/// <summary>
/// Used by Query Builder nested class.
/// See that class for more details on parameters.
/// </summary>
public BreadthFirstSearch(
Func <IGraph <BreadthFirstSearchNode <T> >, int, int, List <BreadthFirstSearchNode <T> > > adjacencyMethod,
Predicate <IGraphSearchNode <T> > failCondition,
Predicate <IGraphSearchNode <T> > matchCondition,
BreadthFirstSearchNode <T>[,] searchGraph,
IGraph <T> sourceGraph)
{
this.adjacencyMethod = adjacencyMethod;
this.failCondition = failCondition;
this.matchCondition = matchCondition;
this.searchGraph = searchGraph;
this.sourceGraph = sourceGraph;
}
/// <summary>
/// Do a Breadth-First search of the source graph to find a node matching
/// the provided criteria.
/// </summary>
/// <param name="rootX">X position to start the search at.</param>
/// <param name="rootY">Y position to start the search at.</param>
/// <returns></returns>
public BreadthFirstSearchNode <T> SearchAt(int rootX, int rootY)
{
if (this.matchCondition == null)
{
return(null);
}
Queue <BreadthFirstSearchNode <T> > queue = new Queue <BreadthFirstSearchNode <T> >();
queue.Enqueue(this.searchGraph[rootX, rootY]);
while (queue.Count > 0)
{
BreadthFirstSearchNode <T> currentNode = queue.Dequeue();
// Found it! Return the node containing successful search path.
if (this.matchCondition(currentNode))
{
return(currentNode);
}
// Still searching.
List <BreadthFirstSearchNode <T> > adjacentNodes =
GetNeighborElements(currentNode.X, currentNode.Y);
foreach (BreadthFirstSearchNode <T> adjacentNode in adjacentNodes)
{
if (this.failCondition != null &&
this.failCondition(adjacentNode))
{
adjacentNode.SearchStatus = BreadthFirstSearchNode.SearchState.Checked;
continue;
}
if (adjacentNode.SearchStatus == BreadthFirstSearchNode.SearchState.Unchecked)
{
adjacentNode.SearchStatus = BreadthFirstSearchNode.SearchState.Queued;
adjacentNode.PreviousNode = currentNode;
queue.Enqueue(adjacentNode);
}
}
// Finished checking this node.
currentNode.SearchStatus = BreadthFirstSearchNode.SearchState.Checked;
}
// No match found.
return(null);
}
/// <summary>
/// Creates a mirror of an existing graph, but decorated with search markers.
/// </summary>
/// <param name="sourceGraph">Graph to duplicate.</param>
/// <returns></returns>
private static BreadthFirstSearchNode <T>[,] AssembleSearchArray(IGraph <T> sourceGraph)
{
int width = sourceGraph.Width;
int height = sourceGraph.Height;
BreadthFirstSearchNode <T>[,] searchArray = new BreadthFirstSearchNode <T> [width, height];
for (int y = 0; y < height; y++)
{
for (int x = 0; x < width; x++)
{
searchArray[x, y] =
new BreadthFirstSearchNode <T>(sourceGraph.GetElement(x, y), x, y);
}
}
return(searchArray);
}
/// <summary>
/// Create a new query for a graph object.
/// </summary>
/// <param name="sourceGraph">Graph to search.</param>
public Query(IGraph <T> sourceGraph)
{
this.sourceGraph = sourceGraph;
this.searchGraph = AssembleSearchArray(sourceGraph);
}