Xtext: DSL reference to attribute

Question

For example

i have a grammar like this one:

Bundle:
    'Bundle'
    name= ID '{'
    car+=Car+
    service +=Service*
    '}'
    ;

Car:
    'Car'
    name=ID
    extra+=Extra*
    '}'
;   

Extra:
    name= ID '=' type=STRING
;

Service:
    'Service' att=STRING 'for' ref+=Reference*
;

Reference:
    //Ref to car oder Ref to Car.Extra 
;

In my model i want to create a Service like:

Service "ServiceName" for car1
Service "ServiceName" for car2 (extra1 extra2)

How can i resolve the reference to Extras of a Car?

Answer 1

this can be done with simple cross refs

Service:
    'Service' att=STRING 'for' car=[Car] ('(' extras+=[Extra]+ ')')?
;

And a corresponding scope provider

package org.xtext.example.mydsl.scoping

import org.eclipse.emf.ecore.EReference
import org.eclipse.xtext.scoping.IScope
import org.eclipse.xtext.scoping.Scopes
import org.eclipse.xtext.scoping.impl.AbstractDeclarativeScopeProvider
import org.xtext.example.mydsl.myDsl.Service

class MyDslScopeProvider extends AbstractDeclarativeScopeProvider {

    def IScope scope_Service_extras(Service ctx, EReference ref) {
        return Scopes.scopeFor(ctx.car.extra)
    }

}