/// <summary>
/// Flattens the tree structure into list.
/// </summary>
/// <param name="root">
/// The root.
/// </param>
/// <returns>
/// The <see>
/// <cref>IEnumerable</cref>
/// </see>
/// .
/// </returns>
public static IEnumerable <BDDNode> Traverse(BDDNode root)
{
var stack = new Stack <BDDNode>();
var visited = new HashSet <BDDNode>();
stack.Push(root);
while (stack.Count > 0)
{
BDDNode current = stack.Pop();
if (visited.Contains(current))
{
continue;
}
visited.Add(current);
yield return(current);
if (current.GetType() != typeof(BDDVariableNode))
{
continue;
}
stack.Push(current.HighNode);
stack.Push(current.LowNode);
}
}
/// <summary>
/// Creates a new node or returns reference to existing node if it shares the same properties.
/// </summary>
/// <param name="value">
/// The value.
/// </param>
/// <param name="highNode">
/// The high node.
/// </param>
/// <param name="lowNode">
/// The low node.
/// </param>
/// <returns>
/// The <see cref="BDDNode"/>.
/// </returns>
public BDDNode CreateNode(int value, BDDNode highNode, BDDNode lowNode)
{
if (highNode == lowNode)
{
return(lowNode);
}
if (this.h.ContainsKey(new Tuple <int, BDDNode, BDDNode>(value, highNode, lowNode)))
{
return(this.h[new Tuple <int, BDDNode, BDDNode>(value, highNode, lowNode)]);
}
BDDNode n = new BDDVariableNode(value, highNode, lowNode);
this.h.Add(new Tuple <int, BDDNode, BDDNode>(value, highNode, lowNode), n);
return(n);
}
/// <summary>
/// Initializes a new instance of the <see cref="BDDNode"/> class.
/// </summary>
/// <param name="highNode">
/// The high node.
/// </param>
/// <param name="lowNode">
/// The low node.
/// </param>
protected BDDNode(BDDNode highNode, BDDNode lowNode)
{
this.HighNode = highNode;
this.LowNode = lowNode;
}
/// <summary>
/// Initializes a new instance of the <see cref="BDDVariableNode"/> class.
/// </summary>
/// <param name="variable">
/// The variable.
/// </param>
/// <param name="highNode">
/// The high node.
/// </param>
/// <param name="lowNode">
/// The low node.
/// </param>
public BDDVariableNode(int variable, BDDNode highNode, BDDNode lowNode) : base(highNode, lowNode)
{
this.Variable = variable;
}
