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Stop caching derived to base casts, return immediately. #4

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Stop caching derived to base casts, return immediately. #4

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16 changes: 15 additions & 1 deletion fast_dynamic_cast.h
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,9 @@ namespace fast_dcast
// Pointer to __vftable
using v_table_ptr = const uintptr_t*;

template < bool _B >
struct negation : std::bool_constant<!_B>{};

template < typename _Ty >
__forceinline v_table_ptr get_vtable(const _Ty* ptr)
{
Expand All @@ -81,7 +84,9 @@ namespace fast_dcast
// Should be nothrow but this decreases performance. In practice this is not
// an issue.
template < typename _To, typename _From >
__forceinline _To fast_dynamic_cast(_From* ptr)
__forceinline
std::enable_if_t<negation<std::is_same<clean_type_t<_To>, clean_type_t<_From>>::value || std::is_base_of<clean_type_t<_To>, clean_type_t<_From>>::value>::value, _To>
fast_dynamic_cast(_From* ptr)
{
// Not required, dynamic_cast already produces a compile-time error in this case
// static_assert(std::is_polymorphic<_From>::value, "Type is not polymorphic!");
Expand Down Expand Up @@ -111,6 +116,15 @@ namespace fast_dcast
}
};

// From derived to base.
template < typename _To, typename _From >
__forceinline
std::enable_if_t<std::is_same<clean_type_t<_To>, clean_type_t<_From>>::value || std::is_base_of<clean_type_t<_To>, clean_type_t<_From>>::value, _To>
fast_dynamic_cast(_From* ptr)
{
return ptr;
}

// const T*
template < typename _To, typename _From >
__forceinline const _To fast_dynamic_cast(const _From* ptr)
Expand Down