public virtual NodeHistoryState Append(HistoryNode current)
{
if (current == null)
{
throw new ArgumentNullException(nameof(current));
}
var historyNodes = BackNodes.Append(Current).ToArray();
var backNodes = historyNodes.TakeLast(_maxHistoryNodes);
return(new NodeHistoryState(current, _maxHistoryNodes, backNodes, forwardNodes: null));
}
public NodeHistoryState(HistoryNode current,
int maxHistoryNodes,
IEnumerable <HistoryNode> backNodes = null,
IEnumerable <HistoryNode> forwardNodes = null)
{
if (maxHistoryNodes < 1)
{
throw new ArgumentException($"{nameof(maxHistoryNodes)} must be positive", nameof(maxHistoryNodes));
}
_maxHistoryNodes = maxHistoryNodes;
Current = current ?? throw new ArgumentNullException(nameof(current));
BackNodes = backNodes?.ToArray() ?? Enumerable.Empty <HistoryNode>();
ForwardNodes = forwardNodes?.ToArray() ?? Enumerable.Empty <HistoryNode>();
}
public virtual NodeHistoryState GoBackTo(HistoryNode historyNode)
{
const int maxBackAttempts = 1000;
NodeHistoryState result = this;
for (int i = 0; i < maxBackAttempts; i++)
{
result = result.GoBack();
if (historyNode.Equals(result.Current))
{
return(result);
}
}
throw new Exception("the history node was not found");
}
