private VarEnum GetComType(ref Type argumentType)
{
if (argumentType == typeof(Missing))
{
//actual variant type will be VT_ERROR | E_PARAMNOTFOUND
return(VarEnum.VT_RECORD);
}
if (argumentType.IsArray)
{
//actual variant type will be VT_ARRAY | VT_<ELEMENT_TYPE>
return(VarEnum.VT_ARRAY);
}
if (argumentType == typeof(UnknownWrapper))
{
return(VarEnum.VT_UNKNOWN);
}
else if (argumentType == typeof(DispatchWrapper))
{
return(VarEnum.VT_DISPATCH);
}
else if (argumentType == typeof(VariantWrapper))
{
return(VarEnum.VT_VARIANT);
}
else if (argumentType == typeof(BStrWrapper))
{
return(VarEnum.VT_BSTR);
}
else if (argumentType == typeof(ErrorWrapper))
{
return(VarEnum.VT_ERROR);
}
else if (argumentType == typeof(CurrencyWrapper))
{
return(VarEnum.VT_CY);
}
// Many languages require an explicit cast for an enum to be used as the underlying type.
// However, we want to allow this conversion for COM without requiring an explicit cast
// so that enums from interop assemblies can be used as arguments.
if (argumentType.IsEnum)
{
argumentType = Enum.GetUnderlyingType(argumentType);
return(GetComType(ref argumentType));
}
// COM cannot express valuetype nulls so we will convert to underlying type
// it will throw if there is no value
if (TypeUtils.IsNullableType(argumentType))
{
argumentType = TypeUtils.GetNonNullableType(argumentType);
return(GetComType(ref argumentType));
}
//generic types cannot be exposed to COM so they do not implement COM interfaces.
if (argumentType.IsGenericType)
{
return(VarEnum.VT_UNKNOWN);
}
VarEnum primitiveVarEnum;
if (TryGetPrimitiveComType(argumentType, out primitiveVarEnum))
{
return(primitiveVarEnum);
}
// We could not find a way to marshal the type as a specific COM type
return(VT_DEFAULT);
}
