variants: avoid type punning issue

[bison.git] / data / c++.m4

                                                            -*- Autoconf -*-

# C++ 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/>.

m4_include(b4_pkgdatadir/[c.m4])

# b4_comment(TEXT, [PREFIX])
# --------------------------
# Put TEXT in comment. Prefix all the output lines with PREFIX.
m4_define([b4_comment],
[b4_comment_([$1], [$2// ], [$2// ])])


## ---------------- ##
## Default values.  ##
## ---------------- ##

b4_percent_define_default([[parser_class_name]], [[parser]])

# Don't do that so that we remember whether we're using a user
# request, or the default value.
#
# b4_percent_define_default([[api.location.type]], [[location]])

b4_percent_define_default([[filename_type]], [[std::string]])
b4_percent_define_default([[api.namespace]], m4_defn([b4_prefix]))

b4_percent_define_default([[global_tokens_and_yystype]], [[false]])
b4_percent_define_default([[define_location_comparison]],
                          [m4_if(b4_percent_define_get([[filename_type]]),
                                 [std::string], [[true]], [[false]])])



## ----------- ##
## Namespace.  ##
## ----------- ##

m4_define([b4_namespace_ref], [b4_percent_define_get([[api.namespace]])])


# Don't permit an empty b4_namespace_ref.  Any `::parser::foo' appended to it
# would compile as an absolute reference with `parser' in the global namespace.
# b4_namespace_open would open an anonymous namespace and thus establish
# internal linkage.  This would compile.  However, it's cryptic, and internal
# linkage for the parser would be specified in all translation units that
# include the header, which is always generated.  If we ever need to permit
# internal linkage somehow, surely we can find a cleaner approach.
m4_if(m4_bregexp(b4_namespace_ref, [^[	 ]*$]), [-1], [],
[b4_complain_at(b4_percent_define_get_loc([[api.namespace]]),
                [[namespace reference is empty]])])

# Instead of assuming the C++ compiler will do it, Bison should reject any
# invalid b4_namepsace_ref that would be converted to a valid
# b4_namespace_open.  The problem is that Bison doesn't always output
# b4_namespace_ref to uncommented code but should reserve the ability to do so
# in future releases without risking breaking any existing user grammars.
# Specifically, don't allow empty names as b4_namespace_open would just convert
# those into anonymous namespaces, and that might tempt some users.
m4_if(m4_bregexp(b4_namespace_ref, [::[	 ]*::]), [-1], [],
[b4_complain_at(b4_percent_define_get_loc([[api.namespace]]),
                [[namespace reference has consecutive "::"]])])
m4_if(m4_bregexp(b4_namespace_ref, [::[	 ]*$]), [-1], [],
[b4_complain_at(b4_percent_define_get_loc([[api.namespace]]),
                [[namespace reference has a trailing "::"]])])

m4_define([b4_namespace_open],
[b4_user_code([b4_percent_define_get_syncline([[api.namespace]])
[namespace ]m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref),
                                                [^\(.\)[	 ]*::], [\1])),
                         [::], [ { namespace ])[ {]])])

m4_define([b4_namespace_close],
[b4_user_code([b4_percent_define_get_syncline([[api.namespace]])
m4_bpatsubst(m4_dquote(m4_bpatsubst(m4_dquote(b4_namespace_ref[ ]),
                                    [^\(.\)[	 ]*\(::\)?\([^][:]\|:[^:]\)*],
                                    [\1])),
             [::\([^][:]\|:[^:]\)*], [} ])[} // ]b4_namespace_ref])])


# b4_token_enums
# --------------
# Output the definition of the tokens as enums.
m4_define([b4_token_enums],
[[enum yytokentype
      {
        ]m4_join([,
        ],
                 b4_symbol_map([b4_token_enum]))[
      };]dnl
])




## ----------------- ##
## Semantic Values.  ##
## ----------------- ##

# b4_semantic_type_declare
# ------------------------
# Declare semantic_type.
m4_define([b4_semantic_type_declare],
[    /// Symbol semantic values.
m4_ifdef([b4_stype],
[    union semantic_type
    {
b4_user_stype
    };],
[m4_if(b4_tag_seen_flag, 0,
[[    typedef int semantic_type;]],
[[    typedef ]b4_api_PREFIX[STYPE semantic_type;]])])])


# b4_public_types_declare
# -----------------------
# Define the public types: token, semantic value, location, and so forth.
# Depending on %define token_lex, may be output in the header or source file.
m4_define([b4_public_types_declare],
[[#ifndef ]b4_api_PREFIX[STYPE
]b4_semantic_type_declare[
#else
    typedef ]b4_api_PREFIX[STYPE semantic_type;
#endif]b4_locations_if([
    /// Symbol locations.
    typedef b4_percent_define_get([[api.location.type]],
                                  [[location]]) location_type;])[

    /// Syntax errors thrown from user actions.
    struct syntax_error : std::runtime_error
    {
      syntax_error (]b4_locations_if([const location_type& l, ])[const std::string& m);]b4_locations_if([
      location_type location;])[
    };

    /// Tokens.
    struct token
    {
      ]b4_token_enums[
    };

    /// (External) token type, as returned by yylex.
    typedef token::yytokentype token_type;

    /// Internal symbol number.
    typedef int symbol_number_type;

    /// Internal symbol number for tokens (subsumed by symbol_number_type).
    typedef ]b4_int_type_for([b4_translate])[ token_number_type;

    /// A complete symbol.
    ///
    /// Expects its Base type to provide access to the symbol type
    /// via type_get().
    ///
    /// Provide access to semantic value]b4_locations_if([ and location])[.
    template <typename Base>
    struct basic_symbol : Base
    {
      /// Alias to Base.
      typedef Base super_type;

      /// Default constructor.
      basic_symbol ();

      /// Copy constructor.
      basic_symbol (const basic_symbol& other);
]b4_variant_if([[
      /// Constructor for valueless symbols, and symbols from each type.
]b4_type_foreach([b4_basic_symbol_constructor_declare])], [[
      /// Constructor for valueless symbols.
      basic_symbol (typename Base::kind_type t]b4_locations_if([,
                    const location_type& l])[);]])[

      /// Constructor for symbols with semantic value.
      basic_symbol (typename Base::kind_type t,
                    const semantic_type& v]b4_locations_if([,
                    const location_type& l])[);

      ~basic_symbol ();

      /// Destructive move, \a s is emptied into this.
      void move (basic_symbol& s);

      /// The semantic value.
      semantic_type value;]b4_locations_if([

      /// The location.
      location_type location;])[

    private:
      /// Assignment operator.
      basic_symbol& operator= (const basic_symbol& other);
    };

    /// Type access provider for token (enum) based symbols.
    struct by_type
    {
      /// Default constructor.
      by_type ();

      /// Copy constructor.
      by_type (const by_type& other);

      /// The symbol type as needed by the constructor.
      typedef token_type kind_type;

      /// Constructor from (external) token numbers.
      by_type (kind_type t);

      /// Steal the symbol type from \a that.
      void move (by_type& that);

      /// The (internal) type number (corresponding to \a type).
      /// -1 when this symbol is empty.
      symbol_number_type type_get () const;

      /// The token.
      token_type token () const;

      enum { empty = 0 };

      /// The symbol type.
      /// -1 when this symbol is empty.
      token_number_type type;
    };

    /// "External" symbols: returned by the scanner.
    typedef basic_symbol<by_type> symbol_type;

]b4_symbol_constructor_declare])


# b4_public_types_define
# ----------------------
# Provide the implementation needed by the public types.
m4_define([b4_public_types_define],
[[  inline
  ]b4_parser_class_name[::syntax_error::syntax_error (]b4_locations_if([const location_type& l, ])[const std::string& m)
    : std::runtime_error (m)]b4_locations_if([
    , location (l)])[
  {}

  // basic_symbol.
  template <typename Base>
  inline
  ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol ()
    : value ()
  {}

  template <typename Base>
  inline
  ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (const basic_symbol& other)
    : Base (other)
    , value ()]b4_locations_if([
    , location (other.location)])[
  {
    ]b4_variant_if([b4_symbol_variant([other.type_get ()], [value], [copy],
                                      [other.value])],
                   [value = other.value;])[
  }


  template <typename Base>
  inline
  ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join(
          [typename Base::kind_type t],
          [const semantic_type& v],
          b4_locations_if([const location_type& l]))[)
    : Base (t)
    , value (]b4_variant_if([], [v])[)]b4_locations_if([
    , location (l)])[
  {]b4_variant_if([[
    (void) v;
    ]b4_symbol_variant([this->type_get ()], [value], [copy], [v])])[}

]b4_variant_if([[
  // Implementation of basic_symbol constructor for each type.
]b4_type_foreach([b4_basic_symbol_constructor_define])], [[
  /// Constructor for valueless symbols.
  template <typename Base>
  inline
  ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join(
          [typename Base::kind_type t],
          b4_locations_if([const location_type& l]))[)
    : Base (t)
    , value ()]b4_locations_if([
    , location (l)])[
  {}]])[

  template <typename Base>
  inline
  ]b4_parser_class_name[::basic_symbol<Base>::~basic_symbol ()
  {]b4_variant_if([[
    // User destructor.
    symbol_number_type yytype = this->type_get ();
    switch (yytype)
    {
]b4_symbol_foreach([b4_symbol_destructor])dnl
[   default:
      break;
    }

    // Type destructor.
  ]b4_symbol_variant([[yytype]], [[value]], [[template destroy]])])[
  }

  template <typename Base>
  inline
  void
  ]b4_parser_class_name[::basic_symbol<Base>::move (basic_symbol& s)
  {
    super_type::move(s);
    ]b4_variant_if([b4_symbol_variant([this->type_get ()], [value], [move],
                                      [s.value])],
                   [value = s.value;])[]b4_locations_if([
    location = s.location;])[
  }

  // by_type.
  inline
  ]b4_parser_class_name[::by_type::by_type ()
     : type (empty)
  {}

  inline
  ]b4_parser_class_name[::by_type::by_type (const by_type& other)
    : type (other.type)
  {}

  inline
  ]b4_parser_class_name[::by_type::by_type (token_type t)
    : type (yytranslate_ (t))
  {}

  inline
  void
  ]b4_parser_class_name[::by_type::move (by_type& that)
  {
    type = that.type;
    that.type = empty;
  }

  inline
  int
  ]b4_parser_class_name[::by_type::type_get () const
  {
    return type;
  }
]b4_token_ctor_if([[
  inline
  ]b4_parser_class_name[::token_type
  ]b4_parser_class_name[::by_type::token () const
  {
    // YYTOKNUM[NUM] -- (External) token number corresponding to the
    // (internal) symbol number NUM (which must be that of a token).  */
    static
    const ]b4_int_type_for([b4_toknum])[
    yytoken_number_[] =
    {
  ]b4_toknum[
    };
    return static_cast<token_type> (yytoken_number_[type]);
  }
]])[]dnl
b4_symbol_constructor_define])


# b4_symbol_constructor_declare
# b4_symbol_constructor_define
# -----------------------------
# Declare/define symbol constructors for all the value types.
# Use at class-level.  Redefined in variant.hh.
m4_define([b4_symbol_constructor_declare], [])
m4_define([b4_symbol_constructor_define], [])


# b4_yytranslate_define
# ---------------------
# Define yytranslate_.  Sometimes used in the header file,
# sometimes in the cc file.
m4_define([b4_yytranslate_define],
[[  // Symbol number corresponding to token number t.
  inline
  ]b4_parser_class_name[::token_number_type
  ]b4_parser_class_name[::yytranslate_ (]b4_token_ctor_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_lhs_value([TYPE])
# --------------------
# Expansion of $<TYPE>$.
m4_define([b4_lhs_value],
[b4_symbol_value([yyval], [$1])])


# b4_rhs_value(RULE-LENGTH, NUM, [TYPE])
# --------------------------------------
# Expansion of $<TYPE>NUM, where the current rule has RULE-LENGTH
# symbols on RHS.
m4_define([b4_rhs_value],
[b4_symbol_value([yysemantic_stack_@{($1) - ($2)@}], [$3])])


# b4_lhs_location()
# -----------------
# Expansion of @$.
m4_define([b4_lhs_location],
[(yyloc)])


# b4_rhs_location(RULE-LENGTH, NUM)
# ---------------------------------
# Expansion of @NUM, where the current rule has RULE-LENGTH symbols
# on RHS.
m4_define([b4_rhs_location],
[(yylocation_stack_@{($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;])


## ---------##
## Values.  ##
## ---------##

# b4_yylloc_default_define
# ------------------------
# Define YYLLOC_DEFAULT.
m4_define([b4_yylloc_default_define],
[[/* 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  = YYRHSLOC (Rhs, 1).begin;                   \
          (Current).end    = YYRHSLOC (Rhs, N).end;                     \
        }                                                               \
      else                                                              \
        {                                                               \
          (Current).begin = (Current).end = YYRHSLOC (Rhs, 0).end;      \
        }                                                               \
    while (/*CONSTCOND*/ false)
# endif
]])