/// <summary>
/// If the type parameter is <see cref="NoFlip"/>, nodes are iterated from the smallest
/// to the largest key (left to right); if the parameter is <see cref="DoFlip"/>,
/// nodes are iterated from the largest to the smallest key (right to left).
/// </summary>
internal bool SiftRecursive <T>(NodeTraversalActions <TKey, TValue, BinaryNode <TKey, TValue>, NodeTraversalAction> nodeActions)
where T : FlipBase <T>
{
if (!nodeActions.InvokePreAction(this))
{
return(false);
}
if (GetLeftChild <T>() != null && !GetLeftChild <T>().SiftRecursive <T>(nodeActions))
{
return(false);
}
if (!nodeActions.InvokeInAction(this))
{
return(false);
}
if (GetRightChild <T>() != null && !GetRightChild <T>().SiftRecursive <T>(nodeActions))
{
return(false);
}
if (!nodeActions.InvokePostAction(this))
{
return(false);
}
return(true);
}
private bool HandleSift <T>(
Stack <NodeTraversalToken <BinaryNode <TKey, TValue>, NodeTraversalAction> > stack,
NodeTraversalActions <TKey, TValue, BinaryNode <TKey, TValue>, NodeTraversalAction> nodeActions)
where T : FlipBase <T>
{
// First and only visit to this node
if (!nodeActions.InvokePreAction(this))
{
return(false);
}
// Push actions in reverse order
var right = GetRightChild <T>();
var left = GetLeftChild <T>();
if (right != null)
{
if (nodeActions.HasPostAction)
{
stack.Push(GetNodeTraversalToken(this, NodeTraversalAction.PostAction));
}
stack.Push(GetNodeTraversalToken(right, NodeTraversalAction.Sift));
}
else if (left != null && nodeActions.HasPostAction)
{
// We need to store the action (it has to be executed after sifting through Left)
stack.Push(GetNodeTraversalToken(this, NodeTraversalAction.PostAction));
}
if (left != null)
{
if (nodeActions.HasInAction)
{
stack.Push(GetNodeTraversalToken(this, NodeTraversalAction.InAction));
}
stack.Push(GetNodeTraversalToken(left, NodeTraversalAction.Sift));
}
else
{
// Handle missing children -- we can only invoke actions right away if children are null from left to right
if (!nodeActions.InvokeInAction(this))
{
return(false);
}
if (right == null)
{
if (!nodeActions.InvokePostAction(this))
{
return(false);
}
}
}
return(true);
}
/// <summary>
/// If the type parameter is <see cref="NoFlip"/>, nodes are iterated from the smallest
/// to the largest key (left to right); if the parameter is <see cref="DoFlip"/>,
/// nodes are iterated from the largest to the smallest key (right to left).
/// </summary>
private bool Sift <T>(NodeTraversalActions <TKey, TValue, BinaryNode <TKey, TValue>, NodeTraversalAction> nodeActions)
where T : FlipBase <T>
{
// We have to use an iterative way because the default stack size of .net apps is 1MB
// and it's impractical to change it.....
var stack = nodeActions.TraversalStack;
Debug.Assert(stack.Count == 0);
stack.Push(GetNodeTraversalToken(this, NodeTraversalAction.Sift));
try
{
while (stack.Count > 0)
{
var token = stack.Pop();
switch (token.Action)
{
case NodeTraversalAction.Sift:
if (!token.Node.HandleSift <T>(stack, nodeActions))
{
return(false);
}
break;
case NodeTraversalAction.InAction:
if (!nodeActions.InvokeInAction(token.Node))
{
return(false);
}
break;
case NodeTraversalAction.PostAction:
if (!nodeActions.InvokePostAction(token.Node))
{
return(false);
}
break;
default:
throw new ArgumentOutOfRangeException();
}
}
}
finally
{
stack.Clear();
}
return(true);
}
