/**
* Returns an undirected view of the specified graph. If the specified graph is directed,
* returns an undirected view of it. If the specified graph is already undirected, just returns
* it.
*
* @param g the graph for which an undirected view is to be returned
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @return an undirected view of the specified graph, if it is directed, or or the specified
* graph itself if it is already undirected.
*
* @throws IllegalArgumentException if the graph is neither directed nor undirected
* @see AsUndirectedGraph
*/
public static Graph <V, E> undirectedGraph <V, E>(Graph <V, E> g)
{
if (g.getType().isDirected())
{
throw new NotImplementedException();
//return new AsUndirectedGraph<>(g);
}
else if (g.getType().isUndirected())
{
return(g);
}
else
{
throw new ArgumentException("graph must be either directed or undirected");
}
}
/**
* Adds all the vertices and all the edges of the specified source digraph to the specified
* destination digraph, reversing all of the edges. If you want to do this as a linked view of
* the source graph (rather than by copying to a destination graph), use
* {@link EdgeReversedGraph} instead.
*
* <p>
* The behavior of this operation is undefined if any of the specified graphs is modified while
* operation is in progress.
*
* @param destination the graph to which vertices and edges are added
* @param source the graph used as source for vertices and edges to add
* @param <V> the graph vertex type
* @param <E> the graph edge type
*
* @see EdgeReversedGraph
*/
public static void addGraphReversed <V, E>(Graph <V, E> destination, Graph <V, E> source)
{
if (!source.getType().isDirected() || !destination.getType().isDirected())
{
throw new ArgumentException("graph must be directed");
}
addAllVertices(destination, source.vertexSet());
foreach (E edge in source.edgeSet())
{
destination.addEdge(source.getEdgeTarget(edge), source.getEdgeSource(edge));
}
}