// rotateLeft performs a left rotation around the node.
func (tc *treeContext) rotateLeft(node *proto.RangeTreeNode) (*proto.RangeTreeNode, error) {
right, err := tc.getNode(node.RightKey)
if err != nil {
return nil, err
}
if right.Black {
return nil, util.Error("rotating a black node")
}
node.RightKey = right.LeftKey
right.LeftKey = &node.Key
right.Black = node.Black
node.Black = false
tc.setNode(node)
tc.setNode(right)
return right, nil
}
// insert performs the insertion of a new range into the RangeTree. It will
// recursively call insert until it finds the correct location. It will not
// overwrite an already existing key, but that case should not occur.
func (tc *treeContext) insert(node *proto.RangeTreeNode, key proto.Key) (*proto.RangeTreeNode, error) {
if node == nil {
// Insert the new node here.
node = &proto.RangeTreeNode{
Key: key,
}
tc.setNode(node)
} else if key.Less(node.Key) {
// Walk down the tree to the left.
left, err := tc.getNode(node.LeftKey)
if err != nil {
return nil, err
}
left, err = tc.insert(left, key)
if err != nil {
return nil, err
}
if node.LeftKey == nil || !(*node.LeftKey).Equal(left.Key) {
node.LeftKey = &left.Key
tc.setNode(node)
}
} else {
// Walk down the tree to the right.
right, err := tc.getNode(node.RightKey)
if err != nil {
return nil, err
}
right, err = tc.insert(right, key)
if err != nil {
return nil, err
}
if node.RightKey == nil || !(*node.RightKey).Equal(right.Key) {
node.RightKey = &right.Key
tc.setNode(node)
}
}
return tc.walkUpRot23(node)
}
// rotateLeft performs a left rotation around the node.
func (tc *treeContext) rotateLeft(node *proto.RangeTreeNode) (*proto.RangeTreeNode, error) {
right, err := tc.getNode(node.RightKey)
if err != nil {
return nil, err
}
right, err = tc.replaceNode(node, right)
if err != nil {
return nil, err
}
node.RightKey = right.LeftKey
if right.LeftKey != nil {
rightLeft, err := tc.getNode(right.LeftKey)
if err != nil {
return nil, err
}
rightLeft.ParentKey = node.Key
tc.setNode(rightLeft)
}
right.LeftKey = node.Key
node.ParentKey = right.Key
tc.setNode(right)
tc.setNode(node)
return right, nil
}