How to generate code from custom scoping through instances?

Question

I'm trying to write a code generator using xtext. There are instances of types declared in the corresponding DSL, attributes can be referenced through those instances by custom scoping (see code for example). The linking is performed directly from referencing element to attribute, so that there is no information about the surrounding instance - but for code generation, I exactly need the qualified name that is added in the DSL file. Is there any other possibility so that I can figure out through which instance the actual feature is referenced?

My first idea was to recall the ScopeProvider at code generation, which works but does not react on two instances of same type because the first matching Attribute is chosen - so if there are multiple instances, the generator cannot distinguish which one is meant.

Second idea was to include information from the corresponding DSL file, but I don't have any idea how to get this work. I already searched a lot if it is possible to get the corresponding DSL-file from the current model, but could not find any helpful answer.

Third idea was to include the instance as a hidden field in the referencing element - but I could not find any solution for this approach too.

Small extract of Grammar (simplified):

Screen:
    (features += ScreenFeature)*
;

ScreenFeature:
    name=ID ':' type=[ClientEntity]
;

ClientEntity:
    (features += Feature)*
;

Feature:
    name=ID ':' type=DefaultValue
;

DefaultValue:
    'String'|'int'|'double'|'boolean'
;

ChangeViewParam:
    param=[ScreenFeature|QualifiedName] ':' value=[ScreenFeature|QualifiedName]
;

DSL-Example:

ClientEntity Car {
    id : int
    name : String
}

Screen Details {
    car : Car
    car2 : Car
    [...]
    car2.id : car.id
}

Generation output of first approach (line: car2.id : car.id) :

car.id : car.id

Expected:

car2.id : car.id

I hope you can understand my problem and have an idea how to solve it. Thanks for your help!

Answer 1

You can use

org.eclipse.xtext.nodemodel.util.NodeModelUtils.findNodesForFeature(EObject, EStructuralFeature) to obtain the nodes for YourDslPackage.Literals.CHANGE_VIEW_PARAM__PARAM (should be only one) and ask that one for its text.

Alternatively you could split your param=[ScreenFeature|QualifiedName] into two references