/// <summary>
/// Returns the sequence of predecessor edges 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 triples containing the predecessor node, the edge linking the predecessor
/// to the specified node and the edge index.
/// </returns>
public static IEnumerable <Tuple <Node <TNodeValue, TEdgeLabel>, Edge <TNodeValue, TEdgeLabel>, int> > PredecessorEdges <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)
{
int edgeIndex = 0;
foreach (var successor in predecessor.Successors)
{
if (successor.Target == node)
{
yield return(Tuple.Create(predecessor, successor, edgeIndex));
break;
}
edgeIndex++;
}
}
}
/// <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(nameof(source));
}
if (!source.Contains(node))
{
throw new ArgumentException("The specified node does not belong to the graph.", nameof(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 successors 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 successors.</param>
/// <param name="node">The node for which to obtain the sequence of successors.</param>
/// <returns>
/// A sequence of <see cref="T:Bonsai.Dag.Node`2{T,U}"/> that contains all the successors
/// to the specified node.
/// </returns>
public static IEnumerable <Node <TNodeValue, TEdgeLabel> > Successors <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 successor in node.Successors)
{
yield return(successor.Target);
}
}