public void SetSelection(TextSegment segment)
{
SelectionStart = segment.StartOffset;
SelectionEnd = segment.EndOffset;
}
private void FixTreeOnDelete(TextSegment node, TextSegment parentNode)
{
Debug.Assert(node == null || node.parent == parentNode);
if (parentNode == null)
{
return;
}
// warning: node may be null
var 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);
}
}
public TextSegment GetSelectionAsSegment()
{
TextSegment result = null;
if (SelectionStart < SelectionEnd)
{
result = new TextSegment { StartOffset = SelectionStart, EndOffset = SelectionEnd };
}
else
{
result = new TextSegment { StartOffset = SelectionEnd, EndOffset = SelectionStart };
}
return result;
}
private void FixTreeOnInsert(TextSegment 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);
var 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
var grandparentNode = parentNode.parent;
var 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);
}
}
void ISegmentTree.Remove(TextSegment s)
{
RemoveSegment(s);
}
void ISegmentTree.UpdateAugmentedData(TextSegment node)
{
UpdateAugmentedData(node);
}
void ISegmentTree.Add(TextSegment s)
{
AddSegment(s);
}
private static bool GetColor(TextSegment node)
{
return(node != null ? node.color : BLACK);
}
