public TrieNode Delete(TrieNode node, TrieKey key)
{
TrieNode kv_node = null;
if (node.NodeType == TrieNode.TrieNodeType.BranchNode)
{
if (key.IsEmpty)
{
node.BranchNodeSetValue(null);
}
else
{
int index = key.GetHex(0);
TrieNode child = node.BranchNodeGetChild(index);
if (child == null)
{
return(node);
}
TrieNode new_node = Delete(child, key.Shift(1));
node.BranchNodeSetChild(index, new_node);
if (new_node != null)
{
return(node);
}
}
int compact_index = node.BranchNodeCompactIndex();
if (compact_index < 0)
{
return(node);
}
node.Dispose();
if (compact_index == 16)
{
return(new TrieNode(this, TrieKey.Empty(true), node.BranchNodeGetValue()));
}
else
{
kv_node = new TrieNode(this, TrieKey.SingleHex(compact_index), node.BranchNodeGetChild(compact_index));
}
}
else
{
TrieKey k = key.MatchAndShift(node.KVNodeGetKey());
if (k == null)
{
return(node);
}
else if (node.NodeType == TrieNode.TrieNodeType.KVNodeValue)
{
if (k.IsEmpty)
{
node.Dispose();
return(null);
}
else
{
return(node);
}
}
else
{
TrieNode child = Delete(node.KVNodeGetChildNode(), k);
if (child == null)
{
throw new System.Exception("Shouldn't happen");
}
kv_node = node.KVNodeSetValueOrNode(child);
}
}
TrieNode new_child = kv_node.KVNodeGetChildNode();
if (new_child.NodeType != TrieNode.TrieNodeType.BranchNode)
{
TrieKey new_key = kv_node.KVNodeGetKey().Concat(new_child.KVNodeGetKey());
TrieNode new_node = new TrieNode(this, new_key, new_child.KVNodeGetValueOrNode());
new_child.Dispose();
kv_node.Dispose();
return(new_node);
}
else
{
return(kv_node);
}
}