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Added etl::visitor_from_type_list

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This commit is contained in:
John Wellbelove 2026-02-03 08:58:24 +00:00
parent 3826e2ab2e
commit 58619ec675
2 changed files with 23 additions and 11 deletions
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21
include/etl/visitor.h
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@ -205,21 +205,20 @@ namespace etl
virtual void visit(T1) = 0;
};
//*****************************************************************
/// The visitor class for an etl::type_list.
/// Expands the type_list into the existing variadic visitor.
///\ingroup visitor
//*****************************************************************
//***************************************************************************
/// Helper to turn etl::type_list<TTypes...> into etl::visitor<TTypes...>
template <typename TList>
struct visitor_from_type_list;
template <typename... TTypes>
class visitor<etl::type_list<TTypes...>> : public visitor<TTypes...>
struct visitor_from_type_list<etl::type_list<TTypes...>>
{
ETL_STATIC_ASSERT(sizeof...(TTypes) != 0, "etl::type_list must not be empty");
public:
using visitor<TTypes...>::visit;
using type = etl::visitor<TTypes...>;
};
template <typename TTypeList>
using visitor_from_type_list_t = typename visitor_from_type_list<TTypeList>::type;
#else
//*****************************************************************

13
test/test_visitor.cpp
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@ -747,6 +747,19 @@ namespace
#endif
}
#if !defined(ETL_VISITOR_FORCE_CPP03_IMPLEMENTATION)
//*************************************************************************
TEST(test_visitor_from_type_list)
{
using Visitor1 = etl::visitor<Square&, Circle&, const Triangle&>;
using TypeList = etl::type_list<Square&, Circle&, const Triangle&>;
using Visitor2 = etl::visitor_from_type_list_t<TypeList>;
CHECK_TRUE((std::is_same<Visitor1, Visitor2>::value));
}
#endif
#if !defined(ETL_VISITOR_FORCE_CPP03_IMPLEMENTATION)
//*************************************************************************
TEST(test_visitable_from_type_list)