/// <summary>
/// Performs the set operation on a given data structure.
/// </summary>
private static SortedInt32KeyNode <HashBucket> UpdateRoot(SortedInt32KeyNode <HashBucket> root, int hashCode, IEqualityComparer <HashBucket> hashBucketEqualityComparer, HashBucket newBucket)
{
bool mutated;
if (newBucket.IsEmpty)
{
return(root.Remove(hashCode, out mutated));
}
else
{
return(root.SetItem(hashCode, newBucket, hashBucketEqualityComparer, out bool replacedExistingValue, out mutated));
}
}
/// <summary>
/// Removes the specified key. Callers are expected to validate arguments.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="mutated">Receives a value indicating whether this node tree has mutated because of this operation.</param>
/// <returns>The new AVL tree.</returns>
private SortedInt32KeyNode <TValue> RemoveRecursive(int key, out bool mutated)
{
if (this.IsEmpty)
{
mutated = false;
return(this);
}
else
{
SortedInt32KeyNode <TValue> result = this;
if (key == _key)
{
// We have a match.
mutated = true;
// If this is a leaf, just remove it
// by returning Empty. If we have only one child,
// replace the node with the child.
if (_right.IsEmpty && _left.IsEmpty)
{
result = EmptyNode;
}
else if (_right.IsEmpty && !_left.IsEmpty)
{
result = _left;
}
else if (!_right.IsEmpty && _left.IsEmpty)
{
result = _right;
}
else
{
// We have two children. Remove the next-highest node and replace
// this node with it.
var successor = _right;
while (!successor._left.IsEmpty)
{
successor = successor._left;
}
bool dummyMutated;
var newRight = _right.Remove(successor._key, out dummyMutated);
result = successor.Mutate(left: _left, right: newRight);
}
}
else if (key < _key)
{
var newLeft = _left.Remove(key, out mutated);
if (mutated)
{
result = this.Mutate(left: newLeft);
}
}
else
{
var newRight = _right.Remove(key, out mutated);
if (mutated)
{
result = this.Mutate(right: newRight);
}
}
return(result.IsEmpty ? result : MakeBalanced(result));
}
}