data/variant.hh

   1 # C++ skeleton for Bison
   2
   3 # Copyright (C) 2002-2013 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 #ifndef YYASSERT
  76 # include <cassert>
  77 # define YYASSERT assert
  78 #endif
  79 ]])
  80
  81 # b4_variant_define
  82 # -----------------
  83 # Define "variant".
  84 m4_define([b4_variant_define],
  85 [[  /// A char[S] buffer to store and retrieve objects.
  86   ///
  87   /// Sort of a variant, but does not keep track of the nature
  88   /// of the stored data, since that knowledge is available
  89   /// via the current state.
  90   template <size_t S>
  91   struct variant
  92   {
  93     /// Type of *this.
  94     typedef variant<S> self_type;
  95
  96     /// Empty construction.
  97     variant ()]b4_parse_assert_if([
  98       : tname (YY_NULL)])[
  99     {}
 100
 101     /// Construct and fill.
 102     template <typename T>
 103     variant (const T& t)]b4_parse_assert_if([
 104       : tname (typeid (T).name ())])[
 105     {
 106       YYASSERT (sizeof (T) <= S);
 107       new (buffer.raw) T (t);
 108     }
 109
 110     /// Destruction, allowed only if empty.
 111     ~variant ()
 112     {]b4_parse_assert_if([
 113       YYASSERT (!tname);
 114     ])[}
 115
 116     /// Instantiate an empty \a T in here.
 117     template <typename T>
 118     T&
 119     build ()
 120     {]b4_parse_assert_if([
 121       YYASSERT (!tname);
 122       YYASSERT (sizeof (T) <= S);
 123       tname = typeid (T).name ();])[
 124       return *new (buffer.raw) T;
 125     }
 126
 127     /// Instantiate a \a T in here from \a t.
 128     template <typename T>
 129     T&
 130     build (const T& t)
 131     {]b4_parse_assert_if([
 132       YYASSERT (!tname);
 133       YYASSERT (sizeof (T) <= S);
 134       tname = typeid (T).name ();])[
 135       return *new (buffer.raw) T (t);
 136     }
 137
 138     /// Accessor to a built \a T.
 139     template <typename T>
 140     T&
 141     as ()
 142     {]b4_parse_assert_if([
 143       YYASSERT (tname == typeid (T).name ());
 144       YYASSERT (sizeof (T) <= S);])[
 145       {
 146         void *dummy = buffer.raw;
 147         return *static_cast<T*> (dummy);
 148       }
 149     }
 150
 151     /// Const accessor to a built \a T (for %printer).
 152     template <typename T>
 153     const T&
 154     as () const
 155     {]b4_parse_assert_if([
 156       YYASSERT (tname == typeid (T).name ());
 157       YYASSERT (sizeof (T) <= S);])[
 158       {
 159         const void *dummy = buffer.raw;
 160         return *static_cast<const T*> (dummy);
 161       }
 162     }
 163
 164     /// Swap the content with \a other, of same type.
 165     ///
 166     /// Both variants must be built beforehand, because swapping the actual
 167     /// data requires reading it (with as()), and this is not possible on
 168     /// unconstructed variants: it would require some dynamic testing, which
 169     /// should not be the variant's responsability.
 170     /// Swapping between built and (possibly) non-built is done with
 171     /// variant::move ().
 172     template <typename T>
 173     void
 174     swap (self_type& other)
 175     {]b4_parse_assert_if([
 176       YYASSERT (tname);
 177       YYASSERT (tname == other.tname);])[
 178       std::swap (as<T>(), other.as<T>());
 179     }
 180
 181     /// Move the content of \a other to this.
 182     ///
 183     /// Destroys \a other.
 184     template <typename T>
 185     void
 186     move (self_type& other)
 187     {]b4_parse_assert_if([
 188       YYASSERT (!tname);])[
 189       build<T>();
 190       swap<T>(other);
 191       other.destroy<T>();
 192     }
 193
 194     /// Copy the content of \a other to this.
 195     template <typename T>
 196     void
 197     copy (const self_type& other)
 198     {
 199       build<T> (other.as<T> ());
 200     }
 201
 202     /// Destroy the stored \a T.
 203     template <typename T>
 204     void
 205     destroy ()
 206     {
 207       as<T> ().~T ();]b4_parse_assert_if([
 208       tname = YY_NULL;])[
 209     }
 210
 211   private:
 212     /// Prohibit blind copies.
 213     self_type& operator=(const self_type&);
 214     variant (const self_type&);
 215
 216     /// A buffer large enough to store any of the semantic values.
 217     /// Long double is chosen as it has the strongest alignment
 218     /// constraints.
 219     union
 220     {
 221       long double align_me;
 222       char raw[S];
 223     } buffer;]b4_parse_assert_if([
 224
 225     /// Whether the content is built: if defined, the name of the stored type.
 226     const char *tname;])[
 227   };
 228 ]])
 229
 230
 231 ## -------------------------- ##
 232 ## Adjustments for variants.  ##
 233 ## -------------------------- ##
 234
 235
 236 # b4_semantic_type_declare
 237 # ------------------------
 238 # Declare semantic_type.
 239 m4_define([b4_semantic_type_declare],
 240 [    /// An auxiliary type to compute the largest semantic type.
 241     union union_type
 242     {]b4_type_foreach([b4_char_sizeof])[};
 243
 244     /// Symbol semantic values.
 245     typedef variant<sizeof(union_type)> semantic_type;dnl
 246 ])
 247
 248
 249 # How the semantic value is extracted when using variants.
 250
 251 # b4_symbol_value(VAL, [TYPE])
 252 # ----------------------------
 253 m4_define([b4_symbol_value],
 254 [m4_ifval([$2],
 255           [$1.as< $2 >()],
 256           [$1])])
 257
 258 # b4_symbol_value_template(VAL, [TYPE])
 259 # -------------------------------------
 260 # Same as b4_symbol_value, but used in a template method.
 261 m4_define([b4_symbol_value_template],
 262 [m4_ifval([$2],
 263           [$1.template as< $2 >()],
 264           [$1])])
 265
 266
 267
 268 ## ------------- ##
 269 ## make_SYMBOL.  ##
 270 ## ------------- ##
 271
 272
 273 # b4_symbol_constructor_declare_(SYMBOL-NUMBER)
 274 # ---------------------------------------------
 275 # Declare the overloaded version of make_symbol for the (common) type of
 276 # these SYMBOL-NUMBERS.  Use at class-level.
 277 m4_define([b4_symbol_constructor_declare_],
 278 [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
 279 [    static inline
 280     symbol_type
 281     make_[]b4_symbol_([$1], [id]) (dnl
 282 b4_join(b4_symbol_if([$1], [has_type],
 283                      [const b4_symbol([$1], [type])& v]),
 284         b4_locations_if([const location_type& l])));
 285
 286 ])])])
 287
 288
 289 # b4_symbol_constructor_declare
 290 # -----------------------------
 291 # Declare symbol constructors for all the value types.
 292 # Use at class-level.
 293 m4_define([b4_symbol_constructor_declare],
 294 [    // Symbol constructors declarations.
 295 b4_symbol_foreach([b4_symbol_constructor_declare_])])
 296
 297
 298
 299 # b4_symbol_constructor_define_(SYMBOL-NUMBER)
 300 # --------------------------------------------
 301 # Define symbol constructor for this SYMBOL-NUMBER.
 302 m4_define([b4_symbol_constructor_define_],
 303 [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
 304 [  b4_parser_class_name::symbol_type
 305   b4_parser_class_name::make_[]b4_symbol_([$1], [id]) (dnl
 306 b4_join(b4_symbol_if([$1], [has_type],
 307                      [const b4_symbol([$1], [type])& v]),
 308         b4_locations_if([const location_type& l])))
 309   {
 310     return symbol_type (b4_join([token::b4_symbol([$1], [id])],
 311                                 b4_symbol_if([$1], [has_type], [v]),
 312                                 b4_locations_if([l])));
 313
 314   }
 315
 316 ])])])
 317
 318
 319 # b4_basic_symbol_constructor_declare
 320 # ----------------------------------
 321 # Generate a constructor declaration for basic_symbol from given type.
 322 m4_define([b4_basic_symbol_constructor_declare],
 323 [[
 324   basic_symbol (]b4_join(
 325           [typename Base::kind_type t],
 326           b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[ v]),
 327           b4_locations_if([const location_type& l]))[);
 328 ]])
 329
 330 # b4_basic_symbol_constructor_define
 331 # ----------------------------------
 332 # Generate a constructor implementation for basic_symbol from given type.
 333 m4_define([b4_basic_symbol_constructor_define],
 334 [[
 335   template <typename Base>
 336   ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join(
 337           [typename Base::kind_type t],
 338           b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[ v]),
 339           b4_locations_if([const location_type& l]))[)
 340     : Base (t)
 341     , value (]b4_symbol_if([$1], [has_type], [v])[)]b4_locations_if([
 342     , location (l)])[
 343   {}
 344 ]])
 345
 346 # b4_symbol_constructor_define
 347 # ----------------------------
 348 # Define the overloaded versions of make_symbol for all the value types.
 349 m4_define([b4_symbol_constructor_define],
 350 [  // Implementation of make_symbol for each symbol type.
 351 b4_symbol_foreach([b4_symbol_constructor_define_])])