private void addEdge(String id, String source, String target)
throws ParseException {
if (stack.size() > 1
&& (!root.edges.contains(id) || !stack.get(stack.size() - 2).edges
.contains(id)))
throw new ParseException("parent cluster "
+ stack.get(stack.size() - 2).name
+ " do not contain the edge");
if (stack.size() == 1)
tlp.sendEdgeAdded(sourceId, id, source, target, false);