-
-  if (len_)
-    {
-      Slice< LocationType, LocationStack > slice (location_stack_, len_);
-      YYLLOC_DEFAULT (yyloc, slice, len_);
-    }
-
-  switch (n_)
+  {
+    Slice<LocationType, LocationStack> slice (yylocation_stack_, yylen_);
+    YYLLOC_DEFAULT (yyloc, slice, yylen_);
+  }
+  YY_REDUCE_PRINT (yyn_);
+  switch (yyn_)
     {
       ]b4_actions[
     }
@@ -451,181 +647,207 @@ yy::]b4_parser_class_name[::parse ()
 ]/* Line __line__ of lalr1.cc.  */
 b4_syncline([@oline@], [@ofile@])[
 
-  state_stack_.pop (len_);
-  semantic_stack_.pop (len_);
-  location_stack_.pop (len_);
+  yypop_ (yylen_);
 
-#if YYDEBUG
-  if (debug_)
-    {
-      YYCDEBUG << "state stack now";
-      for (StateStack::ConstIterator i = state_stack_.begin ();
-          i != state_stack_.end (); ++i)
-       YYCDEBUG << ' ' << *i;
-      YYCDEBUG << std::endl;
-    }
-#endif
+  YY_STACK_PRINT ();
 
-  semantic_stack_.push (yyval);
-  location_stack_.push (yyloc);
+  yysemantic_stack_.push (yyval);
+  yylocation_stack_.push (yyloc);
 
   /* Shift the result of the reduction.  */
-  n_ = r1_[n_];
-  state_ = pgoto_[n_ - ntokens_] + state_stack_[0];
-  if (0 <= state_ && state_ <= last_ && check_[state_] == state_stack_[0])
-    state_ = table_[state_];
+  yyn_ = yyr1_[yyn_];
+  yystate_ = yypgoto_[yyn_ - yyntokens_] + yystate_stack_[0];
+  if (0 <= yystate_ && yystate_ <= yylast_
+      && yycheck_[yystate_] == yystate_stack_[0])
+    yystate_ = yytable_[yystate_];
   else
-    state_ = defgoto_[n_ - ntokens_];
+    yystate_ = yydefgoto_[yyn_ - yyntokens_];
   goto yynewstate;
 
-  /* Report and recover from errors.  This is very incomplete.  */
- yyerrlab:
+/*------------------------------------.
+| yyerrlab -- here on detecting error |
+`------------------------------------*/
+yyerrlab:
   /* If not already recovering from an error, report this error.  */
-  if (!errstatus)
-    {
-      ++nerrs;
+  yyreport_syntax_error_ ();
 
-#if YYERROR_VERBOSE
-      n_ = pact_[state_];
-      if (pact_ninf_ < n_ && n_ < last_)
-       {
-         message = "syntax error, unexpected ";
-         message += name_[ilooka_];
-         {
-           int count = 0;
-           for (int x = (n_ < 0 ? -n_ : 0); x < ntokens_ + nnts_; ++x)
-             if (check_[x + n_] == x && x != terror_)
-               ++count;
-           if (count < 5)
-             {
-               count = 0;
-               for (int x = (n_ < 0 ? -n_ : 0); x < ntokens_ + nnts_; ++x)
-                 if (check_[x + n_] == x && x != terror_)
-                   {
-                     message += (!count++) ? ", expecting " : " or ";
-                     message += name_[x];
-                   }
-             }
-         }
-       }
-      else
-#endif
-       message = "syntax error";
-      error_ ();
-    }
-  goto yyerrlab1;
-
-  /* Error raised explicitly by an action.  */
- yyerrlab1:
-  if (errstatus == 3)
+  yyerror_range_[0] = location;
+  if (yyerrstatus_ == 3)
     {
-      /* If just tried and failed to reuse lookahead token after an
+      /* If just tried and failed to reuse look-ahead token after an
         error, discard it.  */
 
       /* Return failure if at end of input.  */
-      if (looka_ == eof_)
-       goto yyabortlab;
-      YYCDEBUG << "Discarding token " << looka_
-            << " (" << name_[ilooka_] << ")." << std::endl;
-      looka_ = empty_;
+      if (yylooka_ <= yyeof_)
+        {
+          /* If at end of input, pop the error token,
+            then the rest of the stack, then return failure.  */
+         if (yylooka_ == yyeof_)
+            for (;;)
+              {
+                 yyerror_range_[0] = yylocation_stack_[0];
+                 yypop_ ();
+                if (yystate_stack_.height () == 1)
+                  YYABORT;
+                 yydestruct_ ("Error: popping",
+                              yystos_[yystate_stack_[0]],
+                              &yysemantic_stack_[0],
+                              &yylocation_stack_[0]);
+              }
+        }
+      else
+        {
+          yydestruct_ ("Error: discarding", yyilooka_, &value, &location);
+          yylooka_ = yyempty_;
+        }
     }
 
-  /* Else will try to reuse lookahead token after shifting the error
+  /* Else will try to reuse look-ahead token after shifting the error
      token.  */
+  goto yyerrlab1;
+
+
+/*---------------------------------------------------.
+| yyerrorlab -- error raised explicitly by YYERROR.  |
+`---------------------------------------------------*/
+yyerrorlab:
 
-  errstatus = 3;
+#ifdef __GNUC__
+  /* Pacify GCC when the user code never invokes YYERROR and the label
+     yyerrorlab therefore never appears in user code.  */
+  if (0)
+     goto yyerrorlab;
+#endif
+
+  yyerror_range_[0] = yylocation_stack_[yylen_ - 1];
+  yypop_ (yylen_);
+  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 (;;)
     {
-      n_ = pact_[state_];
-      if (n_ != pact_ninf_)
+      yyn_ = yypact_[yystate_];
+      if (yyn_ != yypact_ninf_)
        {
-         n_ += terror_;
-         if (0 <= n_ && n_ <= last_ && check_[n_] == terror_)
+         yyn_ += yyterror_;
+         if (0 <= yyn_ && yyn_ <= yylast_ && yycheck_[yyn_] == yyterror_)
            {
-             n_ = table_[n_];
-             if (0 < n_)
+             yyn_ = yytable_[yyn_];
+             if (0 < yyn_)
                break;
            }
        }
 
       /* Pop the current state because it cannot handle the error token.  */
-      if (state_stack_.height () == 1)
-       goto yyabortlab;
-
-#if YYDEBUG
-      if (debug_)
-       {
-         if (stos_[state_] < ntokens_)
-           {
-             YYCDEBUG << "Error: popping token "
-                    << token_number_[stos_[state_]]
-                    << " (" << name_[stos_[state_]];
-# ifdef YYPRINT
-             YYPRINT (stderr, token_number_[stos_[state_]],
-                      semantic_stack_.top ());
-# endif
-             YYCDEBUG << ')' << std::endl;
-           }
-         else
-           {
-             YYCDEBUG << "Error: popping nonterminal ("
-                    << name_[stos_[state_]] << ')' << std::endl;
-           }
-       }
-#endif
-
-      state_ = (state_stack_.pop (), state_stack_[0]);
-      semantic_stack_.pop ();
-      location_stack_.pop ();;
-
-#if YYDEBUG
-      if (debug_)
-       {
-         YYCDEBUG << "Error: state stack now";
-         for (StateStack::ConstIterator i = state_stack_.begin ();
-              i != state_stack_.end (); ++i)
-           YYCDEBUG << ' ' << *i;
-         YYCDEBUG << std::endl;
-       }
-#endif
+      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 ();
     }
 
-  if (n_ == final_)
+  if (yyn_ == yyfinal_)
     goto yyacceptlab;
 
-  YYCDEBUG << "Shifting error token, ";
+  yyerror_range_[1] = location;
+  // Using LOCATION is tempting, but would change the location of
+  // the look-ahead.  YYLOC is available though.
+  YYLLOC_DEFAULT (yyloc, yyerror_range_ - 1, 2);
+  yysemantic_stack_.push (value);
+  yylocation_stack_.push (yyloc);
 
-  semantic_stack_.push (value);
-  location_stack_.push (location);
+  /* Shift the error token. */
+  YY_SYMBOL_PRINT ("Shifting", yystos_[yyn_],
+                  &yysemantic_stack_[0], &yylocation_stack_[0]);
 
-  state_ = n_;
+  yystate_ = yyn_;
   goto yynewstate;
 
   /* Accept.  */
- yyacceptlab:
+yyacceptlab:
   return 0;
 
   /* Abort.  */
- yyabortlab:
+yyabortlab:
+  /* Free the lookahead. */
+  yydestruct_ ("Error: discarding lookahead", yyilooka_, &value, &location);
+  yylooka_ = yyempty_;
   return 1;
 }
 
 void
-yy::]b4_parser_class_name[::lex_ ()
+yy::]b4_parser_class_name[::yylex_ ()
 {
+  YYCDEBUG << "Reading a token: ";
 #if YYLSP_NEEDED
-  looka_ = yylex (&value, &location);
+  yylooka_ = yylex (&value, &location);
 #else
-  looka_ = yylex (&value);
+  yylooka_ = yylex (&value);
 #endif
 }
 
+// Generate an error message, and invoke error.
+void
+yy::]b4_parser_class_name[::yyreport_syntax_error_ ()
+{
+  /* If not already recovering from an error, report this error.  */
+  if (!yyerrstatus_)
+    {
+      ++yynerrs_;
+
+#if YYERROR_VERBOSE
+      yyn_ = yypact_[yystate_];
+      if (yypact_ninf_ < yyn_ && yyn_ < yylast_)
+       {
+         /* 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_;
+         int yyxend = yychecklim < yyntokens_ ? yychecklim : yyntokens_;
+          int count = 0;
+          for (int x = yyxbegin; x < yyxend; ++x)
+            if (yycheck_[x + yyn_] == x && x != yyterror_)
+              ++count;
+
+         message = "syntax error, unexpected ";
+         message += yyname_[yyilooka_];
+          if (count < 5)
+            {
+              count = 0;
+              for (int x = yyxbegin; x < yyxend; ++x)
+                if (yycheck_[x + yyn_] == x && x != yyterror_)
+                  {
+                    message += (!count++) ? ", expecting " : " or ";
+                    message += yyname_[x];
+                 }
+            }
+       }
+      else
+#endif
+       message = "syntax error";
+      error_ ();
+    }
+}
+
+
 /* YYPACT[STATE-NUM] -- Index in YYTABLE of the portion describing
    STATE-NUM.  */
-const ]b4_int_type_for([b4_pact]) yy::b4_parser_class_name::pact_ninf_ = b4_pact_ninf[;
+const ]b4_int_type(b4_pact_ninf, b4_pact_ninf) yy::b4_parser_class_name::yypact_ninf_ = b4_pact_ninf[;
 const ]b4_int_type_for([b4_pact])[
-yy::]b4_parser_class_name[::pact_[] =
+yy::]b4_parser_class_name[::yypact_[] =
 {
   ]b4_pact[
 };
@@ -634,21 +856,21 @@ yy::]b4_parser_class_name[::pact_[] =
    doesn't specify something else to do.  Zero means the default is an
    error.  */
 const ]b4_int_type_for([b4_defact])[
-yy::]b4_parser_class_name[::defact_[] =
+yy::]b4_parser_class_name[::yydefact_[] =
 {
   ]b4_defact[
 };
 
 /* YYPGOTO[NTERM-NUM].  */
 const ]b4_int_type_for([b4_pgoto])[
-yy::]b4_parser_class_name[::pgoto_[] =
+yy::]b4_parser_class_name[::yypgoto_[] =
 {
   ]b4_pgoto[
 };
 
 /* YYDEFGOTO[NTERM-NUM].  */
 const ]b4_int_type_for([b4_defgoto])[
-yy::]b4_parser_class_name[::defgoto_[] =
+yy::]b4_parser_class_name[::yydefgoto_[] =
 {
   ]b4_defgoto[
 };
@@ -656,33 +878,33 @@ yy::]b4_parser_class_name[::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 zero, do what YYDEFACT says.  */
-const ]b4_int_type_for([b4_table]) yy::b4_parser_class_name::table_ninf_ = b4_table_ninf[;
+const ]b4_int_type(b4_table_ninf, b4_table_ninf) yy::b4_parser_class_name::yytable_ninf_ = b4_table_ninf[;
 const ]b4_int_type_for([b4_table])[
-yy::]b4_parser_class_name[::table_[] =
+yy::]b4_parser_class_name[::yytable_[] =
 {
   ]b4_table[
 };
 
 /* YYCHECK.  */
 const ]b4_int_type_for([b4_check])[
-yy::]b4_parser_class_name[::check_[] =
+yy::]b4_parser_class_name[::yycheck_[] =
 {
   ]b4_check[
 };
 
-#if YYDEBUG
 /* STOS_[STATE-NUM] -- The (internal number of the) accessing
    symbol of state STATE-NUM.  */
 const ]b4_int_type_for([b4_stos])[
-yy::]b4_parser_class_name[::stos_[] =
+yy::]b4_parser_class_name[::yystos_[] =
 {
   ]b4_stos[
 };
 
-/* TOKEN_NUMBER_[YYLEX-NUM] -- Internal token number corresponding
+#if YYDEBUG
+/* TOKEN_NUMBER_[YYLEX-NUM] -- Internal symbol number corresponding
    to YYLEX-NUM.  */
 const ]b4_int_type_for([b4_toknum])[
-yy::]b4_parser_class_name[::token_number_[] =
+yy::]b4_parser_class_name[::yytoken_number_[] =
 {
   ]b4_toknum[
 };
@@ -690,23 +912,23 @@ yy::]b4_parser_class_name[::token_number_[] =
 
 /* YYR1[YYN] -- Symbol number of symbol that rule YYN derives.  */
 const ]b4_int_type_for([b4_r1])[
-yy::]b4_parser_class_name[::r1_[] =
+yy::]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])[
-yy::]b4_parser_class_name[::r2_[] =
+yy::]b4_parser_class_name[::yyr2_[] =
 {
   ]b4_r2[
 };
 
 #if YYDEBUG || YYERROR_VERBOSE
 /* YYTNAME[SYMBOL-NUM] -- String name of the symbol SYMBOL-NUM.
-   First, the terminals, then, starting at YYNTOKENS, nonterminals. */
+   First, the terminals, then, starting at \a yyntokens_, nonterminals. */
 const char*
-const yy::]b4_parser_class_name[::name_[] =
+const yy::]b4_parser_class_name[::yyname_[] =
 {
   ]b4_tname[
 };
@@ -715,7 +937,7 @@ const yy::]b4_parser_class_name[::name_[] =
 #if YYDEBUG
 /* YYRHS -- A `-1'-separated list of the rules' RHS. */
 const yy::]b4_parser_class_name[::RhsNumberType
-yy::]b4_parser_class_name[::rhs_[] =
+yy::]b4_parser_class_name[::yyrhs_[] =
 {
   ]b4_rhs[
 };
@@ -723,52 +945,76 @@ yy::]b4_parser_class_name[::rhs_[] =
 /* YYPRHS[YYN] -- Index of the first RHS symbol of rule number YYN in
    YYRHS.  */
 const ]b4_int_type_for([b4_prhs])[
-yy::]b4_parser_class_name[::prhs_[] =
+yy::]b4_parser_class_name[::yyprhs_[] =
 {
   ]b4_prhs[
 };
 
-/* YYRLINE[YYN] -- source line where rule number YYN was defined.  */
+/* YYRLINE[YYN] -- Source line where rule number YYN was defined.  */
 const ]b4_int_type_for([b4_rline])[
-yy::]b4_parser_class_name[::rline_[] =
+yy::]b4_parser_class_name[::yyrline_[] =
 {
   ]b4_rline[
 };
-#endif
+
+// Print the state stack on the debug stream.
+void
+yy::]b4_parser_class_name[::yystack_print_ ()
+{
+  *yycdebug_ << "Stack now";
+  for (StateStack::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
+yy::]b4_parser_class_name[::yyreduce_print_ (int yyrule)
+{
+  unsigned int yylno = yyrline_[yyrule];
+  /* Print the symbols being reduced, and their result.  */
+    *yycdebug_ << "Reducing stack by rule " << yyn_ - 1
+               << " (line " << yylno << "), ";
+  for (]b4_int_type_for([b4_prhs])[ i = yyprhs_[yyn_];
+       0 <= yyrhs_[i]; ++i)
+    *yycdebug_ << yyname_[yyrhs_[i]] << ' ';
+  *yycdebug_ << "-> " << yyname_[yyr1_[yyn_]] << std::endl;
+}
+#endif // YYDEBUG
 
 /* YYTRANSLATE(YYLEX) -- Bison symbol number corresponding to YYLEX.  */
 yy::]b4_parser_class_name[::TokenNumberType
-yy::]b4_parser_class_name[::translate_ (int token)
+yy::]b4_parser_class_name[::yytranslate_ (int token)
 {
   static
   const TokenNumberType
-  translate_[] =
+  translate_table[] =
   {
     ]b4_translate[
   };
-  if ((unsigned) token <= user_token_number_max_)
-    return translate_[token];
+  if ((unsigned int) token <= yyuser_token_number_max_)
+    return translate_table[token];
   else
-    return undef_token_;
+    return yyundef_token_;
 }
 
-const int yy::]b4_parser_class_name[::eof_ = 0;
-const int yy::]b4_parser_class_name[::last_ = ]b4_last[;
-const int yy::]b4_parser_class_name[::nnts_ = ]b4_nterms_number[;
-const int yy::]b4_parser_class_name[::empty_ = -2;
-const int yy::]b4_parser_class_name[::final_ = ]b4_final_state_number[;
-const int yy::]b4_parser_class_name[::terror_ = 1;
-const int yy::]b4_parser_class_name[::errcode_ = 256;
-const int yy::]b4_parser_class_name[::ntokens_ = ]b4_tokens_number[;
-const int yy::]b4_parser_class_name[::initdepth_ = ]b4_stack_depth_init[;
+const int yy::]b4_parser_class_name[::yyeof_ = 0;
+const int yy::]b4_parser_class_name[::yylast_ = ]b4_last[;
+const int yy::]b4_parser_class_name[::yynnts_ = ]b4_nterms_number[;
+const int yy::]b4_parser_class_name[::yyempty_ = -2;
+const int yy::]b4_parser_class_name[::yyfinal_ = ]b4_final_state_number[;
+const int yy::]b4_parser_class_name[::yyterror_ = 1;
+const int yy::]b4_parser_class_name[::yyerrcode_ = 256;
+const int yy::]b4_parser_class_name[::yyntokens_ = ]b4_tokens_number[;
 
-const unsigned yy::]b4_parser_class_name[::user_token_number_max_ = ]b4_user_token_number_max[;
-const yy::]b4_parser_class_name[::TokenNumberType yy::]b4_parser_class_name[::undef_token_ = ]b4_undef_token_number[;
+const unsigned int yy::]b4_parser_class_name[::yyuser_token_number_max_ = ]b4_user_token_number_max[;
+const yy::]b4_parser_class_name[::TokenNumberType yy::]b4_parser_class_name[::yyundef_token_ = ]b4_undef_token_number[;
 
 ]b4_epilogue
 dnl
 @output stack.hh
-b4_copyright([2002, 2003])[
+b4_copyright([Stack handling for Bison C++ parsers], [2002, 2003, 2004])[
 
 #ifndef BISON_STACK_HH
 # define BISON_STACK_HH
@@ -777,34 +1023,35 @@ b4_copyright([2002, 2003])[
 
 namespace yy
 {
-  template < class T, class S = std::deque< T > >
+  template <class T, class S = std::deque<T> >
   class Stack
   {
   public:
 
-    typedef typename S::iterator Iterator;
-    typedef typename S::const_iterator ConstIterator;
+    // Hide our reversed order.
+    typedef typename S::reverse_iterator iterator;
+    typedef typename S::const_reverse_iterator const_iterator;
 
     Stack () : seq_ ()
     {
     }
 
-    Stack (unsigned n) : seq_ (n)
+    Stack (unsigned int n) : seq_ (n)
     {
     }
 
     inline
     T&
-    operator [] (unsigned index)
+    operator [] (unsigned int i)
     {
-      return seq_[index];
+      return seq_[i];
     }
 
     inline
     const T&
-    operator [] (unsigned index) const
+    operator [] (unsigned int i) const
     {
-      return seq_[index];
+      return seq_[i];
     }
 
     inline
@@ -816,73 +1063,272 @@ namespace yy
 
     inline
     void
-    pop (unsigned n = 1)
+    pop (unsigned int n = 1)
     {
       for (; n; --n)
        seq_.pop_front ();
     }
 
     inline
-    unsigned
+    unsigned int
     height () const
     {
       return seq_.size ();
     }
 
-    inline ConstIterator begin () const { return seq_.begin (); }
-    inline ConstIterator end () const { return seq_.end (); }
+    inline const_iterator begin () const { return seq_.rbegin (); }
+    inline const_iterator end () const { return seq_.rend (); }
 
   private:
 
     S seq_;
   };
 
-  template < class T, class S = Stack< T > >
+  template <class T, class S = Stack<T> >
   class Slice
   {
   public:
 
     Slice (const S& stack,
-          unsigned range) : stack_ (stack),
-                            range_ (range)
+          unsigned int range) : stack_ (stack),
+                                range_ (range)
     {
     }
 
     inline
     const T&
-    operator [] (unsigned index) const
+    operator [] (unsigned int i) const
     {
-      return stack_[range_ - index];
+      return stack_[range_ - i];
     }
 
   private:
 
     const S& stack_;
-    unsigned range_;
+    unsigned int range_;
   };
 }
 
 #endif // not BISON_STACK_HH]
 dnl
+@output position.hh
+b4_copyright([Position class for Bison C++ parsers], [2002, 2003, 2004])[
+
+/**
+ ** \file position.hh
+ ** Define the Location class.
+ */
+
+#ifndef BISON_POSITION_HH
+# define BISON_POSITION_HH
+
+# include <iostream>
+# include <string>
+
+namespace yy
+{
+  /// Abstract a Position.
+  class Position
+  {
+  public:
+    /// Initial column number.
+    static const unsigned int initial_column = 0;
+    /// Initial line number.
+    static const unsigned int initial_line = 1;
+
+    /** \name Ctor & dtor.
+     ** \{ */
+  public:
+    /// Construct a Position.
+    Position () :
+      filename (),
+      line (initial_line),
+      column (initial_column)
+    {
+    }
+    /** \} */
+
+
+    /** \name Line and Column related manipulators
+     ** \{ */
+  public:
+    /// (line related) Advance to the COUNT next lines.
+    inline void lines (int count = 1)
+    {
+      column = initial_column;
+      line += count;
+    }
+
+    /// (column related) Advance to the COUNT next columns.
+    inline void columns (int count = 1)
+    {
+      int leftmost = initial_column;
+      int current  = column;
+      if (leftmost <= current + count)
+       column += count;
+      else
+       column = initial_column;
+    }
+    /** \} */
+
+  public:
+    /// File name to which this position refers.
+    std::string filename;
+    /// Current line number.
+    unsigned int line;
+    /// Current column number.
+    unsigned int column;
+  };
+
+  /// Add and assign a Position.
+  inline const Position&
+  operator+= (Position& res, const int width)
+  {
+    res.columns (width);
+    return res;
+  }
+
+  /// Add two Position objects.
+  inline const Position
+  operator+ (const Position& begin, const int width)
+  {
+    Position res = begin;
+    return res += width;
+  }
+
+  /// Add and assign a Position.
+  inline const Position&
+  operator-= (Position& res, const int width)
+  {
+    return res += -width;
+  }
+
+  /// Add two Position objects.
+  inline const Position
+  operator- (const Position& begin, const int width)
+  {
+    return begin + -width;
+  }
+
+  /** \brief Intercept output stream redirection.
+   ** \param ostr the destination output stream
+   ** \param pos a reference to the Position to redirect
+   */
+  inline std::ostream&
+  operator<< (std::ostream& ostr, const Position& pos)
+  {
+    if (!pos.filename.empty ())
+      ostr << pos.filename << ':';
+    return ostr << pos.line << '.' << pos.column;
+  }
+
+}
+#endif // not BISON_POSITION_HH]
 @output location.hh
-b4_copyright([2002, 2003])[
+b4_copyright([Location class for Bison C++ parsers], [2002, 2003, 2004])[
+
+/**
+ ** \file location.hh
+ ** Define the Location class.
+ */
 
 #ifndef BISON_LOCATION_HH
 # define BISON_LOCATION_HH
 
+# include <iostream>
+# include <string>
+# include "position.hh"
+
 namespace yy
 {
-  struct Position
+
+  /// Abstract a Location.
+  class Location
   {
-    int line;
-    int column;
+    /** \name Ctor & dtor.
+     ** \{ */
+  public:
+    /// Construct a Location.
+    Location (void) :
+      begin (),
+      end ()
+    {
+    }
+    /** \} */
+
+
+    /** \name Line and Column related manipulators
+     ** \{ */
+  public:
+    /// Reset initial location to final location.
+    inline void step (void)
+    {
+      begin = end;
+    }
+
+    /// Extend the current location to the COUNT next columns.
+    inline void columns (unsigned int count = 1)
+    {
+      end += count;
+    }
+
+    /// Extend the current location to the COUNT next lines.
+    inline void lines (unsigned int count = 1)
+    {
+      end.lines (count);
+    }
+    /** \} */
+
+
+  public:
+    /// Beginning of the located region.
+    Position begin;
+    /// End of the located region.
+    Position end;
   };
 
-  struct Location
+  /// Join two Location objects to create a Location.
+  inline const Location operator+ (const Location& begin, const Location& end)
   {
-    Position first;
-    Position last;
-  };
+    Location res = begin;
+    res.end = end.end;
+    return res;
+  }
+
+  /// Add two Location objects.
+  inline const Location operator+ (const Location& begin, unsigned int width)
+  {
+    Location res = begin;
+    res.columns (width);
+    return res;
+  }
+
+  /// Add and assign a Location.
+  inline Location& operator+= (Location& res, unsigned int width)
+  {
+    res.columns (width);
+    return res;
+  }
+
+  /** \brief Intercept output stream redirection.
+   ** \param ostr the destination output stream
+   ** \param loc a reference to the Location to redirect
+   **
+   ** Avoid duplicate information.
+   */
+  inline std::ostream& operator<< (std::ostream& ostr, const Location& loc)
+  {
+    Position last = loc.end - 1;
+    ostr << loc.begin;
+    if (loc.begin.filename != last.filename)
+      ostr << '-' << last;
+    else if (loc.begin.line != last.line)
+      ostr << '-' << last.line  << '.' << last.column;
+    else if (loc.begin.column != last.column)
+      ostr << '-' << last.column;
+    return ostr;
+  }
+
 }
 
 #endif // not BISON_LOCATION_HH]