/// <summary>
/// Traverses through all the directed graph nodes in such a way as to guarantee that for
/// every node in the sequence, all its predecessors have been visited first.
/// </summary>
/// <typeparam name="TNodeValue">The type of the labels associated with graph nodes.</typeparam>
/// <typeparam name="TEdgeLabel">The type of the labels associated with graph edges.</typeparam>
/// <param name="source">The source directed graph that will be traversed.</param>
/// <returns>
/// A sequence of <see cref="T:Bonsai.Dag.Node`2{T,U}"/> that contains the set of all
/// graph nodes in topological sort order.
/// </returns>
public static IEnumerable <Node <TNodeValue, TEdgeLabel> > TopologicalSort <TNodeValue, TEdgeLabel>(this DirectedGraph <TNodeValue, TEdgeLabel> source)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
IEnumerable <Node <TNodeValue, TEdgeLabel> > topologicalOrder;
if (!Bonsai.Dag.TopologicalSort.TrySort(source, out topologicalOrder))
{
return(Enumerable.Empty <Node <TNodeValue, TEdgeLabel> >());
}
return(topologicalOrder);
}
public static DirectedGraphDescriptor <TNodeValue, TEdgeLabel> ToDescriptor <TNodeValue, TEdgeLabel>(this DirectedGraph <TNodeValue, TEdgeLabel> source)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
var descriptor = new DirectedGraphDescriptor <TNodeValue, TEdgeLabel>();
ToDescriptor(source, descriptor);
return(descriptor);
}
/// <summary>
/// Traverses through all the directed graph nodes in depth-first order.
/// </summary>
/// <typeparam name="TNodeValue">The type of the labels associated with graph nodes.</typeparam>
/// <typeparam name="TEdgeLabel">The type of the labels associated with graph edges.</typeparam>
/// <param name="source">The source directed graph that will be traversed.</param>
/// <returns>
/// A sequence of <see cref="T:Bonsai.Dag.Node`2{T,U}"/> that contains the set of all
/// graph nodes in depth-first order.
/// </returns>
public static IEnumerable <Node <TNodeValue, TEdgeLabel> > DepthFirstSearch <TNodeValue, TEdgeLabel>(this DirectedGraph <TNodeValue, TEdgeLabel> source)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
var visited = new HashSet <Node <TNodeValue, TEdgeLabel> >();
var stack = new Stack <Node <TNodeValue, TEdgeLabel> >();
return(from root in source
from node in DepthFirstSearch(root, visited, stack)
select node);
}
/// <summary>
/// Returns the sequence of predecessors to the specified node.
/// </summary>
/// <typeparam name="TNodeValue">The type of the labels associated with graph nodes.</typeparam>
/// <typeparam name="TEdgeLabel">The type of the labels associated with graph edges.</typeparam>
/// <param name="source">The source directed graph to search for predecessors.</param>
/// <param name="node">The node for which to obtain the sequence of predecessors.</param>
/// <returns>
/// A sequence of <see cref="T:Bonsai.Dag.Node`2{T,U}"/> that contains all the predecessors
/// to the specified node.
/// </returns>
public static IEnumerable <Node <TNodeValue, TEdgeLabel> > Predecessors <TNodeValue, TEdgeLabel>(this DirectedGraph <TNodeValue, TEdgeLabel> source, Node <TNodeValue, TEdgeLabel> node)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
if (!source.Contains(node))
{
throw new ArgumentException("The specified node does not belong to the graph.", "node");
}
foreach (var predecessor in source)
{
foreach (var successor in predecessor.Successors)
{
if (successor.Target == node)
{
yield return(predecessor);
break;
}
}
}
}
/// <summary>
/// Returns the sequence of all the nodes in the directed graph that have zero outgoing edges.
/// </summary>
/// <typeparam name="TNodeValue">The type of the labels associated with graph nodes.</typeparam>
/// <typeparam name="TEdgeLabel">The type of the labels associated with graph edges.</typeparam>
/// <param name="source">The directed graph to search for sinks.</param>
/// <returns>
/// A sequence of <see cref="T:Bonsai.Dag.Node`2{T,U}"/> that contains all the nodes in the
/// directed graph that have zero outgoing edges.
/// </returns>
public static IEnumerable <Node <TNodeValue, TEdgeLabel> > Sinks <TNodeValue, TEdgeLabel>(this DirectedGraph <TNodeValue, TEdgeLabel> source)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
foreach (var node in source)
{
if (node.Successors.Count == 0)
{
yield return(node);
}
}
}
/// <summary>
/// Returns the sequence of all the nodes in the directed graph that have zero incoming edges.
/// </summary>
/// <typeparam name="TNodeValue">The type of the labels associated with graph nodes.</typeparam>
/// <typeparam name="TEdgeLabel">The type of the labels associated with graph edges.</typeparam>
/// <param name="source">The directed graph to search for sources.</param>
/// <returns>
/// A sequence of <see cref="T:Bonsai.Dag.Node`2{T,U}"/> that contains all the nodes in the
/// directed graph that have zero incoming edges.
/// </returns>
public static IEnumerable <Node <TNodeValue, TEdgeLabel> > Sources <TNodeValue, TEdgeLabel>(this DirectedGraph <TNodeValue, TEdgeLabel> source)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
foreach (var node in source)
{
if (!source.Predecessors(node).Any())
{
yield return(node);
}
}
}
public static bool TrySort <TNodeValue, TEdgeLabel>(
DirectedGraph <TNodeValue, TEdgeLabel> source,
out IEnumerable <Node <TNodeValue, TEdgeLabel> > topologicalOrder)
{
return(TopologicalSort <TNodeValue, TEdgeLabel> .TrySort(source, out topologicalOrder));
}