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Checking the EClass of an EObject in a pattern [message #1746772]

Fri, 04 November 2016 08:27

Eclipse User

Hello,

I have two EClasses "Employee" and its subclass "PartTimeEmployee" in my metamodel. I am trying to specify a pattern which should only match for direct instances of Employee (and not for instances of the subclass).

The pattern below for example will match for PartTimeEmployee instances as well.

pattern findEmployee(e : Employee){
Employee(e);
}

Is it possible to check in a pattern if the EClass of e is Employee and nothing else? I am looking for something like e.eClass() as provided by EMF.

Cheers,
Erhan

Re: Checking the EClass of an EObject in a pattern [message #1746785 is a reply to message #1746772]

Fri, 04 November 2016 10:56

Eclipse User

Hi,

sadly, there is no built-in support for this feature as of now. As a workaround, I can suggest something like follows:

pattern specialEmployee(e : PartTimeEmployee) {
PartTimeEmployee(e);
} or {
// Put all direct subclasses into separate bodies
}

pattern findEmployee(e : Employee){
Employee(e);
neg find specialEmployee(e);
}

I know this is not really easy to use, but this is currently the only way to use it.

However, could you elaborate your use case why you need this functionality? We might be capable of suggesting an alternative approach here; or if the issue seems general, we might also update the query language/runtimes to support this use case as well.

Best regards,
Zoltán

Re: Checking the EClass of an EObject in a pattern [message #1746810 is a reply to message #1746785]

Fri, 04 November 2016 16:01

Eclipse User

Hello,

I am using patterns to parse a graph with respect to a grammar. Each original grammar rule creates objects with specific types, so parsing a given graph with patterns must be specific on types as well. (if my grammar rule creates Employee, then I should exactly parse Employee and not some subtypes). This parser will be then used for model transformation, consistency checking etc.

Your solution is still a managable one with one additional pattern for each type. Thanks for that! Nevertheless, I'd be of course even more happy to hear about a new language feature addressing this issue in the future Smile

Cheers,
Erhan

Re: Checking the EClass of an EObject in a pattern [message #1746824 is a reply to message #1746810]

Sat, 05 November 2016 04:21

Eclipse User

Hi Erhan,

I see, I cannot provide any real alternative here. Maybe you could do this instanceof check in your transfomation rules, etc., but still, this is only a workaround.

I have opened a ticket https://bugs.eclipse.org/bugs/show_bug.cgi?id=507094 for this issue; however, I don't know when will it be addressed.

Cheers,
Zoltán

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