/**
* Returns a valid instance selection for the current selection of the tree viewer. Returns <code>
* null</code> if there is none.
*
* @return a valid instance selection for the current selection of the tree viewer or <code>null
* </code>
*/
private InstanceSelection getValidSelection() {
ISelection viewerSelection = treeViewer.getSelection();
if (!(viewerSelection instanceof ITreeSelection) || viewerSelection.isEmpty()) return null;
ITreeSelection treeSelection = (ITreeSelection) treeViewer.getSelection();
TreePath firstPath = treeSelection.getPaths()[0]; // XXX use all paths
// instead of first
// only?
InstanceValidationMessage firstMessage;
Iterator<InstanceValidationMessage> restIter;
if (firstPath.getLastSegment() instanceof InstanceValidationMessage) {
firstMessage = (InstanceValidationMessage) firstPath.getLastSegment();
restIter = Iterators.emptyIterator();
} else {
Collection<InstanceValidationMessage> messages =
contentProvider.getMessages(treeSelection.getPaths()[0]);
if (messages.isEmpty()) return null; // shouldn't happen, but doesn't really matter
restIter = messages.iterator();
firstMessage = restIter.next();
}
InstanceService is = PlatformUI.getWorkbench().getService(InstanceService.class);
// check first message for valid instance reference
if (firstMessage.getInstanceReference() == null
|| is.getInstance(firstMessage.getInstanceReference()) == null) return null;
Set<InstanceReference> references = new HashSet<InstanceReference>();
references.add(firstMessage.getInstanceReference());
while (restIter.hasNext()) references.add(restIter.next().getInstanceReference());
return new DefaultInstanceSelection(references.toArray());
}
