data/variant.hh

   1 # C++ skeleton for Bison
   2
   3 # Copyright (C) 2002-2012 Free Software Foundation, Inc.
   4
   5 # This program is free software: you can redistribute it and/or modify
   6 # it under the terms of the GNU General Public License as published by
   7 # the Free Software Foundation, either version 3 of the License, or
   8 # (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 # GNU General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU General Public License
  16 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17
  18
  19 ## --------- ##
  20 ## variant.  ##
  21 ## --------- ##
  22
  23 # b4_symbol_variant(YYTYPE, YYVAL, ACTION, [ARGS])
  24 # ------------------------------------------------
  25 # Run some ACTION ("build", or "destroy") on YYVAL of symbol type
  26 # YYTYPE.
  27 m4_define([b4_symbol_variant],
  28 [m4_pushdef([b4_dollar_dollar],
  29             [$2.$3< $][3 >(m4_shift3($@))])dnl
  30   switch ($1)
  31     {
  32 b4_type_foreach([b4_type_action_])[]dnl
  33       default:
  34         break;
  35     }
  36 m4_popdef([b4_dollar_dollar])dnl
  37 ])
  38
  39
  40 # _b4_char_sizeof_counter
  41 # -----------------------
  42 # A counter used by _b4_char_sizeof_dummy to create fresh symbols.
  43 m4_define([_b4_char_sizeof_counter],
  44 [0])
  45
  46 # _b4_char_sizeof_dummy
  47 # ---------------------
  48 # At each call return a new C++ identifier.
  49 m4_define([_b4_char_sizeof_dummy],
  50 [m4_define([_b4_char_sizeof_counter], m4_incr(_b4_char_sizeof_counter))dnl
  51 dummy[]_b4_char_sizeof_counter])
  52
  53
  54 # b4_char_sizeof(SYMBOL-NUMS)
  55 # ---------------------------
  56 # To be mapped on the list of type names to produce:
  57 #
  58 #    char dummy1[sizeof(type_name_1)];
  59 #    char dummy2[sizeof(type_name_2)];
  60 #
  61 # for defined type names.
  62 m4_define([b4_char_sizeof],
  63 [b4_symbol_if([$1], [has_type],
  64 [
  65 m4_map([      b4_symbol_tag_comment], [$@])dnl
  66       char _b4_char_sizeof_dummy@{sizeof([b4_symbol([$1], [type])])@};
  67 ])])
  68
  69
  70 # b4_variant_includes
  71 # -------------------
  72 # The needed includes for variants support.
  73 m4_define([b4_variant_includes],
  74 [b4_parse_assert_if([[#include <typeinfo>]])[
  75 #include <cstdlib>  // abort
  76 #ifndef YYASSERT
  77 # include <cassert>
  78 # define YYASSERT assert
  79 #endif
  80 ]])
  81
  82 # b4_variant_define
  83 # -----------------
  84 # Define "variant".
  85 m4_define([b4_variant_define],
  86 [[  /// A char[S] buffer to store and retrieve objects.
  87   ///
  88   /// Sort of a variant, but does not keep track of the nature
  89   /// of the stored data, since that knowledge is available
  90   /// via the current state.
  91   template <size_t S>
  92   struct variant
  93   {
  94     /// Type of *this.
  95     typedef variant<S> self_type;
  96
  97     /// Empty construction.
  98     inline
  99     variant ()]b4_parse_assert_if([
 100       : built (false)
 101       , tname (YY_NULL)])[
 102     {}
 103
 104     /// Instantiate a \a T in here.
 105     template <typename T>
 106     inline T&
 107     build ()
 108     {]b4_parse_assert_if([
 109       YYASSERT (!built);
 110       YYASSERT (!tname);
 111       YYASSERT (sizeof (T) <= S);
 112       built = true;
 113       tname = typeid (T).name ();])[
 114       return *new (buffer.raw) T;
 115     }
 116
 117     /// Instantiate a \a T in here from \a t.
 118     template <typename T>
 119     inline T&
 120     build (const T& t)
 121     {]b4_parse_assert_if([
 122       YYASSERT (!built);
 123       YYASSERT (!tname);
 124       YYASSERT (sizeof (T) <= S);
 125       built = true;
 126       tname = typeid (T).name ();])[
 127       return *new (buffer.raw) T (t);
 128     }
 129
 130     /// Construct and fill.
 131     template <typename T>
 132     inline
 133     variant (const T& t)]b4_parse_assert_if([
 134       : built (true)
 135       , tname (typeid (T).name ())])[
 136     {
 137       YYASSERT (sizeof (T) <= S);
 138       new (buffer.raw) T (t);
 139     }
 140
 141     /// Accessor to a built \a T.
 142     template <typename T>
 143     inline T&
 144     as ()
 145     {]b4_parse_assert_if([
 146       YYASSERT (built);
 147       YYASSERT (tname == typeid (T).name ());
 148       YYASSERT (sizeof (T) <= S);])[
 149       return reinterpret_cast<T&> (buffer.raw);
 150     }
 151
 152     /// Const accessor to a built \a T (for %printer).
 153     template <typename T>
 154     inline const T&
 155     as () const
 156     {]b4_parse_assert_if([
 157       YYASSERT (built);
 158       YYASSERT (tname == typeid (T).name ());
 159       YYASSERT (sizeof (T) <= S);])[
 160       return reinterpret_cast<const T&> (buffer.raw);
 161     }
 162
 163     /// Swap the content with \a other, of same type.
 164     template <typename T>
 165     inline void
 166     swap (variant<S>& other)
 167     {]b4_parse_assert_if([
 168       YYASSERT (tname == other.tname);])[
 169       std::swap (as<T>(), other.as<T>());]b4_parse_assert_if([
 170       std::swap (built, other.built);
 171       std::swap (tname, other.tname);])[
 172     }
 173
 174     /// Assign the content of \a other to this.
 175     /// Destroys \a other.
 176     template <typename T>
 177     inline void
 178     build (variant<S>& other)
 179     {
 180       build<T>();
 181       swap<T>(other);
 182       other.destroy<T>();
 183     }
 184
 185     /// Copy the content of \a other to this.
 186     /// Destroys \a other.
 187     template <typename T>
 188     inline void
 189     copy (const variant<S>& other)
 190     {
 191       build<T> (other.as<T> ());
 192     }
 193
 194     /// Destroy the stored \a T.
 195     template <typename T>
 196     inline void
 197     destroy ()
 198     {
 199       as<T> ().~T ();]b4_parse_assert_if([
 200       built = false;
 201       tname = YY_NULL;])[
 202     }
 203
 204     /// Prohibit blind copies.
 205     //  private:
 206     self_type& operator=(const self_type&)
 207     {
 208       abort ();
 209     }
 210
 211   private:
 212     /// A buffer large enough to store any of the semantic values.
 213     /// Long double is chosen as it has the strongest alignment
 214     /// constraints.
 215     union
 216     {
 217       long double align_me;
 218       char raw[S];
 219     } buffer;]b4_parse_assert_if([
 220     /// Whether something is contained.
 221     bool built;
 222     /// If defined, the name of the stored type.
 223     const char* tname;])[
 224   };
 225 ]])
 226
 227
 228 ## -------------------------- ##
 229 ## Adjustments for variants.  ##
 230 ## -------------------------- ##
 231
 232
 233 # b4_semantic_type_declare
 234 # ------------------------
 235 # Declare semantic_type.
 236 m4_define([b4_semantic_type_declare],
 237 [    /// An auxiliary type to compute the largest semantic type.
 238     union union_type
 239     {]b4_type_foreach([b4_char_sizeof])[};
 240
 241     /// Symbol semantic values.
 242     typedef variant<sizeof(union_type)> semantic_type;dnl
 243 ])
 244
 245
 246 # How the semantic value is extracted when using variants.
 247
 248 # b4_symbol_value(VAL, [TYPE])
 249 # ----------------------------
 250 m4_define([b4_symbol_value],
 251 [m4_ifval([$2],
 252           [$1.as< $2 >()],
 253           [$1])])
 254
 255 # b4_symbol_value_template(VAL, [TYPE])
 256 # -------------------------------------
 257 # Same as b4_symbol_value, but used in a template method.
 258 m4_define([b4_symbol_value_template],
 259 [m4_ifval([$2],
 260           [$1.template as< $2 >()],
 261           [$1])])
 262
 263
 264
 265 ## ------------- ##
 266 ## make_SYMBOL.  ##
 267 ## ------------- ##
 268
 269
 270 # b4_symbol_constructor_declare_(SYMBOL-NUMBER)
 271 # ---------------------------------------------
 272 # Declare the overloaded version of make_symbol for the (common) type of
 273 # these SYMBOL-NUMBERS.  Use at class-level.
 274 m4_define([b4_symbol_constructor_declare_],
 275 [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
 276 [    static inline
 277     symbol_type
 278     make_[]b4_symbol_([$1], [id]) (dnl
 279 b4_join(b4_symbol_if([$1], [has_type],
 280                      [const b4_symbol([$1], [type])& v]),
 281         b4_locations_if([const location_type& l])));
 282
 283 ])])])
 284
 285
 286 # b4_symbol_constructor_declare
 287 # -----------------------------
 288 # Declare symbol constructors for all the value types.
 289 # Use at class-level.
 290 m4_define([b4_symbol_constructor_declare],
 291 [    // Symbol constructors declarations.
 292 b4_symbol_foreach([b4_symbol_constructor_declare_])])
 293
 294
 295
 296 # b4_symbol_constructor_define_(SYMBOL-NUMBER)
 297 # --------------------------------------------
 298 # Define symbol constructor for this SYMBOL-NUMBER.
 299 m4_define([b4_symbol_constructor_define_],
 300 [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
 301 [  b4_parser_class_name::symbol_type
 302   b4_parser_class_name::make_[]b4_symbol_([$1], [id]) (dnl
 303 b4_join(b4_symbol_if([$1], [has_type],
 304                      [const b4_symbol([$1], [type])& v]),
 305         b4_locations_if([const location_type& l])))
 306   {
 307     return symbol_type (b4_join([token::b4_symbol([$1], [id])],
 308                                 b4_symbol_if([$1], [has_type], [v]),
 309                                 b4_locations_if([l])));
 310   }
 311
 312 ])])])
 313
 314
 315 # b4_symbol_constructor_define
 316 # ----------------------------
 317 # Define the overloaded versions of make_symbol for all the value types.
 318 m4_define([b4_symbol_constructor_define],
 319 [  // Implementation of make_symbol for each symbol type.
 320 b4_symbol_foreach([b4_symbol_constructor_define_])])