# b4_symbol_value_template(VAL, [TYPE])
# -------------------------------------
-# Same as b4_symbol_value, but used in a template method.
+# Same as b4_symbol_value, but used in a template method. It makes
+# a difference when using variants.
m4_copy([b4_symbol_value], [b4_symbol_value_template])
-# How the semantic value is extracted when using variants.
-b4_variant_if([
- # 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])])
-]) # b4_variant_if
-
# b4_lex_symbol_if([IF-YYLEX-RETURNS-A-COMPLETE-SYMBOL], [IF-NOT])
# ----------------------------------------------------------------
# --------------------
# Expansion of $<TYPE>$.
m4_define([b4_lhs_value],
-[b4_symbol_value([yylhs.value], [$1])])
+ [b4_symbol_value([yylhs.value], [$1])])
# b4_lhs_location()
# -----------------
# Expansion of @$.
m4_define([b4_lhs_location],
-[yylhs.location])
+ [yylhs.location])
# b4_rhs_data(RULE-LENGTH, NUM)
m4_define([b4_rhs_location],
[b4_rhs_data([$1], [$2]).location])
+
# b4_symbol_action(SYMBOL-NUM, KIND)
# ----------------------------------
# Run the action KIND (destructor or printer) for SYMBOL-NUM.
b4_symbol_foreach([b4_symbol_constructor_definition_])])])
-# 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-NUM)
-# ---------------------------
-# A comment describing this symbol.
-m4_define([b4_char_sizeof_],
-[ // b4_symbol([$1], [tag])
-])
-
-# 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([$1], [has_type],
-[
-m4_map([b4_char_sizeof_], [$@])dnl
- char _b4_char_sizeof_dummy@{sizeof([b4_symbol([$1], [type])])@};
-])])
-
-
# b4_yytranslate_definition
# -------------------------
# Define yytranslate_. Sometimes we want it in the header file,
m4_define([b4_location_constructors])
m4_include(b4_pkgdatadir/[location.cc])])
m4_include(b4_pkgdatadir/[stack.hh])
+b4_variant_if([m4_include(b4_pkgdatadir/[variant.hh])])
# We do want M4 expansion after # for CPP macros.
m4_changecom()
]b4_namespace_open[
]b4_locations_if([ class position;
class location;])[
-]b4_variant_if(
-[[
- /// 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
- {]b4_assert_if([
- /// Whether something is contained.
- bool built;
-])[
- /// Empty construction.
- inline
- variant ()]b4_assert_if([
- : built(false)])[
- {}
-
- /// Instantiate a \a T in here.
- template <typename T>
- inline T&
- build()
- {]b4_assert_if([
- assert(!built);
- built = true;])[
- return *new (buffer.raw) T;
- }
-
- /// Instantiate a \a T in here from \a t.
- template <typename T>
- inline T&
- build(const T& t)
- {]b4_assert_if([
- assert(!built);
- built = true;])[
- return *new (buffer.raw) T(t);
- }
-
- /// Construct and fill.
- template <typename T>
- inline
- variant (const T& t)]b4_assert_if([
- : built(true)])[
- {
- new (buffer.raw) T(t);
- }
-
- /// Accessor to a built \a T.
- template <typename T>
- inline T&
- as()
- {]b4_assert_if([
- assert(built);])[
- return reinterpret_cast<T&>(buffer.raw);
- }
-
- /// Const accessor to a built \a T (for %printer).
- template <typename T>
- inline const T&
- as() const
- {]b4_assert_if([
- assert(built);])[
- return reinterpret_cast<const T&>(buffer.raw);
- }
-
- /// Swap the content with \a other.
- template <typename T>
- inline void
- swap(variant<S>& other)
- {
- std::swap(as<T>(), other.as<T>());
- }
-
- /// Assign the content of \a other to this.
- /// Destroys \a other.
- template <typename T>
- inline void
- build(variant<S>& other)
- {
- build<T>();
- swap<T>(other);
- other.destroy<T>();
- }
-
- /// Destroy the stored \a T.
- template <typename T>
- inline void
- destroy()
- {
- as<T>().~T();]b4_assert_if([
- built = false;])[
- }
-
- /// A buffer large enough to store any of the semantic values.
- /// Long double is chosen as it has the strongest alignment
- /// constraints.
- union {
- long double align_me;
- char raw[S];
- } buffer;
- };
-]])[
+]b4_variant_if([b4_variant_definition])[
]b4_namespace_close[
]b4_locations_if([#include "location.hh"])[
/* Variants are always initialized to an empty instance of the
correct type. The default $$=$1 rule is NOT applied when using
variants */
- ]b4_symbol_variant([[yyr1_@{yyn@}]], [yylhs.value], [build])[],[
+ ]b4_symbol_variant([[yyr1_@{yyn@}]], [yylhs.value], [build]),[
/* If YYLEN is nonzero, implement the default value of the action:
`$$ = $1'. Otherwise, use the top of the stack.
yylhs.state = yystate;
YY_SYMBOL_PRINT ("-> $$ =", yylhs);
]b4_variant_if([[
- // Destroy the lhs symbols.
+ // Destroy the rhs symbols.
for (int i = 0; i < yylen; ++i)
- // Destroy a variant which value may have be swapped with
- // yylhs.value. The value of yylhs.value (hence maybe one of
- // these lhs symbols) depends on what does the default
- // contruction for this type. In the case of pointers for
- // instance, nothing is done, so the value is junk. Therefore
- // do not try to report the content in the debug trace, it's
- // junk. Hence yymsg = 0. Besides, that keeps exactly the same
- // traces as with the other Bison skeletons.
+ // Destroy a variant which value may have been swapped with
+ // yylhs.value (for instance if the action was "std::swap($$,
+ // $1)"). The value of yylhs.value (hence possibly one of these
+ // rhs symbols) depends on the default contruction for this
+ // type. In the case of pointers for instance, no
+ // initialization is done, so the value is junk. Therefore do
+ // not try to report the value of symbols about to be destroyed
+ // in the debug trace, it's possibly junk. Hence yymsg = 0.
+ // Besides, that keeps exactly the same traces as with the other
+ // Bison skeletons.
yy_destroy_ (0, yystack_[i]);]])[
yypop_ (yylen);
yypush_ (0, yylhs);
goto yynewstate;
- /*------------------------------------.
- | yyerrlab -- here on detecting error |
- `------------------------------------*/
+ /*--------------------------------------.
+ | yyerrlab -- here on detecting error. |
+ `--------------------------------------*/
yyerrlab:
/* If not already recovering from an error, report this error. */
if (!yyerrstatus_)
projects / bison.git / blobdiff