/**
* {@inheritDoc}
*/
public override E addEdge(V sourceVertex, V targetVertex)
{
assertVertexExist(sourceVertex);
assertVertexExist(targetVertex);
if (!allowingMultipleEdges && containsEdge(sourceVertex, targetVertex))
{
return(default(E));
}
if (!allowingLoops && sourceVertex.Equals(targetVertex))
{
throw new ArgumentException(LOOPS_NOT_ALLOWED);
}
E e = edgeFactory.createEdge(sourceVertex, targetVertex);
if (containsEdge(e))
{ // this restriction should stay!
return(default(E));
}
else
{
intrusiveEdgesSpecifics.add(e, sourceVertex, targetVertex);
specifics.addEdgeToTouchingVertices(e);
return(e);
}
}
