grammar org.xtext.example.mydsl.MyDsl with org.eclipse.xtext.common.Terminals

generate myDsl "http://www.xtext.org/example/mydsl/MyDsl"

Model:	applications+=Application*;
Application:	"Application" name=ID "{" tasks+=Task* "}";
Task:	"Task" name=ID "{" ports += Port* edges += Edge* "}";
Port:	"Port" name=ID ";";
Edge:	"Edge" "to" from=[Port | FQN] ";";
FQN:	ID ("."ID )* ;

Application app1 { 
	Task task1 {
		Port p1;
		Edge a to p1;
	}
	
	Task task2 {
		Port p1;
		Edge a to task1.p1;
	}
}

Application app2 {
	Task task1 {
		Port p1;
		Edge a to app1.task1.p1; // Should not be allowed, as app1 !== app2
	}
}

 public IScope scope_Port(Edge context, EReference reference) {
	Application app = (Application) context.eContainer().eContainer();
	
	List<Port> elements = new ArrayList<Port>(); 
	for (Task t : app.getTasks()) {
		elements.addAll(t.getPorts());
	}
	
	return Scopes.scopeFor(elements);
}

public IScope scope_Port(Edge context, EReference reference) {
	EObject parent = context;
	
	// Check for containment in an Application object
	while (parent != null && !(parent instanceof Application)) {
		parent = parent.eContainer();
	}
	if(parent == null) {
		return IScope.NULLSCOPE;
	}
	
	final Application app = (Application) parent;
	// Add all port objects that are in this Application
	List<Port> elements = new ArrayList<Port>(); 
	for (Task t : app.getTasks()) {
		elements.addAll(t.getPorts());
	}
	
	// get the default/original scope, which uses shorthand FQNs
	IScope originalScope = delegateGetScope(context, reference);
	
	Predicate<IEObjectDescription> predicate = new Predicate<IEObjectDescription>(){
		public boolean apply(IEObjectDescription input) {
			if (input == null) {
				return false;
			}
			
			EObject parent = input.getEObjectOrProxy();
			// Search for the containing Application again
			while (parent != null && !(parent instanceof Application)) {
				parent = parent.eContainer();
			}
			// Only return true if the app is the same object as the application that contains this element
			return app.equals(parent);
		};
	};
	// Apply the predicate to the original scope
	return new FilteringScope(originalScope, predicate);
}