Hyperlink support for Import statements

In Xtext DSL’s, it is quite common to have cross-references (represented using referenceName = [reference-type]). You can have cross-references within or across files (a.k.a Resource). In the latter case, you’ll require explicit imports in order to reference the types. You could have implicit-imports, but it is out of the scope of current discussion.

In the editor, shortcuts “CTRL + Left Mouse click or F3” can be used for navigation. It works out-of-the-box for cross-references, but fails for import statements, especially for languages that extend from the Terminals grammar. Hyperlink detection for import statements can be enabled by customizing the HyperlinkHelper.

public class EntityDslHyperlinkHelper extends TypeAwareHyperlinkHelper {

    @Inject
    private IQualifiedNameConverter.DefaultImpl qNameConvertor;

    @Inject
    private EntityDslIndex entityDslIndex;

    @Override
    public void createHyperlinksByOffset(XtextResource resource, int offset, IHyperlinkAcceptor acceptor) {
        final EObject eObject = getEObjectAtOffsetHelper().resolveElementAt(resource, offset);
        if (eObject instanceof Import) {
            final ImportWrapper iImport = new ImportWrapper((Import) eObject);
            if (!iImport.isWildcard()) {
                final Optional<ITextRegion> textRegion = getTextRegion(iImport.getImport(), offset);
                if (textRegion.isPresent()) {
                    final Region region = new Region(textRegion.get().getOffset(), textRegion.get().getLength());
                    final Optional<EObject> importedEntity = iImport.getImportedEntity();
                    if (importedEntity.isPresent())
                        this.createHyperlinksTo(resource, region, importedEntity.get(), acceptor);
                    return;
                }
            }
        }
        super.createHyperlinksByOffset(resource, offset, acceptor);
    }

    protected Optional<ITextRegion> getTextRegion(Import iImport, final int offset) {
        final List<INode> nodes = NodeModelUtils.findNodesForFeature(iImport,
                EntityDslPackage.Literals.IMPORT__IMPORTED_NAMESPACE);
        return nodes.stream().map(INode::getTextRegion).filter(textRegion -> textRegion.contains(offset)).findFirst();
    }

    private class ImportWrapper {

        private final Import iImport;

        public ImportWrapper(final Import iImport) {
            this.iImport = iImport;
        }

        public Import getImport() {
            return iImport;
        }

        protected boolean isWildcard() {
            final QualifiedName qualifiedImport = qNameConvertor.toQualifiedName(iImport.getImportedNamespace());
            return qualifiedImport.getLastSegment().equals("*");
        }

        protected Optional<EObject> getImportedEntity() {
            final QualifiedName entityQName = qNameConvertor.toQualifiedName(iImport.getImportedNamespace());
            final IEObjectDescription importedEod = entityDslIndex.getEntity(entityQName, iImport);
            if (importedEod == null)
                return Optional.empty();

            final EObject eObject = importedEod.getEObjectOrProxy();
            final EObject resolved = eObject.eIsProxy()
                    ? EcoreUtil.resolve(eObject, iImport.eResource().getResourceSet())
                    : eObject;
            return Optional.of(resolved);
        }

    }
}

In the overridden method #createHyperlinksByOffset(), we do the following - 1) Check if the object at a given offset is an instance of Import and wrap it in the ImportWrapper, 2) Resolve the imported Entity Object using ImportWrapper#getImportedEntity(), 3) Call method #createHyperlinksTo() that creates an XtextHyperlink instance.

The ImportWrapper provides a utility API for working with Import objects. The class EntityDslIndex provides utility API for working with the Xtext index (PS - Enriching Xtext Index API)

Source - org.nb.xtext.example.hyperlink.entitydsl, org.nb.xtext.example.hyperlink.entitydsl References - XbaseHyperLinkHelper, https://www.eclipse.org/forums/index.php/t/521907/ Discussion - https://www.eclipse.org/forums/index.php/t/1092463/