How to resolve EObjects coming from a DSL file residing in an eclipse plugin

Question

I have a DSL (dsl1) with cross references to ecore model ecoe1. All works fine if the resources resides in the workspace. But when I run my DSL plugin in a second eclipse instance and try to import the dsl1 instance from the plugin into a second DSL dsl2 that resides in the workspace of the second eclipse instance I can not resolve the references to the ecore1 objects. The objects are present but all attributes are empty (null). I tried all six resolving methods from EcoreUtil but nothing works.
Has any body an idea what I can try else to solve this issue ?

Answer 1

Christian Dietrich wrote on Sun, 02 August 2015 01:54what do you mean by "import". if you model project in the second workspace is a plugin project and the libary plugin is on the classpath of that plugin project it should work fine
I use the "importURI" mechanism to import other ecore models into my dsl. All projects are plugin projects.
The library plugin of the dsl1 is implicit on the classpath it gets reexported from the model plugin of dsl2. I even tried to have it explicit on the classpath in the ui project of dsl2 but it does not work either.
I have written a small example of the problem see the atachment.
Here is the description of the example:
The example constists of three workspaces. Workspace1 contains the definition of dsl1 where the part of interest is:
// /org.xtext.example.mydsl.resolvebug.dsl1/src/org/xtext/example/mydsl/resolvebug/dsl1/DSL1.xtext
grammar org.xtext.example.mydsl.resolvebug.dsl1.DSL1 with org.eclipse.xtext.common.Terminals
import "http://www.eclipse.org/2008/Xtext" as xt
generate dSL1 "http://www.xtext.org/example/mydsl/resolvebug/dsl1/DSL1"
RULE1:
"grammar" name=ID "ref" ref=[xt::Grammar]
I have defined a name provider that should produce the following name schema for RULE1 objects: <name>_<Grammar.name>. The relevant code is in /org.xtext.example.mydsl.resolvebug.dsl1/src-xtend/org/xtext/example/mydsl/resolvebug/dsl1/utils/GeneratedDSL1QualifiedNameProviderSwitch.xtend:
override caseRULE1(RULE1 object) {
val sb1 = new StringBuilder;
if (object.getName != null) {
sb1.append(object.getName)
sb1.append("_")
val sb2 = new StringBuilder;
if (object.getRef != null) {
var ref = object.getRef
if (ref instanceof EObject) {
ref = EcoreUtils.resolve(ref, object)
sb2.append(GeneratedXtextQualifiedNameProvider.doApply(ref).toString)
sb1.append(NamingUtils.lastSegment(sb2.toString))
sb1
What EcoreUtils.resolve does is explained below.
The GeneratedXtextQualifiedNameProvider.doApply(ref) effectively does the following:
override caseGrammar(Grammar object) {
val sb1 = new StringBuilder;
val sb2 = new StringBuilder;
if (object.getName != null) {
sb2.append(object.getName)
sb1.append(NamingUtils.lastSegment(sb2.toString))
sb1
The workspace2 contains the definition of dsl2 which references RULE1 objects:
grammar org.xtext.example.mydsl.resolvebug.dsl2.DSL2 with org.eclipse.xtext.common.Terminals
import "http://www.xtext.org/example/mydsl/resolvebug/dsl1/DSL1" as dsl1
generate dSL2 "http://www.xtext.org/example/mydsl/resolvebug/dsl2/DSL2"
Greeting:
'Hello' name=ID ref=[dsl1::RULE1];
I have defined a scope provider that uses the obove mentioned name provider to produce names for the referenced objects:
///org.xtext.example.mydsl.resolvebug.dsl2/src-xtend/org/xtext/example/mydsl/resolvebug/dsl2/scoping/GeneratedDSL2ScopeProvider.xtend
def IScope scope_Greeting_ref(EObject model, EReference reference) {
val itemList = GeneratedDSL2MakeRULE1ListSwitch.apply(model)
val scope0 = makeEObjectListScope(itemList, GeneratedDSL1QualifiedNameProvider::PROVIDER
scope0
GeneratedDSL2MakeRULE1ListSwitch.apply(model) retrieves the list of imported RULE1 objects. The import is effectively done by this code:
override caseDSL2(DSL2 object) {
val result = new ArrayList
for (item : object.getImportList) {
result.addAll(doSwitch(item))
result
override caseImport(Import object) {
val uriString = object.getImportURI()
val resourceSet = object.eResource().getResourceSet()
val resource = resourceSet.getResource(URI.createURI(uriString),true)
val itemList = resource.allContents.filter(typeof(RULE1))
val result = EcoreUtils.makeCollection(itemList)
result
The GeneratedDSL1QualifiedNameProvider::PROVIDER is a static instance of the name provider and the method makeEObjectListScope does the following:
val result = new LinkedList
for (eod : objectList) {
var EObject eobj = eod
val container = eod.eContainer
if(container != null) {
eobj = EcoreUtils.resolve(eobj, container)
} else if(eobj.eIsProxy) {
EcoreUtil.resolveAll(eobj)
val qname = nameProvider.getFullyQualifiedName(eobj)
val simpleName = qname.lastSegment
result.add(EObjectDescription.create(simpleName, eobj))
result.add(EObjectDescription.create(qname, eobj))
val resultScope = new SimpleScope(scope, result)
resultScope
where EcoreUtils.resolve() does the following:
if (object.eIsProxy()) {
EcoreUtil.resolveAll(object);
object = (T) EcoreUtil.resolve(object, context);
Resource resource = object.eResource();
if (resource == null) {
resource = context.eResource();
} else {
try {
resource.load(Collections.emptyMap());
} catch (IOException e) {
e.printStackTrace();
return (T) object;
EcoreUtil.resolveAll(resource);
if (resource != null) {
object = (T) EcoreUtil.resolve(object, resource);
ResourceSet objectContext = resource.getResourceSet();
if (objectContext != null){
try {
EcoreUtil.resolveAll(objectContext);
} catch (Throwable e) {
// e.printStackTrace(); // ignore if resolving fails because of link cycles.
return (T) EcoreUtil.resolve(object, objectContext);
return object;
As you can see I tried all methods of resolving proxy objects but all fail as you can see later.
The workspace3 contains an instance of dsl2 which references an instance of dsl1 which is contained in the dsl1 plugin itself.:
dsl2 my.DSL2
import "platform:/plugin/org.xtext.example.mydsl.resolvebug.dsl1/model/Dsl1.dsl1"
Hello hello xtext_ // should be "xtext_Xtext"
Here "hello" is the name of the Greeting object in dsl2 and "xtext_" is the name of the RULE1 object from the referenced dsl1. The name of the RULE1 object should be "xtext_Xtext" as I explained above but it is not because the referenced grammar "Xtext" does not get resolved properly although I have applied all available resolving methods to the grammar object in the name provider.
I hope you can tell me what I have done wrong.