Eclipse Modeling

Imagine you have a language like the one below - 1) Inherits from org.eclipse.xtext.xbase.Xbase, 2) Has support for Imports

grammar o.ss.xtext.entitydsl.EntityDsl with org.eclipse.xtext.xbase.Xbase

generate entityDsl "http://www.ss.o/xtext/entitydsl/EntityDsl"

Model:
	imports=XImportSection?
	'model' name=ID 'extends' parent=JvmTypeReference;	

When you set the parent, an import gets automatically added to your file (377860). One of the problems you “might” face is that the import gets added in the wrong location (example below).

model foo extends 
import java.lang.reflect.AnnotatedArrayType

AnnotatedArrayType

The solution to the problem is to define a class that extends org.eclipse.xtext.xbase.imports.DefaultImportsConfiguration and override the method getImportSectionOffset. You also need to bind the implementation class in your DSL Runtime Module.

class EntityDslImportConfiguration extends DefaultImportsConfiguration {
	
    // Inser import in the right location
	override getImportSectionOffset(XtextResource resource) {
		val head = resource.contents.head
		val node = head?.findActualNodeFor
		if (node != null)
			node.offset
		else
			0
	}	
}

This makes sure the imports get added in the right location.

References:
The XImportSection in Xbase 2.4, BUG 377860
https://www.eclipse.org/forums/index.php/t/486071/, XRobotImportsConfiguration.xtend