/// <summary>
/// Creates rows for the parent and child (if they don't already exist) and adds the child to the parent's list
/// </summary>
/// <param name="parent">The parent Vertex</param>
/// <param name="child">The child Vertex to be added to the parent's Adjacency List</param>
/// <param name="weight">The weigth of the adjacency (optional, defaults to zero)</param>
public void AddEdge(Vertex parent, Vertex child, int weight = 0)
{
AdjacencyRow ParentRow = FindOrCreateAdjacencyRow(parent);
AdjacencyRow ChildRow = FindOrCreateAdjacencyRow(child);
FindOrAddAdjacencyItem(ParentRow, child, weight);
FindOrAddAdjacencyItem(ChildRow, parent, weight);
}
/// <summary>
/// Returns all of the Edges connected to a Vertex as well as the edge's accociated weight
/// </summary>
/// <param name="parent">The Vertex to return all accociated edges</param>
/// <returns>All edges accociated with the parent</returns>
public Tuple <Vertex, int>[] GetNeighbors(Vertex parent)
{
AdjacencyRow row = AdjacencyList.Find(a => a.KeyVertex.Value == parent.Value);
Tuple <Vertex, int>[] result = new Tuple <Vertex, int> [row.AdjacencyCount];
int i = 0;
foreach (Tuple <Vertex, int> edge in row.Edges)
{
result[i] = edge;
i++;
}
return(result);
}
/// <summary>
/// A utility function that will check if an adjacency already exists and will create one if it does not
/// </summary>
/// <param name="checkRow">The row to check for (and possibly add) the adjacency</param>
/// <param name="child">The vertex to get added to the adjacency list</param>
/// <param name="addWeight">The weight to add to the adjacency if it's added (defaults to zero)</param>
private void FindOrAddAdjacencyItem(AdjacencyRow checkRow, Vertex child, int?addWeight)
{
bool ChildAlreadyExists = false;
foreach (var pair in checkRow.Edges)
{
if (pair.Item1.Value == child.Value)
{
ChildAlreadyExists = true;
}
}
if (!ChildAlreadyExists)
{
int weight = addWeight != null ? (int)addWeight : 0;
checkRow.AddEdge(child, weight);
}
}
/// <summary>
/// A utility function that checks for an existing Adjacency Row with the Vertex passed
/// Or creates one if it doesn't exist
/// </summary>
/// <param name="vertex">The Vertex to check for or create in the Adjacency List</param>
/// <returns>The Row that was found or created with the passed in vertex as its key</returns>
private AdjacencyRow FindOrCreateAdjacencyRow(Vertex vertex)
{
AdjacencyRow RowWithKey = null;
foreach (AdjacencyRow row in AdjacencyList)
{
if (row.KeyVertex.Value == vertex.Value)
{
RowWithKey = row;
}
}
if (RowWithKey == null)
{
AddNewAdjacencyRow(vertex);
RowWithKey = AdjacencyList.Find(v => v.KeyVertex.Value == vertex.Value);
}
return(RowWithKey);
}
/// <summary>
/// Overload for AddEdge that lets a user add an Vertex to the Graph without an adjacency
/// </summary>
/// <param name="parent">The Vertex to be added to the graph</param>
public void AddEdge(Vertex parent)
{
AdjacencyRow ParentRow = FindOrCreateAdjacencyRow(parent);
}
