variant.hh
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# C++ skeleton for Bison # Copyright (C) 2002-2015 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/>. ## --------- ## ## variant. ## ## --------- ## # b4_symbol_variant(YYTYPE, YYVAL, ACTION, [ARGS]) # ------------------------------------------------ # Run some ACTION ("build", or "destroy") on YYVAL of symbol type # YYTYPE. m4_define([b4_symbol_variant], [m4_pushdef([b4_dollar_dollar], [$2.$3< $][3 > (m4_shift3($@))])dnl switch ($1) { b4_type_foreach([b4_type_action_])[]dnl default: break; } m4_popdef([b4_dollar_dollar])dnl ]) # _b4_char_sizeof_counter # ----------------------- # A counter used by _b4_char_sizeof_dummy to create fresh symbols. m4_define([_b4_char_sizeof_counter], [0]) # _b4_char_sizeof_dummy # --------------------- # At each call return a new C++ identifier. m4_define([_b4_char_sizeof_dummy], [m4_define([_b4_char_sizeof_counter], m4_incr(_b4_char_sizeof_counter))dnl dummy[]_b4_char_sizeof_counter]) # b4_char_sizeof(SYMBOL-NUMS) # --------------------------- # To be mapped on the list of type names to produce: # # char dummy1[sizeof(type_name_1)]; # char dummy2[sizeof(type_name_2)]; # # for defined type names. m4_define([b4_char_sizeof], [b4_symbol_if([$1], [has_type], [ m4_map([ b4_symbol_tag_comment], [$@])dnl char _b4_char_sizeof_dummy@{sizeof(b4_symbol([$1], [type]))@}; ])]) # b4_variant_includes # ------------------- # The needed includes for variants support. m4_define([b4_variant_includes], [b4_parse_assert_if([[#include <typeinfo>]])[ #ifndef YYASSERT # include <cassert> # define YYASSERT assert #endif ]]) # b4_variant_define # ----------------- # Define "variant". m4_define([b4_variant_define], [[ /// A char[S] buffer to store and retrieve objects. /// /// Sort of a variant, but does not keep track of the nature /// of the stored data, since that knowledge is available /// via the current state. template <size_t S> struct variant { /// Type of *this. typedef variant<S> self_type; /// Empty construction. variant ()]b4_parse_assert_if([ : yytypeid_ (YY_NULLPTR)])[ {} /// Construct and fill. template <typename T> variant (const T& t)]b4_parse_assert_if([ : yytypeid_ (&typeid (T))])[ { YYASSERT (sizeof (T) <= S); new (yyas_<T> ()) T (t); } /// Destruction, allowed only if empty. ~variant () {]b4_parse_assert_if([ YYASSERT (!yytypeid_); ])[} /// Instantiate an empty \a T in here. template <typename T> T& build () {]b4_parse_assert_if([ YYASSERT (!yytypeid_); YYASSERT (sizeof (T) <= S); yytypeid_ = & typeid (T);])[ return *new (yyas_<T> ()) T; } /// Instantiate a \a T in here from \a t. template <typename T> T& build (const T& t) {]b4_parse_assert_if([ YYASSERT (!yytypeid_); YYASSERT (sizeof (T) <= S); yytypeid_ = & typeid (T);])[ return *new (yyas_<T> ()) T (t); } /// Accessor to a built \a T. template <typename T> T& as () {]b4_parse_assert_if([ YYASSERT (*yytypeid_ == typeid (T)); YYASSERT (sizeof (T) <= S);])[ return *yyas_<T> (); } /// Const accessor to a built \a T (for %printer). template <typename T> const T& as () const {]b4_parse_assert_if([ YYASSERT (*yytypeid_ == typeid (T)); YYASSERT (sizeof (T) <= S);])[ return *yyas_<T> (); } /// Swap the content with \a other, of same type. /// /// Both variants must be built beforehand, because swapping the actual /// data requires reading it (with as()), and this is not possible on /// unconstructed variants: it would require some dynamic testing, which /// should not be the variant's responsability. /// Swapping between built and (possibly) non-built is done with /// variant::move (). template <typename T> void swap (self_type& other) {]b4_parse_assert_if([ YYASSERT (yytypeid_); YYASSERT (*yytypeid_ == *other.yytypeid_);])[ std::swap (as<T> (), other.as<T> ()); } /// Move the content of \a other to this. /// /// Destroys \a other. template <typename T> void move (self_type& other) { build<T> (); swap<T> (other); other.destroy<T> (); } /// Copy the content of \a other to this. template <typename T> void copy (const self_type& other) { build<T> (other.as<T> ()); } /// Destroy the stored \a T. template <typename T> void destroy () { as<T> ().~T ();]b4_parse_assert_if([ yytypeid_ = YY_NULLPTR;])[ } private: /// Prohibit blind copies. self_type& operator=(const self_type&); variant (const self_type&); /// Accessor to raw memory as \a T. template <typename T> T* yyas_ () { void *yyp = yybuffer_.yyraw; return static_cast<T*> (yyp); } /// Const accessor to raw memory as \a T. template <typename T> const T* yyas_ () const { const void *yyp = yybuffer_.yyraw; return static_cast<const T*> (yyp); } union { /// Strongest alignment constraints. long double yyalign_me; /// A buffer large enough to store any of the semantic values. char yyraw[S]; } yybuffer_;]b4_parse_assert_if([ /// Whether the content is built: if defined, the name of the stored type. const std::type_info *yytypeid_;])[ }; ]]) ## -------------------------- ## ## Adjustments for variants. ## ## -------------------------- ## # b4_value_type_declare # --------------------- # Declare semantic_type. m4_define([b4_value_type_declare], [[ /// An auxiliary type to compute the largest semantic type. union union_type {]b4_type_foreach([b4_char_sizeof])[}; /// Symbol semantic values. typedef variant<sizeof(union_type)> semantic_type;][]dnl ]) # How the semantic value is extracted when using variants. # b4_symbol_value(VAL, [TYPE]) # ---------------------------- m4_define([b4_symbol_value], [m4_ifval([$2], [$1.as< $2 > ()], [$1])]) # b4_symbol_value_template(VAL, [TYPE]) # ------------------------------------- # Same as b4_symbol_value, but used in a template method. m4_define([b4_symbol_value_template], [m4_ifval([$2], [$1.template as< $2 > ()], [$1])]) ## ------------- ## ## make_SYMBOL. ## ## ------------- ## # b4_symbol_constructor_declare_(SYMBOL-NUMBER) # --------------------------------------------- # Declare the overloaded version of make_symbol for the (common) type of # these SYMBOL-NUMBERS. Use at class-level. m4_define([b4_symbol_constructor_declare_], [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id], [ static inline symbol_type make_[]b4_symbol_([$1], [id]) (dnl b4_join(b4_symbol_if([$1], [has_type], [const b4_symbol([$1], [type])& v]), b4_locations_if([const location_type& l]))); ])])]) # b4_symbol_constructor_declare # ----------------------------- # Declare symbol constructors for all the value types. # Use at class-level. m4_define([b4_symbol_constructor_declare], [ // Symbol constructors declarations. b4_symbol_foreach([b4_symbol_constructor_declare_])]) # b4_symbol_constructor_define_(SYMBOL-NUMBER) # -------------------------------------------- # Define symbol constructor for this SYMBOL-NUMBER. m4_define([b4_symbol_constructor_define_], [b4_symbol_if([$1], [is_token], [b4_symbol_if([$1], [has_id], [ b4_parser_class_name::symbol_type b4_parser_class_name::make_[]b4_symbol_([$1], [id]) (dnl b4_join(b4_symbol_if([$1], [has_type], [const b4_symbol([$1], [type])& v]), b4_locations_if([const location_type& l]))) { return symbol_type (b4_join([token::b4_symbol([$1], [id])], b4_symbol_if([$1], [has_type], [v]), b4_locations_if([l]))); } ])])]) # b4_basic_symbol_constructor_declare # ----------------------------------- # Generate a constructor declaration for basic_symbol from given type. m4_define([b4_basic_symbol_constructor_declare], [[ basic_symbol (]b4_join( [typename Base::kind_type t], b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[ v]), b4_locations_if([const location_type& l]))[); ]]) # b4_basic_symbol_constructor_define # ---------------------------------- # Generate a constructor implementation for basic_symbol from given type. m4_define([b4_basic_symbol_constructor_define], [[ template <typename Base> ]b4_parser_class_name[::basic_symbol<Base>::basic_symbol (]b4_join( [typename Base::kind_type t], b4_symbol_if([$1], [has_type], const b4_symbol([$1], [type])[ v]), b4_locations_if([const location_type& l]))[) : Base (t) , value (]b4_symbol_if([$1], [has_type], [v])[)]b4_locations_if([ , location (l)])[ {} ]]) # b4_symbol_constructor_define # ---------------------------- # Define the overloaded versions of make_symbol for all the value types. m4_define([b4_symbol_constructor_define], [ // Implementation of make_symbol for each symbol type. b4_symbol_foreach([b4_symbol_constructor_define_])])
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