/// <summary>
/// Create a new TrieNode instance.
/// </summary>
/// <param name="character">The character for the TrieNode.</param>
/// <param name="children">Children of TrieNode.</param>
/// <param name="isWord">If root TrieNode to this TrieNode is a word.</param>
/// <param name="wordCount"></param>
internal TrieNode(char character, IDictionary<char, TrieNode> children,
int wordCount, TrieNode parent)
{
Character = character;
Children = children;
WordCount = wordCount;
Parent = parent;
}
/// <summary>
/// Create a new TrieNode instance.
/// </summary>
/// <param name="character">Character of the TrieNode.</param>
internal static TrieNode CreateTrieNode(char character,
TrieNode parent)
{
return new TrieNode(character,
new Dictionary<char, TrieNode>(),
0,
parent
);
}
/// <summary>
/// Recursive method to get all the words starting from given TrieNode.
/// </summary>
private void GetWords(TrieNode trieNode, ICollection<string> words,
StringBuilder buffer)
{
if (trieNode.IsWord)
{
words.Add(buffer.ToString());
}
foreach (var child in trieNode.GetChildren())
{
buffer.Append(child.Character);
GetWords(child, words, buffer);
// Remove recent character
buffer.Length--;
}
}
/// <summary>
/// Create a new Trie instance.
/// </summary>
/// <param name="rootTrieNode">The root TrieNode.</param>
internal Trie(TrieNode rootTrieNode)
{
this.rootTrieNode = rootTrieNode;
}
/// <summary>
/// Recursive method to get longest words starting from given TrieNode.
/// </summary>
private void GetLongestWords(TrieNode trieNode,
ICollection<string> longestWords, StringBuilder buffer, ref int length)
{
if (trieNode.IsWord)
{
if (buffer.Length > length)
{
longestWords.Clear();
length = buffer.Length;
}
if (buffer.Length >= length)
{
longestWords.Add(buffer.ToString());
}
}
foreach (var child in trieNode.GetChildren())
{
buffer.Append(child.Character);
GetLongestWords(child, longestWords, buffer, ref length);
// Remove recent character
buffer.Length--;
}
}
/// <summary>
/// Recursive method to add word. Gets the first char of the word,
/// creates the child TrieNode if null, and recurses with the first
/// char removed from the word. If the word length is 0, return.
/// </summary>
private void AddWord(TrieNode trieNode, char[] word)
{
if (word.Length == 0)
{
trieNode.WordCount++;
return;
}
var c = Utilities.FirstChar(word);
TrieNode child = trieNode.GetChild(c);
if (child == null)
{
child = TrieFactory.CreateTrieNode(c, trieNode);
trieNode.SetChild(child);
}
var cRemoved = Utilities.FirstCharRemoved(word);
AddWord(child, cRemoved);
}
/// <summary>
/// Recursive method to remove word. Remove only if node does not
/// have children and is not a word node and has a parent node.
/// </summary>
private void RemoveNode_Recursive(TrieNode rootTrieNode)
{
if (Children.Count == 0 // should not have any children
&& !IsWord // should not be a word
&& this != rootTrieNode // do not remove root node
)
{
var parent = Parent;
Parent.RemoveChild(Character);
Parent = null;
parent.RemoveNode_Recursive(rootTrieNode);
}
}
internal void SetChild(TrieNode child)
{
Children[child.Character] = child;
}
internal void RemoveNode(TrieNode rootTrieNode)
{
// set this node's word count to 0
WordCount = 0;
RemoveNode_Recursive(rootTrieNode);
}
/// <summary>
/// Create a new Trie instance.
/// </summary>
/// <param name="rootTrieNode">The root TrieNode.</param>
internal Trie(TrieNode rootTrieNode)
{
this.rootTrieNode = rootTrieNode;
}