static int FindNextChild(TrackingSpanNode <T> root, SnapshotPoint point, int currentChildIndex)
{
// If we're already at the end, there's no need to continue searching
if (currentChildIndex == root.Children.Count - 1)
{
return(currentChildIndex + 1);
}
return(FindChild(point, root.Children, left: true, lo: currentChildIndex + 1).Index);
}
/// <summary>
/// Create a tracking span tree for the given buffer.
/// </summary>
/// <param name="buffer">The buffer that all the spans in this tree are in.</param>
/// <param name="keepTrackingCurrent">The tree should not allow tracking spans to point
/// to old versions, at the expense of walking the tree on every text change.</param>
public TrackingSpanTree(ITextBuffer buffer, bool keepTrackingCurrent)
{
if (buffer == null)
{
throw new ArgumentNullException(nameof(buffer));
}
Buffer = buffer;
Count = 0;
// Leave the tracking span parameter as null, since it is
// never used (assumed to always be the entire buffer)
Root = new TrackingSpanNode <T>(default(T), null);
if (keepTrackingCurrent)
{
buffer.Changed += OnBufferChanged;
}
}
static bool RemoveItemFromRoot(T item, SnapshotSpan span, TrackingSpanNode <T> root)
{
if (root.Children.Count == 0)
{
return(false);
}
var result = FindChild(span.Start, root.Children, left: true);
if (result.Index < 0 || result.Index >= root.Children.Count)
{
return(false);
}
// Search from this index onward (there may be empty regions in the way)
for (int i = result.Index; i < root.Children.Count; i++)
{
var child = root.Children[i];
SnapshotSpan childSpan = child.TrackingSpan.GetSpan(span.Snapshot);
// Check to see if we've walked past it
if (childSpan.Start > span.End)
{
return(false);
}
else if (childSpan == span && object.Equals(child.Item, item))
{
root.Children.RemoveAt(i);
root.Children.InsertRange(i, child.Children);
return(true);
}
else if (childSpan.Contains(span))
{
if (RemoveItemFromRoot(item, span, child))
{
return(true);
}
}
}
return(false);
}
/// <summary>
/// Try to add an item to the tree with the given tracking span.
/// </summary>
/// <param name="item">The item to add to the tree.</param>
/// <param name="trackingSpan">The tracking span it is associated with.</param>
/// <returns>The newly added node, if the item was successfully added; <c>null</c> if adding the item to the tree would
/// violate the well-formedness of the tree.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="trackingSpan"/> is <c>null</c>.</exception>
/// <exception cref="ArgumentException">If the tracking mode of <paramref name="trackingSpan"/> is not <see cref="SpanTrackingMode.EdgeExclusive"/>.</exception>
public TrackingSpanNode <T> TryAddItem(T item, ITrackingSpan trackingSpan)
{
if (trackingSpan == null)
{
throw new ArgumentNullException(nameof(trackingSpan));
}
if (trackingSpan.TrackingMode != SpanTrackingMode.EdgeExclusive)
{
throw new ArgumentException("The tracking mode of the given tracking span must be SpanTrackingMode.EdgeExclusive", nameof(trackingSpan));
}
SnapshotSpan spanToAdd = trackingSpan.GetSpan(Buffer.CurrentSnapshot);
TrackingSpanNode <T> node = new TrackingSpanNode <T>(item, trackingSpan);
var newNode = TryAddNodeToRoot(node, spanToAdd, Root);
if (newNode != null)
{
Count++;
}
return(newNode);
}
static TrackingSpanNode <T> TryAddNodeToRoot(TrackingSpanNode <T> newNode, SnapshotSpan span, TrackingSpanNode <T> root)
{
var children = root.Children;
if (children.Count == 0)
{
children.Add(newNode);
return(newNode);
}
FindResult leftResult = FindIndexForAdd(span.Start, children, left: true);
FindResult rightResult = FindIndexForAdd(span.End, children, left: false);
// See if we can add the node anywhere
// The indices cross if the searches fail, and the node is inside a gap.
if (leftResult.Index > rightResult.Index)
{
// Case #1: If the new node should go in a gap between two nodes, just insert it in the correct location
Debug.Assert(leftResult.Type == FindResultType.Outer || rightResult.Type == FindResultType.Outer);
children.Insert(leftResult.Index, newNode);
return(newNode);
}
else
{
if (leftResult.Type == FindResultType.Inner || rightResult.Type == FindResultType.Inner)
{
// Case #2: The new node is contained entirely in a single child node, so add it to that child
// Check the nodes at either end of the resulting indices (they may not be the same index due to
// 0-length nodes that abut the correct child).
if (children[leftResult.Index].TrackingSpan.GetSpan(span.Snapshot).Contains(span))
{
return(TryAddNodeToRoot(newNode, span, children[leftResult.Index]));
}
if (leftResult.Index != rightResult.Index && children[rightResult.Index].TrackingSpan.GetSpan(span.Snapshot).Contains(span))
{
return(TryAddNodeToRoot(newNode, span, children[rightResult.Index]));
}
// This fails if the node isn't fully contained in a single child
}
else
{
// Case #3: The new node contains any number of children, so we:
int start = leftResult.Index;
int count = rightResult.Index - leftResult.Index + 1;
// a) Add all the children this should contain to the new node,
newNode.Children.AddRange(children.Skip(start).Take(count));
// b) Remove them from the existing root node, and
children.RemoveRange(start, count);
// c) Add the new node in their place
children.Insert(start, newNode);
return(newNode);
}
}
// We couldn't find a place to add this node, so return failure
return(null);
}
static IEnumerable <TrackingSpanNode <T> > FindNodes(NormalizedSnapshotSpanCollection spans, TrackingSpanNode <T> root, bool recurse = true, bool contained = false)
{
if (spans == null || spans.Count == 0 || root.Children.Count == 0)
{
yield break;
}
int requestIndex = 0;
SnapshotSpan currentRequest = spans[requestIndex];
// Find the first child
FindResult findResult = FindChild(currentRequest.Start, root.Children, left: true);
int childIndex = findResult.Index;
if (childIndex >= root.Children.Count)
{
yield break;
}
ITextSnapshot snapshot = currentRequest.Snapshot;
SnapshotSpan currentChild = root.Children[childIndex].TrackingSpan.GetSpan(snapshot);
while (requestIndex < spans.Count && childIndex < root.Children.Count)
{
if (currentRequest.Start > currentChild.End)
{
// Find the next child
childIndex = FindNextChild(root, currentRequest.Start, childIndex);
if (childIndex < root.Children.Count)
{
currentChild = root.Children[childIndex].TrackingSpan.GetSpan(snapshot);
}
}
else if (currentChild.Start > currentRequest.End)
{
// Skip to the next request
if (++requestIndex < spans.Count)
{
currentRequest = spans[requestIndex];
}
}
else
{
// Yield the region then move to the next
if (!contained || currentRequest.Contains(currentChild))
{
yield return(root.Children[childIndex]);
}
if (recurse)
{
foreach (var result in FindNodes(spans, root.Children[childIndex], recurse, contained))
{
yield return(result);
}
}
// Find the next child
childIndex = FindNextChild(root, currentRequest.Start, childIndex);
if (childIndex < root.Children.Count)
{
currentChild = root.Children[childIndex].TrackingSpan.GetSpan(snapshot);
}
}
}
}
/// <summary>
/// Check if a given node is a toplevel node (has no parents).
/// </summary>
/// <param name="node">The node to check.</param>
/// <returns><c>true</c> if the node has no parent node.</returns>
public bool IsNodeTopLevel(TrackingSpanNode <T> node)
{
return(Root.Children.Contains(node));
}