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Added etl::type_list to etl::variant

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This commit is contained in:
John Wellbelove 2026-01-25 11:10:38 +01:00
parent 682b1e7011
commit 61796bee8f
2 changed files with 59 additions and 6 deletions
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26
include/etl/private/variant_variadic.h
View File

@ -253,7 +253,7 @@ namespace etl
template <size_t Index, typename... TTypes>
struct variant_alternative<Index, etl::variant<TTypes...>>
{
using type = etl::nth_type_t<Index, TTypes...>;
using type = etl::nth_type_t<Index, typename etl::variant<TTypes...>::type_list>;
};
template <size_t Index, typename T>
@ -370,7 +370,6 @@ namespace etl
//***************************************************************************
/// A template class that can store any of the types defined in the template parameter list.
/// Supports up to 8 types.
///\ingroup variant
//***************************************************************************
template <typename... TTypes>
@ -378,6 +377,8 @@ namespace etl
{
public:
using type_list = etl::type_list<TTypes...>;
//***************************************************************************
/// get() is a friend function.
//***************************************************************************
@ -1217,13 +1218,26 @@ namespace etl
size_t type_id;
};
//***************************************************************************
/// Delcare a variant using an etl::type_list.
//***************************************************************************
template <typename... TTypes>
class variant<etl::type_list<TTypes...>> : public etl::variant<TTypes...>
{
public:
using base_type = etl::variant<TTypes...>;
using type_list = typename base_type::type_list;
using base_type::base_type; // inherit all ctors
};
//***************************************************************************
/// Checks if the variant v holds the alternative T.
//***************************************************************************
template <typename T, typename... TTypes>
ETL_CONSTEXPR14 bool holds_alternative(const etl::variant<TTypes...>& v) ETL_NOEXCEPT
{
constexpr size_t Index = etl::type_list_index_of_type<etl::type_list<TTypes...>, T>::value;
{
constexpr size_t Index = etl::type_list_index_of_type<typename etl::variant<TTypes...>::type_list, T>::value;
return (Index == variant_npos) ? false : (v.index() == Index);
}
@ -1254,7 +1268,7 @@ namespace etl
get(etl::variant<TTypes...>& v)
{
#if ETL_USING_CPP17 && !defined(ETL_VARIANT_FORCE_CPP11)
static_assert(Index < sizeof...(TTypes), "Index out of range");
static_assert(Index < etl::type_list_size<typename etl::variant<TTypes...>::type_list>::value, "Index out of range");
#endif
ETL_ASSERT(Index == v.index(), ETL_ERROR(etl::variant_incorrect_type_exception));
@ -1427,7 +1441,7 @@ namespace etl
template <typename... TTypes>
struct variant_size<etl::variant<TTypes...>>
: etl::integral_constant<size_t, sizeof...(TTypes)>
: etl::integral_constant<size_t, etl::type_list_size<typename etl::variant<TTypes...>::type_list>::value>
{
};

39
test/test_variant_variadic.cpp
View File

@ -462,6 +462,45 @@ namespace
test_variant_t variant_etl;
CHECK_TRUE((std::is_same<test_variant_t::type_list, etl::type_list<DefaultConstructible, int, std::string>>::value));
CHECK_TRUE(etl::holds_alternative<DefaultConstructible>(variant_etl));
CHECK_FALSE(etl::holds_alternative<int>(variant_etl));
CHECK_FALSE(etl::holds_alternative<std::string>(variant_etl));
CHECK_EQUAL(1, etl::get<0U>(variant_etl).value);
CHECK_TRUE(etl::holds_alternative<0U>(variant_etl));
CHECK_FALSE(etl::holds_alternative<1U>(variant_etl));
CHECK_FALSE(etl::holds_alternative<2U>(variant_etl));
CHECK_TRUE(etl::holds_alternative(0U, variant_etl));
CHECK_FALSE(etl::holds_alternative(1U, variant_etl));
CHECK_FALSE(etl::holds_alternative(2U, variant_etl));
CHECK_FALSE(etl::holds_alternative(99U, variant_etl));
}
//*************************************************************************
TEST(test_constructor_default_variant_from_type_list)
{
struct DefaultConstructible
{
DefaultConstructible()
: value(1)
{
}
int value = 0;
};
using variant_types = etl::type_list<DefaultConstructible, int, std::string>;
using test_variant_t = etl::variant<variant_types>;
CHECK_NO_THROW(test_variant_t variant_etl);
test_variant_t variant_etl;
CHECK_TRUE((std::is_same<test_variant_t::type_list, variant_types>::value));
CHECK_TRUE(etl::holds_alternative<DefaultConstructible>(variant_etl));
CHECK_FALSE(etl::holds_alternative<int>(variant_etl));
CHECK_FALSE(etl::holds_alternative<std::string>(variant_etl));