Generate names for nested element

Question

I have a grammar like this:

Entity:
    'entity' name=ID '{'
        (properties+=Property)*

        (revision=Revision)?
    '}'

Revision:
    'revision' '{'
        (properties+=Property)+
    '}'

The editor gives me lots of errors for the revisions because they don't have a name. Since a revision is always a child of Entity, can I assign it a name automatically? Something like name=this.parent.name + "_REV"?

Answer 1

The solution is to extend DefaultDeclarativeQualifiedNameProvider:

import org.eclipse.xtext.naming.DefaultDeclarativeQualifiedNameProvider;
import org.eclipse.xtext.naming.QualifiedName;
import model.Revision;

public class ModelQualifiedNameProvider extends DefaultDeclarativeQualifiedNameProvider {

    public final static String REVISION_TABLE_EXTENSION = "_REV";
    public final static String REVISION_TYPE_EXTENSION = "Rev";

    public QualifiedName qualifiedName( Revision obj ) {
        QualifiedName qn = getFullyQualifiedName( obj.eContainer() );

        String typeName = qn.getLastSegment() + REVISION_TABLE_EXTENSION;

        QualifiedName result = qn.skipLast( 1 );
        result = result.append( typeName );

        return result;
    }

}

Make sure you get the method signature right! Xtext reflectively invokes QualifiedName qualifiedName(MyType ele) and if you upgrade from 1.0 to 2.0, don't forget to update the signature: Change the return type from String to QualifiedName