private void AddNode(int layer, DAG.Node parentNode, int vertexIndex,
List <DAG.Arc> layerArcs, List <DAG.Arc> usedArcs,
List <DAG.Node> nextLayer)
{
// look up the mapping or create a new mapping for the vertex index
int mappedVertexIndex;
if (vertexMapping.ContainsKey(vertexIndex))
{
mappedVertexIndex = vertexMapping[vertexIndex];
}
else
{
vertexMapping[vertexIndex] = vertexCount;
mappedVertexIndex = vertexCount;
vertexCount++;
}
// find an existing node if there is one
var arc = new DAG.Arc(parentNode.vertexIndex, mappedVertexIndex);
if (usedArcs.Contains(arc))
{
return;
}
DAG.Node existingNode = null;
foreach (var otherNode in nextLayer)
{
if (otherNode.vertexIndex == mappedVertexIndex)
{
existingNode = otherNode;
break;
}
}
// if there isn't, make a new node and add it to the layer
if (existingNode == null)
{
existingNode = dag.MakeNode(mappedVertexIndex, layer);
nextLayer.Add(existingNode);
}
// add the edge label to the node's edge label list
int originalParentIndex =
GetOriginalVertexIndex(parentNode.vertexIndex);
string edgeLabel = GetEdgeLabel(originalParentIndex, vertexIndex);
int edgeColor = ConvertEdgeLabelToColor(edgeLabel);
existingNode.AddEdgeColor(parentNode.vertexIndex, edgeColor);
parentNode.AddEdgeColor(mappedVertexIndex, edgeColor);
dag.AddRelation(existingNode, parentNode);
layerArcs.Add(arc);
}