public TextAnchor CreateAnchor(int offset)
{
Log("CreateAnchor(" + offset + ")");
TextAnchor anchor = new TextAnchor(document);
anchor.node = new TextAnchorNode(anchor);
if (root == null)
{
// creating the first text anchor
root = anchor.node;
root.totalLength = root.length = offset;
}
else if (offset >= root.totalLength)
{
// append anchor at end of tree
anchor.node.totalLength = anchor.node.length = offset - root.totalLength;
InsertAsRight(root.RightMost, anchor.node);
}
else
{
// insert anchor in middle of tree
TextAnchorNode n = FindNode(ref offset);
Debug.Assert(offset < n.length);
// split segment 'n' at offset
anchor.node.totalLength = anchor.node.length = offset;
n.length -= offset;
InsertBefore(n, anchor.node);
}
DeleteMarkedNodes();
return(anchor);
}
/*
* 1. A node is either red or black.
* 2. The root is black.
* 3. All leaves are black. (The leaves are the NIL children.)
* 4. Both children of every red node are black. (So every red node must have a black parent.)
* 5. Every simple path from a node to a descendant leaf contains the same number of black nodes. (Not counting the leaf node.)
*/
private void CheckNodeProperties(TextAnchorNode node, TextAnchorNode parentNode, bool parentColor, int blackCount, ref int expectedBlackCount)
{
if (node == null)
{
return;
}
Debug.Assert(node.parent == parentNode);
if (parentColor == RED)
{
Debug.Assert(node.color == BLACK);
}
if (node.color == BLACK)
{
blackCount++;
}
if (node.left == null && node.right == null)
{
// node is a leaf node:
if (expectedBlackCount == -1)
{
expectedBlackCount = blackCount;
}
else
{
Debug.Assert(expectedBlackCount == blackCount);
}
}
CheckNodeProperties(node.left, node, node.color, blackCount, ref expectedBlackCount);
CheckNodeProperties(node.right, node, node.color, blackCount, ref expectedBlackCount);
}
private void UpdateAugmentedData(TextAnchorNode n)
{
if (!n.IsAlive)
{
MarkNodeForDelete(n);
}
int totalLength = n.length;
if (n.left != null)
{
totalLength += n.left.totalLength;
}
if (n.right != null)
{
totalLength += n.right.totalLength;
}
if (n.totalLength != totalLength)
{
n.totalLength = totalLength;
if (n.parent != null)
{
UpdateAugmentedData(n.parent);
}
}
}
private void MarkNodeForDelete(TextAnchorNode node)
{
if (!nodesToDelete.Contains(node))
{
nodesToDelete.Add(node);
}
}
private static void AppendTreeToString(TextAnchorNode node, StringBuilder b, int indent)
{
if (node.color == RED)
{
b.Append("RED ");
}
else
{
b.Append("BLACK ");
}
b.AppendLine(node.ToString());
indent += 2;
if (node.left != null)
{
b.Append(' ', indent);
b.Append("L: ");
AppendTreeToString(node.left, b, indent);
}
if (node.right != null)
{
b.Append(' ', indent);
b.Append("R: ");
AppendTreeToString(node.right, b, indent);
}
}
/// <summary>
/// Swaps the anchors stored in the two nodes.
/// </summary>
private void SwapAnchors(TextAnchorNode n1, TextAnchorNode n2)
{
if (n1 != n2)
{
TextAnchor anchor1 = (TextAnchor)n1.Target;
TextAnchor anchor2 = (TextAnchor)n2.Target;
if (anchor1 == null && anchor2 == null)
{
// -> no swap required
return;
}
n1.Target = anchor2;
n2.Target = anchor1;
if (anchor1 == null)
{
// unmark n1 from deletion, mark n2 for deletion
nodesToDelete.Remove(n1);
MarkNodeForDelete(n2);
anchor2.node = n1;
}
else if (anchor2 == null)
{
// unmark n2 from deletion, mark n1 for deletion
nodesToDelete.Remove(n2);
MarkNodeForDelete(n1);
anchor1.node = n2;
}
else
{
anchor1.node = n2;
anchor2.node = n1;
}
}
}
private void InsertText(int offset, int length, bool defaultAnchorMovementIsBeforeInsertion)
{
if (length == 0 || root == null || offset > root.totalLength)
{
return;
}
// find the range of nodes that are placed exactly at offset
// beginNode is inclusive, endNode is exclusive
if (offset == root.totalLength)
{
PerformInsertText(FindActualBeginNode(root.RightMost), null, length, defaultAnchorMovementIsBeforeInsertion);
}
else
{
TextAnchorNode endNode = FindNode(ref offset);
Debug.Assert(endNode.length > 0);
if (offset > 0)
{
// there are no nodes exactly at offset
endNode.length += length;
UpdateAugmentedData(endNode);
}
else
{
PerformInsertText(FindActualBeginNode(endNode.Predecessor), endNode, length, defaultAnchorMovementIsBeforeInsertion);
}
}
DeleteMarkedNodes();
}
private void InsertAsRight(TextAnchorNode parentNode, TextAnchorNode newNode)
{
Debug.Assert(parentNode.right == null);
parentNode.right = newNode;
newNode.parent = parentNode;
newNode.color = RED;
UpdateAugmentedData(parentNode);
FixTreeOnInsert(newNode);
}
private static TextAnchorNode Sibling(TextAnchorNode node)
{
if (node == node.parent.left)
{
return(node.parent.right);
}
else
{
return(node.parent.left);
}
}
private void InsertBefore(TextAnchorNode node, TextAnchorNode newNode)
{
if (node.left == null)
{
InsertAsLeft(node, newNode);
}
else
{
InsertAsRight(node.left.RightMost, newNode);
}
}
private void RemoveNode(TextAnchorNode removedNode)
{
if (removedNode.left != null && removedNode.right != null)
{
// replace removedNode with it's in-order successor
TextAnchorNode leftMost = removedNode.right.LeftMost;
RemoveNode(leftMost); // remove leftMost from its current location
// and overwrite the removedNode with it
ReplaceNode(removedNode, leftMost);
leftMost.left = removedNode.left;
if (leftMost.left != null)
{
leftMost.left.parent = leftMost;
}
leftMost.right = removedNode.right;
if (leftMost.right != null)
{
leftMost.right.parent = leftMost;
}
leftMost.color = removedNode.color;
UpdateAugmentedData(leftMost);
if (leftMost.parent != null)
{
UpdateAugmentedData(leftMost.parent);
}
return;
}
// now either removedNode.left or removedNode.right is null
// get the remaining child
TextAnchorNode parentNode = removedNode.parent;
TextAnchorNode childNode = removedNode.left ?? removedNode.right;
ReplaceNode(removedNode, childNode);
if (parentNode != null)
{
UpdateAugmentedData(parentNode);
}
if (removedNode.color == BLACK)
{
if (childNode != null && childNode.color == RED)
{
childNode.color = BLACK;
}
else
{
FixTreeOnDelete(childNode, parentNode);
}
}
}
private static TextAnchorNode Sibling(TextAnchorNode node, TextAnchorNode parentNode)
{
Debug.Assert(node == null || node.parent == parentNode);
if (node == parentNode.left)
{
return(parentNode.right);
}
else
{
return(parentNode.left);
}
}
// Sorts the nodes in the range [beginNode, endNode) by MovementType
// and inserts the length between the BeforeInsertion and the AfterInsertion nodes.
private void PerformInsertText(TextAnchorNode beginNode, TextAnchorNode endNode, int length, bool defaultAnchorMovementIsBeforeInsertion)
{
Debug.Assert(beginNode != null);
// endNode may be null at the end of the anchor tree
// now we need to sort the nodes in the range [beginNode, endNode); putting those with
// MovementType.BeforeInsertion in front of those with MovementType.AfterInsertion
List <TextAnchorNode> beforeInsert = new List <TextAnchorNode>();
//List<TextAnchorNode> afterInsert = new List<TextAnchorNode>();
TextAnchorNode temp = beginNode;
while (temp != endNode)
{
TextAnchor anchor = (TextAnchor)temp.Target;
if (anchor == null)
{
// afterInsert.Add(temp);
MarkNodeForDelete(temp);
}
else if (defaultAnchorMovementIsBeforeInsertion
? anchor.MovementType != AnchorMovementType.AfterInsertion
: anchor.MovementType == AnchorMovementType.BeforeInsertion)
{
beforeInsert.Add(temp);
// } else {
// afterInsert.Add(temp);
}
temp = temp.Successor;
}
// now again go through the range and swap the nodes with those in the beforeInsert list
temp = beginNode;
foreach (TextAnchorNode node in beforeInsert)
{
SwapAnchors(node, temp);
temp = temp.Successor;
}
// now temp is pointing to the first node that is afterInsert,
// or to endNode, if there is no afterInsert node at the offset
// So add the length to temp
if (temp == null)
{
// temp might be null if endNode==null and no afterInserts
Debug.Assert(endNode == null);
}
else
{
temp.length += length;
UpdateAugmentedData(temp);
}
}
private TextAnchorNode FindActualBeginNode(TextAnchorNode node)
{
// now find the actual beginNode
while (node != null && node.length == 0)
{
node = node.Predecessor;
}
if (node == null)
{
// no predecessor = beginNode is first node in tree
node = root.LeftMost;
}
return(node);
}
private void CheckProperties(TextAnchorNode node)
{
int totalLength = node.length;
if (node.left != null)
{
CheckProperties(node.left);
totalLength += node.left.totalLength;
}
if (node.right != null)
{
CheckProperties(node.right);
totalLength += node.right.totalLength;
}
Debug.Assert(node.totalLength == totalLength);
}
/// <summary>
/// Finds the node at the specified offset.
/// After the method has run, offset is relative to the beginning of the returned node.
/// </summary>
private TextAnchorNode FindNode(ref int offset)
{
TextAnchorNode n = root;
while (true)
{
if (n.left != null)
{
if (offset < n.left.totalLength)
{
n = n.left; // descend into left subtree
continue;
}
else
{
offset -= n.left.totalLength; // skip left subtree
}
}
if (!n.IsAlive)
{
MarkNodeForDelete(n);
}
if (offset < n.length)
{
return(n); // found correct node
}
else
{
offset -= n.length; // skip this node
}
if (n.right != null)
{
n = n.right; // descend into right subtree
}
else
{
// didn't find any node containing the offset
return(null);
}
}
}
private void RotateRight(TextAnchorNode p)
{
// let q be p's left child
TextAnchorNode q = p.left;
Debug.Assert(q != null);
Debug.Assert(q.parent == p);
// set q to be the new root
ReplaceNode(p, q);
// set p's left child to be q's right child
p.left = q.right;
if (p.left != null)
{
p.left.parent = p;
}
// set q's right child to be p
q.right = p;
p.parent = q;
UpdateAugmentedData(p);
UpdateAugmentedData(q);
}
private void DeleteMarkedNodes()
{
CheckProperties();
while (nodesToDelete.Count > 0)
{
int pos = nodesToDelete.Count - 1;
TextAnchorNode n = nodesToDelete[pos];
// combine section of n with the following section
TextAnchorNode s = n.Successor;
if (s != null)
{
s.length += n.length;
}
RemoveNode(n);
if (s != null)
{
UpdateAugmentedData(s);
}
nodesToDelete.RemoveAt(pos);
CheckProperties();
}
CheckProperties();
}
private void ReplaceNode(TextAnchorNode replacedNode, TextAnchorNode newNode)
{
if (replacedNode.parent == null)
{
Debug.Assert(replacedNode == root);
root = newNode;
}
else
{
if (replacedNode.parent.left == replacedNode)
{
replacedNode.parent.left = newNode;
}
else
{
replacedNode.parent.right = newNode;
}
}
if (newNode != null)
{
newNode.parent = replacedNode.parent;
}
replacedNode.parent = null;
}
internal void OnDeleted(DelayedEvents delayedEvents)
{
node = null;
delayedEvents.DelayedRaise(Deleted, this, EventArgs.Empty);
}
public void HandleTextChange(OffsetChangeMapEntry entry, DelayedEvents delayedEvents)
{
//Log("HandleTextChange(" + entry + ")");
if (entry.RemovalLength == 0)
{
// This is a pure insertion.
// Unlike a replace with removal, a pure insertion can result in nodes at the same location
// to split depending on their MovementType.
// Thus, we handle this case on a separate code path
// (the code below looks like it does something similar, but it can only split
// the set of deletion survivors, not all nodes at an offset)
InsertText(entry.Offset, entry.InsertionLength, entry.DefaultAnchorMovementIsBeforeInsertion);
return;
}
// When handling a replacing text change, we need to:
// - find all anchors in the deleted segment and delete them / move them to the appropriate
// surviving side.
// - adjust the segment size between the left and right side
int offset = entry.Offset;
int remainingRemovalLength = entry.RemovalLength;
// if the text change is happening after the last anchor, we don't have to do anything
if (root == null || offset >= root.totalLength)
{
return;
}
TextAnchorNode node = FindNode(ref offset);
TextAnchorNode firstDeletionSurvivor = null;
// go forward through the tree and delete all nodes in the removal segment
while (node != null && offset + remainingRemovalLength > node.length)
{
TextAnchor anchor = (TextAnchor)node.Target;
if (anchor != null && (anchor.SurviveDeletion || entry.RemovalNeverCausesAnchorDeletion))
{
if (firstDeletionSurvivor == null)
{
firstDeletionSurvivor = node;
}
// This node should be deleted, but it wants to survive.
// We'll just remove the deleted length segment, so the node will be positioned
// in front of the removed segment.
remainingRemovalLength -= node.length - offset;
node.length = offset;
offset = 0;
UpdateAugmentedData(node);
node = node.Successor;
}
else
{
// delete node
TextAnchorNode s = node.Successor;
remainingRemovalLength -= node.length;
RemoveNode(node);
// we already deleted the node, don't delete it twice
nodesToDelete.Remove(node);
if (anchor != null)
{
anchor.OnDeleted(delayedEvents);
}
node = s;
}
}
// 'node' now is the first anchor after the deleted segment.
// If there are no anchors after the deleted segment, 'node' is null.
// firstDeletionSurvivor was set to the first node surviving deletion.
// Because all non-surviving nodes up to 'node' were deleted, the node range
// [firstDeletionSurvivor, node) now refers to the set of all deletion survivors.
// do the remaining job of the removal
if (node != null)
{
node.length -= remainingRemovalLength;
Debug.Assert(node.length >= 0);
}
if (entry.InsertionLength > 0)
{
// we are performing a replacement
if (firstDeletionSurvivor != null)
{
// We got deletion survivors which need to be split into BeforeInsertion
// and AfterInsertion groups.
// Take care that we don't regroup everything at offset, but only the deletion
// survivors - from firstDeletionSurvivor (inclusive) to node (exclusive).
// This ensures that nodes immediately before or after the replaced segment
// stay where they are (independent from their MovementType)
PerformInsertText(firstDeletionSurvivor, node, entry.InsertionLength, entry.DefaultAnchorMovementIsBeforeInsertion);
}
else if (node != null)
{
// No deletion survivors:
// just perform the insertion
node.length += entry.InsertionLength;
}
}
if (node != null)
{
UpdateAugmentedData(node);
}
DeleteMarkedNodes();
}
private static bool GetColor(TextAnchorNode node)
{
return(node != null ? node.color : BLACK);
}
private void FixTreeOnInsert(TextAnchorNode node)
{
Debug.Assert(node != null);
Debug.Assert(node.color == RED);
Debug.Assert(node.left == null || node.left.color == BLACK);
Debug.Assert(node.right == null || node.right.color == BLACK);
TextAnchorNode parentNode = node.parent;
if (parentNode == null)
{
// we inserted in the root -> the node must be black
// since this is a root node, making the node black increments the number of black nodes
// on all paths by one, so it is still the same for all paths.
node.color = BLACK;
return;
}
if (parentNode.color == BLACK)
{
// if the parent node where we inserted was black, our red node is placed correctly.
// since we inserted a red node, the number of black nodes on each path is unchanged
// -> the tree is still balanced
return;
}
// parentNode is red, so there is a conflict here!
// because the root is black, parentNode is not the root -> there is a grandparent node
TextAnchorNode grandparentNode = parentNode.parent;
TextAnchorNode uncleNode = Sibling(parentNode);
if (uncleNode != null && uncleNode.color == RED)
{
parentNode.color = BLACK;
uncleNode.color = BLACK;
grandparentNode.color = RED;
FixTreeOnInsert(grandparentNode);
return;
}
// now we know: parent is red but uncle is black
// First rotation:
if (node == parentNode.right && parentNode == grandparentNode.left)
{
RotateLeft(parentNode);
node = node.left;
}
else if (node == parentNode.left && parentNode == grandparentNode.right)
{
RotateRight(parentNode);
node = node.right;
}
// because node might have changed, reassign variables:
parentNode = node.parent;
grandparentNode = parentNode.parent;
// Now recolor a bit:
parentNode.color = BLACK;
grandparentNode.color = RED;
// Second rotation:
if (node == parentNode.left && parentNode == grandparentNode.left)
{
RotateRight(grandparentNode);
}
else
{
// because of the first rotation, this is guaranteed:
Debug.Assert(node == parentNode.right && parentNode == grandparentNode.right);
RotateLeft(grandparentNode);
}
}
private void FixTreeOnDelete(TextAnchorNode node, TextAnchorNode parentNode)
{
Debug.Assert(node == null || node.parent == parentNode);
if (parentNode == null)
{
return;
}
// warning: node may be null
TextAnchorNode sibling = Sibling(node, parentNode);
if (sibling.color == RED)
{
parentNode.color = RED;
sibling.color = BLACK;
if (node == parentNode.left)
{
RotateLeft(parentNode);
}
else
{
RotateRight(parentNode);
}
sibling = Sibling(node, parentNode); // update value of sibling after rotation
}
if (parentNode.color == BLACK &&
sibling.color == BLACK &&
GetColor(sibling.left) == BLACK &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
FixTreeOnDelete(parentNode, parentNode.parent);
return;
}
if (parentNode.color == RED &&
sibling.color == BLACK &&
GetColor(sibling.left) == BLACK &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
parentNode.color = BLACK;
return;
}
if (node == parentNode.left &&
sibling.color == BLACK &&
GetColor(sibling.left) == RED &&
GetColor(sibling.right) == BLACK)
{
sibling.color = RED;
sibling.left.color = BLACK;
RotateRight(sibling);
}
else if (node == parentNode.right &&
sibling.color == BLACK &&
GetColor(sibling.right) == RED &&
GetColor(sibling.left) == BLACK)
{
sibling.color = RED;
sibling.right.color = BLACK;
RotateLeft(sibling);
}
sibling = Sibling(node, parentNode); // update value of sibling after rotation
sibling.color = parentNode.color;
parentNode.color = BLACK;
if (node == parentNode.left)
{
if (sibling.right != null)
{
Debug.Assert(sibling.right.color == RED);
sibling.right.color = BLACK;
}
RotateLeft(parentNode);
}
else
{
if (sibling.left != null)
{
Debug.Assert(sibling.left.color == RED);
sibling.left.color = BLACK;
}
RotateRight(parentNode);
}
}