C++ parsing an Attribute with a SELECT data type

[Adam Gall]

Hello,

I'm writing a C++/CLI wrapper for interacting with STEPCode from a .NET application. What I'm looking to do is parse an AP214 STEP file, and return a list of entities with their attributes. This is going well for the most part, but I'm a bit stuck on how to get the underlying data out of a SELECT_TYPE attribute.

Below is a snippet of my method for parsing an attribute. I can identity from select->ValueType() if the SELECT is (for example) representing an entity, but I am not sure how to get the SDAI_Application_instance reference from this point? I understand that SDAI_Select is an abstract base class, but there seems no way to identify the sub class type.

void AttributeWrapper::CreateAttributeValue(STEPattribute * original) {
    switch (original->NonRefType()) {

        case INTEGER_TYPE:
            integerValue = (int)attribute->Integer();
            break;
        case REAL_TYPE:
            realValue = (double)*attribute->Real();
            break;
        case NUMBER_TYPE:
            numberValue = (double)*attribute->Number();
            break;
        case STRING_TYPE:
        {
            string value;
            SDAI_String* sdaiString = attribute->String();
            stringValue = marshal_as<String^>(sdaiString->asStr(value));
            break;
        }
        case ENTITY_TYPE:
        {
            SDAI_Application_instance* stepEntity = original->Entity();

            const EntityDescriptor* descriptor = stepEntity->getEDesc();
            String^ entityType = gcnew String(descriptor->Name());
            entityValue = gcnew EntityWrapper(stepEntity->GetFileId(), entityType, &stepEntity->attributes);
            break;
        }
        case SELECT_TYPE:
        {
            SDAI_Select* select = original->Select();
            BASE_TYPE selectType = select->ValueType();
 
            if (selectType == ENTITY_TYPE) {
               // How do I get the Entity?
            }
            break;
        }

        ... other data types...

    }

}

Any help would be appreciated. Feel free to correct me if I'm misunderstanding anything, I've only been working with STEP for the past week!

Thanks,

Adam

[Anton Shabalin]

Hi Adam,

I believe that you can just reinterpret your SDAI_Select type to STEPentity.

Look an example: 

 if (cf_entity->IsA(e_plane_angle_measure_with_unit))

                {

                    auto val_comp = GetAttribute(cf_entity, "value_component");

                    SdaiMeasure_value *v = (SdaiMeasure_value *)val_comp->Select();

                    std::string vc_type = v->CurrentUnderlyingType()->Name();

                    if (v->IsPlane_angle_measure() == LTrue)

                    {

                        angle_factor = (double)*v;                        

                    }

                    //auto un_comp  = GetAttribute(cf_entity, "unit_component");                    

                }//if e_plane_angle_measure_with_unit