/// <summary>
/// Applies operation "op" to BDD "u1" and "u2"
/// </summary>
/// <param name="nodeFactory">
/// The node factory.
/// </param>
/// <param name="op">
/// The operation.
/// </param>
/// <param name="u1">
/// The first BDD represented by root node.
/// </param>
/// <param name="u2">
/// The second BDD represented by root node.
/// </param>
/// <returns>
/// The <see cref="BDDNode"/>.
/// </returns>
private BDDNode Apply(BDDNodeFactory nodeFactory, BDDOperator op, BDDNode u1, BDDNode u2)
{
if (u1 == null)
{
return(u2);
}
var g = new Dictionary <Tuple <BDDNode, BDDNode>, BDDNode>();
return(this.App(nodeFactory, op, g, u1, u2));
}
/// <summary>
/// Recursive helper for "Apply". Applies operation "op" to BDD "u1" and "u2" using a lookup table "g" for efficience (dynamic programming).
/// </summary>
/// <param name="nodeFactory">
/// The node factory.
/// </param>
/// <param name="op">
/// The op.
/// </param>
/// <param name="g">
/// The g.
/// </param>
/// <param name="u1">
/// The first BDD represented by root node.
/// </param>
/// <param name="u2">
/// The second BDD represented by root node.
/// </param>
/// <returns>
/// The <see cref="BDDNode"/>.
/// </returns>
/// <exception cref="ArgumentOutOfRangeException">
/// Default throw.
/// </exception>
private BDDNode App(BDDNodeFactory nodeFactory, BDDOperator op, Dictionary <Tuple <BDDNode, BDDNode>, BDDNode> g, BDDNode u1, BDDNode u2)
{
BDDNode u;
if (g.ContainsKey(new Tuple <BDDNode, BDDNode>(u1, u2)))
{
return(g[new Tuple <BDDNode, BDDNode>(u1, u2)]);
}
if (u1.GetType() == typeof(BDDTerminalNode) && u2.GetType() == typeof(BDDTerminalNode))
{
switch (op)
{
case BDDOperator.BDD_OPERATOR_AND:
u = nodeFactory.CreateNode(((BDDTerminalNode)u1).Value && ((BDDTerminalNode)u2).Value);
break;
case BDDOperator.BDD_OPERATOR_OR:
u = nodeFactory.CreateNode(((BDDTerminalNode)u1).Value || ((BDDTerminalNode)u2).Value);
break;
default:
throw new ArgumentOutOfRangeException(nameof(op), op, null);
}
}
else if (u1.Variable == u2.Variable)
{
u = nodeFactory.CreateNode(u1.Variable, this.App(nodeFactory, op, g, u1.HighNode, u2.HighNode), this.App(nodeFactory, op, g, u1.LowNode, u2.LowNode));
}
else if (u1.Variable < u2.Variable)
{
u = nodeFactory.CreateNode(u1.Variable, this.App(nodeFactory, op, g, u1.HighNode, u2), this.App(nodeFactory, op, g, u1.LowNode, u2));
}
else
{
u = nodeFactory.CreateNode(u2.Variable, this.App(nodeFactory, op, g, u1, u2.HighNode), this.App(nodeFactory, op, g, u1, u2.LowNode));
}
g.Add(new Tuple <BDDNode, BDDNode>(u1, u2), u);
return(u);
}
/// <summary>
/// Helper method for recursive BDD construction from FaultTree.
/// </summary>
/// <param name="node">
/// The node.
/// </param>
/// <param name="nodeFactory">
/// The node factory.
/// </param>
/// <returns>
/// The <see cref="BDDNode"/>.
/// </returns>
private BDDNode CreateBDD(FaultTreeNode node, BDDNodeFactory nodeFactory)
{
if (node.GetType() == typeof(FaultTreeTerminalNode))
{
return(nodeFactory.CreateNode(((FaultTreeTerminalNode)node).Label));
}
BDDOperator op = BDDOperator.BDD_OPERATOR_AND;
if (node.GetType() == typeof(FaultTreeOrGateNode))
{
op = BDDOperator.BDD_OPERATOR_OR;
}
BDDNode current = null;
foreach (FaultTreeNode tn in node.Childs)
{
BDDNode n = this.CreateBDD(tn, nodeFactory);
current = this.Apply(nodeFactory, op, current, n);
}
return(current);
}
