static void RebalanceUntilRoot(FileItemViewModel pos)
{
while (pos.listParent != null)
{
if (pos == pos.listParent.left)
{
pos = pos.listParent.left = Rebalance(pos);
}
else
{
Debug.Assert(pos == pos.listParent.right);
pos = pos.listParent.right = Rebalance(pos);
}
pos = pos.listParent;
}
FileItemViewModel newRoot = Rebalance(pos);
if (newRoot != pos && pos.treeFlattener != null)
{
Debug.Assert(newRoot.treeFlattener == null);
newRoot.treeFlattener = pos.treeFlattener;
pos.treeFlattener = null;
newRoot.treeFlattener.root = newRoot;
}
Debug.Assert(newRoot.listParent == null);
newRoot.CheckInvariants();
}
FileItemViewModel RotateLeft()
{
/* Rotate tree to the left
*
* this right
* / \ / \
* A right ===> this C
* / \ / \
* B C A B
*/
FileItemViewModel b = right.left;
FileItemViewModel newTop = right;
if (b != null)
{
b.listParent = this;
}
this.right = b;
newTop.left = this;
newTop.listParent = this.listParent;
this.listParent = newTop;
// rebalance the 'this' node - this is necessary in some bulk insertion cases:
newTop.left = Rebalance(this);
return(newTop);
}
void ReplaceWith(FileItemViewModel node)
{
if (listParent != null)
{
if (listParent.left == this)
{
listParent.left = node;
}
else
{
Debug.Assert(listParent.right == this);
listParent.right = node;
}
if (node != null)
{
node.listParent = listParent;
}
listParent = null;
}
else
{
// this was a root node
Debug.Assert(node != null); // cannot delete the only node in the tree
node.listParent = null;
if (treeFlattener != null)
{
Debug.Assert(node.treeFlattener == null);
node.treeFlattener = this.treeFlattener;
this.treeFlattener = null;
node.treeFlattener.root = node;
}
}
}
internal static FileItemViewModel GetNodeByVisibleIndex(FileItemViewModel root, int index)
{
root.GetTotalListLength(); // ensure all list lengths are calculated
Debug.Assert(index >= 0);
Debug.Assert(index < root.totalListLength);
FileItemViewModel node = root;
while (true)
{
if (node.left != null && index < node.left.totalListLength)
{
node = node.left;
}
else
{
if (node.left != null)
{
index -= node.left.totalListLength;
}
if (node.isVisible)
{
if (index == 0)
{
return(node);
}
index--;
}
node = node.right;
}
}
}
static void DeleteNode(FileItemViewModel node)
{
FileItemViewModel balancingNode;
if (node.left == null)
{
balancingNode = node.listParent;
node.ReplaceWith(node.right);
node.right = null;
}
else if (node.right == null)
{
balancingNode = node.listParent;
node.ReplaceWith(node.left);
node.left = null;
}
else
{
FileItemViewModel tmp = node.right;
while (tmp.left != null)
{
tmp = tmp.left;
}
// First replace tmp with tmp.right
balancingNode = tmp.listParent;
tmp.ReplaceWith(tmp.right);
tmp.right = null;
Debug.Assert(tmp.left == null);
Debug.Assert(tmp.listParent == null);
// Now move node's children to tmp:
tmp.left = node.left; node.left = null;
tmp.right = node.right; node.right = null;
if (tmp.left != null)
{
tmp.left.listParent = tmp;
}
if (tmp.right != null)
{
tmp.right.listParent = tmp;
}
// Then replace node with tmp
node.ReplaceWith(tmp);
if (balancingNode == node)
{
balancingNode = tmp;
}
}
Debug.Assert(node.listParent == null);
Debug.Assert(node.left == null);
Debug.Assert(node.right == null);
node.height = 1;
node.totalListLength = -1;
if (balancingNode != null)
{
RebalanceUntilRoot(balancingNode);
}
}
/// <summary>Gets the item at the specified index in the list.</summary>
///
/// <param name="index">The index of the item.</param>
public object this[int index] {
get {
if (index < 0 || index >= this.Count)
{
throw new ArgumentOutOfRangeException();
}
return(FileItemViewModel.GetNodeByVisibleIndex(root, includeRoot ? index : index + 1));
}
set => throw new NotSupportedException();
internal FileItemViewModel GetListRoot()
{
FileItemViewModel node = this;
while (node.listParent != null)
{
node = node.listParent;
}
return(node);
}
/// <summary>Constructs the <see cref="FileTreeFlattener"/>.</summary>
///
/// <param name="modelRoot">The root item of the list.</param>
/// <param name="includeRoot">True if the root is visible in the list.</param>
public FileTreeFlattener(FileItemViewModel modelRoot, bool includeRoot)
{
this.root = modelRoot;
while (root.listParent != null)
{
root = root.listParent;
}
root.treeFlattener = this;
this.includeRoot = includeRoot;
}
static FileItemViewModel ConcatTrees(FileItemViewModel first, FileItemViewModel second)
{
FileItemViewModel tmp = first;
while (tmp.right != null)
{
tmp = tmp.right;
}
InsertNodeAfter(tmp, second);
return(tmp.GetListRoot());
}
void RemoveNodes(FileItemViewModel start, FileItemViewModel end)
{
// Removes all nodes from start to end (inclusive)
// All removed nodes will be reorganized in a separate tree, do not delete
// regions that don't belong together in the tree model!
List <FileItemViewModel> removedSubtrees = new List <FileItemViewModel>();
FileItemViewModel oldPos;
FileItemViewModel pos = start;
do
{
// recalculate the endAncestors every time, because the tree might have been rebalanced
HashSet <FileItemViewModel> endAncestors = new HashSet <FileItemViewModel>();
for (FileItemViewModel tmp = end; tmp != null; tmp = tmp.listParent)
{
endAncestors.Add(tmp);
}
removedSubtrees.Add(pos);
if (!endAncestors.Contains(pos))
{
// we can remove pos' right subtree in a single step:
if (pos.right != null)
{
removedSubtrees.Add(pos.right);
pos.right.listParent = null;
pos.right = null;
}
}
FileItemViewModel succ = pos.Successor();
DeleteNode(pos); // this will also rebalance out the deletion of the right subtree
oldPos = pos;
pos = succ;
} while (oldPos != end);
// merge back together the removed subtrees:
FileItemViewModel removed = removedSubtrees[0];
for (int i = 1; i < removedSubtrees.Count; i++)
{
removed = ConcatTrees(removed, removedSubtrees[i]);
}
}
internal static int GetVisibleIndexForNode(FileItemViewModel node)
{
int index = node.left != null?node.left.GetTotalListLength() : 0;
while (node.listParent != null)
{
if (node == node.listParent.right)
{
if (node.listParent.left != null)
{
index += node.listParent.left.GetTotalListLength();
}
if (node.listParent.isVisible)
{
index++;
}
}
node = node.listParent;
}
return(index);
}
/// <summary>
/// Balances the subtree rooted in <paramref name="node"/> and recomputes the 'height' field.
/// This method assumes that the children of this node are already balanced and have an up-to-date 'height' value.
/// </summary>
/// <returns>The new root node</returns>
static FileItemViewModel Rebalance(FileItemViewModel node)
{
Debug.Assert(node.left == null || Math.Abs(node.left.Balance) <= 1);
Debug.Assert(node.right == null || Math.Abs(node.right.Balance) <= 1);
// Keep looping until it's balanced. Not sure if this is stricly required; this is based on
// the Rope code where node merging made this necessary.
while (Math.Abs(node.Balance) > 1)
{
// AVL balancing
// note: because we don't care about the identity of concat nodes, this works a little different than usual
// tree rotations: in our implementation, the "this" node will stay at the top, only its children are rearranged
if (node.Balance > 1)
{
if (node.right.Balance < 0)
{
node.right = node.right.RotateRight();
}
node = node.RotateLeft();
// If 'node' was unbalanced by more than 2, we've shifted some of the inbalance to the left node; so rebalance that.
node.left = Rebalance(node.left);
}
else if (node.Balance < -1)
{
if (node.left.Balance > 0)
{
node.left = node.left.RotateLeft();
}
node = node.RotateRight();
// If 'node' was unbalanced by more than 2, we've shifted some of the inbalance to the right node; so rebalance that.
node.right = Rebalance(node.right);
}
}
Debug.Assert(Math.Abs(node.Balance) <= 1);
node.height = (byte)(1 + Math.Max(Height(node.left), Height(node.right)));
node.totalListLength = -1; // mark for recalculation
// since balancing checks the whole tree up to the root, the whole path will get marked as invalid
return(node);
}
static void InsertNodeAfter(FileItemViewModel pos, FileItemViewModel newNode)
{
// newNode might be the model root of a whole subtree, so go to the list root of that subtree:
newNode = newNode.GetListRoot();
if (pos.right == null)
{
pos.right = newNode;
newNode.listParent = pos;
}
else
{
// insert before pos.right's leftmost:
pos = pos.right;
while (pos.left != null)
{
pos = pos.left;
}
Debug.Assert(pos.left == null);
pos.left = newNode;
newNode.listParent = pos;
}
RebalanceUntilRoot(pos);
}
FileItemViewModel RotateRight()
{
/* Rotate tree to the right
*
* this left
* / \ / \
* left C ===> A this
* / \ / \
* A B B C
*/
FileItemViewModel b = left.right;
FileItemViewModel newTop = left;
if (b != null)
{
b.listParent = this;
}
this.left = b;
newTop.right = this;
newTop.listParent = this.listParent;
this.listParent = newTop;
newTop.right = Rebalance(this);
return(newTop);
}
FileItemViewModel Successor()
{
if (right != null)
{
FileItemViewModel node = right;
while (node.left != null)
{
node = node.left;
}
return(node);
}
else
{
FileItemViewModel node = this;
FileItemViewModel oldNode;
do
{
oldNode = node;
node = node.listParent;
// loop while we are on the way up from the right part
} while (node != null && node.right == oldNode);
return(node);
}
}
/*private bool isHidden;
* private bool isSelected;
* private bool isExpanded;
* private bool isEditing;*/
/*private BitField16 flags = new BitField16 {
* //[0] = true,
* };
*
#pragma warning disable 0649, IDE1006
* private bool isVisible {
* get => flags[0];
* set => flags[0] = value;
* }
* private bool isHidden {
* get => flags[1];
* set => flags[1] = value;
* }
* private bool isSelected {
* get => flags[2];
* set => flags[2] = value;
* }
* private bool isExpanded {
* get => flags[3];
* set => flags[3] = value;
* }
* private bool isEditing {
* get => flags[4];
* set => flags[4] = value;
* }
* private bool isEventsHooked {
* get => flags[5];
* set => flags[5] = value;
* }
#pragma warning restore 0649, IDE1006*/
//private bool canExpandRecursively = true;
//private bool lazyLoading;
//private bool? isChecked;
private void UpdateIsVisible(bool parentIsVisible, bool updateFlattener)
{
bool newIsVisible = parentIsVisible && !isHidden;
if (isVisible != newIsVisible)
{
isVisible = newIsVisible;
// invalidate the augmented data
FileItemViewModel node = this;
while (node != null && node.totalListLength >= 0)
{
node.totalListLength = -1;
node = node.listParent;
}
// Remember the removed nodes:
List <FileItemViewModel> removedNodes = null;
if (updateFlattener && !newIsVisible)
{
removedNodes = VisibleDescendantsAndSelf().ToList();
}
// also update the model children:
UpdateChildIsVisible(false);
// Validate our invariants:
if (updateFlattener)
{
CheckRootInvariants();
}
// Tell the flattener about the removed nodes:
if (removedNodes != null)
{
var flattener = GetListRoot().treeFlattener;
if (flattener != null)
{
if (!SuppressRefresh)
{
flattener.NodesRemoved(GetVisibleIndexForNode(this), removedNodes);
}
foreach (var n in removedNodes)
{
n.OnIsVisibleChanged();
}
}
}
// Tell the flattener about the new nodes:
if (updateFlattener && newIsVisible)
{
var flattener = GetListRoot().treeFlattener;
if (flattener != null)
{
if (!SuppressRefresh)
{
flattener.NodesInserted(GetVisibleIndexForNode(this), VisibleDescendantsAndSelf());
}
foreach (var n in VisibleDescendantsAndSelf())
{
n.OnIsVisibleChanged();
}
}
}
}
}
static void DumpTree(FileItemViewModel node)
{
node.GetListRoot().DumpTree();
}
static int Height(FileItemViewModel node)
{
return(node != null ? node.height : 0);
}