public void AddNode(Node node)
{
if(!_nodes.Contains(node))
{
_nodes.Add(node);
}
}
public void Connect(Node source, Node target)
{
if (source.Equals(target))
return; //self reference is ignored
AddNode(source);
AddNode(target);
var edge = new Edge(source, target);
if (!_edges.Contains(edge))
{
_edges.Add(edge);
}
}
public DirectedGraph Clone()
{
var result = new DirectedGraph();
foreach (var node in _nodes)
{
var newNode = new Node(node.Name);
result.AddNode(newNode);
}
foreach (var edge in _edges)
{
result.Connect(edge.Source.Name, edge.Target.Name);
}
return result;
}
public Edge(Node source, Node target)
{
//source depends on target
Source = source;
Target = target;
}
public bool Equals(Node other)
{
if (ReferenceEquals(null, other)) return false;
if (ReferenceEquals(this, other)) return true;
return Equals(other.Name, Name);
}
public void Add(Node node)
{
_nodes.Add(node);
}
void visit(Node node)
{
_graph.Remove(node);
AddNode(node);
}
void AddNode(Node node)
{
if(!_order.Contains(node))
{
_order.Add(node);
}
}
void tarjan(Node v, DirectedGraph graph)
{
v.SetIndex(_index);
v.SetLowLink(_index);
_index++;
_stack.Push(v);
foreach (var n in graph.GetTargetsForSource(v))
{
if (n.Index == -1)
{
tarjan(n, graph);
var lowLink = Math.Min(v.LowLink, n.LowLink);
v.SetLowLink(lowLink);
}
else if (_stack.Contains(n))
{
var lowLink = Math.Min(v.LowLink, n.Index);
v.SetLowLink(lowLink);
}
}
if(v.LowLink == v.Index)
{
var cycle = new Cycle();
Node n;
do
{
n = _stack.Pop();
cycle.Add(n);
} while (!v.Equals(n));
_cycles.Add(cycle);
}
}
void Remove(Node node)
{
_nodes.Remove(node);
_edges.RemoveWhere(e => e.Target.Equals(node));
}
IEnumerable<Node> GetTargetsForSource(Node node)
{
foreach (var edge in _edges)
{
if (edge.Source.Equals(node))
yield return edge.Target;
}
yield break;
}
