xml: also use "%empty" with html output

[bison.git] / data / glr.cc

# C++ GLR skeleton for Bison

# 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
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


# This skeleton produces a C++ class that encapsulates a C glr parser.
# This is in order to reduce the maintenance burden.  The glr.c
# skeleton is clean and pure enough so that there are no real
# problems.  The C++ interface is the same as that of lalr1.cc.  In
# fact, glr.c can replace yacc.c without the user noticing any
# difference, and similarly for glr.cc replacing lalr1.cc.
#
# The passing of parse-params
#
#   The additional arguments are stored as members of the parser
#   object, yyparser.  The C routines need to carry yyparser
#   throughout the C parser; that's easy: make yyparser an
#   additional parse-param.  But because the C++ skeleton needs to
#   know the "real" original parse-param, we save them
#   (b4_parse_param_orig).  Note that b4_parse_param is overquoted
#   (and c.m4 strips one level of quotes).  This is a PITA, and
#   explains why there are so many levels of quotes.
#
# The locations
#
#   We use location.cc just like lalr1.cc, but because glr.c stores
#   the locations in a union, the position and location classes
#   must not have a constructor.  Therefore, contrary to lalr1.cc, we
#   must not define "b4_location_constructors".  As a consequence the
#   user must initialize the first positions (in particular the
#   filename member).

# We require a pure interface.
m4_define([b4_pure_flag],      [1])

m4_include(b4_pkgdatadir/[c++.m4])
b4_bison_locations_if([m4_include(b4_pkgdatadir/[location.cc])])

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

# Save the parse parameters.
m4_define([b4_parse_param_orig], m4_defn([b4_parse_param]))

# b4_parse_param_wrap
# -------------------
# New ones.
m4_ifset([b4_parse_param],
[m4_define([b4_parse_param_wrap],
           [[b4_namespace_ref::b4_parser_class_name[& yyparser], [[yyparser]]],]
m4_defn([b4_parse_param]))],
[m4_define([b4_parse_param_wrap],
           [[b4_namespace_ref::b4_parser_class_name[& yyparser], [[yyparser]]]])
])


# b4_yy_symbol_print_define
# -------------------------
# Bypass the default implementation to generate the "yy_symbol_print"
# and "yy_symbol_value_print" functions.
m4_define([b4_yy_symbol_print_define],
[[
/*--------------------.
| Print this symbol.  |
`--------------------*/

]b4_function_define([yy_symbol_print],
    [static void],
    [[FILE *],      []],
    [[int yytype],  [yytype]],
    [[const ]b4_namespace_ref::b4_parser_class_name[::semantic_type *yyvaluep],
                    [yyvaluep]][]dnl
b4_locations_if([,
    [[const ]b4_namespace_ref::b4_parser_class_name[::location_type *yylocationp],
                    [yylocationp]]]),
    b4_parse_param)[
{
]b4_parse_param_use[]dnl
[  yyparser.yy_symbol_print_ (yytype, yyvaluep]b4_locations_if([, yylocationp])[);
}
]])[

# Hijack the initial action to initialize the locations.
]b4_bison_locations_if([m4_define([b4_initial_action],
[yylloc.initialize ();]m4_ifdef([b4_initial_action], [
m4_defn([b4_initial_action])]))])[

# Hijack the post prologue to insert early definition of YYLLOC_DEFAULT
# and declaration of yyerror.
]m4_append([b4_post_prologue],
[b4_syncline([@oline@], [@ofile@])[
]b4_yylloc_default_define[
#define YYRHSLOC(Rhs, K) ((Rhs)[K].yystate.yyloc)
]b4_function_declare([yyerror],
    [static void],b4_locations_if([
    [[const ]b4_namespace_ref::b4_parser_class_name[::location_type *yylocationp],
                        [yylocationp]],])
    b4_parse_param,
    [[const char* msg], [msg]])])


#undef yynerrs
#undef yychar
#undef yylval]b4_locations_if([
#undef yylloc])

m4_if(b4_prefix, [yy], [],
[[/* Substitute the variable and function names.  */
#define yyparse ]b4_prefix[parse
#define yylex   ]b4_prefix[lex
#define yyerror ]b4_prefix[error
#define yydebug ]b4_prefix[debug
]]b4_pure_if([], [[
#define yylval  ]b4_prefix[lval
#define yychar  ]b4_prefix[char
#define yynerrs ]b4_prefix[nerrs]b4_locations_if([[
#define yylloc  ]b4_prefix[lloc]])]))

# Hijack the epilogue to define implementations (yyerror, parser member
# functions etc.).
m4_append([b4_epilogue],
[b4_syncline([@oline@], [@ofile@])[

/*------------------.
| Report an error.  |
`------------------*/

]b4_function_define([yyerror],
    [static void],b4_locations_if([
    [[const ]b4_namespace_ref::b4_parser_class_name[::location_type *yylocationp],
                        [yylocationp]],])
    b4_parse_param,
    [[const char* msg], [msg]])[
{
]b4_parse_param_use[]dnl
[  yyparser.error (]b4_locations_if([[*yylocationp, ]])[msg);
}


]b4_namespace_open[
]dnl In this section, the parse params are the original parse_params.
m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
[  /// Build a parser object.
  ]b4_parser_class_name::b4_parser_class_name[ (]b4_parse_param_decl[)]m4_ifset([b4_parse_param], [
    :])[
#if ]b4_api_PREFIX[DEBUG
    ]m4_ifset([b4_parse_param], [  ], [ :])[yycdebug_ (&std::cerr)]m4_ifset([b4_parse_param], [,])[
#endif]b4_parse_param_cons[
  {
  }

  ]b4_parser_class_name::~b4_parser_class_name[ ()
  {
  }

  int
  ]b4_parser_class_name[::parse ()
  {
    return ::yyparse (*this]b4_user_args[);
  }

#if ]b4_api_PREFIX[DEBUG
  /*--------------------.
  | Print this symbol.  |
  `--------------------*/

  inline void
  ]b4_parser_class_name[::yy_symbol_value_print_ (int yytype,
                           const semantic_type* yyvaluep]b4_locations_if([[,
                           const location_type* yylocationp]])[)
  {]b4_locations_if([[
    YYUSE (yylocationp);]])[
    YYUSE (yyvaluep);
    std::ostream& yyoutput = debug_stream ();
    std::ostream& yyo = yyoutput;
    YYUSE (yyo);
    ]b4_symbol_actions([printer])[
  }


  void
  ]b4_parser_class_name[::yy_symbol_print_ (int yytype,
                           const semantic_type* yyvaluep]b4_locations_if([[,
                           const location_type* yylocationp]])[)
  {
    *yycdebug_ << (yytype < YYNTOKENS ? "token" : "nterm")
               << ' ' << yytname[yytype] << " ("]b4_locations_if([[
               << *yylocationp << ": "]])[;
    yy_symbol_value_print_ (yytype, yyvaluep]b4_locations_if([[, yylocationp]])[);
    *yycdebug_ << ')';
  }

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

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


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

  void
  ]b4_parser_class_name[::set_debug_level (debug_level_type l)
  {
    // Actually, it is yydebug which is really used.
    yydebug = l;
  }

#endif
]m4_popdef([b4_parse_param])dnl
b4_namespace_close
])

# 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],
[m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_orig]))dnl
b4_percent_code_get([[requires]])[

#include <stdexcept>
#include <string>
#include <iostream>]b4_defines_if([
b4_bison_locations_if([[#include "location.hh"]])])[

]b4_YYDEBUG_define[

]b4_namespace_open[
]b4_defines_if([],
[b4_bison_locations_if([b4_position_define
b4_location_define])])[

  /// A Bison parser.
  class ]b4_parser_class_name[
  {
  public:
]b4_public_types_declare[

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

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

    /// 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);

  public:
    /// 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);

# if ]b4_api_PREFIX[DEBUG
  public:
    /// \brief Report a symbol value on the debug stream.
    /// \param yytype       The token type.
    /// \param yyvaluep     Its semantic value.]b4_locations_if([[
    /// \param yylocationp  Its location.]])[
    virtual void yy_symbol_value_print_ (int yytype,
                                         const semantic_type* yyvaluep]b4_locations_if([[,
                                         const location_type* yylocationp]])[);
    /// \brief Report a symbol on the debug stream.
    /// \param yytype       The token type.
    /// \param yyvaluep     Its semantic value.]b4_locations_if([[
    /// \param yylocationp  Its location.]])[
    virtual void yy_symbol_print_ (int yytype,
                                   const semantic_type* yyvaluep]b4_locations_if([[,
                                   const location_type* yylocationp]])[);
  private:
    // Debugging.
    std::ostream* yycdebug_;
#endif

]b4_parse_param_vars[
  };

]dnl Redirections for glr.c.
b4_percent_define_flag_if([[global_tokens_and_yystype]],
[b4_token_defines])
[
#ifndef ]b4_api_PREFIX[STYPE
# define ]b4_api_PREFIX[STYPE ]b4_namespace_ref[::]b4_parser_class_name[::semantic_type
#endif
#ifndef ]b4_api_PREFIX[LTYPE
# define ]b4_api_PREFIX[LTYPE ]b4_namespace_ref[::]b4_parser_class_name[::location_type
#endif

]b4_namespace_close[
]b4_percent_code_get([[provides]])[
]m4_popdef([b4_parse_param])dnl
])

b4_defines_if(
[b4_output_begin([b4_spec_defines_file])
b4_copyright([Skeleton interface for Bison GLR parsers in C++],
             [2002-2013])[

// C++ GLR 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()])

# Let glr.c (and b4_shared_declarations) believe that the user
# arguments include the parser itself.
m4_pushdef([b4_parse_param], m4_defn([b4_parse_param_wrap]))
m4_include(b4_pkgdatadir/[glr.c])
m4_popdef([b4_parse_param])