void InsertNode(PathTreeNode node, PathTreeNode parentNode, PathTreeNode previousNode)
{
parentNode.ChildrenCount += 1;
node.Parent = parentNode;
if (previousNode == null)
{
// We're inserting at the beginning.
node.Next = parentNode.FirstChild;
parentNode.FirstChild = node;
return;
}
// We are appending inbetween other nodes
var next = previousNode.Next;
previousNode.Next = node;
node.Previous = previousNode;
node.Next = next;
if (next != null)
{
next.Previous = node;
}
}
internal static (PathTreeNode root, PathTreeNode leaf) CreateSubTree(string path, int start)
{
PathTreeNode lastNode = null, rootNode = null;
while (start < path.Length)
{
var nextSep = path.IndexOf(Path.DirectorySeparatorChar, start);
int length = nextSep == -1 ? path.Length - start : nextSep - start;
if (length != 0)
{
var node = new PathTreeNode(path, start, length);
if (lastNode != null)
{
lastNode.FirstChild = node;
node.Parent = lastNode;
lastNode.ChildrenCount = 1;
}
else
{
rootNode = node;
}
lastNode = node;
}
start = start + length + 1;
}
return(rootNode, lastNode);
}
bool IsDeadSubtree(PathTreeNode node)
{
// We do a DFS here, looking for any live node in a tree.
// We know that leaves are live, so DFS works better here.
var stack = new Stack <PathTreeNode>();
stack.Push(node);
while (stack.Count != 0)
{
node = stack.Pop();
if (node.IsLive)
{
return(false);
}
var child = node.FirstChild;
while (child != null)
{
stack.Push(child);
child = child.Next;
}
}
return(true);
}
public PathTree()
{
rootNode = new PathTreeNode("", 0, 1);
if (!Platform.IsWindows)
{
rootNode.FirstChild = new PathTreeNode("/", 0, 0)
{
Parent = rootNode,
};
}
}
bool TryFind(string path, out PathTreeNode result, out PathTreeNode parent, out PathTreeNode previousNode, out int lastIndex)
{
lastIndex = 0;
parent = rootNode;
var currentNode = parent.FirstChild;
previousNode = null;
while (currentNode != null)
{
int currentIndex = path.IndexOf(Path.DirectorySeparatorChar, lastIndex);
int comparisonResult = string.Compare(currentNode.FullPath, currentNode.Start, path, lastIndex, currentNode.Length);
// We need to insert in this node's position.
if (comparisonResult > 0)
{
break;
}
// Keep searching.
if (comparisonResult < 0)
{
previousNode = currentNode;
currentNode = currentNode.Next;
continue;
}
// We found this segment in the tree.
lastIndex = currentIndex + 1;
// We found the node already, register the ID.
if (currentIndex == -1 || lastIndex == path.Length)
{
result = currentNode;
return(true);
}
// We go to the first child of this segment and repeat the algorithm.
parent = currentNode;
previousNode = null;
currentNode = parent.FirstChild;
}
result = null;
return(false);
}
public static void Dump(this PathTreeNode rootNode)
{
var firstStack = new List <PathTreeNode> {
rootNode
};
var childListStack = new List <List <PathTreeNode> > {
firstStack
};
while (childListStack.Count > 0)
{
var childStack = childListStack[childListStack.Count - 1];
if (childStack.Count == 0)
{
childListStack.RemoveAt(childListStack.Count - 1);
}
else
{
var tree = childStack[0];
childStack.RemoveAt(0);
string indent = "";
for (int i = 0; i < childListStack.Count - 1; i++)
{
indent += (childListStack[i].Count > 0) ? "| " : " ";
}
Console.WriteLine(indent + "+- " + tree.Segment);
if (tree.FirstChild != null)
{
var treeChildren = new List <PathTreeNode>();
var child = tree.FirstChild;
while (child != null)
{
treeChildren.Add(child);
child = child.Next;
}
childListStack.Add(treeChildren);
}
}
}
}
public void CreateSubTree(string sep)
{
var path = MakePath("a", "b", "c") + sep;
var(first, leaf) = PathTreeNode.CreateSubTree(path, 0);
PathTreeNode a;
if (Platform.IsWindows)
{
AssertPathTreeSubtree(first, "C:");
Assert.AreEqual(1, first.ChildrenCount);
a = first.FirstChild;
}
else
{
a = first;
}
AssertPathTreeSubtree(a, "a");
Assert.AreEqual(1, a.ChildrenCount);
var b = a.FirstChild;
Assert.AreSame(a, b.Parent);
AssertPathTreeSubtree(b, "b");
Assert.AreEqual(1, b.ChildrenCount);
var c = b.FirstChild;
Assert.AreSame(b, c.Parent);
AssertPathTreeSubtree(c, "c");
Assert.AreEqual(0, c.ChildrenCount);
Assert.AreSame(c, leaf);
Assert.IsNull(c.FirstChild);
void AssertPathTreeSubtree(PathTreeNode node, string segment)
{
Assert.AreEqual(segment, node.Segment);
Assert.IsNull(node.Next);
Assert.AreSame(node.FirstChild, node.LastChild);
}
}
public PathTreeNode AddNode(string path, object id)
{
if (TryFind(path, out var result, out var parent, out var previousNode, out var lastIndex))
{
result.RegisterId(id);
return(result);
}
// At this point, we need to create a new node.
var(first, leaf) = PathTreeNode.CreateSubTree(path, lastIndex);
if (id != null)
{
leaf.RegisterId(id);
}
InsertNode(first, parent, previousNode);
return(leaf);
}
public void JustSlash()
{
var(node, leaf) = PathTreeNode.CreateSubTree(Path.DirectorySeparatorChar.ToString(), 0);
Assert.IsNull(node);
Assert.IsNull(leaf);
}
[TestCase(1)] // Should not crash
public void EmptySubTrie(int startIndex)
{
var(node, leaf) = PathTreeNode.CreateSubTree(string.Empty, startIndex);
Assert.IsNull(node);
Assert.IsNull(leaf);
}