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     /// Both variants must be built beforehand.
 165     template <typename T>
 166     inline void
 167     swap (variant<S>& other)
 168     {]b4_parse_assert_if([
 169       YYASSERT (built);
 170       YYASSERT (other.built);
 171       YYASSERT (tname == other.tname);])[
 172       std::swap (as<T>(), other.as<T>());
 173     }
 174
 175     /// Assign the content of \a other to this.
 176     /// Destroys \a other.
 177     template <typename T>
 178     inline void
 179     build (variant<S>& other)
 180     {
 181       build<T>();
 182       swap<T>(other);
 183       other.destroy<T>();
 184     }
 185
 186     /// Copy the content of \a other to this.
 187     /// Destroys \a other.
 188     template <typename T>
 189     inline void
 190     copy (const variant<S>& other)
 191     {
 192       build<T> (other.as<T> ());
 193     }
 194
 195     /// Destroy the stored \a T.
 196     template <typename T>
 197     inline void
 198     destroy ()
 199     {
 200       as<T> ().~T ();]b4_parse_assert_if([
 201       built = false;
 202       tname = YY_NULL;])[
 203     }
 204
 205     /// Prohibit blind copies.
 206     //  private:
 207     self_type& operator=(const self_type&)
 208     {
 209       abort ();
 210     }
 211
 212     variant (const self_type&)
 213     {
 214       abort ();
 215     }
 216
 217   private:
 218     /// A buffer large enough to store any of the semantic values.
 219     /// Long double is chosen as it has the strongest alignment
 220     /// constraints.
 221     union
 222     {
 223       long double align_me;
 224       char raw[S];
 225     } buffer;]b4_parse_assert_if([
 226     /// Whether something is contained.
 227     bool built;
 228     /// If defined, the name of the stored type.
 229     const char* tname;])[
 230   };
 231 ]])
 232
 233
 234 ## -------------------------- ##
 235 ## Adjustments for variants.  ##
 236 ## -------------------------- ##
 237
 238
 239 # b4_semantic_type_declare
 240 # ------------------------
 241 # Declare semantic_type.
 242 m4_define([b4_semantic_type_declare],
 243 [    /// An auxiliary type to compute the largest semantic type.
 244     union union_type
 245     {]b4_type_foreach([b4_char_sizeof])[};
 246
 247     /// Symbol semantic values.
 248     typedef variant<sizeof(union_type)> semantic_type;dnl
 249 ])
 250
 251
 252 # How the semantic value is extracted when using variants.
 253
 254 # b4_symbol_value(VAL, [TYPE])
 255 # ----------------------------
 256 m4_define([b4_symbol_value],
 257 [m4_ifval([$2],
 258           [$1.as< $2 >()],
 259           [$1])])
 260
 261 # b4_symbol_value_template(VAL, [TYPE])
 262 # -------------------------------------
 263 # Same as b4_symbol_value, but used in a template method.
 264 m4_define([b4_symbol_value_template],
 265 [m4_ifval([$2],
 266           [$1.template as< $2 >()],
 267           [$1])])
 268
 269
 270
 271 ## ------------- ##
 272 ## make_SYMBOL.  ##
 273 ## ------------- ##
 274
 275
 276 # b4_symbol_constructor_declare_(SYMBOL-NUMBER)
 277 # ---------------------------------------------
 278 # Declare the overloaded version of make_symbol for the (common) type of
 279 # these SYMBOL-NUMBERS.  Use at class-level.
 280 m4_define([b4_symbol_constructor_declare_],
 281 [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
 282 [    static inline
 283     symbol_type
 284     make_[]b4_symbol_([$1], [id]) (dnl
 285 b4_join(b4_symbol_if([$1], [has_type],
 286                      [const b4_symbol([$1], [type])& v]),
 287         b4_locations_if([const location_type& l])));
 288
 289 ])])])
 290
 291
 292 # b4_symbol_constructor_declare
 293 # -----------------------------
 294 # Declare symbol constructors for all the value types.
 295 # Use at class-level.
 296 m4_define([b4_symbol_constructor_declare],
 297 [    // Symbol constructors declarations.
 298 b4_symbol_foreach([b4_symbol_constructor_declare_])])
 299
 300
 301
 302 # b4_symbol_constructor_define_(SYMBOL-NUMBER)
 303 # --------------------------------------------
 304 # Define symbol constructor for this SYMBOL-NUMBER.
 305 m4_define([b4_symbol_constructor_define_],
 306 [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id],
 307 [  b4_parser_class_name::symbol_type
 308   b4_parser_class_name::make_[]b4_symbol_([$1], [id]) (dnl
 309 b4_join(b4_symbol_if([$1], [has_type],
 310                      [const b4_symbol([$1], [type])& v]),
 311         b4_locations_if([const location_type& l])))
 312   {
 313     return symbol_type (b4_join([token::b4_symbol([$1], [id])],
 314                                 b4_symbol_if([$1], [has_type], [v]),
 315                                 b4_locations_if([l])));
 316   }
 317
 318 ])])])
 319
 320
 321 # b4_symbol_constructor_define
 322 # ----------------------------
 323 # Define the overloaded versions of make_symbol for all the value types.
 324 m4_define([b4_symbol_constructor_define],
 325 [  // Implementation of make_symbol for each symbol type.
 326 b4_symbol_foreach([b4_symbol_constructor_define_])])