Model:
command+=Commands;

Commands:
	command= ('create'|'close'|'open'|'copy');
	name = ID
        "{"
	argtlist+=Arg*			
        "}"	
;
	
Arg:
        argType = ID
	argName = STRING
;

create testing {
        file "File1"  //only argType file and folder is shown in content assist       
        folder "Folder"    //only argType file and folder is shown in content assist       
}

class MyDslProposalProvider extends AbstractMyDslProposalProvider {
	
	override completeArg_ArgType(EObject model, Assignment assignment, ContentAssistContext context, ICompletionProposalAcceptor acceptor) {
		val commands = EcoreUtil2.getContainerOfType(model, Commands)
		if (commands != null) {
			println(commands.command)
		}
	}
	
}