cross-file reference and link in xtext

Question

I created a new DSL by using xtext as follows. (Actually I will access the DSL on RCP application.)

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

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


Configuration:
components+=(Component)*;

Component:
'Component' name=ID
'{'
(('display' display=STRING) &
('dependency' dependency=[Component|ID])?)
'}'
 ;

I have two files: sample1.mydsl

 Component comp1 {
     display "comp1"
     children comp2
 }

sampl2.mydsl

 Component comp2 {
      display "comp2"
 }

On RCP Application, I will compose a tree view with the Configuration model. But when I get comp2 object from getChildren() method of comp1 object, sometimes I couldn't get the comp2 object exactly.

I loaded the model data as below:

    private List<ConfigurationItem> itemList;

    void loadData() {
    project =               ResourcesPlugin.getWorkspace().getRoot().getProject("test");

    XtextResourceSet resourceSet = (XtextResourceSet) injector
        .getInstance(XtextResourceSetProvider.class)
        .get(project);
    resourceSet.addLoadOption(XtextResource.OPTION_RESOLVE_ALL, Boolean.TRUE);

    IFile[] samples = findFiles(resources);

    List<Resource> resourceList = new ArrayList<Resource>();
    for (IFile sample : samples) {
        Resource resourceSample = resourceSet.getResource(
                URI.createURI(sample.getLocationURI().toString(), true), true);
        resourceList.add(resourceSample);
    }

    for (Resource resource : resourceList) {
        System.out.println("resource = " + resource.toString());
        try {
            resource.load(null);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        EcoreUtil.resolveAll(resource);
    }

    // add all to configuration item list
    for (Resource rc : resourceList) {
        Configuration config = (Configuration) rc.getContents().get(0);
        itemList.addAll(config.getConfigurationItems().toArray(new ConfigurationItem[config.getConfigurationItems().size()]));
    }

}

test code

for (ConfigurationItem item : itemList) {
   if (item.getName().equals("comp1") {
      Component[] comps = item.getChildren();
      for (Component comp : comps) {
         if (comp != null) {
             System.out.println("comp display : " + comp.getDisplay());
         }
      }
  }

}

result
```
comp display : null
```

I expected the result to be "comp display : comp2".

But Sometimes the result is "comp display : comp2"

and sometimes the result is "comp display : null"

I think it is because of the lazy linking of xtext.

How can always I get correct result -> "comp display : comp2"?

I Hope someone can help me solve it. Thanks.

It should work if you remove the 'resolveAll' option from your code. It should not be necessary and in general it is to be avoided. EMF will resolve your model transparently thus the 'resolveAll' thing is a relict from earlier days. Does that solve your issue? — Sebastian Zarnekow
@Sebastian Zarnekow Thank you. It seems to be well. Now I need to test it more. I will report the result after testing. — user2663410
@ Sebastian Zarnekow I have tried to test it many times. I still have the problem. Sometimes returns "comp display : null". — user2663410
and you should remove the resolve_all load option from the resourceset as well — Christian Dietrich

Gaetan Gaetan · Accepted Answer · 2015-12-07T08:02:44

you can try the followingcode:

  void loadData() {
    project =               ResourcesPlugin.getWorkspace().getRoot().getProject("test");
    ResourceSet resourceSet = new ResourceSetImpl();
IFile[] samples = findFiles(project);
List<Resource> resourceList = new ArrayList<Resource>();
for (IFile sample : samples) {
    Resource resourceSample = resourceSet.getResource(
            URI.createURI(sample.getFullPath().toString()), true);
    resourceList.add(resourceSample);
}


// add all to configuration item list
for (Resource rc : resourceList) {
    Configuration config = (Configuration) rc.getContents().get(0);
    itemList.addAll(config.getConfigurationItems()));
}
}

cross-file reference and link in xtext

On RCP Application, I will compose a tree view with the Configuration model. But when I get comp2 object from getChildren() method of comp1 object, sometimes I couldn't get the comp2 object exactly.

3 Answers