Search code examples
xtextxtend

Register HoverProvider with Xtend

I try to implement a custom HoverProvider according to this tutorial: enter link description here

However, I'm stuck translating to Java code of MyDSLUiModuleto Xtend. The register-method should read like this:

 def Class<? extends IEObjectDocumentationProvider> bindIEObjectDocumentationProviderr() {
    return MyDSLHoverProvider.class
}

However, this doesn't compile since MyDSLHoverProvider only implements the IEObjectDocumentationProvider but not extend this class (MyDSLHoverProvider is the same as in the tutorial).

Therefore this error is thrown: Type mismatch: cannot convert from Class<? extends Class> to Class<? extends IEObjectDocumentationProvider>

How can I get around this error?

Btw: If I test my DSL in an Eclipse instance, I get a wierd NPE:

!ENTRY org.eclipse.oomph.setup.ui 2 0 2016-09-16 16:42:34.203 !MESSAGE java.lang.NullPointerException !STACK 0 java.lang.NullPointerException at org.eclipse.oomph.setup.ui.SetupUIPlugin.performStartup(SetupUIPlugin.java:373) at org.eclipse.oomph.setup.ui.SetupUIPlugin.access$4(SetupUIPlugin.java:344) at org.eclipse.oomph.setup.ui.SetupUIPlugin$1$1.run(SetupUIPlugin.java:241) at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)

I have no clue where this exception comes from.

The class MyDSLHoverProvider looks like this:

import org.eclipse.emf.ecore.EObject
import org.eclipse.xtext.documentation.IEObjectDocumentationProvider

class MyDSLHoverProvider implements IEObjectDocumentationProvider {

    override getDocumentation(EObject o) {
        println("Hover: " + o)
        if (o instanceof MyFieldElements) {
            return "This is a nice Greeting with nice <b>markup</b> in the <i>documentation</i>";
        }
    }

}

Edit: I found a way to display the tooltips, but it seems strange. A tooltip is shown for this rule:

name = ID

but if I rename it to

myField = ID

the tooltip is not triggered.

Is this the expected behaviour?

Solution

  • the correct Xtend syntax is

    def Class<? extends IEObjectDocumentationProvider> bindIEObjectDocumentationProviderr() {
    return MyDSLHoverProvider
}

    or

    def Class<? extends IEObjectDocumentationProvider> bindIEObjectDocumentationProviderr() {
    MyDSLHoverProvider
}

    MyDSLHoverProvider.classis the same as MyDslHoverProvider.class.getClass() in Java